Pro Aspnet Extensibility

CYAN MAGENTA

YELLOW BLACK PANTONE 123 C

BOOKS FOR PROFESSIONALS BY PROFESSIONALS ®

THE EXPERT’S VOICE ® IN .NET Companion eBook Available

Pro ASP.NET Extensibility This book is intended for advanced web developers interested in learning about the internal workings of ASP.NET. I assume that you already have some experience writing web applications, that you’ve actively created some web projects, and you want to take your skills a step further. What if your next customer wishes to run a large server cluster, a site with thousands of pages, complex navigation, and heavy database access? ASP.NET can handle this, but its out-of-the-box features won’t be adequate. This book covers situations like these in detail and shows you what to do when ASP.NET reaches its limits. You’ll learn how to extend, customize, and enhance this platform to get what you want. “No more compromise” is my motto. Throughout my years of experience programming ASP.NET, I’ve noticed that developers often complain about incorrect behavior, supposed bugs, incomplete implementations, or missing features. In most of these situations I don’t agree that ASP.NET is deficient or faulty. I’ll demonstrate that the key to success with ASP.NET is a deep understanding of the platform that goes beyond the basics. ASP.NET is not perfect—it has its rough edges, like any other piece of software. However, Version 3.5 is top of the line, providing almost everything you need in order to get your professional projects functioning well. Really, really well. This is what I’d like to tell you: learn, explore, understand, and you will be the professional developer you want to be. Jörg Krause ASP.NET MCP

THE APRESS ROADMAP

Companion eBook

Pro ASP.NET 3.5 in C# 2008

Pro ASP.NET Extensibility

Practical ASP.NET 3.5

Ultra-fast ASP.NET

Pro ASP.NET Extensibility

Dear Reader,

Pro

ASP.NET Extensibility Explore how to break through ASP.NET’s boundaries and extend, customize, and enhance the platform

Beginning ASP.NET 3.5 in C# 2008

See last page for details on $10 eBook version

ISBN 978-1-4302-1983-5 90000

www.apress.com

Krause

SOURCE CODE ONLINE

Jörg Krause

Shelve in .NET User level: Intermediate–Advanced

9 781430 219835

this print for content only—size & color not accurate

spine = 0.829" 432 page count

Download at WoweBook.Com

Pro ASP.NET Extensibility

Jörg Krause

Download at WoweBook.Com

Pro ASP.NET Extensibility Copyright © 2009 by Jörg Krause All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher. ISBN-13 (pbk): 978-1-4302-1983-5 ISBN-13 (electronic): 978-1-4302-1984-2 Printed and bound in the United States of America 9 8 7 6 5 4 3 2 1 Trademarked names may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, we use the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. Lead Editor: Jonathan Hassell Technical Reviewer: Stefan Turalski Editorial Board: Clay Andres, Steve Anglin, Mark Beckner, Ewan Buckingham, Tony Campbell, Gary Cornell, Jonathan Gennick, Jonathan Hassell, Michelle Lowman, Matthew Moodie, Jeffrey Pepper, Frank Pohlmann, Douglas Pundick, Ben Renow-Clarke, Dominic Shakeshaft, Matt Wade, Tom Welsh Project Manager: Kylie Johnston Copy Editor: Katie Stence Associate Production Director: Kari Brooks-Copony Production Editor: Laura Esterman Compositor: Diana Van Winkle Proofreader: Dan Shaw Indexer: BIM Indexing & Proofreading Services Artist: April Milne Cover Designer: Kurt Krames Manufacturing Director: Tom Debolski Distributed to the book trade worldwide by Springer-Verlag New York, Inc., 233 Spring Street, 6th Floor, New York, NY 10013. Phone 1-800-SPRINGER, fax 201-348-4505, e-mail kn`ano)ju
Download at WoweBook.Com

Contents at a Glance

About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi About the Technical Reviewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

CHAPTER 1

Understanding ASP.NET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

CHAPTER 2

Worker and Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

CHAPTER 3

Modules and Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107

CHAPTER 4

Providers and Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153

CHAPTER 5

Extending the Resource Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .197

CHAPTER 6

Page and Session Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .245

CHAPTER 7

Security and User Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .273

CHAPTER 8

Site Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .341

CHAPTER 9

Control Extensibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .373

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .395

iii Download at WoweBook.Com

Download at WoweBook.Com

Contents

About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi About the Technical Reviewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

CHAPTER 1

Understanding ASP.NET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 A Promise in Advance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 The Low-Level Architecture of Request Handling . . . . . . . . . . . . . . . . . . . . . . . . . . .1 What Is ASP.NET? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 The Lifetime of a Request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Request Comes In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Getting into the .NET Runtime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 HttpContext and HttpApplication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 Flowing Through the ASP.NET Pipeline . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 Modules and Handlers Using HttpModule and HttpHandler . . . . . . . . . . . . .19 The Life Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 IIS7 Integrated Pipeline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 The Application’s Pipeline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 The Request Arrives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 The Page’s Life Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 Page Request Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 Events Fired Within the Life Cycle’s Stages . . . . . . . . . . . . . . . . . . . . . . . . . .27 Additional Page Life Cycle Considerations . . . . . . . . . . . . . . . . . . . . . . . . . .29 Dynamic Controls and Data Binding Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Dynamic Control Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Data Binding Events for Data-Bound Controls . . . . . . . . . . . . . . . . . . . . . . .30 Login Control Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 View State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 Why Understanding View State Is Important . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 A Word Regarding Control State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 The Page Cycle from the View State Perspective . . . . . . . . . . . . . . . . . . . . . . . . . .33 Step One—Instantiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 Step Two—Initializing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 Step Three—Loading the View State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 Step Four—Loading Postback Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 Step Five—Loading Step . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42 v Download at WoweBook.Com

vi

NCO NTENT S

Step Six—Raising Postback Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42 Step Seven—Storing the View State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 Step Eight—Rendering the Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 The True Role of View State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 View State Anti-Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44 Forcing a Default. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 Persisting Constant Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 Persisting Cheap Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 Initializing Child Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48 Attaching Dynamic Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50 Initializing Dynamically Created Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . .51 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

CHAPTER 2

Worker and Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53 Managing the Worker Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53 Managing Worker Processes and AppDomains in IIS7 . . . . . . . . . . . . . . . .53 Understanding and Using Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70 ASP.NET Thread Usage on IIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70 Tune the Threading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73 Threading and Asynchronous Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . .77 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105

CHAPTER 3

Modules and Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107 Module, Handlers, and IIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107 Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108 IIS7 Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108 The IIS7 Managed Module Starter Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113 Building a Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115 Interaction Between Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119 Configuration and Deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120 Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122 Built-In Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122 Extending ASP.NET Using Http Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . .122 Building a Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124 Advanced Usage of Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136 Asynchronous Pages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138 Prepare Pages for Asynchronous Operation. . . . . . . . . . . . . . . . . . . . . . . . .138 Using a Public Web Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .140 Configuration and Deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143

Download at WoweBook.Com

NC O N T E N T S

Testing and Debugging Modules and Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . .146 Debug Using IIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147 Set Up Tracing for Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .152

CHAPTER 4

Providers and Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153 The Provider Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153 Goals of the Provider Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .154 Default Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .154 Built-In Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156 Extending Built-In Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156 The Anatomy of a Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157 Making the Provider Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158 Configuring the Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158 General Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160 Initialization Procedure of a Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160 Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161 Thread Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161 Creating a Custom Provider-Based Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163 Limitations of the Code Samples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163 Creating a Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164 Creating the Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165 Configuring Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .170 Using the Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172 Extending the Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .174 How to Scaffold a Configuration Section . . . . . . . . . . . . . . . . . . . . . . . . . . .174 Anatomy of a Configuration Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .174 The Class Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .175 Attributes to Control Elements’ Behaviors . . . . . . . . . . . . . . . . . . . . . . . . . .176 Definition of a Simple Configuration Section . . . . . . . . . . . . . . . . . . . . . . . .176 Usage of a Custom Configuration Section . . . . . . . . . . . . . . . . . . . . . . . . . .180 Accessing the Configuration Declaratively . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181 Extending the Expression Binding Syntax . . . . . . . . . . . . . . . . . . . . . . . . . .181 Introduction to Expression Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181 Creating an Expression Builder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183 Accessing Settings for Non-Compiled Pages . . . . . . . . . . . . . . . . . . . . . . . .187 Beyond Simple Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .188 Design-Time Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .189 Implementing an Expression Builder with Design-Time Support . . . . . . .190 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195

Download at WoweBook.Com

vii

viii

NCO NTENT S

CHAPTER 5

Extending the Resource Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .197 Principles of Resource Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .197 The Fallback Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .197 Using Global Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .198 Limitations of the Existing Provider. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .198 Programming a Custom Resource Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .198 Extending the Provider Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .198 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200 Implementing the Custom Provider. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .201 Configure the Resource Provider. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .208 Using the Custom Resource Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .208 Implementing Design-Time Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .209 Register the Design-Time Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .209 Edit Resources at Runtime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219 How It Works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219 Creating an Online Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243

CHAPTER 6

Page and Session Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .245 The Page State Persister . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .245 A Look Back. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .245 The Default Page State Persister . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .246 State Storage in ASP.NET. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .246 Persisting Page State Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .247 View State Explained . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .247 Control State Explained . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .247 The Default Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249 Changing the Default Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251 Developing a Custom Page State Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251 Choosing the Data Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .252 Analyzing a Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .252 Implementing the Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .252 Extending the Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .254 Maintaining the Storage by Using the Health Monitor. . . . . . . . . . . . . . . . .254 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .256 Session State Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .256 The Session State Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .256 Identifying the Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .258 The Internal State Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .260 Improving the Session State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .263 Implementing the Session State Store Provider . . . . . . . . . . . . . . . . . . . . . . . . . .264 The Session State Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .264 Download at WoweBook.Com

NC O N T E N T S

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266 Implementation of a File-Based Session State Persister . . . . . . . . . . . . . .267 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .272

CHAPTER 7

Security and User Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .273 Built-In Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .273 Authentication Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .276 Authorization Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .276 The User Management Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .277 Extending Membership and Role Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .281 Why Create a Membership Provider? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .281 Solution Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .282 Developing Membership and Role Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .282 Create Web Service–Driven Membership Provider . . . . . . . . . . . . . . . . . . .282 Create Web Service–Driven Role Provider . . . . . . . . . . . . . . . . . . . . . . . . . .282 Configuring the Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .298 Implementing the Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300 Configuring the Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308 Testing the Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308 Extending Profile Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310 The Profile Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310 Understanding the Profile Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .310 Configuring Custom Profile Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314 Implementing a Custom Profile Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314 Preparation Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314 Implementing the Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .319 A Client Side–Driven Profile Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .325 Extending Web Parts Personalization Providers. . . . . . . . . . . . . . . . . . . . . . . . . . .329 Understanding the Web Parts Personalization Provider . . . . . . . . . . . . . . .329 Implementing a Custom Personalization Provider . . . . . . . . . . . . . . . . . . . .331 Testing the Custom Web Part Personalization Provider . . . . . . . . . . . . . . .339 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340

CHAPTER 8

Site Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .341 Site Map Providers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .341 Internal Site Map Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .341 Localization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .343 Security Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .343 Reasons to Write a Custom Sitemap Provider . . . . . . . . . . . . . . . . . . . . . . .343 Writing a Custom Sitemap Provider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .344 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .344 Learning About the Base Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .344 Download at WoweBook.Com

ix

x

NCO NTENT S

Implementing a SQL Server–Based Navigation . . . . . . . . . . . . . . . . . . . . . .348 Suggestions for Extending the Example . . . . . . . . . . . . . . . . . . . . . . . . . . . .354 Extending the VirtualPathProvider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .354 Using the VirtualPathProvider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .354 Register the VirtualPathProvider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .355 Prerequisites for a VirtualPathProvider . . . . . . . . . . . . . . . . . . . . . . . . . . . . .356 Helpful Classes for Path and File Operations . . . . . . . . . . . . . . . . . . . . . . . .357 Creating a Virtual Path Provider to Get Themes from Database . . . . . . . .358 Limitations of the VirtualPathProvider Approach . . . . . . . . . . . . . . . . . . . . .371 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .372

CHAPTER 9

Control Extensibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .373 Adaptive Control Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .373 The Default Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .374 Using Control Adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .376 Using Page Adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .379 Device-Specific Filter for Adaptive Behavior . . . . . . . . . . . . . . . . . . . . . . . .381 Using Control Adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .385 Device Friendly Adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .385 CSS Friendly Adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .385 Other Adapter Ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .385 Writing a Custom Control Adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .385 Steps for Creating the Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .385 The Example Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .386 Why Use HtmlTextWriter? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .390 Configure the Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .390 Writing a Custom Page Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .391 Steps for Creating the Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .391 Configure the Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .393 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .394

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .395

Download at WoweBook.Com

About the Author

NJÖRG KRAUSE has been working with software and software technology since the early 1980s, beginning with a ZX 81 and taking his first steps as a programmer in BASIC and assembly language. He studied information technology at Humboldt University, Berlin, but in the 1990s he left early to start his own company. He has worked with Internet technology and software development since the early days when CompuServe and FidoNet dominated. He’s been with Microsoft Technologies and Software since Windows 95. In 1998, he worked on one of the first commercial e-commerce solutions, and wrote his first book in Germany, E-Commerce and Online Marketing, published by Carl Hanser Verlag, Munich. Due to its wide success, he started working as a freelance consultant and author in order to share his experience and knowledge with others. He has written several books for Hanser, Addison-Wesley, and other major publishers in Germany—a total of more than 40 titles. He also publishes articles in magazines and speaks at conferences in Germany, including BASTA. Currently, Jörg works as a senior consultant for Microsoft Technologies at Computacenter AG & Co. oHG in Berlin. In his occasional spare time, Jörg enjoys reading thrillers and science fiction, as well as playing badminton in the winter and golf in the summer.

xi Download at WoweBook.Com

Download at WoweBook.Com

About the Technical Reviewer

NSTEFAN TURALSKI is a nice chap who is capable of performing both magical and trivial things with a little help from code, libraries, tools, APIs, and servers. Wearing many hats, he has experience in almost all aspects of the software life cycle, and is especially skilled in business analysis, design, implementation, testing, and QA, as well as team management. His main areas of interest are quite wide but include emerging technologies with recent focus on RIA (Silverlight and AIR), cloud computing, functional programming, and software engineering at large. Before he realized that he enjoys criticizing other people’s work more, Stefan published several technical articles mainly about .NET technology, SOA, software engineering, and mobile development. For the last 10-plus years, he has been building solutions ranging from Perl scripts, integrations of SQLite, and Web sites, to highly scalable .NET and COM+ enterprise-class systems. Feel free to contact him at opab]j*pqn]hoge
xiii Download at WoweBook.Com

Download at WoweBook.Com

Acknowledgments

I

’d like to mention the people who helped me create this book and make it what it is. First, I’d like to thank David White and his daughter, Rebekah, for their amazing work smoothing my style and cajoling it into readable English. I know you had a challenging task. I can’t forget the support from Jonathan Hassell for my first steps into the Apress world, as well as the continuing help from Kylie Johnston. Thanks for your frequent reminders about the deadline, Kylie. They really motivate lazy writers back to the keyboard. Thanks to our technical reviewer, Stefan, who opened my mind with his remarks and code style ideas, and pointed out the mistakes that I made in haste. His work greatly improved the quality of this book. Last, but not least, I’d like to thank my family and friends for understanding when I went back to the computer to continue writing or fighting with Visual Studio, while they sat on the terrace for a barbeque. Believe me, it was much harder for me than for you.

xv Download at WoweBook.Com

Download at WoweBook.Com

Introduction

What Does This Book Cover? ASP.NET is an established and well-known web application framework, and there are several books on the market with different emphases and at different levels. However, ASP.NET is becoming more and more a foundation technology upon which larger and larger projects are being built. Developers are facing increasing complexity and greater demands to fulfill in their daily tasks. This book examines in-depth the technology beyond the basic ASP.NET topics available elsewhere. It’s full of practical tips and tricks from an experienced developer. You’ll learn not only how things work, but also why. By adopting this knowledge, you will succeed in extending and adapting highly useful functionality in your own projects. Extensibility is covered in great depth. Developers have a tendency to use a framework, language, or piece of software “as is.” Even in the age of open source software, most developers don’t look inside existing code or attempt to adapt it to fit their needs. Instead, they write their own code. For years, I’ve been asking developers why they avoid third-party code and go to such lengths in order to write essentially the same software. It’s usually because if they’ve created it, they know that they can control, understand, and master it. With .NET 2.0, Microsoft shifted the ASP.NET framework towards a new paradigm—the paradigm of extensibility. This allows developers to extend Microsoft’s software and adapt the parts to behave exactly as you would have designed. Microsoft encourages you to change existing behaviors, add features, modify settings, and basically do whatever you want in order to get the most out of their framework. However, never ignore infrastructure parts of the framework or replace them completely with your own code. Almost every ASP.NET book explains ASP.NET from the ground up—some are in-depth and some provide clear details, but ASP.NET is always treated “as is.” Their failing is in treating ASP.NET like concrete—when, in fact, it’s like Lego™. My underlying motivation for writing this book was to educate developers about this overlooked aspect of ASP.NET: the many ways it can be extended.

Conventions Used in This Book We understand that you’re eager to start reading and learning, but it is worth taking a few seconds to look over this section—it will help you to get the most out of this book. Several icons and font conventions are used throughout:

s 3CREENMESSAGES CODELISTINGS ANDCOMMANDSAMPLESAPPEARINikjkol]_apula.



s 4HESAMEikjkol]_abkjp is used for HTML, ASP.NET controls (declarative listings), and XML snippets.



s )MPORTANTPARTSOFALISTINGAREHIGHLIGHTEDIN^kh`ikjkol]_a.



s #ODE RELATEDTEXTINCLUDESMANYREFERENCESTOCODE SUCHASMETHODNAMES CLASSNAMES namespaces, members, and so on. This is a mixture of common framework names and the ones I’ve used in examples. To distinguish between them, all framework names (from the Microsoft world) are set in ikjkol]_a, while all private names are set in italics.



s 4OEMPHASIZEORQUOTETHINGS hQUOTESvAREOCCASIONALLYUSED xvii Download at WoweBook.Com

xviii

NINT ROD UC TION

Several icons highlight important definitions, cautions, and conclusions.

NTip

This is a tip.

NNote

A note that explains a topic further but is not required for understanding the main topic.

NCaution

A warning to keep you from common pitfalls.

Who This Book Is For This book is intended for advanced web developers interested in learning about the internal workings of ASP.NET. I assume that you already have some experience writing small web applications, that you’ve actively created some web projects, and you want to take your skills a step further. What if your next customer wishes to run a large server cluster, a site with thousands of pages, complex navigation, and heavy database access? ASP.NET can handle this, but its out-of-the-box features won’t be adequate. This book covers situations such as these in detail and shows you what to do when ASP.NET reaches its limits. You’ll learn how to extend, customize, and enhance this platform to get what you want. “No more compromise” is my motto. Throughout my years of experience programming ASP.NET, I’ve noticed that developers often complain about incorrect behavior, supposed bugs, incomplete implementations, or missing features. In most of these situations, I don’t agree that ASP.NET is deficient or faulty. I’ll demonstrate that the key to success with ASP.NET is a deep understanding of the platform that goes beyond the basics. ASP.NET is not perfect—it has its rough edges, like any other piece of software. However, Version 3.5 is top-of-the-line, providing almost everything you need in order to get your professional projects functioning well. Really, really well. This is what I’d like to tell you: learn, explore, understand, and you will be the professional developer you want to be. I also assume that you already have some basic knowledge of skills and technologies often required as a web developer:

s (4-, #33 AND*AVA3CRIPT



s 6ISUAL3TUDIOBASICS SUCHASCREATINGAPROJECT RUNNING ANDDEBUGGINGIT



s !30.%4BASICS SUCHASPUTTINGACONTROLONTOTHEPAGE CUSTOMIZINGIT CREATINGAUSEROR custom control, and so on



s "ASICKNOWLEDGEOFHOWTOOBTAINDATABASEACCESS ASWELLASUSING,).1TOQUERYITAND write data back



s 5SING8-,ASEITHERADATASOURCEORSTORAGE

There is no information specific to the topics in this book, but I use all of these techniques with the example code.

Download at WoweBook.Com

NI N T R O D U C T I O N

Prerequisites This book is based on ASP.NET 3.5. As a basic platform, I use Visual Studio 2008, running on Windows Server 2008 with IIS7. When a client is involved, I use Windows Vista SP1. A similar platform is helpful for getting samples running. Because the last radical change in IIS took place between IIS5 and IIS6, it’s not possible to transform anything to IIS5 level. However, much of the information pertaining to IIS7 may also be true for IIS6—a bit of backward compatibility! Nevertheless, I’d encourage you to look to the future and work with the most current tools and platforms you can obtain.

How This Book Is Organized There are many ways of structuring a book. From my long-term experience in writing and publishing books, I know that people read books very differently. Some read from beginning to end, just like a novel, while others start where they find an interesting topic. There is no book that can cover all reading styles! However, this book follows the same successful strategy I’ve used many times before. I start with the basics: low-level concepts and background information necessary to really understand a theme. Then I proceed systematically through all sections in an independent order. This allows you to read from beginning to end—or to dip into an interesting chapter and skip the others. The many references in the book, pointing to sections where related parts are described in more detail, will help you get the information you need. This book is full of code and examples, which are all available for download at sss*]lnaoo* _ki in the Downloads section of this book’s home page. Included with the package are subfolders named after each chapter: “chapter01,” “chapter02,” etc. These folders contain several sample solutions or Web sites in separate folders. Almost all examples are fully functional. Smaller code snippets that can’t run on their own aren’t included to avoid confusion.

Download at WoweBook.Com

xix

Download at WoweBook.Com

CHAPTER

1

Understanding ASP.NET

T

his chapter looks under the covers of ASP.NET. Many fundamentals of ASP.NET just scratch the surface, but to get the most out of the framework it is a good idea to look much deeper. This chapter includes:

s (OW!30.%4WORKSINTERNALLYANDTHERELEVANTFEATURESNEEDEDFORYOUREVERYDAYTASKS



s 4HEBEHIND THE SCENESCONCEPTSTHEAPPLICATIONLIFECYCLE THEPAGELIFECYCLE ANDTHECON trol creation process



s 4HESTEPSTAKENTOTRANSLATEYOUR&*]olt and &*_o files into compiled code



s 4HECOMMON!30.%4FEATURES SUCHASFORMSTICKINESSANDVIEWSTATE ANDBEYOND

A Promise in Advance !30.%4ISAPOWERFULANDFLEXIBLEARCHITECTUREFORBUILDINGWEBAPPLICATIONS4HEHIGH LEVELPARTSˆ 7EB&ORMSAND7EB3ERVICESˆAREWELLKNOWN(OWEVER ASYOURAPPLICATIONSSCALEUPINREALLIFE sooner or later you encounter performance issues, or find that things which seemed easy become CHALLENGING4HATISWHATTHISBOOKPROVIDESˆALOOKBEYONDTHEBIGPICTURE4HELITTLEDETAILSARE harder to understand and sometimes more abstract, less fun for more work. But let me begin with a promise: it’s worth the effort.

The Low-Level Architecture of Request Handling Understanding the innermost parts of a platform is highly satisfying. You will feel confident know ing that you can write better applications and recognize why they work. In this section, you will examine the internals of ASP.NET in order to understand how requests flow through the processing pipeline. A processing pipeline is a chain of processing elements arranged so that the output of one is the input of the next. According to ASP.NET, these elements are the internal steps required to pro cess a request. This is not aimed at those learning the basics or creating a simple interactive page. This is what you need to know when you write or build large sites that involve hundreds of pages handling requests from thousands of users. 7EB&ORMSAND7EB3ERVICESAREBOTHSOPHISTICATED HIGH LEVELIMPLEMENTATIONSOF(440HAN DLERS(440HANDLERS are parts of the processing pipeline that manage incoming requests that use the (YPERTEXT4RANSFER0ROTOCOLBYCREATINGTHEREQUIREDCONTENT4HEYAREBUILTONTOPOFTHE!30.%4 framework and exposed as one of the default project templates in Visual Studio. Most developers are happy with these project types, and are ignorant of, or misunderstand, the additional potential that EXISTS4HEBASIC(440HANDLERSAREBUILTWITHMANAGEDCODE4HISMEANSTHATYOUCANGETHIGHLYCUS tomized behavior processing requests through the pipeline by using your very own code. 1 Download at WoweBook.Com

2

CH APT ER 1 N U NDER S TA NDING A S P . NET

What Is ASP.NET? In general terms, ASP.NET is a request processing engine. It takes an incoming request and passes it through its internal pipeline to an end point, where you as a developer can attach code to process that REQUEST4HISENGINEISCOMPLETELYSEPARATEFROM(440RUNTIMEANDTHE7EB3ERVER)NFACT THE(440 runtime is a component that you can host in your own applications outside of Internet Information Services (IIS) or any server side application altogether. Visual Studio and the integrated development server is a good example of an implementation that is neither based on nor related to IIS. 4HE(440RUNTIME is responsible for routing requests through this pipeline, a complex yet very elegant mechanism. Several interrelated objects, extensible via subclassing or through interfaces, are available for customization work. This makes the framework highly adaptable. In this book, I’ll cover most of these extensibility points and show that there are virtually no limits when using ASP.NET. 4HROUGHTHISMECHANISMITSPOSSIBLETOHOOKINTOLOW LEVELINTERFACES SUCHASAUTHENTICATION authorization, and caching. You can even filter content by routing incoming requests that match a specific signature directly to your code. Of course, there are a lot of different ways to accomplish THESAMETHINGˆBUTALLOFTHEAPPROACHESARESTRAIGHTFORWARDTOIMPLEMENT The Internet Service API1 (ISAPI) is a common Win32 API. The ASP.NET engine interfaces with IIS through an ISAPI extension. This extension hosts .NET through the ASP.NET runtime. The ASP. NET engine was written entirely in managed code, and all of the extensibility functionality is pro vided via “managed code extensions.” The impressive part of ASP.NET is that it is very powerful but simple to work with. Despite its breadth and complexity, accomplishing your desired outcomes is easy. ASP.NET enables you to perform tasks that were previously the domain of ISAPI extensions ANDFILTERSON))3)3!0)ISALOW LEVEL7IN!0)THATHASAVERYSPARTANINTERFACE&OR.%4DEVELOP ers it could be very difficult to develop anything on top of this interface. Writing ISAPI filters in C++ ISNOTINCLUDEDINMOSTCURRENTAPPLICATION LEVELDEVELOPMENT(OWEVER SINCE)3!0)ISLOW LEVEL it is likely very fast. Thus, for some time ISAPI development has been largely relegated to providing BRIDGEINTERFACESTOOTHERAPPLICATIONORPLATFORMS SUCHAS0(0"UT)3!0)DIDNOTBECOMEOBSOLETE with the appearance of ASP.NET. ISAPI provides the core interface from the Web Server, and ASP.NET uses the unmanaged ISAPI code portion to retrieve input and send output back to the client. The content that ISAPI provides is passed using common objects like DpplNamqaop and DpplNaolkjoa that expose the unmanaged data as managed objects. Back in the .NET world it becomes very easy to use these objects in your own code. I’ll discuss later in the section “Getting into the .NET Runtime” how the unmanaged and man aged world interoperate.

The Lifetime of a Request The lifetimeSTARTSWITHAN(440REQUEST7HENEVERTHEUSERTYPES in a URL, clicks on a hyperlink, or SUBMITSAN(4-,FORMONTHEBROWSER AREQUESTISSENTTOTHESERVER

NNote

It’s essentially the same for Web Services. A client application calls an ASP.NET–based Web Service by sending a request. Therefore, I refer to the term Request and don’t differentiate between Web Service and browser requests. You can assume that the examples given are intended to run in a browser environment.

For the sake of clarity, I left out the steps made behind the scenes in the browser and through the protocol stacks. This includes port assignment within the TCP/IP stack and name resolution using the DNS protocol. As long as we’re talking about ASP.NET, there is no direct influence on DNS, so let’s keep this in mind but not complicate the description with side effects. 1. API means Application Programming Interface. Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

DOMAIN NAME SYSTEM The Domain Name System (DNS) is hierarchical naming system for internet resources. Mainly these are computers that get human readable names—the hostnames—the DNS translates into IP addresses. Beginning with some root servers, the DNS is a hierarchy of name resolution servers for particular levels of the hostname. The protocol running between the servers and clients is called DNS protocol. .NET Framework supports DNS with several classes. However, for ASP.NET applications usually there is no need to program directly against this low-level protocol. The request focused on begins when the name resolution process is done.

On the server side the Web Server picks up the request. In this description, I’ll focus mainly on IIS7 with some words for IIS6, which is still widely used. Additionally, I focus on preferred mode RUNNING!30.%4ON))3ˆTHEINTEGRATEDMODE(OWEVER MOSTPARTSWILLNOTREFERTOASPECIFIC version, so the term IIS covers all from IIS5 to IIS7 (and beyond, probably). Within IIS the request ISUSUALLYROUTEDTOTHEASPXPAGE(OWTHISPROCESSWORKSINTERNALLYDEPENDSENTIRELYONTHE(440 handler that handles the request. The mapping between the .aspx extension and the ISAPI DLL, aspnet_isapi.dll, is responsible for this. Every request you want served by ASP.NET must be routed BYITSASSIGNEDAPPLICATIONEXTENSION4HISMEANSTHATTHEEXTENSIONISAPRE DEFINED YETVOLUNTARY DEFINITION)MAGINEIFYOUMAPPEDHTMLPAGESTOBEPROCESSEDBY!30.%4ASWELLˆITWOULDNTBE OBVIOUSTHAT!30.%4WASDOINGTHETRICK(ENCE THEEXTENSIONISTHEBASICMAPPINGWHERETHEPRO cessing starts. This means, too, that different extensions might route to different handlers. For instance, the *]oit extension is routed to the Web Service handler. Instead of opening a page and starting a page parser, this request does not open a file but a specially attributed class that identifies the implemen tation. Many other handlers are installed with ASP.NET, and you are also able to define your own. All of these handlers are mapped to the ASP.NET ISAPI extension and configured in web.config to GETROUTEDTOASPECIFICIMPLEMENTATION3EETHEFOLLOWINGEXAMPLEIN,ISTING FROMGLOBALDEFINI tion web.config file that holds the majority of default mappings. Listing 1-1. Extract of Global web.config Showing Some of the Default Mappings 8dpplD]j`hano: 8]``l]pd9pn]_a*]t`ran^9&pula9Ouopai*Sa^*D]j`hano*Pn]_aD]j`han± r]he`]pa9pnqa+: 8]``l]pd9Sa^Naokqn_a*]t`ran^9CAP± pula9Ouopai*Sa^*D]j`hano*=ooai^huNaokqn_aHk]`anr]he`]pa9pnqa+: 8]``l]pd9&*]t`ran^9&pula9Ouopai*Sa^*DpplJkpBkqj`D]j`hanr]he`]pa9pnqa+: 8]``l]pd9&*]oltran^9&± pula9Ouopai*Sa^*QE*L]caD]j`hanB]_pknur]he`]pa9pnqa+: 8]``l]pd9&*]odtran^9&± pula9Ouopai*Sa^*QE*OeilhaD]j`hanB]_pknur]he`]pa9pnqa+: 8]``l]pd9&*]oitran^9&± pula9Ouopai*Sa^*Oanre_ao*Lnkpk_kho*Sa^Oanre_aD]j`hanB]_pknu(± Ouopai*Sa^*Oanre_ao(Ranoekj9.*,*,*,(?qhpqna9jaqpn]h(± Lq^he_GauPkgaj9^,/b1b3b--`1,]/]r]he`]pa9b]hoa+: 8]``l]pd9&*]o]tran^9&± pula9Ouopai*Sa^*DpplBkn^e``ajD]j`hanr]he`]pa9pnqa+: 8]``l]pd9&*]o_tran^9&± pula9Ouopai*Sa^*DpplBkn^e``ajD]j`hanr]he`]pa9pnqa+: 8]``l]pd9&*i]opanran^9&± pula9Ouopai*Sa^*DpplBkn^e``ajD]j`hanr]he`]pa9pnqa+:

Download at WoweBook.Com

3

4

CH APT ER 1 N U NDER S TA NDING A S P . NET

8]``l]pd9&*ogejran^9&± pula9Ouopai*Sa^*DpplBkn^e``ajD]j`hanr]he`]pa9pnqa+: 8]``l]pd9&*^nksoanran^9&± pula9Ouopai*Sa^*DpplBkn^e``ajD]j`hanr]he`]pa9pnqa+: 8]``l]pd9&*oepai]lran^9&± pula9Ouopai*Sa^*DpplBkn^e``ajD]j`hanr]he`]pa9pnqa+: 8]``l]pd9&*_kjbecran^9&± pula9Ouopai*Sa^*DpplBkn^e``ajD]j`hanr]he`]pa9pnqa+: 8]``l]pd9&ran^9CAP(DA=@(LKOP± pula9Ouopai*Sa^*@ab]qhpDpplD]j`hanr]he`]pa9pnqa+: 8]``l]pd9&ran^9&± pula9Ouopai*Sa^*DpplIapdk`Jkp=hhksa`D]j`hanr]he`]pa9pnqa+: 8+dpplD]j`hano: In the extract, you find a handler that services a request, like L]caD]j`hanB]_pknu for &*]olt pages, as well as some that suppress access to the extension, like DpplBkn^e``ajD]j`han for &*_kjbec files.In coding terms the handler is a type, implemented by a .NET class that handles a specific extension. You can also attach your own handlers to existing extensions and route the request through both your own and the default implementation. A summary of all basic mappings ALREADYAVAILABLEARESHOWNIN4ABLE  Table 1-1. Application Mappings Assigned to aspnet_isapi.dll

Extension

Resource Type

Comments

*]o]t

ASP.NET application files

Usually the global.asax file only.

*]o_t

ASP.NET user control files

Usually these files are not called directly.

*]odt

(440HANDLERS

4HEMANAGEDCOUNTERPARTOF)3!0)EXTENSIONSSEE Chapter 3 for details.

*]oit

ASP.NET Web Services

Obsolete since the appearance of Windows Communication Foundation (WCF).

*]olt

ASP.NET web pages

The regular page handler.

*]t`

!30.%4INTERNAL(440HANDLER

5SEDFOREMBEDDEDRESOURCESLIKE*AVA3CRIPTOR images pulled from compiled code.

*or_

7EB3ERVICEHANDLER

7#& BASEDSERVICESNOWHASITSOWNEXTENSION

Let’s talk about the &*]oit extension shown in the table. With the introduction of .NET 3.0, Microsoft moved all the communication stuff like .NET remoting and Web Services to Windows Communication Foundation (WCF) base library.24HISMEANSTHATTHE!30.%4 BASED7EB3ERVICES are superseded. Even though they are still fully supported, it makes sense to consider moving Web Service projects from ASP.NET platform to WCF. It’s not a significant change, as most classes are SIMILARAND7#&HASSOMEMOREPOWERFULAPPROACHES(OWEVER )DONTCOVER7#&INTHISBOOK and therefore the following description is limited to the ASP.NET portion.

From ISAPI to ASP.NET The purpose of ISAPI is to access a Web Server like IIS on a very low level. The interface is optimized for performance, but it’s also very simple and straightforward. For most developers with .NET expe rience it’s pretty hard to use, because the coding style you use in .NET to, say, create sophisticated infrastructure solutions, is the opposite of the style you see when coding ISAPI extensions in C++. 2. The old assemblies and namespaces are still supported, of course. Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

-ANYHIGH LEVELWEBDEVELOPMENTLANGUAGESSUCHAS0(0 0ERL ANDEVEN!30.%4 AREBUILTON top of ISAPI. ISAPI is good for writing such environments. For application developers it’s not the best way to WRITEOURSITESONTIMEANDWITHINBUDGET(OWEVER )3!0)ISTHELAYERTHE!30.%4ENGINEISBUILT on, and a good understanding of the relation between ISAPI and ASP.NET is helpful for getting the most out of ASP.NET. For ASP.NET the ISAPI level is just acting as a routing layer. The heavy stuff, such as processing and request management, occurs inside the ASP.NET engine and is mostly done in managed code. You can think of ISAPI as a sort of protocol. This protocol supports two flavors, ISAPI extensions AND)3!0)FILTERS%XTENSIONSACTASATRANSACTIONINTERFACETHEYHANDLETHEFLOWOFDATAINTOANDOUT of the Web Server. Each request coming down the pipeline is going through the extensions and the code decides how they are treated. As you might imagine, ASP.NET is such an extension. ASP.NET has several ways to give you as much control as possible to hook into this extension and modify THEDEFAULTBEHAVIOR4HELOW LEVEL)3!0)INTERFACESARENOWAVAILABLEASHIGH LEVEL.%4INTERFACES named EDpplD]j`han and EDpplIk`qha. This is very powerful and still provides good performance, BECAUSEITSAWELL WRITTENBALANCEBETWEENLEANACCESSTOTHELOWERLEVELANDANEASY TO USEHIGH level API. Like any other ISAPI extension, the code is provided as a DLL and is hooked into the IIS man agement. You can find this DLL here: 8*JAPBn]iaskng@en:X]oljap[eo]le*`hh. If you have several versions of .NET framework installed, you may wonder why there is just one such DLL in the tree. I predict that you will find this in the v2.0.50727 folder or at least in one with v2.0 at the beginning. If you have .NET 1 installed, another version might reside in a folder named v1.1.*. The reason is that Microsoft has added a lot of features in .NET 3.0 and .NET 3.5 regarding ASP.NET, BUTITSINTERFACESTOTHELOW LEVELPORTIONARESTILLTHESAME!LLNEWFUNCTIONALITYISCOMPLETELYWRITTEN in managed code. This is indeed a transition, as it shows that it’s possible to write infrastructure com ponents in managed code. With powerful hardware the performance loss is not that critical, whereas the benefits regarding security, reliability, and shorter development cycles matter.

NNote

With the upcoming .NET 4.0, a new engine appears on the horizon that is closer to IIS7 and has several internal improvements. For now, it seems as though most of the techniques and internal behaviors described here have barely changed.

Extension Mapping As you have already seen, the Web Server recognizes resource requests by analyzing the file exten sion. The first step to get the ASP.NET ISAPI extension running is a mapping between the several file types and the DLL I mentioned earlier. In IIS7 you can see this by following these steps: 1. Open Internet Information Services (IIS) Manager. 2. Choose the server node. 3. In the right pane scroll to the IIS table. 4. $OUBLE CLICK(ANDLER-APPINGS In the table you will see a column Path with the extensions already assigned. In the column (ANDLERYOUWILLSEETHEASSIGNEDMODULE&ORTHE&*]olt extension you will see the following mappings:

s 0AGE(ANDLER&ACTORY )NTEGRATED



s 0AGE(ANDLER&ACTORY )3!0) 



s 0AGE(ANDLER&ACTORY )3!0)  ONA BITSYSTEMONLY Download at WoweBook.Com

5

6

CH APT ER 1 N U NDER S TA NDING A S P . NET

!DDITIONALLY WITH.%4 3TWOADDITIONALMAPPINGSAREINSTALLEDONA BITMACHINE 

s 0AGE(ANDLER&ACTORY )NTEGRATED 



s 0AGE(ANDLER&ACTORY )3!0) ?BIT

For the unmanaged side you will see the Eo]leIk`qha handler and for the managed one .NET TYPESUSEDTOHANDLETHEPAGES&IGURE SHOWSPARTOFTHEMAPPINGTO)3!0)EXTENSION

Figure 1-1. IIS7 maps extensions like *.aspx to ISAPI extensions. If the mapping isn’t there, ASP.NET is probably not correctly installed. Don’t try to map this by hand. There is a lot of configuration that happens behind the scenes. Because you probably have several ASP.NET versions running parallel on the same machine, your application might fail to work JUSTBYCOMPLAININGABOUTWRONGVERSION4HISDOESNOTREQUIREYOUTORE REGISTERTHEVERSIONNEEDED Applying the appropriate version is made in the application pool settings. In IIS6 the properties of a specific site of a Web Server let you choose the right framework. In IIS7 it has been moved to the application pool settings dialog. Each application pool can run only one version of the runtime. To set another framework for a specific site, you have to create another application pool, set the appropriate FRAMEWORKVERSION ANDASSIGNTHEAPPLICATIONPOOLTOTHESITE ASSHOWNIN&IGURE  (OWEVER IFTHEINSTALLATIONISDESTROYEDORINCOMPLETE ATOOLMIGHTHELP4OREGISTEROR RE REGISTERTHEMAPPINGS JUSTINVOKETHEFOLLOWINGCOMMAND _`8*JapBn]iaskng@ena_pknu: ]oljap[naceeo)e Again, this command is not available for all .NET framework versions. The tools delivered with 6ERSIONWILLDOTHETRICK EVENIFYOURUNOR7ITH!30.%4 ANEW)3!0)$,,WILLBE INTRODUCEDˆBUTBACKWARDCOMPATIBILITYISSTILLGUARANTEED)FYOUSTILLHAVE6ERSIONXSITESRUN ning, another version is available. It’s a bit tricky, but in order to run two different ASP.NET versions, just register with the highest available.

3. Naming not yet finalized at date of printing Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Figure 1-2. Add a new application pool and get the right framework there.

Request Comes In When a request comes in, IIS checks for the script map and routes the request to the associated extension. In the case of ASP.NET let’s assume that the request is something like Default.aspx, so it’s BEINGROUTEDTOASPNET?ISAPIDLLSEE&IGURE   I assume that you have already worked with and probably configured the application pool. The application pool was introduced with IIS6 and allows the complete isolation of applications from each other. This means that IIS is able to completely separate things happening in one application from those in another. Putting applications together in one pool could still make sense, because another pool would create its own worker process and could use up many resources. Each applica tion pool is represented by separate worker process and seen on the list of processes as a separate entry. Separate applications make the Web Server more reliable. If an application hangs, consumes too much CPU time, or behaves unpredictably, it influences its entire pool. Other application pools (and the applications within them) will continue to run. Additionally, the application pools are highly configurable. You’ve already learned that the framework version can be different for each pool, which is very useful for migration scenarios. You can configure the security environment by choosing the impersonation level and customizing the rights given to a web application. Applica tion pools are executables that run as any other program. This makes them easy to monitor and configure. Although this does not sound very “low level,” application pools are highly optimized to talk directly to the kernel mode driver http.sys. Incoming requests are directly routed to the pool attached to the application. At this point, you might be wondering where InetInfo has gone. You may have heard of it in the context of previous versions of ASP.NET. If not, it’s just a helper process mainly used for debugging purposes of Internet Information Services. It is still there, but it is basi cally just an administration and configuration service. The flow of data through the IIS system goes as directly and quickly as possible, straight down from http.sys to the application pools. This is one reason why IIS7 is much faster and more reliable than any other IIS before it. An IIS7 application pool also has intrinsic knowledge of ASP.NET and in turn ASP.NET can COMMUNICATEWITHTHENEWLOW LEVEL!0)STHATALLOWDIRECTACCESSTOTHE(440#ACHE!0)S4HIS can offload caching from the ASP.NET level directly into the Web Server’s cache, which again will improve performance drastically. In IIS7, ISAPI extensions run in the Application Pool’s worker process. The .NET runtime also runs in this same process, and consequently communication between the ISAPI extension and the .%4RUNTIMERUNShIN PROCESS vWHICHISINHERENTLY more efficient.

Download at WoweBook.Com

7

8

CH APT ER 1 N U NDER S TA NDING A S P . NET

Figure 1-3. Request flow through IIS and down to ASP.NET runtime (simplified)

Getting into the .NET Runtime Now let’s look at what happens to the request when accessing the managed level. The worker process w3wp.exe hosts the .NET runtime, and the ISAPI DLL calls into a small set of unmanaged INTERFACESVIALOW LEVEL#/- Unfortunately, not much information is available from Microsoft. Apart from a few blogs that one can’t always trust, it’s hard to say how the interaction between ASP. NET and ISAPI is made. Reading the manual doesn’t help either. Microsoft states that the API “sup ports the .NET Framework infrastructure and is not intended to be used directly from your code,” which confirms the existence of the interface but nothing more. Using a disassembly tool like .NET Reflector (from na`)c]pa*_om) is one way to look into the details. Let’s examine the System.Web DLL, which contains everything we’d like to know. First,  #OMPONENT/BJECT-ODEL ANINTERFACESTANDARDFORSOFTWARECOMPONENTRY Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

the entry point is the namespace Ouopai*Sa^*Dkopejc, where you’ll see how the runtime interacts WITHTHE)3!0)PART ASSHOWNIN&IGURE 

Figure 1-4. If there is no information available, you can use Reflector to reveal the internal code. If the runtime handles a request, it calls the Lnk_aooNamqaop method of the EEO=LENqjpeia inter face. The interface is part of ISAPI and exposed as COM. The first parameter will return a pointer WHICHGIVESACCESSTOTHE)3!0)MODULEASSHOWNIN,ISTING  Listing 1-2. Definition of the ProcessRequest Method Wnapqnj6I]nod]h=o$Qji]j]ca`Pula*E0%Y ejpLnk_aooNamqaop$WEjYEjpLpna_^(± WEj(I]nod]h=o$Qji]j]ca`Pula*E0%YejpqoaLnk_aooIk`ah%7 The parameter called “ecb” returns the ISAPI Extension Control Block (ECB, (Microsoft)) that is passed as an unmanaged resource. The method takes the ECB and uses it as the base input and OUTPUTINTERFACEUSEDWITHTHE2EQUESTAND2ESPONSEOBJECTS!N)3!0)%#"CONTAINSALLLOW LEVEL request information. This includes server variables, an input stream for form variables, as well as an output stream that is used to write data back to the client. The output is later accessible via the Response objects, but you can see the tight relation between incoming request and outgoing response. The ecb pointer basically provides access to the functionality of an ISAPI request. The Lnk_aooNamqaop method is the entry and exit point where this resource initially enters the street up to our managed code world and where the managed processing ends.

Threads and Processes So far thingsARENOTQUITEEASY BUTTHEFLOWOFTHEREQUESTTHROUGHTHECODEISSTRAIGHT(OWEVER in real life things tend to become more complex. The ISAPI extension runs requests asynchro nously. This means that the ISAPI extension immediately returns on the calling worker process or IIS thread, but keeps the ECB for the current request alive. The ECB then includes a mechanism for letting ISAPI know when the request is complete. This asynchronous processing releases the Download at WoweBook.Com

9

10

CH APT ER 1 N U NDER S TA NDING A S P . NET

ISAPI worker thread immediately, and forwards processing to a separate thread that is managed by ASP.NET. We’ll look into threading later to understand what ASP.NET is doing. For now, ASP.NET receives this ECB reference and uses it internally to retrieve information about the current request. This includes such information as server variables, POST data, and output returning to the server. The ECB data block stays alive until the request finishes or times out in IIS. The ASP.NET engine continues to communicate with it until the request is done. Any output is written into the ISAPI output stream using the appropriate method call, and when the request is done, the ISAPI EXTENSIONISNOTIFIEDOFREQUESTCOMPLETION4HEEXTENSIONWILLTHENFREETHE%#"FROMMEMORY*UST REMEMBERTHATINTHISCRUELUNMANAGEDWORLDTHECODEISRESPONSIBLEFORHANDLINGALLIN MEMORY ACTIONS ANDNOTRELEASINGMEMORYLEADSTOMEMORYLEAKS(OWEVER THEIMPLEMENTATIONISVERYEFFI cient, as the .NET classes essentially act as a thin wrapper around ISAPI.

Loading the .NET Runtime Again, not much information about the loading procedure is available. I assume that the runtime is loaded, if not yet present, when the first request to ASP.NET is made by a mapped extension. The managed EO=LENqjpeia is then instantiated and starts talking to the unmanaged world. For isolation purposes, each virtual directory creates a new application domain (AppDomain). Within this App Domain the EO=LENqjpeia resides. Starting the application is also the beginning of the application’s life cycle, which we’ll look into later in the section called “The Life Cycles.” It’s also likely that the instantiation is made by the unmanaged part, because the wrapper interface is exposing the ?kiReoe^ha attribute. This makes it available from the other side. To create the ISAPIRuntime instance, the =ll@ki]ejB]_pknu*?na]pa method is called. The fol LOWINGCODESNIPPETIN,ISTING  CREATEDWITH2EFLECTOR SHOWSHOWITSDONEINTERNALLY Listing 1-3. The Code of the AppDomainFactory.Create Method Wnapqnj6I]nod]h=o$Qji]j]ca`Pula*Ejpanb]_a%Y lq^he_k^fa_p?na]pa$opnejc]llE`(opnejc]llL]pd% w k^fa_pk^f.7 pnu w eb$]llL]pdW,Y99#*#% w BehaEjbkejbk9jasBehaEjbk$]llL]pd%7 ]llL]pd9ejbk*BqhhJ]ia7 y eb$OpnejcQpeh*OpnejcAj`oSepd$]llL]pd(#XX#%% w ]llL]pd9]llL]pd'<X7 y EO=LE=llhe_]pekjDkop]llDkop9jasEO=LE=llhe_]pekjDkop$]llE`(]llL]pd(b]hoa%7 EO=LENqjpeiak9$EO=LENqjpeia%pdeo*[]llI]j]can*?na]paK^fa_pEjpanj]h$± ]llE`(pulakb$EO=LENqjpeia%(± ]llDkop(b]hoa(jqhh%7 k*Op]npLnk_aooejc$%7 k^f.9jasK^fa_pD]j`ha$k%7 y _]p_d$At_alpekj% w pdnks7 y napqnjk^f.7 y Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Even if it is not visible in this code snippet, internally the appId is used to cache the relation with the requested virtual directory. Therefore subsequent calls do not start the application again, but process the existing =ll@ki]ej. Finally, in this code Op]npLnk_aooejc forces ISAPI to process the request, and, because it is asynchronous, the call returns immediately and the method returns the ECB as type k^fa_p, as shownIN&IGURE 

Figure 1-5. Behind the scenes, the first request is responsible for the creation of a new application.

Download at WoweBook.Com

11

12

CH APT ER 1 N U NDER S TA NDING A S P . NET

Handle the Request Within the Runtime The managed part is now alive, and ISAPI is able to call it whenever there is something available for processing. In basic ASP.NET terms, everything begins here. The AppDomain, the applica tion life cycle, and the first page cycle are born here and live for varying lengths of time. From now on, we’re back in the managed world. But there is a bit more you should know about the whole procedure. IIS is a multithreaded host and so is ISAPI. Each request is processed asynchronously, running in its own thread. Again, a look into the code using Reflector reveals what ASP.NET is doing here. The Lnk_aooNamqaop method receives an ISAPI ecb object and server type as parameters. The method is thread safe, so multiple ISAPI threads can safely call this single returned object instance simultaneously. lq^he_ejpLnk_aooNamqaop$EjpLpna_^(ejpeSNPula% w EjpLpnvank9EjpLpn*Vank7 eb$eSNPula99.% w vank9a_^7 a_^9Qjo]baJ]peraIapdk`o*CapA_^$vank%7 y EO=LESknganNamqaopsn9jqhh7 pnu w ^kkhqoaKKL9eSNPula99-7 sn9EO=LESknganNamqaop*?na]paSknganNamqaop$a_^(qoaKKL%7 sn*Ejepe]heva$%7 opnejc]llL]pdPn]joh]pa`9sn*Cap=llL]pdPn]joh]pa`$%7 opnejc]ll@ki]ej=llL]pdEjpanj]h9DpplNqjpeia*=ll@ki]ej=llL]pdEjpanj]h7 eb$$]ll@ki]ej=llL]pdEjpanj]h99jqhh% xxOpnejcQpeh*Amq]hoEcjkna?]oa$]llL]pdPn]joh]pa`(± ]ll@ki]ej=llL]pdEjpanj]h%% w DpplNqjpeia*Lnk_aooNamqaopJk@ai]j`$sn%7 napqnj,7 y DpplNqjpeia*Odqp`ksj=ll@ki]ej$± =llhe_]pekjOdqp`ksjNa]okj*Lduoe_]h=llhe_]pekjL]pd?d]jca`( ON*CapOpnejc$Dkopejc[Lduo[L]pd[?d]jca`(jask^fa_pWY± w]ll@ki]ej=llL]pdEjpanj]h(]llL]pdPn]joh]pa`y± %%7 napqnj-7 y _]p_d$At_alpekjat_alpekj% w ++naikra`bkno]gakb_h]nepu y y The code is just a part of the complete method. I have removed the catch block to focus on the working code. The method receives the pointer to an ECB data block and passes it to the ?na]paSknganNamqaop method. This method is responsible for creating the EO=LESknganNamqaop object. From now on there is a Namqaop object available that is able to talk directly to the ISAPI layer. The EO=LESknganNamqaop (defined in the Ouopai*Sa^*Dkopejc namespace) class is an abstract subclass of DpplSknganNamqaop4HISCLASSHOLDSALLTHEKNOWLEDGETOTALK(440)TSAPIECEOFCAKE and although it would take too much time to go into here, it’s worth a closer look if you like. I’d ENCOURAGEYOUTOGOONANDFINDOUTHOWTHINGSWORKUNDERTHEHOOD*USTOPENTHEMETHOD Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Lnk_aooNamqaop in Reflector, click on EO=LESknganNamqaop and then on the DpplSknganNamqaop subclass. At the end of the listing of signatures of either class, click on the link Expand Methods and there you have it. Since there is an abstract class, eventually there must be some implementation elsewhere. The factory method that creates the type using ?na]paSknganNamqaop method is able to return one of the following four types available:

s EO=LESknganNamqaopEjLnk_BknEEO3



s EO=LESknganNamqaopEjLnk_BknEEO2



s EO=LESknganNamqaopEjLnk_



s EO=LESknganNamqaopKqpKbLnk_

It’s a Bit in the ECB that drives the decision. This means that finally the ISAPI module controls the way ASP.NET handles requests. Because ASP.NET is not limited to IIS, it’s simply the version of IIS that is responsible for the factory’s selection. EO=LESknganNamqaopEjLnk_ type is for all IIS ver sions up to and including version 6, and EO=LESknganNamqaopEjLnk_BknEEO3type serves all versions FROMANDABOVE4HISSOUNDSSILLYˆTHEREISNO))3INEXISTENCEˆBUTTHE!30.%4ENGINEWOULD be robust against new versions as long as the ISAPI module is able to emulate IIS7 behavior. Whenever you have trouble understanding what is going on in your application, whether it’s with creating and sending headers, receiving weird stuff, or getting wrong data down the wire, it’s worth taking a closer look here. DpplSknganNamqaopISMEANTTOPROVIDEAHIGH LEVELABSTRACTIONAROUNDTHE LOW LEVELINTERFACES REGARDLESSOFTHESOURCEOFTHEDATA(OWEVER READINGANDUNDERSTANDINGARETWO different things. Let’s take an example of how to deal with all the internals. The next listing shows you HOWTHEWELL KNOWN1UERY3TRINGISRETRIEVEDFROMTHE%#"-OVINGDOWNTHECLASSHIERARCHY YOULL find that it’s partly implemented in the base class and partly in the EO=LESknganNamqaopEjLnk_ class. For IIS6 and IIS7 there is no distinct change here, so you can skip these classes for now. ejpanj]hkranne`aejpCapMqanuOpnejcN]s>upao?kna$^upaWY^qbban(ejpoeva% w eb$^]oa*[a_^99EjpLpn*Vank% w napqnj,7 y napqnjQjo]baJ]peraIapdk`o*A_^CapMqanuOpnejcN]s>upao$^]oa*[a_^(^qbban(oeva%7 y W@hhEilknp$sa^ajceja*`hh%Y ejpanj]hop]pe_atpanjejpA_^CapMqanuOpnejcN]s>upao$EjpLpnlA?>(^upaWY^qbban(± ejpoeva%7 Again, nothing is thrilling here. These classes are all very thin wrappers around native method calls. In fact, ASP.NET does not provide any significant overhead to the request procedure. That MEANS!30.%4ISEXTREMELYFASTˆASFASTAS))3WITHNATIVECODE)FYOUFEELORKNOW THATYOUR application is slow, then you know that in most cases it will be a problem in your code. Let’s focus on the managed side of the world and learn more about what’s going on here.

HttpContext and HttpApplication You’re probably already familiar with the Dppl?kjpatp and Dppl=llhe_]pekj classes. Instances of these classes are created whenever a request hits the engine. At a glance, the steps are:

s #REATEANEWDppl?kjpatp instance for the request.



s 2ETRIEVEANDppl=llhe_]pekj instance (or create one, if it’s the first request).



s #ALLDppl=llhe_]pekj*Ejep to set up pipeline events.



s #ALLDppl=llhe_]pekj*NaoqiaLnk_aooejc to start the ASP.NET pipeline processing. Download at WoweBook.Com

13

14

CH APT ER 1 N U NDER S TA NDING A S P . NET

Wrapping the Request: HttpContext 4HECONTEXTOFAN(440REQUESTISAVAILABLETHROUGHOUTTHELIFETIMEOFTHEREQUEST&OREASEOFUSE it’s always accessible through the static Dppl?kjpatp*?qnnajp property. Because every request usu ally starts a new thread, or recycles a free one from the thread pool, your code runs in that thread. In Chapter 2 I’ll explain in more detail the thread and processing behavior. For now, this isn’t needed TOUNDERSTANDTHEREQUESTPROCESSINGONTHECONTEXTLEVEL4HECURRENTCONTEXTHASAONE TO ONE relation to the request for that thread. This context object is also the place where all other objects required to process the request are stored: Namqaop, Naolkjoa, =llhe_]pekj, Oanran, and ?]_da. At any time during request processing Dppl?kjpatp*?qnnajp gives you access to all these. There are several shortcuts, so you may use the Page’s property ?kjpatp instead, but it’s exactly the same object. You may already use several collections available in the =llhe_]pekj, Oaooekj, and ?]_da objects. Even the Dppl?kjpatp class contains a useful collection that provides a store for request spe cific data. The big difference to the other data collections is the life time. The Dppl?kjpatp represents exactly the current request. If the processing is finished and the data sent to the server, which in TURNSENDSITBACKTOTHECLIENT THENTHECOLLECTIONSAREALSODISPOSEDOF(OWEVER THE#ONTEXTEXISTS before the page’s life span begins and ends after it finishes. Technically it’s an object and it ends when it gets disposed. This data storage is therefore a bit more powerful than simple page members. ,ISTING SHOWSHOWTOUSE?kjpatp*Epaio to get information about the request processing elapsed time. At the >acejNamqaop event a timestamp is stored and retrieved later at Aj`Namqaop. Both events are part of the page’s life cycle and are explained in more detail later in the section “The Page’s Life Cycle.” Listing 1-4. Get Request Information Using Events in global.ascx =llhe_]pekj[>acejNamqaop$k^fa_poaj`an(Arajp=ncoa% w eb$Oappejco*@ab]qhp*Hkccejc% w ?kjpatp*Epaio*=``$HkcPeia(@]paPeia*Jks%7 y y lnkpa_pa`rke`=llhe_]pekj[Aj`Namqaop$k^fa_poaj`an(Arajp=ncoa% w eb$Oappejco*@ab]qhp*Hkccejc% w @]paPeiaaj`9@]paPeia*Jks7 PeiaOl]jol]j9aj`*Oq^pn]_p$$@]paPeia%?kjpatp*EpaioWHkcPeiaY%7 Ouopai*@e]cjkope_o*@a^qc*SnepaHeja$ol]j*Pkp]hIehheoa_kj`o(NamqaopPeia%7 y y This sample uses two events defined in the global.ascx code behind file. You might be thinking of how to put the results into a database or log file, but for now the output to a Visual Studio console WINDOWWILLDOSEE&IGURE   If you feel that the values shown in the figure are too high, you need to be aware that I’m run ning the entire environment in a Virtual PC console, and that the timestamps shown are expressed in milliseconds.

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Figure 1-6. Get time information about the request while debugging.

The Core Type: HttpApplication The Dppl=llhe_]pekjB]_pknu is responsible for creating an appropriate number of Dppl=llhe_]pekj objects. The load and the number of threads required affect how it handles incoming requests. The size of the pool is limited to the I]tSknganPdna]`o setting in the Lnk_aooIk`ah key in the machine. config WHICHBYDEFAULTIS3INCETHEDAYSOF.%4ITSSTILLANAUTO CONFIGUREDENTRY 8lnk_aooIk`ah]qpk?kjbec9pnqa+: Change this to the following: 8lnk_aooIk`ah]qpk?kjbec9b]hoai]tSknganPdna]`o9/,+: You can find more information about threading in Chapter 2. 4HEPOOLSTARTSOUTWITHASMALLERNUMBERˆUSUALLYONEˆANDITTHENGROWSASMULTIPLESIMUL taneous requests are processed. The pool is monitored so that under load it grows to a maximum number of instances. Later the pool is scaled back to a smaller number as the load drops. Once you have the right number of instances of Dppl=llhe_]pekj, you have the real entry point within the managed world for an incoming request. Dppl=llhe_]pekj is like an outer container for the whole application. For easy access the events related to the application are mapped in the global.asax file, which is the declarative expression of this class. This is true for all mapped requests handled by ASP.NET handlers. Other requests might be handled inside custom modules but would not appear in global.asax when running IIS7 integrated mode. The definition of global.asax in global.asax.cs reveals: lq^he__h]ooChk^]h6Ouopai*Sa^*Dppl=llhe_]pekj During each request handling in the ASP.NET pipeline, several events let you control and INTERCEPTTHEVARIOUSSTATESOFTHEAPPLICATIONSLIFECYCLE,ISTING SHOWSALLOFTHEM EVENIFTHE majority is never used in an application. In the next few sections, I’ll dig deeper into the world of application events. Listing 1-5. Events Available on Application Level (Pulled from HttpApplication) lq^he_arajpArajpD]j`han>acejNamqaop7 lq^he_arajpArajpD]j`han=qpdajpe_]paNamqaop7 lq^he_arajpArajpD]j`hanLkop=qpdajpe_]paNamqaop7 lq^he_arajpArajpD]j`han=qpdknevaNamqaop7 lq^he_arajpArajpD]j`hanLkop=qpdknevaNamqaop7 lq^he_arajpArajpD]j`hanNaokhraNamqaop?]_da7 lq^he_arajpArajpD]j`hanLkopNaokhraNamqaop?]_da7 lq^he_arajpArajpD]j`hanI]lNamqaopD]j`han7 lq^he_arajpArajpD]j`hanLkopI]lNamqaopD]j`han7 Download at WoweBook.Com

15

16

CH APT ER 1 N U NDER S TA NDING A S P . NET

lq^he_arajpArajpD]j`han=_mqenaNamqaopOp]pa7 lq^he_arajpArajpD]j`hanLkop=_mqenaNamqaopOp]pa7 lq^he_arajpArajpD]j`hanLnaNamqaopD]j`hanAta_qpa7 lq^he_arajpArajpD]j`hanLkopNamqaopD]j`hanAta_qpa7 lq^he_arajpArajpD]j`hanQl`]paNamqaop?]_da7 lq^he_arajpArajpD]j`hanLkopQl`]paNamqaop?]_da7 lq^he_arajpArajpD]j`hanHkcNamqaop7 lq^he_arajpArajpD]j`hanLkopHkcNamqaop7 lq^he_arajpArajpD]j`hanAj`Namqaop7 lq^he_arajpArajpD]j`han@eolkoa`7 lq^he_arajpArajpD]j`hanAnnkn7 lq^he_arajpArajpD]j`hanLkopNaha]oaNamqaopOp]pa7 lq^he_arajpArajpD]j`hanLnaOaj`Namqaop?kjpajp7 lq^he_arajpArajpD]j`hanLnaOaj`NamqaopDa]`ano7 lq^he_arajpArajpD]j`hanNaha]oaNamqaopOp]pa7 "YWRITINGSOMETHINGLIKETHEFOLLOWINGINTOTHECODE BEHINDFILE YOUATTACHANEVENTTOALL requests against the dedicated handler: lnkpa_pa`rke`=llhe_]pekj[>acejNamqaop$k^fa_poaj`an(Arajp=ncoa% Avoiding an explicit delegate definition is just for the sake of convenience. The whole handling of =ll@ki]ej, Dppl=llhe_]pekj, and threads might look confusing. Remember that the server has to handle multiple incoming requests simultaneously. Each ASP. NET application runs in its own AppDomain, where several instances of Dppl=llhe_]pekj can run in parallel, supplied from the pool managed by the factory. To get a better understanding of this, let’s EXAMINETHEINFORMATIONYOUCANEXTRACTFROMRELATEDOBJECTS*USTTOCLARIFYTYPICALUSAGESCENARIOS THEFOLLOWINGCODESAMPLESRUNON))3 BASEDSYSTEMSONLY/THER7EB3ERVERSDOESNOTSUPPORT application pools. )N,ISTING  THEVALUESAREWRITTENINTOH]^ah controls named appId, threadId, domainId, threadInfo, and threadApart2EFERTO&IGURE TOSEETHEOUTPUT Listing 1-6. Retrieving Information About the Application (Excerpt) lnkpa_pa`rke`L]ca[Hk]`$k^fa_poaj`an(Arajp=ncoa% w Cqe`e`9$Cqe`%=llhe_]pekjW=llE`Y7 pdeo*]llE`*Patp9e`*PkOpnejc$%7 pdeo*pdna]`E`*Patp9Pdna]`*?qnnajpPdna]`*I]j]ca`Pdna]`E`*PkOpnejc$%7 pdeo*`ki]ejE`*Patp9=ll@ki]ej*?qnnajp@ki]ej*Bneaj`huJ]ia7 pdeo*pdna]`Ejbk*Patp9Pdna]`*?qnnajpPdna]`*EoPdna]`LkkhPdna]`;± LkkhPdna]`6JkPdna]`7 pdeo*pdna]`=l]np*Patp9Pdna]`*?qnnajpPdna]`*Cap=l]npiajpOp]pa$%*PkOpnejc$%7 Pdna]`*Ohaal$0,,,%7 y The Ohaal call allows you to open several browser instances and hit F5 to refresh the page WITHINTHEFOUR SECONDPERIODINORDERTOSEEHOWITWORKS4HISSIMULATESTHEBEHAVIORWHENSEV eral requests come in while previous requests are still running. An application by definition has no internal id. To create one, add the following code to the global.asax code behind: rke`=llhe_]pekj[Op]np$k^fa_poaj`an(Arajp=ncoa% w =llhe_]pekjW=llE`Y9Cqe`*JasCqe`$%7 y

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

&IGURE SHOWSTHREESCREENSMADEWITHINTHEFOUR SECONDPERIODUSINGTHREEDIFFERENT browser windows.

Figure 1-7. The application’s id changes as the thread id does. You can see that the application id and the thread id change. If you remove the Ohaal com mand and request the pages one by one, the application id is always the same. Usually the thread is recycled from the pool and the id is also unchanged. The abbreviation ‘MTA’ for the thread’s apartment model stands for Multi Threaded Apart ment. You can override this apartment state in ASP.NET pages with the =ol?kil]p9pnqa attribute in the
Download at WoweBook.Com

17

18

CH APT ER 1 N U NDER S TA NDING A S P . NET

Flowing Through the ASP.NET Pipeline You now have a good overview of what happens when a request comes in, and of how the (TTP#ONTEXTAND(TTP!PPLICATIONOBJECTSSTARTUPASTHEYWAITTOBEUSEDINYOURCODE4HEREARE several steps following this startup sequence worth investigating further. In each step, you’ll find events and callbacks to intercept the process and customize or optimize its behavior. &IGURE ILLUSTRATESWHATHAPPENSDURINGTHEVARIOUSSTATES)FYOULOOKINTOTHECODEUSING Reflector, you can find the steps in subclass =llhe_]pekjOpalI]j]can and the additional steps for IIS7 in LelahejaOpalI]j]can.

Figure 1-8. Events that build the pipeline The most important information here is that modules precede handlers. Modules are respon sible for all requests, whereas handlers support a specific extension, like &*]olt. You can find an IN DEPTHEXPLANATIONABOUTBOTHMODULESANDHANDLERSIN#HAPTER4OHAVEABRIEFOVERVIEW LETSRECALLTHEWAY!30.%4HANDLESEACHREQUESTTHROUGHTHEPIPELINE-ODULESAND(ANDLERS are the two processing points of this pipeline. Modules are just like a filter. The modules are called before and after the handler executes. Examples for related events in the pipeline are BeginRequest, AuthenticationRequest event, EndRequest event, etc. You may intercept, participate, and modify each request. Despite this, you may think of it as a program that executes some code for the request.

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

An .aspx page can be thought of as a handler, which implements specific functions. They are loaded and executed at the particular state of the processing pipeline, if configured properly in web.config file. The figure shows only the minimum number required to execute a page. You’ll find a closer look at all these events in the next section. For now, it’s enough to know when and why the modules and handlers get executed. This is the major part of the pipeline business, which I’ll also discuss in the next section.

Modules and Handlers Using HttpModule and HttpHandler Dppl=llhe_]pekj and Dppl?kjpatp are merely containers for incoming messages. They build the pipeline by forming a chain of events that commence in a defined order, and they hold together data related to the request in order to give other instances easy access to the information involved in the PROCESS(OWEVER THEREALWORKISDONEINOTHERPROCESSINGUNITS PARTICULARLYTHEMODULESANDHAN dlers. Modules are built on top of the DpplIk`qhaCLASS(ANDLERSAREBUILTONTOPOFTHEDpplD]j`hano class. Both are abstract classes and need concrete implementations. In addition, both are highly configurable and act as a chain of instances. This means that you can attach as many modules and handlers as you like and the request will flow through all of these instances. 3EVERALTASKSCOULDBEHANDLEDINBOTHLEVELSˆHOWEVER THEREISADIFFERENTINTENTIONBEHIND THEM-ODULESTENDTOCONTROLTASKSONALOWERLEVELTHEIRNATUREISMOREBASICTHANTHATOFHAN dlers. Think of modules as the right place to prepare data being processed by handlers or modify data subsequently when the regular treatment by a handler is completed. IIS programming aficio nados can think of modules as ISAPI filters. The good news is that programming ASP.NET modules using .NET is much easier than developing filters for IIS. Moving on from IIS, let’s focus on the amazing things that become possible as ASP.NET is extended. The natural order of modules and handlers is: 1. 5SEMODULETOPRE PROCESSAREQUEST 2. Use handler to process the request. 3. 5SEMODULEAGAINTOPOST PROCESSTHEREQUEST ASP.NET comes with several default handlers, such as the very basic ones for &*]oltpages or Web Services. Some default modules exist that are responsible for simple tasks like authentication and caching. In an ideal world, the modules are transparent to the handlers. This means that han dlers don’t know about the modules that work before or after their own processing. ASP.NET allows several easy ways to create your own modules and handlers. This is usually the first approach of extending the standard behavior of ASP.NET. Let’s take ACLOSERLOOKATTHISTECHNIQUE&IGURE SHOWSHOWMODULESANDHANDLERSFITINTOTHE!30.%4 process model. In Chapter 3, I’ll discuss the process of developing custom modules and custom handlers with some clever examples. By now it’s enough to know that several modules process the request one after another on both the request and the response path. Whereas only one handler processes the request finally, it’s either an internal handler or a custom one. (OWEVER ALLTHESETECHNIQUESAREBASEDONTHEBEHAVIOROFTHEPIPELINE4HISPIPELINEFIRESTHE events that form theSO CALLEDLIFECYCLES

Download at WoweBook.Com

19

20

CH APT ER 1 N U NDER S TA NDING A S P . NET

Figure 1-9. Modules and handlers fit closely in the ASP.NET model.

The Life Cycles The life cycle is a term used in almost every introduction to ASP.NET. This term is absolutely crucial for a complete understanding and the correct usage of ASP.NET. To break things down let’s divide the different life cycles into three parts:

s 4HEAPPLICATIONSLIFECYCLE



s 4HEPAGESLIFECYCLE



s 4HECONTROLSLIFECYCLE Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

4HEFOLLOWINGSECTIONSCOVERTHISIN DEPTH4HEBEHAVIOROFTHECYCLESISSLIGHTLYDIFFERENT between IIS versions, but the overall description is the same. The following explanations focus on ))3AND&RAMEWORKBEHAVIOR WHICHISVALIDFOR.%4UPTOTHEUPCOMING IIS7 can run in two different modes. The IIS integrated mode is the new native one, whereas the classic mode mimics the behavior of IIS5 or IIS6. The integrated mode has several advantages and should be preferred if there is no explicit requirement to step down.

IIS7 Integrated Pipeline The IIS7 integrated pipeline is a unified request processing pipeline. Each incoming request is handled by this pipeline and routed through the internal parts of IIS. The pipeline supports both managed and native code modules. You may already know about creating managed modules based on the EDpplIk`qha interface. Once implemented and hooked into the pipeline, the module receives all events used to interact with the request passing through the pipe. The term “unified request processing pipeline” needs some more investigation. IIS6 provided two different pipelines: one for native and one for managed code. This is obviously for historical rea sons, because the managed world came after the IIS world. In IIS 7 both pipelines united to become the unified request processing pipeline. For ASP.NET developers this has several benefits:

s 4HEINTEGRATEDPIPELINERAISESALLEXPOSEDEVENTS WHICHENABLESEXISTING!30.%4MODULES to work in the integrated mode.



s "OTHNATIVE CODEANDMANAGED CODEMODULESCANBECONFIGUREDATTHE7EB3ERVER 7EB site, or Web application level.



s -ANAGED CODEMODULESCANBEINVOKEDATCERTAINSTAGESINTHEPIPELINE



s -ODULESAREREGISTEREDANDENABLEDORDISABLEDTHROUGHANAPPLICATIONSWeb.config file.

4HECONFIGURATIONOFMODULESINCLUDESTHEBUILT IN!30.%4MANAGED CODEMODULESFORSES SIONSTATE FORMSAUTHENTICATION PROFILES ANDROLEMANAGEMENT&URTHERMORE MANAGED CODE modules can be enabled or disabled for all requests, regardless of whether the request is for an ASP. NET resource like an *]olt file or a static file like an image. Invoking modules at any stage means that this may happen before any server processing occurs for the request, after all server processing has occurred, or anywhere in between.

The Application’s Pipeline In more generic terms the pipeline describes the flow through several instances within the IIS. Each step processes the request in a distinct way and fires appropriate events. This forces inter actions with the modules and applications attached by configuration. The variety of actions you CANPERFORMRANGESFROMNONETOTOTALCONTROL(OWEVER DOINGNOTHINGLETSTHEBUILT INMODULES accomplish their job and handle the basic page processing. From the perspective of the extensibil ITYOF!30.%4 hTOTALCONTROLvISWHATWERELOOKINGFOR&IGURE SHOWSTHEAPPLICATIONLIFECYCLE events.

Download at WoweBook.Com

21

22

CH APT ER 1 N U NDER S TA NDING A S P . NET

Figure 1-10. Application’s life cycle events 4WOSTATESARENEWIN))3-AP(ANDLER and Log Request. This gives developers much more control over the request process. Some modules are managed, whereas others are written in native CODE9OUCANADDYOUROWNMODULESINEITHERWAY(OWEVER ASA.%4DEVELOPER YOUDPROBABLY prefer writing in managed code and I would strongly recommend this. (Native code is an option if YOUNEEDTOCREATEAHIGH PERFORMANCEMODULE which performs simple functions.)

The Request Arrives The application life cycle begins when a request is made for an application resource sent by a client application, such as a browser, to the Web Server. In integrated mode, the unified pipeline handles all requests. When the pipeline receives a request, it’s being passed through stages that are common to all requests. These stages are represented internally by the NamqaopJkpebe_]pekj enumeration. The enumeration is defined in the Ouopai*Sa^ namespace. All request stages can be configured to Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

allow developers to take advantage of ASP.NET functionality. That functionality is encapsulated in M ANAGED CODEMODULESTHATHAVEACCESSTOTHEREQUESTPIPELINE&ORINSTANCE EVENTHOUGHTHEHTM FILENAMEEXTENSIONISNOTMAPPEDBYDEFAULTTO!30.%4 AREQUESTFORAN(4-,PAGESTILLINVOKES ASP.NET modules. This enables you to take advantage of ASP.NET authentication and authorization for all resources.

Unified Pipeline Receives the First Request When the unified pipeline receives the first request for any resource in an application, an instance of the =llhe_]pekjI]j]can class is created. Its core function is to build the application domain (AppDomain) in which the request is processed. Application domains provide isolation between applications for global variables and enable each application to be unloaded separately. In the application domain, an instance of the DkopejcAjrenkjiajp class is created, which provides access to information about the application, such as the name of the folder where the application is stored. You can find both types in the Ouopai*Sa^*Dkopejc namespace. The first request has several additional tasks. You will notice this because the elapsed time for THEPAGETOBEDELIVEREDISLONGERTHANALLSUBSEQUENTREQUESTS$URINGTHEFIRSTREQUEST TOP LEVEL items in the application are compiled, if required. This includes application code in the project. By THEWAY SINCETHEDAYSOF6ISUAL3TUDIO THEREISNOLONGERASPECIALCODEFOLDERNAMED!PP? Code. Even if you name a folder this, it will have no special function. Code that resides in any folder at any level is compiled in one assembly per project.

Response Objects Are Created for Each Request After the application domain has been created and the DkopejcAjrenkjiajp object has been instan tiated, application objects such as Dppl?kjpatp, DpplNamqaop, and DpplNaolkjoa are created and initialized. These objects exist throughout the lifetime of the request and give developers full access to all related data. The Dppl?kjpatp class contains objects that are specific to the current application request, such as the DpplNamqaop and DpplNaolkjoa objects. The DpplNamqaop object contains information about the current request, which includes cookies and browser information. The DpplNaolkjoa object contains the response that is about to be sent to the client, which includes all rendered output and header data, such as cookies. Dppl?kjpatp*?qnnajp gives you permanent access to the current con text through a static method. For easy access the L]ca class has properties like Namqaop and Naolkjoa that return instances of the very same related objects.

Differences Between IIS6 and IIS7 We’re currently in the transition period from IIS6 to IIS7. While IIS7 is the best choice for a Web Server on Microsoft platforms, there are still many servers with IIS6 in production. Because you may already have a deep understanding of processing ASP.NET based on IIS6, the following explanation focuses on the key differences between IIS6 and IIS7, running in both Integrated mode and with the .NET Framework 3.5 or later. The following properties are specific to IIS7 with Integrated mode. You must run IIS7 to take advantage of the following features. The DpplNaolkjoa object has a new property Oq^Op]pqo?k`a. This is useful for setting codes for tracking failed requests. The Da]`ano property of the DpplNaolkjoa object provides access to response headers for the response. Two properties of the Dppl?kjpatp object, EoLkopJkpebe_]pekj and ?qnnajpJkpebe_]pekj, are used when one event handler handles several Dppl=llhe_]pekj events. This might happen when you try to simplify your code and use a osep_H BLOCKTODISTINGUISHBETWEENCON crete events. ?qnnajpJkpebe_]pekj returns a value from enumeration NamqaopJkpebe_]pekj. This enum does not have specific values for the post events. To recognize the post event just read the Boolean value from EoLkopJkpebe_]pekj. Download at WoweBook.Com

23

24

CH APT ER 1 N U NDER S TA NDING A S P . NET

Both the Da]`ano and OanranR]ne]^hao property of the DpplNamqaop objectAREWRITE ENABLED

An HttpApplication Object Is Assigned to the Request After all application objects have been initialized, the application is started by creating an instance of the Dppl=llhe_]pekj class. If the application has a chk^]h*]o]t file, ASP.NET instead creates an instance of the chk^]h*]o]t class that is derived from the Dppl=llhe_]pekj class. It then uses the derived class to represent the application. This way you get access to the application events simply by overwriting the handlers within the chk^]h*]o]t code portion.

NNote

The first time that an ASP.NET page or process is requested in an application, a new instance of the

Dppl=llhe_]pekj class is created. However, to maximize performance, Dppl=llhe_]pekj instances might be

reused for multiple requests.

Request Is Processed by the Pipeline The Dppl=llhe_]pekj class performs several tasks while the request is being processed. Each step fires a specific request to allow you to run code when the event is raised. Without any further action, all incoming requests will fire all events and the attached modules will be invoked in sequence. To take advantage of extensibility, some interfaces come into the scope. EDpplIk`qha is the basic inter face for custom modules. In IIS7’s integrated mode you can use the module’s Ejep method to attach the required events. One step you’re supposed to perform is the request validation. Imagine hackers trying to send malicious markup or other intrusions. The following list of events shows all steps you can run pri vate code in. Validating the request should take place as early as possible, according to the following list in >acejNamqaop.

s 2AISETHE>acejNamqaop event.



s 2AISETHE=qpdajpe_]paNamqaop event.



s 2AISETHELkop=qpdajpe_]paNamqaop event.



s 2AISETHE=qpdknevaNamqaop event.



s 2AISETHELkop=qpdknevaNamqaop event.



s 2AISETHENaokhraNamqaop?]_da event.



s 2AISETHELkopNaokhraNamqaop?]_da event.



s 2AISETHEI]lNamqaopD]j`han event. An appropriate handler is selected based on the file name extension of the requested resource. The handler can be a native code module, such as the IIS7 Op]pe_BehaIk`qha( or a managed module, such as the L]caD]j`hanB]_pknu class.



s 2AISETHELkopI]lNamqaopD]j`han event.



s 2AISETHE=_mqenaNamqaopOp]pa event.



s 2AISETHELkop=_mqenaNamqaopOp]pa event.



s 2AISETHELnaNamqaopD]j`hanAta_qpa event. Call either the Lnk_aooNamqaop method for syn chronous calls or the asynchronous version EDppl=ouj_D]j`han*>acejLnk_aooNamqaop of the appropriate EDpplD]j`han class.



s 2AISETHELkopNamqaopD]j`hanAta_qpa event.



s 2AISETHENaha]oaNamqaopOp]pa event.

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T



s 2AISETHELkopNaha]oaNamqaopOp]pa event.



s 0ERFORMRESPONSEFILTERINGIFTHEBehpan property is defined.



s 2AISETHEQl`]paNamqaop?]_da event.



s 2AISETHELkopQl`]paNamqaop?]_da event.



s 2AISETHEHkcNamqaop event.



s 2AISETHELkopHkcNamqaop event.



s 2AISETHEAj`Namqaop event.



s 2AISETHELnaOaj`NamqaopDa]`ano event.



s 2AISETHELnaOaj`Namqaop?kjpajp event.

The Page’s Life Cycle After understanding the application’s life cycle, you’re now ready to move further along the path taken by the request. The request is now being processed until the resources are prepared and ready TOBESERVED&ORSTATICRESOURCESITSEASYTHEDATAISALLREADYTOSENDTOTHECLIENT%XAMPLESOF STATICRESOURCESINCLUDEIMAGES *AVA3CRIPTFILES ANDEMBEDDEDOBJECTS 4HEMOREEXCITINGINFOR mation is how dynamic resources are processed. The basic steps in the page’s life cycle include initialization, instantiating controls, restoring and maintaining state, running event handler code, and rendering. As you saw in the application’s life cycle, you will be able to interact with the processing and change the handling for your intended effects. Some steps during the page’s life cycle are more complex and require a closer look in order to take full advantage of their customization potential. One major portion is the view state handling. I’ll dedicate a whole section to explaining view state later in section “View State.” It is also important for you to understand the page life cycle. As a developer creating custom controls, for instance, you must be familiar with the life cycle in order to correctly initialize controls, populate control properties with view state data, and run any control behavior code. You may have heard of a control life cycle, too. You may already know that a page in ASP.NET is a sort of special IZEDCONTROL ANDTHEREFOREACONTROLSLIFECYCLEISVERYSIMILAR(OWEVER PAGESHAVEMORE events available.

NTip When an application operates in the context of Visual Studio while you run a debug session, the application starts with the launch of the integrated Web Server. When the debug session ends and you launch the application again using the F5 key, the integrated Web Server will run the same application domain. This means that between the debug sessions no new application life cycle is being started. To force the application to restart you can right click the notification icon in the system tray and stop the Web Server.

What About Master Page Life Cycle? You might miss information regarding master pages here. The master page itself does not have any stages, because it’s not an object created and run standalone. The master page hierarchy is used to resolve the final construct of the page requested, and then the page’s life cycle begins. Therefore, the master page is treated like a control, with some events related to the page’s life cycle events, but again, not with its own life cycle.

Download at WoweBook.Com

25

26

CH APT ER 1 N U NDER S TA NDING A S P . NET

Page Request Stages The page request occurs before the page life cycle begins. When the page is requested by a client, ASP.NET determines whether the page needs to be parsed and compiled, or whether a cached ver sion of the page can be sent in response without executing the page. In each case the “life” of the page begins.

Start In this step, page properties such as Namqaop and Naolkjoa are set. These properties give you access to the current DpplNamqaop and DpplNaolkjoa instances created through the application’s life cycle. You can access all information related to the request using pdeo*Namqaop* (In later stages you can modify the response created and stored in pdeo*Naolkjoa.) At this stage, the page also deter mines whether the request is a postback or a new request and sets the EoLkop>]_g property. This involves two checks: whether the request is done as a POST, and whether it comes from the same ASP.NET page. Additionally, during the Start step, the page’s QE?qhpqna property is set. At this point you can perform any action based on the automatically recognized page culture. Alternatively, you can force the culture property, so that the correct resources are obtained. (Forcing the culture doesn’t work in other steps.)

Page Initialization During page initialization step, controls on the page become available and each control’s QjemqaE@ property is set. The QjemqaE@ is used later on postbacks to assign control state in order to make forms sticky. Any themes are also applied to the page. If the current request is a postback, the post back data has not yet been loaded and control property values have not been restored to the values from view state.

Load During load, if the current request is a postback, control properties are loaded with information recovered from view state and control state. For a regular request via GET, view state and control state are set to their respective default states.

Validation During this step the R]he`]pa method of all validator controls is called. The EoR]he` property of all validator controls is set, and as a summary the page’s EoR]he` property is set, too.

Postback Event Handling If the request is a postback, any event handlers are called, such as button click events.

Rendering Before rendering, view state is saved for the page and all controls. Rendering is the process that CREATESTHE(4-,THATMAKESTHEPAGEVISIBLEINABROWSER%ACHCONTROLISRESPONSIBLEFORRENDER INGITSELF4HISFEATUREANDTHEEXTENSIBLEDESIGNTIMESUPPORTISAMAJOROPPORTUNITYFORTHIRD PARTY control vendors. Their controls can encapsulate all the clever design time experience and runtime functionality within each control. That means during the rendering phase, the page calls the Naj`an method for each control, providing a PatpSnepan instance that writes its output to the KqplqpOpna]i of the page’s Naolkjoa property.

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Unload Unload is called after the page has been fully rendered, sent to the client, and is ready to be dis carded. At this point, page properties such as Naolkjoa and Namqaop are unloaded and any cleanup is performed.

Events Fired Within the Life Cycle’s Stages Within each stage of the life cycle of a page, the page raises events that you can handle to run your own code. For control events, you bind the event handler to the event, either declaratively using attributes such as kj_he_g, or in code. When inheriting a class from the L]ca class, you can override methods from the page’s base class. It’s a common technique to create your own base page classes that derive from L]ca and to handle common tasks there. For example, you can override the page’s Ejepe]heva?qhpqna method to dynamically set culture information. Overriding event handlers or attaching events are two different methods to perform almost the same action. If you use the Page_<event> syntax, you don’t need to HANDLETHEBASEIMPLEMENTATION(OWEVER IFYOUOVERRIDETHEMETHODYOUMUSTHANDLETHEBASE implementation and therefore call the base method. You can do this at the beginning, at the end, or anywhere in between. Despite this, a regular attach event handler can be used as well. Additionally, the =qpkArajpSenaql attribute of signature already mentioned. 0AGESALSOSUPPORTAUTOMATICEVENTWIRE UP MEANINGTHAT!30.%4LOOKSFORMETHODSWITH particular names and automatically runs those methods when certain events are raised. If the =qpkArajpSenaql attribute of the , such as L]ca[Hk]` and L]ca[Ejep. The following sections list all the page events. Some events that do not map directly to the cor RESPONDINGSTAGESARELESSCRUCIALBUTGIVEYOUMORECONTROLFROMTHEEXTENSIBILITYPERSPECTIVEˆFOR example, when you create custom controls that require a very specific behavior.

PreInit Event Use this event to check the EoLkop>]_g property to determine whether this is the first time the page ISBEINGPROCESSED#REATEORRE CREATEDYNAMICCONTROLS9OUMAYALSOSETMASTERPAGESANDTHE Pdaia property dynamically. Read or set any profile property values. If the request is a postback, the values of the controls have not yet been restored from view state during LnaEjep state. If you set a control property at this stage, its value might be overwritten in the next event.

Init Event This event is raised after all controls have been initialized and any skin settings have been applied. Use this event to read or initialize control properties.

InitComplete Event This event is raised by the Page object. Use this event for processing tasks that require all initializa tion be complete.

Download at WoweBook.Com

27

28

CH APT ER 1 N U NDER S TA NDING A S P . NET

PreLoad Event Use this event if you need to perform processing on your page or control before the Load event. Before the Page instance raises this event, it loads view state for itself and all controls, and then processes any postback data included with the Namqaop instance.

Load Event The Page calls the KjHk]` event method on the L]ca, then recursively does the same for each child control, which does the same for each of its child controls until the page and all controls are loaded. Use the overridden KjHk]` event method to set properties in controls and establish database connections. In a postback request during Hk]` event, if the page contains validator controls, check the EoR]he` property of the L]ca and of individual validation controls before performing any processing.

Control events After Load the control events occur. Use these events to handle specific control events, such as a Button control’s Click event or a TextBox control’s TextChanged event.

LoadComplete Event Use this event for tasks that require all other controls on the page be loaded.

PreRender Event Before this event occurs, the L]ca object calls Ajoqna?deh`?kjpnkho for each control and for the page itself. Each data bound control whose @]p]Okqn_aE@ property is set calls its @]p]>ej` method. The LnaNaj`an event occurs for each control on the page. Use the event to make final changes to the con tents of the page or its controls. 4HERENDERPROCESSITSELFDOESNOTHAVEANEVENTITHAPPENSAFTERLnaNaj`an and before QjHk]` and can be intercepted by overwriting the Naj`an method.

SaveStateComplete Event Before this event occurs, view state has been saved for the page and for all controls. Any changes to the page or controls at this point will be ignored. See the section about view state later in this chap ter to learn more about its specific behavior. Use this event to perform tasks that require view state to be saved, but that do not make any changes to controls.

Unload Event This event occurs for each control and, when all control events are done, for the page. In controls, use this event to do final cleanup for specific actions, such as closing database connections. For the page itself, use this event to do final cleanup work, such as closing open files and database connec TIONS FINISHINGUPLOGGINGOROTHERREQUEST SPECIFICTASKS During the Qjhk]` stage, the page and its controls have been rendered, so you cannot make further changes to the response stream. If you attempt to call a method, such as the Naolkjoa*Snepa method, the page will throw an exception.

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Additional Page Life Cycle Considerations Server controls have their own life cycle that is similar to the page life cycle. A control’s Ejep and Hk]` events occur during the corresponding page events. Due to the hierarchical nature of the page’s controls, this happens recursively. For the event order this means in turn the events appear in reverse order. This is clearly the expected behavior, because the Ejep event on page level indicates that all subsequent EjepEVENTSARECOMPLETED9OUMAYREADTHEEVENTASh)S)NITIALIZEDv(OW ever, the Hk]` event for a container occurs before the Hk]` events for its child controls, which is the opposite behavior. This is so that you can have access to the process before any other processing takes place. From the perspective of the Ejep event, it doesn’t make sense to do anything before it appears, because there is nothing you can access in your code. You can change the properties of a control by handling the events for the control, such as the ?he_g event for the >qppkj control. Control events appear after the page’s Hk]` event has been fired.

Dynamic Controls and Data Binding Events The page and control life cycles define a chain of events to give you maximum control over the cre ATIONANDRUNTIMEOFTHECONTROL(OWEVER THECONTROLHANDLINGHASMOREPOSSIBILITIESTHANYOUCAN achieve with such a straightforward model. You will see a different behavior when adding controls DYNAMICALLY&URTHERMORE DATA BOUNDCONTROLSWORKINTERNALLYSLIGHTLYDIFFERENTDUETOTHEWAY data templates are parsed and executed.

Dynamic Control Events The page life cycle and control life cycle are very similar because of the nature of a L]ca as a class derived from ?kjpnkh(OWEVER YOUCANADDCONTROLSDYNAMICALLYˆAFEATUREWHICHDOESNTMAKE SENSEFORPAGES9OUMIGHTASSUMETHATADDINGCONTROLSISNOTVERYCOMMONIN!30.%4(OWEVER IMAGINETHATDECLARATIVELYAUTHOREDCONTROLSWITHINTEMPLATESOFDATA BOUNDCONTROLSARETREATED like dynamically added controls. Their events are not initially synchronized with the other controls ONTHEPAGE4HELIFETIMEOFSUCHCONTROLSBEGINSWITHTHEIRINSTANTIATIONTHEYRAISETHELIFECYCLE events one after the other until the control has caught up to the event during which it was added to the Controls collection. 5SUALLYTHISHASNOIMPLICATIONSFORDEVELOPERS5NLESSYOUHAVENESTEDDATA BOUNDCONTROLS YOUDONTNEEDTOBECONCERNEDABOUTTHIS&ORNESTEDDATA BOUNDCONTROLS THISBEHAVIORISABIT different. If a child control has been data bound, but its container control has not yet been bound, the data in the child control and the data in its container control can be out of sync. Imagine that you have a GridView control and that each row contains a bound @nkl@ksjHeop control. Furthermore, assume that the @nkl@ksjHeop’s data properties, such as @]p]Okqn_aE@, are set declaratively. The @nkl@ksjHeop will now bind to its datasource when the @]p]>ej`ejc event of the containing Cne`ReasROWOCCURS(OWEVER THECne`Reas might not yet have raised its Nks@]p]>kqj` event. In that case the @nkl@ksjHeop and containing control are out of sync. To avoid this you simply PUTTHEDATASOURCECONTROLˆTHEONEYOUHAVESETINTHE@]p]Okqn_aE@PROPERTYˆWITHINTHESAME template. Additionally, remove the declarative assignment and set it programmatically during the Nks@]p]>kqj` event. In this event the container’s data are bound and both controls can stay in sync. 3EE,ISTING FORASIMPLIFIEDSCENARIOTHATFULLYSUPPORTSANESTEDDATA BOUNDCONTROLWITHIN a template.

Download at WoweBook.Com

29

30

CH APT ER 1 N U NDER S TA NDING A S P . NET

Listing 1-7. Binding Nested Controls Within a Container’s Template 8dpihtihjo9dppl6++sss*s/*knc+-555+tdpih: 8da]`nqj]p9oanran: 8pepha:8+pepha: 8+da]`: 8^k`u: 8bknie`9bkni-nqj]p9oanran: 8`er: 8]ol6Cne`ReasE@9Cne`Reas-nqj]p9oanran=qpkCajan]pa?khqijo9B]hoa @]p]Okqn_aE@9Tih@]p]Okqn_a-kj`]p]^ej`ejc9Cne`Reas-[@]p]>ej`ejc kj`]p]^kqj`9Cne`Reas-[@]p]>kqj`kjejep9Cne`Reas-[Ejep kjhk]`9Cne`Reas-[Hk]`kjlnanaj`an9Cne`Reas-[LnaNaj`an kjnks`]p]^kqj`9Cne`Reas-[Nks@]p]>kqj`: 8?khqijo: 8]ol6Pailh]paBeah`Da]`anPatp9Ata_qpekjOui^kh OknpAtlnaooekj9Ata_qpekjOui^kh: 8EpaiPailh]pa: 8]ol6@nkl@ksjHeopnqj]p9oanrane`9``?kii]j` @]p]Okqn_aE@9K^fa_p@]p]Okqn_a- Oaha_pa`R]hqa9#8!>ej`$@ab]qhp%!:#: 8+]ol6@nkl@ksjHeop: 8]ol6K^fa_p@]p]Okqn_aE@9K^fa_p@]p]Okqn_a-nqj]p9oanran Oaha_pIapdk`9CapR]hqao PulaJ]ia9@]p]:8+]ol6K^fa_p@]p]Okqn_a: 8]ol6H]^ahE@9H]^ah-nqj]p9oanran Patp9#8!Ar]h$Ata_qpekjOui^kh%!:#:8+]ol6H]^ah: 8+EpaiPailh]pa: 8+]ol6Pailh]paBeah`: 8]ol6>kqj`Beah`@]p]Beah`9J]iaDa]`anPatp9J]ia OknpAtlnaooekj9J]ia+: 8+?khqijo: 8Ailpu@]p]Pailh]pa: Ailpu 8+Ailpu@]p]Pailh]pa: 8+]ol6Cne`Reas: 8+`er: 8]ol6Tih@]p]Okqn_aE@9Tih@]p]Okqn_a-nqj]p9oanran @]p]Beha9z+=ll[@]p]+@]p]*tih:8+]ol6Tih@]p]Okqn_a: 8+bkni: 8+^k`u: 8+dpih: -OVINGTHENESTEDDATASOURCEˆTHEK^fa_p@]p]Okqn_aINTHEEXAMPLEˆWITHINTHETEMPLATE assures that the events fires in the expected order.

Data Binding Events for Data-Bound Controls To help you understand the relationship between the page life cycle and data binding events, 4ABLE LISTSDATA RELATEDEVENTSINDATA BOUNDCONTROLS2EMEMBERTHATNOTALLCONTROLSSUP PORTALLEVENTSSHOWNINTHETABLE3OMEDATA BOUNDCONTROLSDONOTHAVEROWS FORINSTANCE WHICH means that a RowDataBound event cannot occur.

NNote

In the description of data-bound control’s behavior, I often refer to the term “containing control.” If there is no containing control, this assumes that the page is the container. Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Table 1-2. Relationship Between Life Cycle Events and Data-Bound Events

Event

Typical Behavior

Usage Hints

DataBinding

Raised before LnaNaj`an of containing control. Open database connections This is the beginning of binding procedure. here, if required.

RowCreated

Raised after each row gets bound.

Manipulate content that does not depend on data binding.

ItemCreated

Raised after each item gets bound.

Manipulate content that does not depend on data binding.

RowDataBound

Bound data is now available for the row.

Format data, get and filter child rows or related data.

ItemDataBound

Bound data is now available for the item.

Format data, pull and filter child rows or related data.

DataBound

Marks the end of binding operation. All rows are bound now.

Do any action that requires all data available.

Login Control Events The login controls, which handle login and authentication, are highly sophisticated and powerful. 4HEYSUPPORTˆLIKETHEDATA BOUNDCONTROLSEVENTSˆSOMESPECIALEVENTSRELATEDTOTHEIRINTERNAL behavior. In most scenarios, the controls work well out of the box or just need some configuration using the web.configFILE(OWEVER IFYOUNEEDTOCHANGEORCUSTOMIZETHEBEHAVIOROREXTENDTHE AVAILABLEFEATURES YOULLNEEDTOKNOWTHEEVENTSFIREDDURINGTHEIRLIFECYCLESEE4ABLE  4HESE events are additional to the regular events raised by all controls, as previously explained in the sec tion “Dynamic Control Events.” Table 1-3. Relationship Between Life Cycle Events and Logging-In Events

Event

Typical Behavior

Usage Hints

LoggingIn

Raised during postback after LoadComplete.

Tasks required before the login procedure, such as opening a database connec tion, if required.

Authenticate

Raised next after LoggingIn.

Customize the authentica tion behavior itself.

LoggedIn

Raised after authentication.

Action required after success ful authentication, such as redirect to another page.

LoginError

Raised after failed authentication.

Do any action to handle failed authentication, such as displaying instructions.

View State The ASP.NET view state is a mechanism to track changes of the state of pages from one postback to the next. Postback occurs whenever a page sends the contents of a form back to the server. The NAMECOMESFROMTHEUNDERLYING(440COMMAND0/34THATISUSEDHEREANDTHEWAYTHATITTAKES the contents back to the server. View state is turned on by default and most developers don’t care Download at WoweBook.Com

31

32

CH APT ER 1 N U NDER S TA NDING A S P . NET

about it. It contains the values of properties of ASP.NET controls changed since the last page cycle ANDISSTOREDINASERIALIZEDANDENCRYPTEDFORMATWITHINTHEPAGE ASSHOWNIN&IGURE %ACH postback sends all the information stored in it back to the server. As you may know, using view state in the default manner can lead to huge pages that consume a lot of bandwidth. It’s not easy to understand view state completely, and simply disabling it leads to controls not working or having fewer features. The real internal behavior is confusing and hard to understand. As long as you deal with simple applications, a basic idea might be enough. But when it comes to your own controls, complex pages, ORUSING!*!8 AGOODUNDERSTANDINGISAPREREQUISITE

Why Understanding View State Is Important Misunderstanding view state leads to leaking of sensitive data, being exploited by view state attacks, poor page performance, poor scalability, and headaches. Whatever you want to achieve with your APPLICATION &IGURE SHOWSTHESOURCEOFAPAGEWHICHYOUNEVERWANTTOSEE

Figure 1-11. The view state’s form field could grow. Simply disabling view state will not help, however, because you will probably lose some fea TURESTHATYOUNEEDANDLIKE%SPECIALLYCOMPLEXDATA BOUNDCONTROLSHOLDTHEIRSTATESFORPAGINGOR SORTINGINTHEVIEWSTATE)NFACT NOTHINGISWRONGWITHVIEWSTATEITSJUSTTHEWRONGORINAPPROPRI ate usage of it that causes problems. Now let’s move on by starting back at the beginning.

What View State Is Supposed to Do and Not Do

s 3TORESVALUESOFCONTROLSPROPERTIESBYKEYS SIMILARTOAHASHTABLE



s 4RACKSCHANGESTOINITIALVALUES



s 3ERIALIZESANDDESERIALIZESASAVEDDICTIONARYINAHIDDENFORMFIELD



s 2ESTORESSTOREDVALUESINTOCONTROLSPROPERTIES

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

These features are well known. Much more important is what the view state does not do:

s 2ETAINTHESTATEOFCLASSMEMBERSWITHOUTADDITIONALCODE



s 2EMEMBERSTATEINFORMATIONACROSSPAGELOADSPAGERELOADSBY'%4REQUEST



s !VOIDTHENEEDTOREPOPULATEDATAONEVERYREQUEST



s (OLDDATAINCONTROLSTHATAREPOSTEDBACKˆTHESO CALLEDSTICKYFORMBEHAVIOR

The last bullet point is probably the most confusing here. Many developers think that this is the only task that the view state has to do. Although the view state is involved in the process of holding the control’s visible data, it is not the originator of the process. That would be the initializing phase that retrieves the form’s data to set the control’s state, often described as “retaining the control state” or short, “control state.” View state is held in a hidden field with the name [[REASOP=PAh(IDDENvMEANSTHATTHE browser does not render the field, but the field itself and its content are visible in the page’s source. )TNEEDSTHEBANDWIDTHTWICEˆTHEFIRSTTIMEWHENTHEPAGEISSENTTOTHEBROWSERANDTHESECOND time when the browser sends the page back (that is, when a postback happens). A postback occurs VERYFREQUENTLYWHENAUSERNAVIGATESWITHINTHEAPPLICATIONANDUNLESSYOUUSEHYPERLINKSALMOST all actions are based on a form being sent back.

A Word Regarding Control State When talking about view state quite often the discussion includes the control state. The control state holds privately used control properties, especially for custom and complex controls in another serializable collection. Those data are stored within the view state storage that means by default the control state is part of the view state’s hidden field. Disabling the view state disables the control STATE TOO(OWEVER THEREISNODECLARATIVEWAYTOCONTROLTHECONTROLSTATESEPARATELY)NTHISDISCUS sion, the control state is just a matter of fact and you shouldn’t be worried about just another state of controls. Because it is essential for some controls, it is also not that critical because of the mini mal amount of dataWELL DEVELOPEDCONTROLSMIGHT hold there.

The Page Cycle from the View State Perspective The page cycle is very important to understanding view state completely, as several levels of the cycle treat view state explicitly. You can refer to the previous section to get an idea of the page cycle in a nutshell. In this section, I will repeat the major steps that actually handle view state. Each time the server receives a request for an .aspx page it will be processed by the ASP.NET engine through a specific number of steps. These include checking access security and restoring the session state. The session state holds data related to the current session, like session variables or logon information. At the end of the process the engine creates a class that consists of the markup CONVERTEDINTOCODEANDCODE BEHIND4HISSTEPGENERATESANINSTANCEOFTHATCLASS WHICHYIELDSTHE content of the Lnk_aooNamqaop method of the page’s handler. The page life cycle begins with the call to this method. Next, the initialization of the controls of the page occurs, followed by the life cycle phases of those controls. This includes the processing of the VIEWSTATE HANDLINGOFPOSTBACKDATAANDRELATEDEVENTSANDFINALLYTHEPROCESSINGOF(4-,CONTENT 4HELIFECYCLEOFTHEPAGEENDSWHENTHE(4-,ISCOMPLETELYRENDEREDANDHANDEDOVERTOTHE Web Server. The Web Server is responsible for sending the data over the wire to the browser. While the Web Server is sending the data, the garbage collector is already freeing up the released memory. 4HISISTRUEFORALLREQUESTSWITHOUTANYINTERACTIONORCUSTOMCODEREQUIRED(OWEVER WITHINTHIS cycle, view state has an extraordinary function and it makes your life as a control developer easier if you understand life cycles and their relation to view state. Download at WoweBook.Com

33

34

CH APT ER 1 N U NDER S TA NDING A S P . NET

Step One—Instantiation The instantiation is the beginning of the life cycle of the page. The class built from markup and code, which represents the page, is instantiated and launched. But what actually happens and WHEREDOESTHEPAGESCODEGETSTORED!30.%4PAGESCONSISTOF(4-,MARKUPWITHCONTROLSAND code. First, the ASP.NET engine converts the text portion of the page and all markup into web con TROLS4HATMEANSTHEPAGEISNOWCOMPLETELYMADEOFCODE-OSTPARTSTHATCONSISTOF(4-,ARE replaced by Hepan]h?kjpnkh controls. Literals contain text that doesn’t need any further processing. This is required in order to avoid the extensive recognition process from ASP.NET engine. The ASP. .%4ENGINEISABLETORECOGNIZECHANGESMADETOEITHERMARKUPORCODEANDRE RUNSTHEPROCESS IF required. The features provided for a page are inherited from the L]ca class (Ouopai*Sa^*QE*L]ca). If code behind is being used, one more step is required. Using the l]npe]h keyword this class is MARRIEDWITHTHECODE BEHINDCLASSTHATISASSOCIATEDWITHTHE!308 page.

Building the Hierarchy of Controls The page is the top level of the hierarchy of controls. Because the L]ca class itself inherits from ?kjpnkh, it’s a control, too. Each control has exactly one parent and none, one, or many children. The elements placed declaratively in the page are children of the highest level. There is no limit to nesting levels for the control hierarchy. This leads to vast trees made of complex controls. One important control is DpihBkni (full name is Ouopai*Sa^*QE*Dpih?kjpnkho*DpihBkni). It cre ates the 8bkni: tag and determines the content sent during postback. The view state information is NECESSARILYPLACEDHERE9OUCANSEETHISINTHESAMPLESHOWNIN,ISTING  Listing 1-8. Simple ASPX Page with Controls 8dpihtihjo9dppl6++sss*s/*knc+-555+tdpih: 8da]`nqj]p9oanran: 8pepha:8+pepha: 8+da]`: 8^k`u: 8d-: =lnaoo)ReasOp]pa8+d-: 8bknie`9bkni-nqj]p9oanran: 8`er: 8]ol6Patp>ktnqj]p9oanranE@9ptpJ]ia+: 8^n+: =naukq_]hha`] 8]ol6@nkl@ksjHeopnqj]p9oanranE@9``hSd]p: 8]ol6HeopEpaiR]hqa9COaha_pa`9Pnqa:Caag8+]ol6HeopEpai: 8]ol6HeopEpaiR]hqa9J:Jan`8+]ol6HeopEpai: 8]ol6HeopEpaiR]hqa9S:@kj#pgjks8+]ol6HeopEpai: 8+]ol6@nkl@ksjHeop: 8^n+: 8]ol6>qppkjnqj]p9oanranE@9^pjOaj`Patp9Oaj`+: 8+`er: 8+bkni: 8+^k`u: 8+dpih: &IGURE SHOWSHOWITWILLLOOKLIKEINTHE6ISUAL3TUDIODESIGNER

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Figure 1-12. Simple page in Visual Studio Designer 4HE!30.%4ENGINEGENERATESTHEOUTPUTCODE AFRAGMENTOFWHICHISSHOWNIN,ISTING  Listing 1-9. Simple ASPX Page from Last Listing Compiled into Code in Debug Mode lq^he__h]oo`ab]qhp[]olt6[@ab]qhp(ENamqenaoOaooekjOp]pa(EDpplD]j`han w lner]paop]pe_k^fa_p[[beha@alaj`aj_eao7 lner]paop]pe_^kkh[[ejepe]heva`7 W@a^qccanJkjQoan?k`aY lq^he_`ab]qhp[]olt$% w ^]oa*=llNah]peraRenpq]hL]pd9z+@ab]qhp*]olt7 eb$[[ejepe]heva`% w opnejcWYrenpq]hBeha@alaj`aj_eao9jasopnejcWYwz+@ab]qhp*]olty7 [[beha@alaj`aj_eao9± ^]oa*CapSn]lla`Beha@alaj`aj_eao$renpq]hBeha@alaj`aj_eao%7 [[ejepe]heva`9pnqa7 y y W@a^qccanJkjQoan?k`aY lner]paDpihPepha[[>qeh`?kjpnkh[[_kjpnkh.$% w napqnjjasDpihPepha$%7 y W@a^qccanJkjQoan?k`aY lner]parke`[[>qeh`?kjpnkh[[_kjpnkh/$HeopEpai?khha_pekj[[_pnh% w HeopEpaiepai9pdeo*[[>qeh`?kjpnkh[[_kjpnkh0$%7 [[_pnh*=``$epai%7 HeopEpaiepai.9pdeo*[[>qeh`?kjpnkh[[_kjpnkh1$%7 [[_pnh*=``$epai.%7 HeopEpaiepai/9pdeo*[[>qeh`?kjpnkh[[_kjpnkh2$%7 [[_pnh*=``$epai/%7 y W@a^qccanJkjQoan?k`aY lner]paHeopEpai[[>qeh`?kjpnkh[[_kjpnkh0$% w HeopEpaiepai9jasHeopEpai$%7 epai*R]hqa9C7 epai*Oaha_pa`9pnqa7 epai*Patp9Caag7 Download at WoweBook.Com

35

36

CH APT ER 1 N U NDER S TA NDING A S P . NET

napqnjepai7 y W@a^qccanJkjQoan?k`aY lner]paHeopEpai[[>qeh`?kjpnkh[[_kjpnkh1$% w HeopEpaiepai9jasHeopEpai$%7 epai*R]hqa9J7 epai*Patp9Jan`7 napqnjepai7 y W@a^qccanJkjQoan?k`aY lner]paHeopEpai[[>qeh`?kjpnkh[[_kjpnkh2$% w HeopEpaiepai9jasHeopEpai$%7 epai*R]hqa9S7 epai*Patp9@kj#pgjks7 napqnjepai7 y W@a^qccanJkjQoan?k`aY lner]pa>qppkj[[>qeh`?kjpnkh^pjOaj`$% w >qppkj^qppkj9jas>qppkj$%7 ^]oa*^pjOaj`9^qppkj7 ^qppkj*=llhuOpuhaOdaapOgej$pdeo%7 ^qppkj*E@9^pjOaj`7 ^qppkj*Patp9Oaj`7 napqnj^qppkj7 y W@a^qccanJkjQoan?k`aY lner]pa@nkl@ksjHeop[[>qeh`?kjpnkh``hSd]p$% w @nkl@ksjHeopheop9jas@nkl@ksjHeop$%7 ^]oa*``hSd]p9heop7 heop*=llhuOpuhaOdaapOgej$pdeo%7 heop*E@9``hSd]p7 pdeo*[[>qeh`?kjpnkh[[_kjpnkh/$heop*Epaio%7 napqnjheop7 y W@a^qccanJkjQoan?k`aY lner]paDpihBkni[[>qeh`?kjpnkhbkni-$% w DpihBknibkni9jasDpihBkni$%7 ^]oa*bkni-9bkni7 bkni*E@9bkni-7 EL]noan=__aookn]__aookn9bkni7 ]__aookn*=``L]noa`Oq^K^fa_p$± jasHepan]h?kjpnkh$XnXj8`er:XnXj%%7 Patp>kt^kt9pdeo*[[>qeh`?kjpnkhptpJ]ia$%7 ]__aookn*=``L]noa`Oq^K^fa_p$^kt%7 ]__aookn*=``L]noa`Oq^K^fa_p$± jasHepan]h?kjpnkh$XnXj8^n+:XnXj± =naukq_]hha`]XnXj%%7 Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

@nkl@ksjHeopheop9pdeo*[[>qeh`?kjpnkh``hSd]p$%7 ]__aookn*=``L]noa`Oq^K^fa_p$heop%7 ]__aookn*=``L]noa`Oq^K^fa_p$± jasHepan]h?kjpnkh$XnXj8^n+:XnXj%%7 >qppkj^qppkj9pdeo*[[>qeh`?kjpnkh^pjOaj`$%7 ]__aookn*=``L]noa`Oq^K^fa_p$^qppkj%7 ]__aookn*=``L]noa`Oq^K^fa_p$± jasHepan]h?kjpnkh$XnXj8+`er:XnXj%%7 napqnjbkni7 y W@a^qccanJkjQoan?k`aY lner]paDpihDa]`[[>qeh`?kjpnkhDa]`-$% w DpihDa]`da]`9jasDpihDa]`$da]`%7 ^]oa*Da]`-9da]`7 da]`*E@9Da]`-7 DpihPephapepha9pdeo*[[>qeh`?kjpnkh[[_kjpnkh.$%7 EL]noan=__aookn]__aookn9da]`7 ]__aookn*=``L]noa`Oq^K^fa_p$pepha%7 napqnjda]`7 y W@a^qccanJkjQoan?k`aY lner]parke`[[>qeh`?kjpnkhPnaa$`ab]qhp[]olt[[_pnh% w pdeo*Ejepe]heva?qhpqna$%7 EL]noan=__aookn]__aookn9[[_pnh7 ]__aookn*=``L]noa`Oq^K^fa_p$± jasHepan]h?kjpnkh$XnXjXnXj8@K?PULAdpihLQ>HE?X)++S/?++@P@TDPIH-*,± Pn]joepekj]h++AJXXdppl6++sss*s/*knc+PN+tdpih-+@P@+tdpih-)± pn]joepekj]h*`p`X:XnXjXnXj8dpihtihjo9Xdppl6++sss*s/*knc+-555+tdpihX:XnXj%%7 DpihDa]`da]`9pdeo*[[>qeh`?kjpnkhDa]`-$%7 ]__aookn*=``L]noa`Oq^K^fa_p$da]`%7 ]__aookn*=``L]noa`Oq^K^fa_p$jasHepan]h?kjpnkh$XnXj8^k`u:XnXj± 8d-:XnXj=lnaoo)ReasOp]pa8+d-:XnXj%%7 DpihBknibkni9pdeo*[[>qeh`?kjpnkhbkni-$%7 ]__aookn*=``L]noa`Oq^K^fa_p$bkni%7 ]__aookn*=``L]noa`Oq^K^fa_p$± jasHepan]h?kjpnkh$XnXj8+^k`u:XnXj8+dpih:XnXj%%7 y W@a^qccanJkjQoan?k`aY lner]paPatp>kt[[>qeh`?kjpnkhptpJ]ia$% w Patp>kt^kt9jasPatp>kt$%7 ^]oa*ptpJ]ia9^kt7 ^kt*=llhuOpuhaOdaapOgej$pdeo%7 ^kt*E@9ptpJ]ia7 napqnj^kt7 y W@a^qccanJkjQoan?k`aY lnkpa_pa`kranne`arke`Bn]iaskngEjepe]heva$% w ^]oa*Bn]iaskngEjepe]heva$%7 pdeo*[[>qeh`?kjpnkhPnaa$pdeo%7 Download at WoweBook.Com

37

38

CH APT ER 1 N U NDER S TA NDING A S P . NET

^]oa*=``Sn]lla`Beha@alaj`aj_eao$[[beha@alaj`aj_eao%7 ^]oa*Namqaop*R]he`]paEjlqp$%7 y W@a^qccanJkjQoan?k`aY lq^he_kranne`aejpCapPulaD]od?k`a$% w napqnj)-234/4305-7 y W@a^qccanJkjQoan?k`aY lq^he_kranne`arke`Lnk_aooNamqaop$Dppl?kjpatp_kjpatp% w ^]oa*Lnk_aooNamqaop$_kjpatp%7 y ++Lnklanpeao lnkpa_pa`Dppl=llhe_]pekj=llhe_]pekjEjop]j_a w cap w napqnjpdeo*?kjpatp*=llhe_]pekjEjop]j_a7 y y lnkpa_pa`@ab]qhpLnkbehaLnkbeha w cap w napqnj$@ab]qhpLnkbeha%pdeo*?kjpatp*Lnkbeha7 y y y The code is not very readable, but this is what generated code is supposed to look like, right? There is no need to do anything special with it, but rather to learn what is going on internally. Note two things here. First, the declarative assignment of attributes is being replaced with simple prop erty assignments. See the following markup: 8]ol6>qppkjpatp9Oaj`: It becomes this in the generated class: ^qppkj-*Patp9Oaj` Second, all literal stuff is placed in strings and copied into the final page “as is,” which is shown in the following snippet: jasHepan]h?kjpnkh$XnXj8+^k`u:XnXj8+dpih:XnXj%% Once the class is complete, the engine proceeds to the next step.

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Step Two—Initializing After creating the control hierarchy, all the controls of the page are moved into the initialization state. This becomes apparent by raising the Ejep event. In this phase not only are the controls ready, but they also have their static, declarative properties assigned.

NNote

“Declarative” is everything that’s written within the markup and not in code fragments.

Whether or not a property has been declaratively assigned, you still can change the value any time BEFORETHERENDERPROCESSISCOMPLETE(OWEVER BECAUSE)MTALKINGABOUTVIEWSTATE THEINITIALIZA tion step plays a special role regarding property values.

View State Tracks Changes View state tracks changes of properties. This is a special function of the Op]pa>]c class defined in the Ouopai*Sa^*QE namespace, which holds the data behind the scenes. Tracking starts during the Initializing step of the page. In order to recognize the default value and the changed one, the Op]pa>]c compares the initialized value set by declarative markup with the current value set any time later programmatically. Even if the results look the same, the view state treats the data in a different way.

View State and Dynamic Controls Using dynamic controls, you’ll know that technically it’s possible to add controls any time before the page render process is complete. The view state is not that flexible. Adding controls using ?kjpnkho*=`` method must take place in the initializing phase. Otherwise, the Op]pa>]c class does not recognize the Ejep event at the right time and does not start tracking changes. You still can add controls anytime, but for those controls the view state will not work. You might find problems here OCCASIONALLY ASTHEMAJORITYOFCONTROLSBEINGADDEDDYNAMICALLYˆSUCHASTHEH]^ahCONTROLˆDONT require property value tracking. The golden rule states that in order to “take care of the view state, whether it’s required or not, add dynamic controls during the Initializing step.”

Step Three—Loading the View State View state data is saved into a hidden field called [[REASOP=PA. It’s transmitted back to the server only during a POST operation, which forces a postback.

NNote

You can completely ignore page requests that use GET for this step. Such requests do not interact with view state at all.

In this step the engine decodes values from the hidden field and assigns them to the controls, looping recursively through the control hierarchy. Also in this phase the validity of the view state is checked. There are several reasons why the view state could become invalid. One reason is that the control hierarchy has been changed during postback and the control is not at the expected place, or removed completely.

Download at WoweBook.Com

39

40

CH APT ER 1 N U NDER S TA NDING A S P . NET

)FEVERYTHINGISFINE THEENGINEPROCEEDSTOTHENEXTSTEP3EETHESECTIONh6IEW3TATE!NTI Patterns” for an example of what’s going on when it went wrong.

Step Four—Loading Postback Data After loading and restoring the view state, the form data is processed. Not all controls can return data. To let the engine know whether it has to look for data sent back, the ELkop>]_g@]p]D]j`han interface is recognized. Each control implementing this interface might send form data back. Form DATAISSENTBACKINTHE(440PROTOCOLASIDnVALUEPAIRS Iu_heajpe`9r]hqa The page class looks for a control with a ?heajpE@ that equals “Myclientid”. When found, it checks whether the control implements the ELkop>]_g@]p]D]j`han interface. If it does this, the page CLASSCALLSTHEONLYMETHODDEFINEDTHEREˆHk]`Lkop@]p]. That means that the control itself manages the loading of data, which opens up a great way of changing behavior and adding custom code. Concerning view state, this behavior is very significant. The ability to get the values of controls back between postbacks is called “sticky form” behavior. It’s one of the best features of ASP.NET. Let me explain this in more detail using the example of a Patp>kt control. The Patp>kt has a property Patp. It also implements the ELkop>]_g@]p]D]j`han interface. Once a page with the textbox control is posted back, the Hk]`Lkop@]p] method reads the value of the control out of the view state and writes it into the PatpPROPERTY4HEDEFAULTVALUEˆTHATWASPROBABLYSETDECLARATIVELYˆISOVERWRITTEN9OU can easily check this with the following definition: 8]ol6Patp>ktnqj]p9oanranE@9ptpJ]iaPatp9+: 4HERENDERPROCESSTRANSFORMSTHISMARKUPINTO(4-,FORM 8ejlqppula9patpe`9ptpJ]iaj]ia9ptpJ]ia+: If the user now enters some text here, like “It’s a geek”, the form transmitted back to the server contains at least this line: ptpJ]ia9Ep#o]caag This data pair becomes part of the Namqaop*Bkni collection. The key is “txtName” and the value is “It’s a geek”. The page class hands this data pair to the Hk]`Lkop@]p] method. Internally there is nothing surprising here. Using Reflector, you can look into the relevant code inside Ouopai*Sa^*`hh SEE,ISTING   Listing 1-10. Disassembled Code of the LoadPostData Method lnkpa_pa`renpq]h^kkhHk]`Lkop@]p]$opnejclkop@]p]Gau(± J]iaR]hqa?khha_pekjlkop?khha_pekj% w ^]oa*R]he`]paArajp$lkop@]p]Gau%7 opnejcpatp9pdeo*Patp7 opnejcopn.9lkop?khha_pekjWlkop@]p]GauY7 eb$pdeo*Na]`Kjhu""patp*Amq]ho$opn.(Opnejc?kil]neokj*Kn`ej]h%% w pdeo*Patp9opn.7 napqnjpnqa7 y napqnjb]hoa7 y

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

This code snippet is from Patp>kt, and the one and only property filled by a postback is Patp. 4HECONTROLMIGHTHAVEBEENSETREAD ONLYANDTHEREFORETHISISCHECKEDFIRSTpdeo*Na]`Kjhu). Also, as the code compares the old value and the new one, it’s written only if the value has been changed. Why is this additional check required? You might assume that comparing takes more time than ASSIGNINGAPROPERTYˆEVENIFTHEREISNOTHINGTORENDERATTHISSTAGE7ELL THEREASONISVIEWSTATE To understand this, take a look into the code for the PatpPROPERTYIN,ISTING  Listing 1-11. Disassembled Code of Text Method of the TextBox Class lq^he_renpq]hopnejcPatp w cap w opnejcopn9$opnejc%pdeo*ReasOp]paWPatpY7 eb$opn9jqhh% w napqnjopn7 y napqnjopnejc*Ailpu7 y oap w pdeo*ReasOp]paWPatpY9r]hqa7 y y The value is not stored in a private field, but only in view state. The tracking feature of the underlying Op]pa>]c class handles changes as well. If nothing has changed, it’s not recommended to assign the value to view state, or the Op]pa>]c class will start tracking. If there is nothing to track, it doesn’t make sense to do so, and the Hk]`Lkop@]p] method is clever enough to know. One major aspect many developers overlook is the role of view state in the handling of postback data. The form data loading procedures do not involve view state. More than that, they try to avoid any interaction with view state. The form data handling and stickiness behavior has nothing to do with the view state. The stickiness is a feature that comes with the ELkop>]_g@]p]D]j`han interface. *USTFORCLARITY ,ISTING SHOWSITINITSENTIREGLORY Listing 1-12. Code of IPostBackDataHandler Interface lq^he_ejpanb]_aELkop>]_g@]p]D]j`han w ^kkhHk]`Lkop@]p]$opnejclkop@]p]Gau(± J]iaR]hqa?khha_pekjlkop?khha_pekj%7 rke`N]eoaLkop@]p]?d]jca`Arajp$%7 y You know now that view state tracks changes and stores these changes. You know, too, that the stickiness of the form has nothing to do with view state. The Hk]`Lkop@]p] method just explores the values sent back to server and restores it into the appropriate properties. .OW ALLTHECONTROLSHAVEBEENINITIALIZED PROPERLYFILLEDWITHDECLARATIVEDATA OVER WRITTEN with data posted back from the browser, and are ready to enter the next state.

Download at WoweBook.Com

41

42

CH APT ER 1 N U NDER S TA NDING A S P . NET

Step Five—Loading Step Most descriptions of ASP.NET put user code into the Hk]` event. In the explanation of life cycles, you read about this important step because it signals to us that the control is now “ready.” Even if you don’t want to do anything else with the control, it’s ready to be rendered. This is why the best step for adding custom code and modifying the behavior of the page is the load step. Internally, it’s much easier, because there is nothing to do within the control. Anything that is supposed to happen here is up to you.

Step Six—Raising Postback Events Several controls can fire events, depending on the form data posted back. After the loading step, the events are fired one by one. For example, the >qppkj control can fire a ?he_g event, whereas the @nkl@ksjHeop fires Oaha_pa`Ej`at?d]jca`. This is another major feature that makes the dynamic portion of an ASP.NET page so powerful and easy to program. There are two kinds of events fired during the page’s postback. One kind is responsible for changes, indicated by the suffix [?d]jca. The implementation of ELkop>]_g@]p]D]j`han is responsible for recognizing this and firing the appropriate event by calling the N]eoaLkop@]p]?d]jca`Arajp method. In the case of the Patp>kt example, the event exposed by the class is KjPatp?d]jca`. The other kind of event is the trigger event. For example, in the case of a >qppkj this is a ?he_g EVENT4HEREISNOSPECIALSTATEREQUIREDANDNODATATOCOMPARE!SYOUCANSEEIN,ISTING  TO handle trigger events the ELkop>]_gArajpD]j`han interface is used. Listing 1-13. Code of IPostBackEventHandler Interface lq^he_ejpanb]_aELkop>]_gArajpD]j`han w rke`N]eoaLkop>]_gArajp$opnejcarajp=ncqiajp%7 y To understand what happens internally, we’ll look into the N]eoaLkop>]_gArajp method. ,ISTING ISFORA>qppkj control. Listing 1-14. Code of Typical Implementation of IPostBackEventHandler Interface lnkpa_pa`renpq]hrke`N]eoaLkop>]_gArajp$opnejcarajp=ncqiajp% w ^]oa*R]he`]paArajp$pdeo*QjemqaE@(arajp=ncqiajp%7 eb$pdeo*?]qoaoR]he`]pekj% w pdeo*L]ca*R]he`]pa$pdeo*R]he`]pekjCnkql%7 y pdeo*Kj?he_g$Arajp=nco*Ailpu%7 pdeo*Kj?kii]j`$jas?kii]j`Arajp=nco$ pdeo*?kii]j`J]ia(pdeo*?kii]j`=ncqiajp%%7 y !SYOUCANSEE THISMETHODRAISESMORETHANONEEVENTINAPREDEFINEDANDHARD CODEDORDER 3EVERALOTHERACTIONSTAKEPLACEFIRSTˆSUCHASVALIDATIONˆBUTTHEEVENTSBEINGFIREDAREUNCONDI tional. Again, all of these events can only happen during a postback. Calling the page using GET will do nothing. If you have a @nkl@ksjheop, and if you change the current index programmatically, nothing will happen unless the page is posted back. This is different from the windows programming model, where the controls can fire events immediately and independently of a particular state. Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Step Seven—Storing the View State After all events have been fired, the current state of each control’s property changes needs to be stored. The tracked changes are retrieved recursively through the controls hierarchy. To get the value back, the O]raReasOp]pa method of each control is called. The collection of data is then serial IZEDANDENCODEDUSING"ASE In the next step, the string is saved to the hidden field with id [[REASOP=PA.

Step Eight—Rendering the Page The render process runs through all the controls and allows them to render. This is done by a recursive call to all Naj`an?kjpnkh methods. The DpihBkni control mentioned at the beginning is responsible for creating the [[REASOP=PA hidden field, which is the container for view state data.

The True Role of View State The eight states of the life cycle are virtually all important for view state. There are several more steps the various life cycles could run through, but these steps don’t affect view state, so I’ll exclude them for now. To understand the view state, it’s crucial to know what the purpose of view state is. As the name implies, view state stores status information. But what kind of status is it? The hierarchy of controls and the default values of properties are defined in the declarative part of the page. Take a look at this markup: 8]ol6H]^ahnqj]p9oanranPatp9Saha]njreasop]paBkjp)>kh`9pnqa+: Neither the text “We learn viewstate” nor the value >kh` of the Bkjp property is stored in view state. The values are assigned during the initializing phase. View state, in contrast, tracks changes made programmatically. This leads to the first definition about view state.

NNote

View state becomes important only if the page contains custom code.

(OWEVER IFAPAGECONTAINSCUSTOMCODE THISDOESNOTNECESSARILYMEANTHATVIEWSTATEISREQUIRED ,ETSLOOKINTOANOTHERCODESNIPPET4HEFOLLOWINGEXAMPLEIN,ISTING HASTWOBUTTONS"OTHCAUSE a postback, but only one has an Kj?he_g event attached and handled to access properties in code. Listing 1-15. Markup of the View State Test 8]ol6H]^ahE@9H]^ahIaoo]canqj]p9oanranPatp9Saha]njreasop]pa:8+]ol6H]^ah: 8^n+: 8]ol6>qppkjE@9>qppkjOq^iepnqj]p9oanrankj_he_g9>qppkjOq^iep[?he_g Patp9?d]jcaPatpSe`pd9-1,lt+: 8^n+: 8]ol6>qppkjE@9>qppkjAilpunqj]p9oanranPatp9Jk?d]jca Se`pd9-1,lt+: !SSHOWNIN,ISTING  THECODEOFTHECLICKHANDLERISSIMPLE TOO Listing 1-16. Code of the Click Handler lnkpa_pa`rke`>qppkjOq^iep[?he_g$k^fa_poaj`an(Arajp=ncoa% w H]^ahIaoo]ca*Patp9DahhkCaag7 y Download at WoweBook.Com

43

44

CH APT ER 1 N U NDER S TA NDING A S P . NET

!TTHEFIRSTCALLOFTHEPAGETHE!308MARKUPISPROCESSEDANDALLVALUESOFPROPERTIESARESET especially the text “We learn viewstate” for the H]^ah. View state stores nothing and therefore con tains only internal information without custom data: 8ejlqppula9de``ajj]ia9[[REASOP=PAe`9[[REASOP=PA± r]hqa9+sAL@sQHHPAtJfIvJ@EtJfNgVCj1]if>oKK]l2?rN^lQI1@5Ihck+: Now click on the button “No Change”. This forces the page to postback and reload, but nothing more happens, because no custom code is involved. Now click on the other button “Change Text”. Again a postback occurs, but now the handler processes the Kj?he_g event. In the code, the text of the label gets a new value. View state is changed to this: 8ejlqppula9de``ajj]ia9[[REASOP=PAe`9[[REASOP=PAr]hqa9+sAL@sQHHPAtJfIvJ@Et fMLV>U?=cILV>U?=cAL@tU?DcNQVTd,>MpEUSto^u>DVSRnESNgVDPaJ--HePr1>F,tO`au,H,Mojg4+: As you see, the coded part is bigger and obviously contains more information. This is no sur prise. If you click now on the other button “No Change”, the page loads as expected and no custom CODEISRUN(OWEVER THETEXTOFTHELABELISSTILLh(ELLOGEEK
v4HEREISNOCUSTOMCODEˆTHEINITIAL izing phase has obviously passed and has set the declaratively assigned values. But the change made PROGRAMMATICALLYINANEARLIERPOSTBACKISSTILLTHEREˆITSPERSISTENT That’s really the purpose of view state. During postbacks, it makes programmatic changes to control properties persistent. To check whether this behavior is really managed by view state, just disable it using the
View State Anti-Patterns Improper use of view state is easily avoided once you really understand how it works. To make things clear, I’ll explain the most frequent misuse scenarios. Examples of how not to use view state will help you understand how to use view state correctly:

s &ORCINGADEFAULT



s 0ERSISTINGSTATICDATA



s 0ERSISTINGhCHEAPvDATA



s )NITIALIZINGCHILDCONTROLS



s !DDINGCONTROLSDYNAMICALLY



s )NITIALIZINGDYNAMICALLYCREATEDCONTROLS I’ll explain each of these scenarios to make things as clear as possible.

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

Forcing a Default Forcing a default value is a very common misuse. Fortunately, it’s even easier to fix. It’s also a good demonstration of the KISS5 principle. The developers of ASP.NET did a tremendous job to give us APOWERFULANDWELL DESIGNEDTOOLKIT4HEWHOLEFRAMEWORKISANINFRASTRUCTURETHINGANDPROVIDES stable and reliable blocks of code for basic stuff. Doing too much infrastructure work is a signal that something is going wrong. Assume that you want to store some private data used in a user control. The following code in ,ISTING USESTHEVIEWSTATE WHICH INPRINCIPLE ISNOTABADIDEA Listing 1-17. DON’T TRY THIS AT HOME: a wrongly written user control lq^he__h]ooIu?kjpnkh6Sa^?kjpnkh w lq^he_opnejcIu@]p] w capwnapqnjReasOp]paWIu@]p]Y]oopnejc7y oapwReasOp]paWIu@]p]Y9r]hqa7y y lnkpa_pa`kranne`aKjHk]`$Arajp=ncoa% w eb$EoLkop>]_g% w pdeo*Iu@]p]9OaooekjW?kjpnkhIu@]p]Y]oopnejc7 y ^]oa*KjHk]`$%7 y y 9OUMAYHAVEWRITTENCODELIKETHISBEFORE)TSNOTABADSTYLEITSSIMPLYWRONG4OUNDER stand my harsh judgment, let’s examine the intent of the control. The developer wrote a user control with the public property MyData. This gives other developers access to it in order to put the control into a defined state using markup like this: 8]he]o6iu_kjpnkhnqj]p9oanranPatp9Odkspdeoh]^ahe`9iu?kjpnkh-+: 4HISCOMPILESANDRUNSWELLWITHOUTANYEXCEPTIONS(OWEVER ITDOESNTWORKASEXPECTED because the MyData property is never set. Instead, the view state of the page starts growing because THEVIEWSTATEFIELDSTORESTHISPRIVATEINFORMATION&ROMTHATPERSPECTIVE ITSDOINGWELLITHOLDS some data. Also, remember the life cycle events. It’s boring to repeat them again and again, but EVERYTHINGIN!30.%4ISBASEDONTHELIFECYCLE)N,ISTING THECODEISWRITTENINTOTHEKjHk]` method. But the Hk]` stage is too late. View state already tracks changes, and now it’s being over written. That’s why it doesn’t make sense to write the data there. Let’s improve our example (see ,ISTING   Listing 1-18. Save to Be Used at Home: A Well-Written Control lq^he__h]ooIu?kjpnkh6Sa^?kjpnkh w lq^he_opnejcIu@]p] w capw eb$ReasOp]paWIu@]p]Y99jqhh% 5. Keep it Simple, Stupid Download at WoweBook.Com

45

46

CH APT ER 1 N U NDER S TA NDING A S P . NET

napqnjOaooekjW?kjpnkhIu@]p]Y]oopnejc7 ahoa napqnjReasOp]paWIu@]p]Y]oopnejc7 y oapwReasOp]paWIu@]p]Y9r]hqa7y y  y This involves less code and it’s working well. The default value in the session is now used without touching view state. Simply putting the control onto the page does not increase the size of view state. KjHk]` is out of the way here. The assignment of properties happens in the Initializing PHASEˆEARLYENOUGHTOSETVALUESPROPERLY)NCASETHEUSEROFTHECONTROLSETSTHE-Y$ATAPROPERTY programmatically, view state is in full cry and stores the changes silently in the hidden field.

Persisting Constant Data A lot of data used in a page’s code never changes during the life of the page or during the user’s ses sion. Assume your application has some “My” section that is customizable by the user. After the user is logged on, his or her name appears at the top of each page. Assume further that a user con trol is being written to achieve this. 8]ol6h]^ahe`9h^hQoannqj]p9oanran+: )NTHECODE BEHINDPORTIONTHENAMEISSET lq^he__h]ooIu?kjpnkh6Sa^?kjpnkh w lnkpa_pa`kranne`aKjHk]`$Arajp=ncoa% w h^hqoan*Patp9?qnnajpQoan*J]ia7 ^]oa*KjHk]`$%7 y y 4HISISCODETHATWOULDWORKWELL(OWEVER ITSDOINGSOMETHINGUNDERTHEHOODTHATYOU don’t want. The label has its own view state and, as a child control of the user control, it will store its changed properties in the parent’s view state. The user control is going to recognize this and store the change of view state. Storing the label’s text value in view state doesn’t make sense as, each time it’s loaded, the value is pulled from the ?qnnajpQoan class. The default behavior of controls is an implicit usage of view state. Either you assign it once, and hold data in view state, or you need to prevent it from using view state. The solution I would recommend looks very easy: 8]ol6h]^ahe`9h^hQoannqj]p9oanranAj]^haReasop]pa9b]hoa+: Disable view state on the control level and it will work like a charm. The next pattern extends this solution by presenting an alternative solution.

Persisting Cheap Data Sometimes you use data that changes frequently, depending on user action or external conditions. Assume you want to show a list of data on your page. It is a small list and it doesn’t change fre QUENTLY"UTITCOULDCHANGEORGROWATANYTIME9OURSITEISALREADYUSINGADATABASEITSFASTAND there is nothing wrong with pulling the data from a table.

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

8]ol6`nkl`ksjheopnqj]p9oanrane`9``hIu@]p]@]p]PatpBeah`9J]ia± @]p]R]hqaBeah`9E@+: 4HEFICTITIOUS CODE BEHINDPORTIONCOULDLOOKLIKETHIS lq^he__h]ooIu?kjpnkh6Sa^?kjpnkh w lnkpa_pa`kranne`aKjHk]`$Arajp=ncoa% w eb$EoLkop>]_g% w ``hIu@]p]*@]p]Okqn_a9@=H*Mqanu@`h@]p]$%7 ``hIu@]p]*@]p]>ej`$%7 y ^]oa*KjHk]`$%7 y y 4HISIS AGAIN WORKINGWELLANDNOBODYWOULDSEEANYISSUESHERE(OWEVER THEREISSOMETHING here that is easily overlooked. Databound controls need to remember their state, for instance, to hold the last selected option of a dropdownlist after postback. I discussed this previously and called this smart behavior “stickiness.” You don’t want to lose the form’s sticky behavior. You might there fore assume that switching view state off is not a solution either. But stickiness is part of the control STATEITSMADEBYCHECKINGTHEFORMDATA)TSNOTRELATEDTOVIEWSTATE ASSOMEDEVELOPERSTHINK The reason you run into trouble with view state is that it grows each time the page reloads. This time the solution is not so simple. Switching off view state is only half of the answer: 8]ol6`nkl`ksjheopnqj]p9oanrane`9``hIu@]p]@]p]PatpBeah`9J]ia± @]p]R]hqaBeah`9E@Aj]^haReasOp]pa9b]hoa+: 4HECODE BEHINDISALMOSTTHESAME EXCEPTYOUPULLTHEDATAEVERYTIMETHECONTROLLOADSNOTE the missing eb statement): Lq^he__h]ooIu?kjpnkh6Sa^?kjpnkh w lnkpa_pa`kranne`aKjHk]`$Arajp=ncoa% w ``hIu@]p]*@]p]Okqn_a9@=H*Mqanu@`h@]p]$%7 ``hIu@]p]*@]p]>ej`$%7 ^]oa*KjHk]`$%7 y y Now view state is as clean as possible. But the sticky form behavior has gone, too. Trying this, you might think you’ve found a bug in this book and that the author is wrong about view state. The fault is not view state itself. It still has no function because the control state is restoring the DATAFROMPOSTBACKVALUES(OWEVER LETSOVERWRITETHISBECAUSETHEKjHk]` event is fired after all states are restored. This is, again, a life cycle issue. Understanding the life cycle leads us to the solu TION-OVETHELASTCODEFRAGMENTASISTOANOTHERSTEPINTHELIFECYCLEˆKjEjep: lq^he__h]ooIu?kjpnkh6Sa^?kjpnkh w lnkpa_pa`kranne`aKjEjep$Arajp=ncoa% w ``hIu@]p]*@]p]Okqn_a9@=H*Mqanu@`h@]p]$%7 ``hIu@]p]*@]p]>ej`$%7

Download at WoweBook.Com

47

48

CH APT ER 1 N U NDER S TA NDING A S P . NET

^]oa*KjEjep$%7 y y This solution is both clean and simple. KjEjep fires before the control state restores the values. It pulls static data from a fast database, puts it directly into the control, forces the render process before the control restores its state, and everything is fine. The render process is an important step here, made by calling the @]p]>ej` method.

NTip You’ll probably want to avoid heavy database access whenever possible. Instead, you’ll probably store small data portions in XML files and maintain changes there. I would recommend using a database anyway. Modern implementations, like Microsoft SQL Server™, hold frequently requested data in memory. The amount of data requested is small, and the connection is usually 1GB or 10GB Ethernet. A powerful data access layer will also cache the data locally, so that in reality nothing is transferred between the servers. The slowest part of the connection is from the Web Server to the user. He or she will have ISDN, DSL, or a mobile connection. Storing the small portion of data in view state sends the data three times over the wire: once when the user loads the page (as visible data in the dropdown control), once in view state, and the third time when the form is sent back (as view state is part of the form’s field collection). Calling a database frequently is not torture; this is the reason for a database.

Initializing Child Controls One paradigm you might hear frequently about ASP.NET is to do things declaratively. Whatever you can do directly within the !308PAGE DOIT
(OWEVER THISHASSOMEIMPLICATIONSANDLIMITATIONS and eventually you must start doing some work programmatically. The trouble is that initializing controls programmatically is not straightforward. As shown before, you can do this in KjHk]`, but this could cause the view state to grow and, in any case, it’s not necessary to use view state when merely setting defaults. Even KjEjep is not the best solution because view state will still track changes and catch the settings. If you need view state and can’t disable it, you’ll have to live with THISBEHAVIOR"ECAUSETHECONTROLSVIEWSTATETRACKSCHANGESFROMTHEBOTTOMUPˆSAY FROMTHE LASTLEAFCONTROLINTHECONTROLHIERARCHYUPTOTHETREESROOTˆTHEKjEjep for child controls is done when the current KjEjep is called. 8]ol6h]^ahe`9h^h@]panqj]p9oanran+: )NTHECODE BEHINDPORTION YOUSETTHETEXTBYASSIGNINGTHECURRENTDATE lq^he__h]ooIu?kjpnkh6Sa^?kjpnkh w lnkpa_pa`kranne`aKjEjep$Arajp=ncoa% w h^h@]pa*Patp9@]paPeia*Jks*PkHkjc@]pa$%7 ^]oa*KjEjep$%7 y y Even if this is the earliest event possible, it’s already too late. The label is initialized before the user control, and view state is already tracking changes. This means that the date persists in view STATE WHICHDOESNTMAKESENSEˆTHISISTHESAMESITUATIONFACEDINTHECURRENTUSERNAMEEXAMPLE Disabling view state has been discussed before, but this is not always a solution. Perhaps you have tried this: 8]ol6h]^ahe`9h^h@]pnqj]p9oanranPatp98!9@]paPeia*Jks*PkHkjc@]paOpnejc$%!:+:

Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

This is not possible, because ASP.NET doesn’t allow the initializing of properties in that way. Using databinding syntax 8!!: is no solution, either. Let’s assume that for some reason you want to assign the value by code. And you want to use view state for some other reason as well. You may think about KjLnaEjep, but this event isn’t recursive and appears only on the page level. So, what’s going on here? It’s interesting that the KjEjep event behaves slightly different depending on how you get access to it. The obvious way is to override the event HANDLER4HISISEASY WELL SUPPORTEDIN)NTELLI3ENSE ANDTHEMOSTCOMMONSOLUTION9OUCANATTACH events declaratively, too. As I said before, this is one of the major paradigms of ASP.NET. 8]ol6h]^ahe`9h^h@]panqj]p9oanranKjEjep9h^h@]pa[Ejep+: 4HISHANDLERISFIREDBEFORETHEINTERNALINITIALIZATIONTAKESPLACEˆBEFORETHEPn]_gReasOp]pa method is called and the view state starts tracking changes. Referring to the control’s life cycle, there ISASUBTLEDIFFERENCEBETWEENTHEDECLARATIVELYATTACHEDEVENTANDOVERRIDINGTHEMETHOD*USTSET THETEXTINTHECODE BEHINDASYOUWOULDBEFORE lq^he__h]ooIu?kjpnkh6Sa^?kjpnkh w lq^he_rke`h^h@]pa[Ejep$k^fa_poaj`an(Arajp=ncoa% w h^h@]pa*Patp9@]paPeia*Jks*PkHkjc@]pa$%7 y y

NTip If you’re wondering whether to use declarative events or just wire up to code—remember the basic rule: “Whatever we can do easily and safely the declarative way is our primary programming technique.” !NOTHERSOLUTIONCOMESTOMINDIFYOUREANEXPERIENCEDDEVELOPEROFOBJECT ORIENTEDSOFTWARE Each object starts its life with the call of the object’s constructor. Usually the constructor is the place TOINITIALIZETHEOBJECT(OWEVER IN!30.%4THELIFEOFCONTROLSBEGINSSOMETIMELATER INTHEINI tialization phase. You may subclass the control and override the constructor to invoke code there, but child controls are not yet present. The various events required are fired some time later. With a custom control it would work. This is indeed another powerful solution. By implementing your own label you can access the constructor without needing to do anything elsewhere: lq^he__h]ooIuH]^ah6H]^ah w lq^he_IuH]^ah$% w pdeo*Patp9@]paPeia*Jks*PkHkjc@]pa$%7 y y This is a slightly modified label that simply initializes itself at the right time without any side effects. The constructor call assures that any tracking begins later.

NNote

The internal “building steps” of an object, like the constructor call, are made before the lifetime of the object begins. By “lifetime,” I mean the life of an object within the control’s or page’s life cycle—not the lifetime of an object within the runtime.

Download at WoweBook.Com

49

50

CH APT ER 1 N U NDER S TA NDING A S P . NET

Attaching Dynamic Controls All controls have a collection of child controls, represented by the property ?kjpnkho. Some controls, such as H]^ah, have an empty collection, because they can’t render children. All controls inherit the collection from ?kjpnkh base class. This is the common way to access the hierarchy of controls. The class behind the collection is defined: lq^he__h]oo?kjpnkh?khha_pekj6E?khha_pekj(EAjqian]^ha There are no obvious limits preventing you from adding new controls at any time. With view state, it’s not that easy. View state can track values only for existing controls. To handle dynamic controls, you need to add them on any page load, whether it’s a postback or regular page load cycle. Attaching dynamic controls must happen in the initializing phase (KjEjep event), because, at an earlier state, there is no hierarchy of controls to which you could attach anything. View state of those dynamically attached controls is then tracked automatically. Remember that this is done recursively through the whole hierarchy, so the Op]pa>]c classWILLNEVERMISSANYTHING(OWEVER THISPOINTIS critical. You might experience the following exception loading the page after postback: WB]eha`hk]`ejcreasop]paY B]eha`pkhk]`reasop]pa*Pda_kjpnkhpnaaejpksde_dreasop]paeo^aejchk]`a`iqop i]p_dpda_kjpnkhpnaapd]ps]oqoa`pko]rareasop]pa`qnejcpdalnarekqonamqaop*Bkn at]ilha(sdaj]``ejc_kjpnkho`uj]ie_]hhu(pda_kjpnkho]``a``qnejc]lkop)^]_giqop i]p_dpdapula]j`lkoepekjkbpda_kjpnkho]``a``qnejcpdaejepe]hnamqaop* Let’s create an example so that you can figure out what is happening internally: lnkpa_pa`rke`L]ca[Ejep$k^fa_poaj`an(Arajp=ncoa% w eb$EoLkop>]_g% w >qppkjiu>qppkj9jas>qppkj$%7 bkni-*?kjpnkho*=``$iu>qppkj%7 iu>qppkj*Patp9?he_gdana7 y ahoa w H]^ahh]^ah9jasH]^ah$%7 bkni-*?kjpnkho*=``$h]^ah%7 y y The intent of this code is obvious. The user has a >qppkj to invoke some action, and, when the action is completed, the button is replaced by a H]^ah control. You might argue that this is not good practice, but let’s examine it for the moment. View state tries to recognize the elements solely by their index. In this example the control at index [0] is the >qppkj. After postback it has been replaced by the H]^ah, using the same index [0]. This does not lead to the exception previously shown, because the restoring code is fairly stupid. It just looks for the right property, and both >qppkj and H]^ah share the same Patp property. While this works, the label now shows the text “Click here”. 7HY4HEEXCEPTIONAPPEARSEVENIFTHISLESS THAN IDEALMETHODFAILS PROBABLYBECAUSETHECONTROL does not provide the expected property. The first solution is simple. Turn off view state for the button control. Since you throw away the button anyway, view state is not required at all. If the view state is being saved, it can’t disturb the NEXTCYCLEˆPROBLEMSOLVED(EREISTHESOLUTIONINALLITSGLORY lnkpa_pa`rke`L]ca[Ejep$k^fa_poaj`an(Arajp=ncoa% w Download at WoweBook.Com

C H A P T E R 1 N U N D E R S T A N D I N G A S P . N E T

eb$EoLkop>]_g% w >qppkjiu>qppkj9jas>qppkj$%7 iu>qppkj*Aj]^haReasOp]pa9b]hoa7 bkni-*?kjpnkho*=``$iu>qppkj%7 iu>qppkj*Patp9?he_gdana7 y ahoa w H]^ahh]^ah9jasH]^ah$%7 bkni-*?kjpnkho*=``$h]^ah%7 y y (ADYOUBEENUSINGVIEWSTATEINTHEPRECEDINGSAMPLE THEPROBLEMWOULDRESOLVEITSELFˆTHAT is, if you had recreated the control after postback, which is one of the basic rules of dynamic con trols creation. The ultimate solution looks like this: lnkpa_pa`rke`L]ca[Ejep$k^fa_poaj`an(Arajp=ncoa% w >qppkjiu>qppkj9jas>qppkj$%7 iu>qppkj*Aj]^haReasOp]pa9b]hoa7 bkni-*?kjpnkho*=``$iu>qppkj%7 iu>qppkj*Patp9?he_gdana7 eb$EoLkop>]_g% w H]^ahh]^ah9jasH]^ah$%7 bkni-*?kjpnkho*=``$h]^ah%7 iu>qppkj*Reoe^ha9b]hoa7 y y (EREYOUARECLOSETOTHEBESTPRACTICE!LLOWALLCONTROLSONTHEPAGETOREMAINUNTOUCHEDAND switch the visibility on and off, as required, via code. The render method is smart enough to not ren der invisible controls. But that’s another topic and would lead us away from view state.

Initializing Dynamically Created Controls I discussed dynamic controls before and, reading the text, you might feel that there are some issues with them. This is indeed something you need to approach carefully, but there are no real issues. The problem is very similar to the one described before. Because you create the control when you choose, you have more influence and this makes your life easier. It does, however, run against the paradigm that says that you should code in a declarative way whenever possible, because you leave the world of declarative definitions completely. In any case, let’s look at how to handle another view state issue correctly. lq^he__h]ooIu?qopki?kjpnkh6?kjpnkh w lnkpa_pa`kranne`arke`?na]pa?deh`?kjpnkho$% w H]^ahh9jasH]^ah$%7 ?kjpnkho*=``$h%7 h*Patp9@]paPeia*Jks*PkHkjc@]pa$%7 y y

Download at WoweBook.Com

51

52

CH APT ER 1 N U NDER S TA NDING A S P . NET

You can create child controls any time, but the ?na]pa?deh`?kjpnkho method is the best opportunity for fitting into the event sequence. The initialize event is called and the control doesn’t miss the tracking of view state. The secret is the behavior of the ?kjpnkho*=`` call. This isn’t just ACOLLECTIONITDOESMUCHMOREWHENTHE=`` method is invoked. Even if all events of the parent hierarchy are complete, the control begins its regular life cycle and all events involved here are fired correctly. That means that the control starts tracking view state immediately after it’s added to the collection. ?na]pa?deh`?kjpnkho always seems too late, as even though it is called at different points in time, it’s always later than KjEjep*USTFORCOMPLETENESS YOUNEEDTOKNOWTHATITSBASED on Ajoqna?deh`?kjpnkho call, which happens in KjLnaNaj`an at the latest. For some reasons the call might come much earlier. It depends on the control’s parts being rendered due to specific condi TIONS4HISHAPPENSVIRTUALLYINDATA BOUNDCONTROLSTHATCANSHOWDIFFERENTTEMPLATESDEPENDING on actual state. Now take a closer look at the solution: lq^he__h]ooIu?qopki?kjpnkh6?kjpnkh w lnkpa_pa`kranne`arke`?na]pa?deh`?kjpnkho$% w H]^ahh9jasH]^ah$%7 h*Patp9@]paPeia*Jks*PkHkjc@]pa$%7 ?kjpnkho*=``$h%7 y y There is only a subtle difference. The control’s properties are set before the control is added, which means that it’s initialized before the KjEjep is fired, and that subsequently it has not yet begun to track the view state. You can also databind controls before they have been added to the parent control’s control hierarchy. This is very powerful and flexible. So real developers write their own custom controls and know how they work internally.

Summary In this chapter you learned about the internal processing of ASP.NET, especially the processing pipeline, which is running a single request and performs the steps required to create the content sent to the client finally. The pipeline forms the life cycle of application, pages, and controls. Dur ing the life cycle several states store current processing step’s data. To rescue data from one request to another, the view state is used. You learned what the view state is for and how to overcome the quirks and traps the implementation has. (OWEVER 7EBAPPLICATIONSHANDLEUSUALLYMORETHANONEREQUESTATATIME4HENEXTCHAPTER extends the description by looking into threading, thread pools, and other stuff required to make an ASP.NET project fast and reliable even if it comes under pressure from multiple requests.

Download at WoweBook.Com

CHAPTER

2

Worker and Threads

I

n the first chapter I looked into the handling of a page request, and, in particular, the application life cycle and page life cycle. This is the fundamental process that runs when anyone requests a page resource. However, Chapter 1 was a simplification of the situation—I assumed that only one request comes in at a time. Reality is quite different. Managing hundreds, or even thousands, of simultaneous requests requires advanced knowledge and skills. In this and subsequent chapters you will learn those skills. This chapter includes:

s (OW!30.%4HANDLESMULTIPLEREQUESTS



s (OWTOMANAGETHEWORKERPROCESSESANDOPTIMIZETHEWORKLOAD



s 4HETHREADMODEL THREADPOOLBEHAVIORANDHOWTOOPTIMIZEITSUSAGE



s (OWTOBUILDASYNCHRONOUS handlers, pages, and tasks

Managing the Worker Process In Chapter 1, you learned about the worker process, w3wp.exe, which executes a request and hosts THE!30.%4ENGINE-ANAGINGTHEWORKERPROCESSISTHEKEYTOMANAGINGHIGHSERVERDEMAND AND keeping your applications stable and reliable.

Managing Worker Processes and AppDomains in IIS7 One of the leading Windows application management tools is Windows Management Instrumentation (WMI)9OUHAVEPROBABLYUSED7-)TOADMINISTERBASIC!30.%4 RELATEDPARTSOF))3)TS a well-known way to access worker processes while your application is running. 4OACCOMMODATETODAYSMANAGED CODEWORLD -ICROSOFTEXPOSEDTHE7-)AND#/-METHOD CALLSVIA.%4)NPREVIOUSPROGRAMMINGENVIRONMENTS THEACCESSTOPROPERTIESANDEVENTSOFTHE MODELSCOMPONENTSISBASEDONUNTYPEDSTRINGS LIKEcapLnklanpu$J]ia%. Instead of invoking 7-)DIRECTLY YOUCANMANAGE))3USING.%4TYPEDCLASSES RATHERTHANUSINGTHOSEUNTYPEDSTRINGS 4HESECLASSESEXPOSEADIRECTINTERFACETOTHE))3MANAGEMENTLEVELANDAPPEARTOBEEASY to use and robust.

53 Download at WoweBook.Com

54

CH APT ER 2 N W OR K ER A ND THR EA DS

GOOD OLD DAYS: WINDOWS MANAGEMENT INSTRUMENTATION Windows exposes the Windows Driver Model as a framework for device drivers. Windows Management Instrumentation (WMI) is a set of extensions that provides information about and notifications from instrumented components. Programming environments and tools use WMI to access the underlying hardware components using the driver model. You can find a good introduction in Wikipedia at: dppl6++aj*segela`e]*knc+sege+Sej`kso[I]j]caiajp[ Ejopnqiajp]pekj. It suggests that WMI is a good tool for automating the management of worker processes and application domains in IIS7. It can also help us find a better way to customize the ASP.NET environment. IIS7 worker processes are spawned by the Windows Process Activation Service (WAS), using w3wp.exe. A worker process can contain AppDomains that are typically created to handle a request.

Prerequisites There areSEVERALPREREQUISITESTOWRITINGSOPHISTICATEDMANAGEMENTAPPLICATIONSUSING6ISUAL3TUDIO&IRSTOFALL ))3ITSELFISAPREREQUISITE.OOTHER7EB3ERVERCURRENTLYSUPPORTSTHESEINTERFACES To test your application, it must run with elevated privileges. If you run the development environMENTON7INDOWS6ISTA YOUMUSTLAUNCH6ISUAL3TUDIOWITH!DMINISTRATORRIGHTS!NAPPLICATION BUILTONSUCHASYSTEMRUNSWELLON7INDOWS3ERVER ASLONGASITRUNSWITH!DMINISTRATOR PRIVILEGES/NCE6ISUAL3TUDIOISRUNNINGWITHTHERIGHTACCOUNT YOUNEEDTOREFERENCETHEADMINISTRATIONASSEMBLIESINYOURPROJECT4HEREARESEVERALMANAGEDASSEMBLIESAVAILABLEINTHE))3 installation folder: 8!Sej@en!:Xouopai/.Xejaponr You will find several assemblies starting with the name “Microsoft.Web.” Depending on what YOUREPLANNINGTODO YOULLNEEDONEORANOTHER&ORTHEMOMENT JUSTREFERENCEALLOFTHEMTO ENSURETHATALLTHEEXAMPLESINTHISCHAPTERRUNPROPERLY(ERESTHELISTOFWHATYOULLNEED

s Ie_nkokbp*Sa^*=`iejeopn]pekj



s Ie_nkokbp*Sa^*I]j]caiajp*=oljap



s Ie_nkokbp*Sa^*I]j]caiajp*=oljap?heajp



s Ie_nkokbp*Sa^*I]j]caiajp



s Ie_nkokbp*Sa^*I]j]caiajp*Eeo



s Ie_nkokbp*Sa^*I]j]caiajp*Eeo?heajp

Tasks to Manage There are several tasks you can manage using the techniques described in this chapter. They will ALLOWYOUTOEXTENDTHEAVAILABLETOOLKITANDCUSTOMIZETHEMANAGEMENTOFTHE!30.%4ENVIRONment. I will focus here on some of the more common tasks, like:

s 6IEWTHECURRENTLYEXECUTINGREQUESTSFORAWORKERPROCESS



s 'ETTHESTATEOFALLWORKERPROCESSES



s 5NLOADASPECIFIC!PP$OMAIN ORALL!PP$OMAINS



s $ISPLAYALL!PP$OMAINSANDTHEIRPROPERTIES

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

There is almost unlimited scope for using the new management classes to extend the existing !30.%4MANAGEMENTCAPABILITIES4HISINCLUDES BUTISNOTLIMITEDTO THEFOLLOWING

s .OTIFYWHENANUNHANDLEDEXCEPTIONOCCURS



s 7ATCHLONG LASTINGREQUESTS



s 7ATCHTHENUMBEROFWORKERTHREADSANDSTATUSOFTHREADPOOL



s 0ROVIDETHENUMBEROFUSERSTHATMATCHSPECIFICCONDITIONS



s -ANAGEINTERNALSETTINGSOF!30.%4AND))3

Back Up Your Configuration It is possibleTHATTHEFOLLOWINGSAMPLESWILLDESTROYORDAMAGEYOUR))3CONFIGURATION!SITSCUMbersome to re-install your development environment after any undesirable side effects, you should TESTINAVIRTUALMACHINEORBACKUPTHE))3CONFIGURATIONOFYOURPRODUCTIONMACHINEBEFOREYOU START4HE!PP#MDTOOLISVERYUSEFULTOMAKEINSTANTBACKUPSOFTHECONFIGURATION)THASSEVERAL options. The basic structure of the command is: =ll?i`?kii]j`K^fa_pPulaE@L]n]iapan The _kii]j` parameter depends on the ObjectType parameter. For backup purposes the K^fa_pPula is >]_gql. You can use the following commands:

s LIST: shows all available backups



s ADD: creates a new backup for the current configuration



s DELETE: delete a backup from disk



s RESTORE: restore a backup and overwrite current configuration

4HEUSAGEISSTRAIGHTFORWARD!GAIN REMEMBERTORUNTHISTOOLWITH!DMINISTRATORPRIVILEGESTO ACCESSTHE))3SETTINGS To make a backup of the configuration: 1. /PENACOMMANDWINDOWWITH!DMINISTRATORRIGHTS 2. .AVIGATETO7IN$IR<SYSTEM
Download at WoweBook.Com

55

56

CH APT ER 2 N W OR K ER A ND THR EA DS

Figure 2-1. Backup command and created Backup folder with IIS7 settings

Basic Tasks The code in,ISTING SHOWSTHETYPICALSTRUCTUREOFAN))3MANAGEMENTCODESNIPPET9OUCAN USEWHATEVERCLIENTENVIRONMENTYOUPREFER9OUCOULDUSEASIMPLE70&7INDOWS0RESENTATION Foundation) client to display the data in a hierarchical format (such as a PnaaReas), or perhaps well-formatted in a Ne_dPatp>kt control. For the purpose of demonstrating sample code, a console application is a simple, satisfactory alternative. I will use the following generic test structure for the listing examples. Listing 2-1. Basic Code Structure for IIS7 Administration Code Snippets qoejcOuopai7 qoejcOuopai*Patp7 qoejcIe_nkokbp*Sa^*=`iejeopn]pekj7 j]iaol]_a=lnaoo*=olJapAtpajoe^ehepu*EEO3?kjokha w op]pe__h]ooEEO3I]j]caiajp w ejpanj]hop]pe_opnejcIapdk`$% w Opnejc>qeh`ano^9jasOpnejc>qeh`an$%7

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

++?k`ackaodana napqnjo^*PkOpnejc$%7 y y y 4HESESTATICMETHODSAREINVOKEDFROMTHECONSOLESENTRYPOINT4HEBASISFORMOSTOPERATIONS is the Ie_nkokbp*Sa^*=`iejeopn]pekj*OanranI]j]can class. From the OanranI]j]can class there are several collections available via corresponding properties:

s 3ITES3ITE#OLLECTION



s 7ORKER0ROCESSES7ORKER0ROCESS#OLLECTION



s &ROM3ITECLASSEXPOSEDBY3ITE#OLLECTION s !PPLICATIONS!PPLICATION#OLLECTION s "INDINGS"INDING#OLLECTION



s &ORM6IRTUAL$IRECTORIESCOLLECTIONEXPOSEDBY!PPLICATIONVIA!PPLICATIONSPROPERTY s 6IRTUAL$IRECTORY6IRTUAL$IRECTORY#OLLECTION

Through these collections you can reach the desired objects and properties for monitoring ANDMANAGING))39OUALWAYSHAVEREADANDWRITEACCESS4HATMEANSYOUCANVIRTUALLYCHANGE all configuration settings programmatically available using the Management Console. To save your changes, you need to explicitly call the ?kiiep?d]jcao method.

Get Information About the Worker Processes In the next example, I show you how to loop through each worker processONA7EB3ERVER9OULL see then how to display the currently executing requests, process ID, and state of each worker process, as well as the application pool to which it belongs.

Get the State of a Worker Process The Ie_nkokbp*Sa^*=`iejeopn]pekj*SknganLnk_aoo object inTHE))3ADMINISTRATIONHASAOp]pa property that indicates whether a worker process is starting, running, or stopping. There are two more properties that particularly interest us: =llLkkhJ]ia and Lnk_aooE`. The =llhe_]pekjLkkh property represents the application pool to which the worker process belongs. The Lnk_aooE` property CONTAINSTHEPROCESS)$THATUNIQUELYIDENTIFIESTHEWORKERPROCESSTHATISANINTEGERVALUE4HE Lnk_aooCqe` methodRETURNSTHEPARTICULAR'UIDSEE,ISTING   Listing 2-2. Getting Information About Worker Processes ejpanj]hop]pe_opnejcOdksSknganLnk_aooao$% w Opnejc>qeh`ano^9jasOpnejc>qeh`an$%7 pnu w OanranI]j]cani]j]can9jasOanranI]j]can$%7 bkna]_d$SknganLnk_aoolnk_eji]j]can*SknganLnk_aooao% w o^*=llaj`Bkni]p$SknganLnk_aoobkqj`6w,yXj(lnk_*Lnk_aooE`%7 o^*=llaj`Bkni]p$Xpx))=llLkkh6w,yXj(lnk_*=llLkkhJ]ia%7 o^*=llaj`Bkni]p$Xpx))Lnk_Cqe`6w,yXj(lnk_*Lnk_aooCqe`%7 o^*=llaj`Bkni]p$Xpx))Op]pa6w,yXj(lnk_*Op]pa*PkOpnejc$%%7

Download at WoweBook.Com

57

58

CH APT ER 2 N W OR K ER A ND THR EA DS

bkna]_d$=llhe_]pekj@ki]ej]ll@kiejlnk_*=llhe_]pekj@ki]ejo% w o^*=llaj`Bkni]p$ Xp'))=llhe_]pekj@ki]ejBkqj`6w,yXj(]ll@ki*E`%7 o^*=llaj`Bkni]p$ XpXpx))=ll@kiLduoL]pd6w,yXj(]ll@ki*Lduoe_]hL]pd%7 o^*=llaj`Bkni]p$ XpXp'))=ll@kiRenpL]pd6w,yXj(]ll@ki*Renpq]hL]pd%7 y y napqnjo^*PkOpnejc$%7 y _]p_d$At_alpekjat% w napqnjat*Iaoo]ca7 y y The worker processes are exposed by the property SknganLnk_aooao. The value should match the number of w3wp.exe instances running in the Windows Task Manager.

NTip

If there are no worker processes but IIS7 is running, open a Web site to force the process to launch.

4HEPROPERTIESUSEDDEPENDONTHEOBJECTYOUWISHTOINVESTIGATESEE&IGURE  2EFERTOTHE DOCUMENTATIONON-3$.TOGETFULLDESCRIPTIONSOFALLAVAILABLEVALUES3EEALSO dppl6++io`j*ie_nkokbp* _ki+aj)qo+he^n]nu+]]/03205*]olt for more details.

Figure 2-2. Watching worker processes To monitor your worker processes, check the Op]pa property. The state of a process can be one of the values defined in the SknganLnk_aooOp]pa enumeration:

s 3TARTING



s 2UNNING



s 3TOPPING



s 5NKNOWN

7HYCANTTHEWORKERPROCESSHAVEASTATEOFh3TOPPEDv!FTERTHEPROCESSHASBEENSHUTDOWN the executable is disposed of and removed from memory. The worker process then disappears from the list of processes. Therefore, the worker is first starting, then running, and, if there is nothing to DO STOPPING4HEREISNTASPECIFICSITUATIONWHERETHESTATEQjgjksj appears, as the name implies. I assume that it occurs when the process dies unexpectedly and hangs.

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

Get Executing Requests One excitingNEWFEATUREOF))3ISTHEABILITYTOSEETHEREQUESTSTHATARECURRENTLYEXECUTINGIN a worker process. You do this with the SknganLnk_aoo*CapNamqaopo method in a manner very similar to the one shown before. Retrieve the worker process and invoke the CapNamqaopo method to get the current requests. The CapNamqaopo method requires an ejp parameter to filter the results for requests that have run for at least the number of milliseconds specified. This is very useful for displaying only longRUNNINGREQUESTS)TSAGOODIDEATOSETTHEVALUETOZEROINITIALLYINORDERTOGETALLREQUESTS AS SHOWNIN,ISTING 

NTip

Capturing a request to test an application within the development environment can be tricky. Use the

Pdna]`*Ohaal method to make the request last long enough to be caught. Use an editor to save the following text into a file called Ohaal*]olt. The complete page for a request that will take a minute to execute: 8!Ouopai*Pdna]`ejc*Pdna]`*Ohaal$2,,,,% Naolkjoa*Snepa$E#ibej]hhubejeoda`***%!:

2UNNINGTHEMANAGEMENTCODE ASIN,ISTING  SHOWSTHATTHEREQUESTISRUNNINGANDDISPLAYSVARIOUSPROPERTIESFORTHEREQUEST4HECODEREQUIRESTHAT))3FEATURESLIKE2EQUEST-ONITOR are properly installed. This is an option you can activate in the Windows Components installation FEATUREOF3YSTEM#ONTROL0ANEL5SEInternet Information Services ° WWW Services ° Health & Diagnostics and check the Request Monitor option. Listing 2-3. Looping Through Some Properties of a Running Worker Process ejpanj]hop]pe_opnejcOdksNamqaop$% w Opnejc>qeh`ano^9jasOpnejc>qeh`an$%7 pnu w OanranI]j]cani]j]can9jasOanranI]j]can$%7 bkna]_d$SknganLnk_aoolnk_eji]j]can*SknganLnk_aooao% w bkna]_d$Namqaopnejlnk_*CapNamqaopo$,%% w o^*=llaj`Bkni]p$Namqaop6Xj%7 o^*=llaj`Bkni]p$Dkopj]ia9w,yXj(n*DkopJ]ia%7 o^*=llaj`Bkni]p$Qnh9w,yXj(n*Qnh%7 o^*=llaj`Bkni]p$Ran^9w,yXj(n*Ran^%7 o^*=llaj`Bkni]p$EL9w,yXj(n*?heajpEL=``n%7 y y napqnjo^*PkOpnejc$%7 y _]p_d$At_alpekjat% w napqnjat*Iaoo]ca7 y y

Download at WoweBook.Com

59

60

CH APT ER 2 N W OR K ER A ND THR EA DS

4HECONSOLESEE&IGURE  SHOWSALLTHEREQUESTSCURRENTLYRUNNINGONAVAILABLEWORKER PROCESSES"EFORERUNNINGTHISONAPRODUCTIONSYSTEM ITWOULDBEADVISABLETOADDSOMEFILTER conditions to avoid returning an excessive number of results.

Figure 2-3. Output shows detailed information about certain requests. Monitoring requests is not particularly suited to a console application. Imagine you have some REQUESTSTHATDONTFUNCTIONASEXPECTED BUTTHEERRORSAREINFREQUENTANDNOTREPRODUCIBLE)N this situation, you could write an application to monitor a specific request and log all relevant data. When the error reappears, your log file should contain information enabling you to track down the error source.

Get Information About the Application Domains The firstTIMEAREQUESTFORAN!30.%4PAGEISRECEIVED THE))3MANAGED engine module creates an APPLICATIONDOMAIN!PP$OMAIN INMEMORY WHICH)EXPLAINEDIN#HAPTER4HE!PP$OMAINPROCESSESREQUESTSFORASPXPAGES ORANYPAGETHATUSESMANAGEDCODE5NLOADINGANDENUMERATING !PP$OMAINSISSTRAIGHTFORWARD4HISSECTIONSHOWSYOUHOWTODOBOTH5NLOADINGAN!PP$OMAIN implicitly unloads all assemblies in there. You may use this to save spaces occupied by assemblies NOLONGERREQUIRED!NOTHERREASONISTHEDISTRIBUTIONOFNEWVERSIONSOFTHERELATEDASSEMBLIES WHICHAREREQUIREDTOBEUNLOADEDFIRSTANDLOADEDAGAINAFTERANUPGRADE"ECAUSETHEUNLOADINGOF INDIVIDUALASSEMBLIESISNOTDIRECTLYSUPPORTED THEUNLOADINGOFTHE!PP$OMAINISQUITE often the only option.

Unloading a Specific AppDomain To unload a specific Ie_nkokbp*Sa^*=`iejeopn]pekj*=ll@ki]ej, you must be able to uniquely idenTIFYIT!PP$OMAINSHAVETHREEKEYPROPERTIESE`, Renpq]hL]pd, and Lduoe_]hL]pd. One of these properties should be sufficient. 4HECODESNIPPETIN,ISTING SHOWSYOUHOWTOOBTAINTHEDESIRED!PP$OMAINUSINGA ,).1QUERY4HENESTEDbnki statements form a join to retrieve the =llhe_]pekj@ki]ejo property for each running SknganLnk_aoo object. The sdana clause restricts the result to the single !PP$OMAINDEFINEDBYTHEGIVENE`. For a real-life application, this value could be a variable. You saw the OdksSknganLnk_aooaoMETHODEARLIERIN,ISTING )TSNOTREQUIRED BUT)VEINCLUDED ITHEREFORDEMONSTRATIONPURPOSESSEE,ISTING  

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

Listing 2-4. Retrieve Information About the Application Domains ejpanj]hop]pe_opnejcQjhk]`=ll@ki]ej$opnejcj]ia% w Opnejc>qeh`ano^9jasOpnejc>qeh`an$%7 opnejce`9+HI+S/OR?+-+NKKP7 pnu w o^*=llaj`$OdksSknganLnk_aooao$%%7 OanranI]j]cani]j]can9jasOanranI]j]can$%7 r]n]ll@ki]ejo9bnkilnk_eji]j]can*SknganLnk_aooao bnki]`_ejlnk_*=llhe_]pekj@ki]ejo sdana]`_*E`99e` oaha_p]`_7 =llhe_]pekj@ki]ej]`9]ll@ki]ejo*BenopKn@ab]qhp8=llhe_]pekj@ki]ej:$%7 eb$]`9jqhh% w ]`*Qjhk]`$%7 napqnjj]ia'qjhk]`a`7 y ahoa w napqnj_]j#pbej`'j]ia7 y y _]p_d$At_alpekjat% w napqnjat*Iaoo]ca7 y y )NCIDENTALLY THE!PP$OMAINSE` property is a path that looks like this: +HI+S/OR?+-+NKKP 4HEhvINTHEPATHLISTEDISTHESITES)$hvUSUALLYCORRESPONDSTOTHEDEFAULT7EBSITE9OU COULDFINDANYNUMBERHERE DEPENDINGONHOWMANYWEBSYOUHAVEONTHEMACHINEYOURECURrently investigating. )FYOUGENERATEALISTOFYOURSERVERS!PP$OMAINSANDTHEIRPROPERTIESFIRST YOULLFINDTHERIGHT ONEEASILYSEE,ISTING WHEREYOUEXTRACTEDTHE!PP$OMAININSTANCESFROMTHECURRENTLYRUNning worker processes). (OWEVER THEPURPOSEOFTHESCRIPTWASTOUNLOADAPARTICULAR!PP$OMAIN4OUNDERSTANDWHAT HAPPENSWHENYOUUNLOADAN!PP$OMAIN RUNTHISSCENARIO

s 2EQUESTAPAGEFROMYOURSERVER



s 7ATCHRUNNINGPROCESSESAND!PP$OMAINSANDRETRIEVETHEPROPERTIES



s ,AUNCHTHECODEANDUNLOADTHEDOMAIN



s 2EQUESTTHEPAGEAGAIN



s 2ETRIEVETHEVERYSAME information from properties.

Download at WoweBook.Com

61

62

CH APT ER 2 N W OR K ER A ND THR EA DS

Unloading All AppDomains The nextEXAMPLEIN,ISTING UNLOADSALL!PP$OMAINS!GAIN )USE,).1ANDGENERICFEATURES 9OUDONTHAVETODOITTHISWAY BUTITRESULTSINCOMPACTANDHIGHLYREADABLECODE4HE,).1STATEment again uses a nested query. Listing 2-5. Unload All AppDomains ejpanj]hop]pe_opnejcQjhk]`=ll@ki]ejo$% w pnu w OanranI]j]cani]j]can9jasOanranI]j]can$%7 Bqj_8=llhe_]pekj@ki]ej(^kkh:qjhk]`Bqj_9± jasBqj_8=llhe_]pekj@ki]ej(^kkh:$Qjhk]`%7 r]n]ll@ki]ejo9bnkilnk_eji]j]can*SknganLnk_aooao bnki]`_ejlnk_*=llhe_]pekj@ki]ejo sdanaqjhk]`Bqj_$]`_%99pnqa oaha_p]`_7 napqnjQjhk]`a`']ll@ki]ejo*?kqjp$%'`ki]ej$o%7 y _]p_d$At_alpekjat% w napqnjat*Iaoo]ca7 y y lner]paop]pe_^kkhQjhk]`$=llhe_]pekj@ki]ej]ll@ki]ej% w pnu w ]ll@ki]ej*Qjhk]`$%7 napqnjpnqa7 y _]p_d w napqnjb]hoa7 y y The unload method is encapsulated in the callback function Qjhk]`)TTAKESTHE!PP$OMAIN as a parameter of type =llhe_]pekj@ki]ej!SBEFORE THEQUERYSTARTSBYRETRIEVINGTHEWORKERPROCESSESANDTHE!PP$OMAINSJOINEDTOTHEM)NTHEsdana clause, the inline method qjhk]`Bqj_$% is used to unload the domain. The Bqj_ type is a predefined typed delegate used to pass a parameter ANDRETRIEVEA"OOLEANRESULTFLAG4HECLAUSEFORCESTHEMETHODCALLTOQjhk]` and the return value DECIDESWHETHERTHE!PP$OMAINBECOMESPARTOFTHERESULTSET4HISLEADSTOADIRECTUSAGEOFTHE ?kqjp method that returns the number of successfully unloaded!PP$OMAINSSEE&IGURE  

Figure 2-4. Number of successfully unloaded AppDomains

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

Enumerating AppDomains Dealing with!PP$OMAINSINAMANAGEMENTENVIRONMENTOFTENSTARTSWITHSHOWINGALLAVAILABLEPROPERTIES&ORLEARNINGPURPOSESITMAKESSENSETOINVESTIGATETHE!PP$OMAINSPROPERTIES ,ISTING SHOWSHOWTOGETTHISINFORMATION4HEHELPFULPROPERTIESFORAN!PP$OMAINARE

s E`



s Renpq]hL]pd



s Lduoe_]hL]pd



s E`ha

IdRETURNSTHECURRENTINTERNAL)DOFTHE!PP$OMAIN4HERenpq]hL]pdISASDEFINEDINTHE))3 SETTINGSFORTHEROOTPATHITISUSUALLYhv5SUALLYTHEPHYSICALLOCATIONOFA7EBSITEISSAMEASTHE PATHUSEDASTHEPATHPARTOFTHE52,!VIRTUALPATHPOINTSTOALOCATIONOFCONTENTSOMEWHEREELSE ONTHE7EB3ERVEROREVENONAREMOTESERVER)FTHEREISNOVIRTUALDIRECTORYTHEVIRTUALPATHEQUALS the root (“/”). The Lduoe_]hL]pd is the full path to the application on local disk. The E`ha property ISARUNTIMEVALUE)TSDEFINEDASejpITRETURNSEITHEROR WHERETHELATTERISTHEVALUEFORANIDLE APPLICATIONDOMAINSEE,ISTING   Listing 2-6. Show Properties of AppDomains ejpanj]hop]pe_opnejcOdks=ll@ki]ejo$% w Opnejc>qeh`ano^9jasOpnejc>qeh`an$%7 pnu w OanranI]j]cani]j]can9jasOanranI]j]can$%7 r]n]ll@ki]ejo9bnkilnk_eji]j]can*SknganLnk_aooao bnki]`_ejlnk_*=llhe_]pekj@ki]ejo oaha_p Opnejc*Bkni]p$<Lduoe_]hL]pd9w,y w0yRenpq]hL]pd9w-y w0yLnk_aooE@9w.y w0yEoE`ha9w/y( ]`_*Lduoe_]hL]pd( ]`_*Renpq]hL]pd( ]`_*E`( ]`_*E`ha( Ajrenkjiajp*JasHeja%7 eb$]ll@ki]ejo*?kqjp$%99,% w o^*=llaj`$_]j#pbej`=ll@ki]ejo%7 y ahoa w bkna]_d$opnejc]`ej]ll@ki]ejo% w o^*=llaj`Heja$]`%7 y y napqnjo^*PkOpnejc$%7 y

Download at WoweBook.Com

63

64

CH APT ER 2 N W OR K ER A ND THR EA DS

_]p_d$At_alpekjat% w napqnjat*Iaoo]ca7 y y 4HE,).1QUERYRETRIEVESTHEWORKERPROCESSESANDTHEATTACHED!PP$OMAINS)NTHEoaha_p clause, the string is constructed to simplify output. You can alter this clause to retrieve the specific VALUESYOUDESIRE7ITHTHIS YOUCANMONITORYOUR!30.%4ENVIRONMENTWITHYOURCUSTOMAPPLICATION WITHOUTREQUIRING)NTERNET)NFORMATION3ERVICES-ANAGER#ONSOLE ASSHOWNIN&IGURE 

Figure 2-5. Information About a Running AppDomain 9OUCANCOMPARETHISINFORMATIONWITHTHATAVAILABLEINTHE))3-ANAGER#ONSOLE/PENTHE))3 Manager Console, navigate to the site, and click on Advanced Settings on Action List to see the settings and check against the values retrieved using the code shown previously. When working with the =llhe_]pekj@ki]ej object, you might see many more properties than were shown in the last example. This is because all settings derive from the ?kjbecqn]pekjOappejco TYPE WHICHCONTAINSSEVERALCOMMONPROPERTIESTHATYOUDONTNEED !DDITIONALVALUESABOUTTHEWORKERPROCESSAREHELPFUL TOO9OUCANADDTHESEEASILYBYEXTENDing the oaha_p clause in this manner: ]`_*SknganLnk_aoo*Lnk_aooE` The object ]`_ is of the current =llhe_]pekj@ki]ejTYPE"YUSINGABACKREFERENCETOTHE SknganLnk_aoo object, all property values available there can be retrieved directly.

Configuring the Worker Process 5NLIKECLASSIC!30 WHICHRUNSINTHESAMEMEMORYSPACEAS))3 !30.%4RUNSASAPROCESSOFITS own. This gives it more flexibility, stability, and power. You can use the configuration file machine. configTOMAKETHE7EBMASTERSJOBALOTEASIER )LLTAKEACLOSERLOOKHEREATTHE!30.%4PROCESSANDTHEATTRIBUTESTHATYOUCANADJUST4HE machine.configFILEISPLAIN8-,ANDEASYTOREAD!STHENAMEIMPLIES ITSADEFINITIONATTHEMACHINE LEVEL3EVERALPORTIONSDEFINETHEDEFAULTVALUESFORTHEAPPLICATIONANDTHEFOLDER SPECIFICweb.config. (OWEVER SOMEPARTSCANTBEOVERWRITTEN ANDTHERESNOPOINTINATTEMPTINGTO alter others.

The machine.config File !SMENTIONEDEARLIER VERSIONOFTHE.%4FRAMEWORKAUGMENTS RATHERTHANREPLACES .%4 &RAMEWORK4HISEXPLAINSWHYTHEmachine.configFILEISSTOREDUNDERTHEHIVE4HEPATHON your machine should look similar to: !Sej@en!XIe_nkokbp*JAPXBn]iaskngXr.*,*1,3.3X?KJBEC

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

4HEREARESEVERALOTHERCONFIGURATIONFILES BUTWEREONLYEXAMININGmachine.config"ECAUSE ITS8-, YOUCANUSE6ISUAL3TUDIOTOEDITIT4HEWORKERPROCESSSETTINGSARESTOREDINTHE 8lnk_aooIk`ah: tag)TSLOCATEDUNDER8ouopai*sa^: and usually looks like this: 8lnk_aooIk`ah]qpk?kjbec9pnqa+: Microsoft sets all common values using the auto configuration option. This is good for most INSTALLATIONS BUTNOTALL4OOPTIMIZETHESETTINGS YOUCANSETTHEVALUEOFTHISATTRIBUTETOb]hoa and change whatever you like: 8lnk_aooIk`ah]qpk?kjbec9b]hoa+: However, changing basic settings is not simple and may lead to servers not responding or perFORMINGPOORLY"EFOREGOINGON LETMEEXPLAIN the various settings.

NNote

Changes made to the 8lnk_aooIk`ah: tag do not have immediate effect. You must restart a worker process to force it to re-read the settings. To restart a worker process, you can open Task Manager, right-click the w3wp.exe found in the task list, and kill the process. The worker process will start again automatically.

Why Customize the machine.config Settings? You mayWONDERWHYANDWHENYOURESUPPOSEDTOCHANGETHEmachine.config settings and the 8lnk_aooIk`ah:SETTINGS,ETSCONSIDERTHEFOLLOWINGSCENARIO

s 9OURNETWORKSUPPORTSONLYONEAPPLICATIONDOMAIN!PP$OMAIN 



s %ACHPAGECAUSESONEREQUESTNOSUBSEQUENT!*!8CALLS 



s !LLREQUESTSGOTOTHESAME)0ADDRESS

In this case, the default settings are very good and there is no reason to change anything. However, other specific scenarios could be problematic:

s 2EQUESTSTOMANY)0ADDRESSES



s &REQUENTREDIRECTS(440STATUSCODE



s 5SINGAUTHENTICATION



s 5SINGMORETHANONE!PP$OMAIN

The following section describes all the lnk_aooIk`ah parameters. (In a later section in this chapTER h#ONFIGURINGTHE4HREAD0OOL v)LLEXPLAINTHISINEVENGREATERDEPTH +EEPINMINDTHAT BEHINDTHESCENES ))3MUSTHANDLETHEAVAILABLERESOURCESTOMANAGEALL incoming requests. If the rate of incoming page requests is such that the fraction of memory in use OR#05POWEREXCEEDSCERTAINLEVELS THEDEFAULTVALUESFORTHElnk_aooIk`ah parameters may not be optimal. However, setting higher values is not always better, as this can lead to higher resource consumption and slow down even a lightly-loaded server handling simple requests. Finding the most appropriate options in the parameter jungle is a challenge.

A First Look into the Attributes ABLE LISTS the lnk_aooIk`ah attributes available. The description column indicates the purpose 4 of each attribute and where to find more information.

Download at WoweBook.Com

65

66

CH APT ER 2 N W OR K ER A ND THR EA DS

Table 2-1. Settings Available for the <processModel> Tag (Excerpt)

Attribute

Default

Description

_heajp?kjja_pa`?da_g

FIVESECONDS

Once a request has been waiting in the queue FORTHISLONG !30.%4CHECKSWHETHERTHECLIent is still connected.

_lqI]og

XFFFFFFFF

3PECIFIESWHICH#05OFAMULTIPROCESSOR SYSTEMRUNS!30.%4PROCESSES4HEVALUEIS ABITMASKWHEREEACHBITREPRESENTSA#05 !SSUMEYOUSETTHEVALUETOXA WHICHIS INBINARYFORM#05SARENUMBEREDBEGINNINGWITH ANDREADFROMRIGHTTOLEFT&ORTHIS VALUE #05SANDAREQUALIFIEDTORUN!30 .%4THREADSAND#05SANDARENOT

aj]^ha

true

%NABLESORDISABLESTHEPROCESSMODEL

e`haPeia

Infinite

The period of inactivity (in time format hh:mm:ss), after which the worker process ENDS&OREXAMPLE AVALUEOFhvWILL CAUSETHEWORKERPROCESSTOSHUTDOWN minutes after the last request is concluded.) “Infinite” prevents the worker process from stopping at all.

hkcHarah

%RRORS

The quantity of errors written to the event log. #HOOSEFROMh!LL vh%RRORS vORh.ONEv

i]t=ll@ki]ejo



The number of application domains in one PROCESS4HEDEFAULTVALUE  ISTHEMAXImum allowed. Lower values are appropriate for hosting providers, for instance.

i]tEkPdna]`o



The maximum number of threads for I/O OPERATIONS COUNTEDONAPER #05BASIS-UST be greater than or equal to iejBnaaPdna]`o in 8dpplNqjpeia:SETTINGS!LLOWEDRANGEIS BETWEENAND3EETHESECTIONh5NDERSTANDINGAND5SING4HREADSvINTHISCHAPTER for more information.

i]tSknganPdna]`o



The maximum number of worker threads, COUNTEDONAPER #05BASIS-USTBE greater than or equal to iejBnaaPdna]`o in 8dpplNqjpeia:SETTINGS!LLOWEDRANGEIS BETWEENAND3EETHESECTIONh5NDERSTANDINGAND5SING4HREADSvINTHISCHAPTER for more information.

iaiknuHeiep



4HEMAXIMUMALLOWEDMEMORYSIZEASA percentage of total system memory that one WORKERPROCESSISALLOWEDTOCONSUME"EYOND this limit, a new worker process is launched and subsequent requests are redirected to this one.

iejEkPdna]`o

1

4HEMINIMUMNUMBEROF)/THREADS3EETHE SECTIONh5NDERSTANDINGAND5SING4HREADSvIN this chapter for more information.

iejSknganPdna]`o

1

The minimum number of worker threads. 3EETHESECTIONh5NDERSTANDINGAND5SING Threads” in this chapter for more information.

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

Attribute

Default

Description

qoanj]ia, l]ooskn`

!UTO'ENERATE

The account used to run the worker process.

lejcBnamqaj_u

Infinite

The time interval in hh:mm:ss format used to ping the worker process to get its state. If the worker process is not running, it is restarted.

lejcPeiakqp

Infinite

The time, also in hh:mm:ss format, waiting FORARESPONSETOAPINGREQUEST!FTERAPING timeout is detected, the process is restarted.

namqaopHeiep

Infinite

The number of requests a single worker PROCESSCANHANDLE"EYONDTHISVALUEANEW worker process starts.

namqaopMqaqaHeiep



The number of requests allowed in the queue. !NYREQUESTBEYONDTHISLIMITRECEIVESTHE (440ERRORh3ERVER4OO"USYvRESPONSE

naolkjoa@a]`hk_gEjpanr]h 

The time period (again in hh:mm:ss format) allowed for the worker process to respond TOAQUEUEDREQUEST!FTERTHETIMEPERIOD expires, the worker process is restarted. The default is three minutes.

naop]npMqaqaHeiep



!FTERANONSTANDARDUNEXPECTED TERMINAtion of the worker process, incoming requests are queued, waiting for the worker process to become available. The value specifies the number of requests queued.

oanranAnnknIaoo]caBeha

-

!FILEPATHEITHERABSOLUTEORRELATIVETOTHE machine.config file path) for a file containing the error message to send to the client when a fatal error occurs. If no file is present or the ATTRIBUTEISNOTSET THESTRINGh3ERVERUNAVAILable” is sent. This is the default setting.

odqp`ksjPeiakqp



The time the worker process is allowed to take when shutting the process down. If this time interval is exceeded, the worker process is forcibly terminated.

peiakqp

Infinite

)FAWORKERPROCESSISNOTRESPONDING !30.%4 launches a new one after the specific period is elapsed.

sa^C]n`aj    

False

!FLAGWHICHINDICATESTHATTHEATTRIBUTECPUMask is being used. If False (default), this MEANSTHATALL#05CORESAREAVAILABLEFOR worker processes and the operating system DECIDESWHICH#05WILLHANDLETHENEXT request.

Download at WoweBook.Com

67

68

CH APT ER 2 N W OR K ER A ND THR EA DS

Additional Settings Outside the ProcessModel Tag The 8lnk_aooIk`ah: tag attributes control most of the relevant settings. However, there are more tags where you can refine the configuration. One important setting is shown in the following: 8ouopai*jap: 8_kjja_pekjI]j]caiajp: 8]``]``naoo9&i]t_kjja_pekj9-,,+: 8+_kjja_pekjI]j]caiajp: 8+ouopai*jap: This does not impact your client connections but controls the connections you make from your APPLICATIONTOOTHERSERVERS SUCHASFETCHING233FEEDSORUSING7EB3ERVICESONANOTHERSERVER4HE default for the attribute i]t_kjja_pekjIS WHICHISOBVIOUSLYTOOLOW)TMEANSYOUCANNOTMAKE MORETHANTWOSIMULTANEOUSCONNECTIONSTOAN)0ADDRESS FROMYOURWEB application. In the preceding sample theVALUEISSETTO

Specific Tasks 5SINGTHESE settings, you can perform specific tasks. The following sections explain how to use the attributes to:

s 2ECYCLETHEWORKERPROCESS



s 3HUTDOWNTHEWORKERPROCESS



s #HECKIFTHECLIENTISSTILLCONNECTED

Recycling the Worker Process !COMMON task configured in this manner is the recycling of the process. This generally improves the stability and reliability of your web application. There are five ways to recycle a process using the attributes peiakqp, namqaopHeiep, iaiknuHeiep, naolkjoa@a]`hk_gEjpanr]h, and the pair lejcBnamqaj_u/lejcPeiakqp. In the following list, they are explained one by one:

s peiakqp9046,,6,, This involves the peiakqp attribute, which simply creates a new process after the specified time interval elapses. For example, the preceding setting will start a new process after HOURS ORTWODAYS4HEFIRSTREQUESTCAUSESTHETIMERTOSTART



s namqaopHeiep9-,,,



!NOTHERWAYISTOUSETHEnamqaopHeiep attributeANDAN)NTEGERVALUE!VALUEOF WILL STARTANEWWORKERPROCESSAFTER REQUESTSHAVEBEENMADE4HISCANBEUSEFULIFYOUR WEBSERVERSPERFORMANCEDEGRADESAFTERASETNUMBEROFREQUESTS4HISCOULDHAPPENIF YOURAPPLICATIONORCOMPONENTSINITDOESNTFREEALLMEMORY



s iaiknuHeiep9/,



!THIRDWAYISTOLETYOURSYSTEMWATCHHOWMUCHMEMORYTHEPROCESSISCONSUMING)NTHE preceding example, the attribute iaiknuHeiepISSETTOOFTHETOTALSYSTEMMEMORY/NCE the limit is reached, the process is killed, a new one is created, and all existing requests are REASSIGNEDTOTHENEWPROCESS4HISISHELPFULWHENYOUHAVEAMEMORYLEAK5SUALLYYOU set this option if you have no influence on the application or parts of it, for example, if your APPLICATIONSSUFFERFROMATHIRD PARTYCOMPONENTOFTHATYOUCANTSURRENDER

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S



s naolkjoa@a]`hk_gEjpanr]h9,,6,.6,,



!FOURTHAPPROACHISTOUSETHEnaolkjoa@a]`hk_gEjpanr]h attribute. The time setting of two minutes will restart the process if there are requests in the queue and if there have been no responses for the last two minutes.



s lejcBnamqaj_u9,,6,,6/,



s lejcPeiakqp9,,6,,6,1

The final method for recycling the process is to use the lejcBnamqaj_u and lejcPeiakqp attributesINTANDEM4HE)3!0)EXTENSIONPINGSTHEPROCESSATTHElejcBnamqaj_u interval, and restarts it if there is no response within the lejcPeiakqp time interval.

IMPACT OF RECYCLING THE WORKER PROCESS Recycling the worker process might have an impact on current state of application and sessions. By default, you will have an “overlapping” recycle. A new worker process will be created, and will start serving new requests. The old worker process will continue serving existing requests. When all existing requests have been services, the old worker process is shut down. Your Web site should experience no down-time. The actual time it takes for the old worker process to finish servicing all requests depends on what the requests are doing. Most requests are served in a short period of time, but suppose one is performing a long-running database query that takes more time. If so, then the old worker process will hang around for a couple of seconds. Be aware that if your web application is using in-process session state, then you will lose all sessions during a recycle. Using ASP.NET you can configure your applications to use the ASP.NET session state service, or an SQL Server to store session state, in which case you will not lose session state.

Shutting Down the Process There are two ways of shutting down the worker process.

s e`haPeiakqp9,,6.,6,, The first way uses the e`haPeiakqp attribute. If the server has not served any requests for MINUTESINTHISEXAMPLE THENITAUTOMATICALLYSHUTSDOWNTHEPROCESS)FANEWREQUEST comes in, a new process is started automatically. This might be useful if you experience long periods of inactivity. The server can then handle other tasks better because there is more free memory.



s odqp@ksjPeiakqp9,,6,,6-, The second way is by using the odqp@ksjPeiakqp attribute. This is used as a last resort after the worker process tries to shut down gracefully and fails. In this case, after the time set here has passed, a low-level kill command is performed on the process to ensure its termination. This is useful in situations where the process has crashed and is no longer responding. The setting shown will force a kill after ten seconds.

Download at WoweBook.Com

69

70

CH APT ER 2 N W OR K ER A ND THR EA DS

Checking Whether the Client Is Still Connected This is useful for eliminating unwanted requests from the queue.

s _heajp?kjja_pa`?da_g9,,6,,6-,



5SERSCANBECOMEIMPATIENT)FYOURWEBSERVERISSLOWTORESPONDTOTHEIRREQUESTS THEY MIGHTCLICKONTHESAMELINKMANYTIMES%VENIFONLYTHELASTREQUESTISRETURNEDTOTHEM the server will process all the previous ones. Furthermore, if the user abandons their session with your server, the queue from that user will remain. In the preceding example, the server will check each request at ten seconds intervals after it has entered the queue, to ensure that the user who made it is still connected. If he or she is not, the server discards that request. TheREQUESTISDISCARDEDALWAYSBEFOREITSPASSEDTOTHEWORKER process.

Understanding and Using Threads )N!30.%4 THREADS are like magic. Threads areWELL KNOWNANDEASYTOPROGRAMUSING.%4TECHNIQUES(OWEVER IN!30.%4 threading is handled behind the scenes and consequently regarded by some developers as unimportant. This common misunderstanding of threading can cause poor performance, unpredictable behavior, and, in the end, unreliable applications.

ASP.NET Thread Usage on IIS 4HREADINGIN!30.%4ISCOMPLICATEDBYTHEVARIOUSCHANGES-ICROSOFTAPPLIEDOVERTHEYEARSWITH EACHNEWVERSIONOF))3!SYOUSAWIN#HAPTER ))3PLAYSAMAJORPARTIN!30.%4SREQUESTPROCESSING"ECAUSEOFTHECO EXISTENCEOF))3AND))3 )WILLFIRSTEXPLAINHOWTHREADSAREHANDLEDIN ))3 ANDTHENTHECHANGESINTHREADINGINTRODUCEDWITH))3 9OUMAYALSOTHINKOFOTHERHOSTINGCAPABILITIES!30.%4SUPPORTS"ECAUSETHREADINGHAS a direct and explicit relation to multiple requests and high workload, other environments, such as 6ISUAL3TUDIOSINTEGRATED7EB3ERVER DONOTHANDLETHREADSINANYSPECIALWAYWORTHDISCUSSING 4HATSTHEREASONWHYAPPLICATIONSMIGHTBEHAVEDIFFERENTLYWHENRUNNINGINEITHER))3ORANOTHER 7EB3ERVER

Thread Usage with IIS6 %ACHREQUESTFROMTHEOUTSIDEWORLDTOTHE7EB3ERVERRUNNING!30.%4ENGINE is handed over to AN)/THREADON))34HISTHREADCOMESFROMTHE#,2#OMMON,ANGUAGE2UNTIME 4HREAD0OOL ANDRETURNSTHESTATUSh0ENDINGvTO))3(AVINGPASSEDTHEWORKONTOTHENEWTHREAD ))3ISNOWFREE to service other requests, such as requests for static resources. 4HE#,24HREAD0OOLWORKSLIKEAQUEUE)TCANADJUSTITSELFACCORDINGTOTHEACTUALWORKLOAD This means that the situation depends on the frequency of incoming requests and the ability of the processor workload to respond to each request. There are two extreme situations you need to take care of. First, you might receive many simultaneous requests that are processed quickly. In this case, THE4HREAD0OOLWILLATTEMPTTORUNONLYONEORTWOTHREADSPER#05TOENSUREAVERYLOWLATENCY (waiting time). 3ECOND YOUMIGHTRECEIVEAFEWREQUESTSWHEREONEISPROCESSORINTENSIVEANDSOMEWHAT LONG RUNNING!DDITIONALINCOMINGREQUESTSWILLCAUSEMORETHREADSTOBESPAWNEDPER#054HE processing time will always be longer in this scenario.

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

!QUEUEISACLEVERWAYTOAVOIDALLOCATINGALOTOFMEMORYFOREACHREQUEST BEFOREPROCESSing starts and memory-expensive objects such as DpplNamqaop are created. Keep in mind that the thread queue is in native memory and has no overhead caused by managed code components. Once a thread is ready for processing, you leave the unmanaged world and start working completely within the managed code realm. 4HE4HREAD0OOL queue is not the only way to handle a lot of incoming requests. Within each !PP$OMAINTHEREAREWAYSTOHANDLEREQUESTSTHATEXCEEDTHENUMBEROFAVAILABLETHREADS)FTHERE ISLOTOFLATENCY THE4HREAD0OOLSTARTSGROWINGANDLAUNCHESMOREACTIVETHREADS(OWEVER THERE are physical limitations; either the system runs out of threads, or the available memory restricts the number of threads.

NNote

By default the ThreadPool has a limitation of 25 worker threads per CPU and 1000 I/O completion threads.

!30.%4SETSITSOWNLIMITSTO4HREAD0OOLUSAGE)FTHISLIMITISEXCEEDED INCOMINGREQUESTSARE still handled, but another queue is now built on the application level and performance becomes significantly worse. You can control the settings with the following parameters of the 8dpplNqjpeia: tag:

s iejBnaaPdna]`o: This parameter specifies the minimum number of free threads for new REQUESTS4HATSUSEDTOASSURETHATREQUESTSTHATNEEDADDITIONALTHREADSINTERNALLYARE HANDLEDPROPERLY4HEDEFAULTVALUEIS



s iejHk_]hNamqaopBnaaPdna]`o: This parameter specifies the number of free threads for local requests. These are requests from a local host in case of child requests issued during processING4HISHELPSPREVENTDEADLOCKSCAUSEDBYRECURSIVERE ENTRIES4HEDEFAULTVALUEIS

0ERFORMANCE#OUNTERSAREWIDELYUSEDIN7INDOWSTOMONITORASYSTEMRUNNINGWITHHIGH WORKLOAD4OOBSERVETHEINTERNALBEHAVIOROFTHE4HREAD0OOL YOUCANUSETHEFOLLOWINGCOUNTER h!30.%4!PPLICATIONS<2EQUESTSIN!PPLICATION1UEUEv !NYVALUEBUTZEROSHOWSTHATTHEREISAPERFORMANCEPROBLEMONTHATSYSTEM ASITINDICATES THATTHE4HREAD0OOLHASATSOMETIMERUN out of threads.

Managing the ThreadPool 5SUALLYTHE4HREAD0OOL does not require managing, because few sites exceed the default limitations. !DDITIONALLY THE]qpk?kjbecSETTINGSALLOWTHE!30.%4ENGINETOOPTIMIZEBEHAVIORASMUCHAS POSSIBLE(OWEVER MAINTAININGAN!30.%4SYSTEMTHATISRUNNINGNEARITSLIMITSISTHEGOALOFTHIS BOOK)FYOUEXPERIENCEPERFORMANCEISSUES ITSTIMETOEXPLOREMANUALINTERVENTION4HEAUTOSETtings assume that the number of concurrently executing requestsPER#05IS!NAPPLICATIONWITH high latency might require higher values.

Thread Usage with IIS7 )N#HAPTER )DISCUSSED))3ANDINTEGRATEDMODESEVERALTIMES!S mentioned earlier, the differENCESBETWEEN))3AND))3ARESIGNIFICANTFORBASICPAGEREQUESTPROCESSING First of all, the queues built on the application level are gone, due to poor performance. The bigGESTDIFFERENCEISTHAT))3RESTRICTSTHENUMBEROFTHREADS WHILE))3RESTRICTSTHENUMBEROFREQUESTS %ACHTHREADIN))3HANDLESAREQUEST ANDTHISˆINDIRECTLYˆLIMITSTHENUMBEROFREQUESTSHANDLEDIN PARALLEL))3ISABLE DUETOTHETIGHTINTEGRATIONOF!30.%4WITHIN))3 TODIRECTLYRESTRICTTHENUMBER OFREQUESTS)TISWHENYOUEMPLOYASYNCHRONOUSPROCESSINGTHATTHISMAKESADIFFERENCE!LTHOUGHTHE processing pipeline is usually synchronous (see Chapter 1), both handlers and modules, can be set up to run asynchronously. I explain this, with examples, in Chapter 3.

Download at WoweBook.Com

71

72

CH APT ER 2 N W OR K ER A ND THR EA DS

For requests that are processed synchronously, the number of threads equals the number of requests, as each request runs in a single thread. If the processing is asynchronous, the number of threads may differ from the number of requests. Imagine that an incoming request starts processINGANDISRUNNINGALONG LASTINGACTION4HETHREADISHANDEDOVERTO!30.%4 AND))3ACCEPTSTHE next incoming request. This leads eventually to more concurrently running requests than threads. !30.%4GETSTHEREQUESTASINCOMING))3)/THREAD4HE#,24HREAD0OOLISIMMEDIATELYASKED TOCREATEANDSTARTANEWTHREAD ANDTHISTHREADBECOMESRESPONSIBLEFORTHISVERYREQUEST!S QUICKLYASITSTARTS ITRETURNSWITHSTATUSOFh0ENDINGv!FTERTHIS ))3CHECKSTHENUMBEROFREQUESTS currently executing. If this value is too high, the next request is put in a process-wide global queue. This queueISINNATIVECODEWITHIN))3

Configuring the ThreadPool In the 8lnk_aooIk`ah: configuration settings are the following parameters:

s ]qpk?kjbec



s i]tSknganPdna]`o



s i]tEkPdna]`o



s iejSknganPdna]`o



s iejEkPdna]`o

4HESETTINGSFOR))3iejBnaaPdna]`o and iejBnaaPdna]`o in the dpplNqjpeia tag are still there, BUTTHEYDONOTHING4HEYARETHEREMERELYFORBACKWARDSCOMPATIBILITY"UTWHERECANYOUFINDTHE SETTINGSFOR))37ITH.%430THESETTINGSBECOMEAVAILABLE1 in web.config, as the following shows: 8ouopai*sa^: 8]llhe_]pekjLkkhi]t?kj_qnnajpNamqaopoLan?LQ9-. i]t?kj_qnnajpPdna]`oLan?LQ9, namqaopMqaqaHeiep91,,,+: 8+ouopai*sa^: The web.config settings override the settings in the Registry mentioned in the footnote. They are not values that you would change frequently. You might experiment with different quantities, but the default is usually appropriate. The current settings are a compromise between requests for static resources such as images, and dynamic resources such as aspx pages. )N#HAPTER )LLEXPLAINTHEEXTENSIBILITYCONCEPTSOFRESOURCEMANAGEMENT4HISINCLUDESTHE CREATIONOFDESIGNTIMEEXPRESSIONSTORETRIEVERESOURCES)TSPOSSIBLETOSUPPRESSCODECOMPILATION when your aspx pages consist solely of declarative markup, resources, and expressions. This is a way TOOPTIMIZEOVERALLSYSTEMPERFORMANCEUNDERPARTICULARCIRCUMSTANCES .OW YOUCOULDTRYSETTINGTHENUMBEROFTHREADSPERREQUESTTO)FYOUHAVEONLYSTATIC requests and no (or very few) dynamic ones, and if these dynamic requests are fast due to such techniques like caching, this might improve performance. Imagine that the requests are now being EXECUTEDWITHINTHE))3)/THREADANDTHATTHEREISNOHANDOVERPROCEDURETOTHE#,24HREAD0OOL Less overhead leads to faster resource processing. The opposite scenario appears when you have many heavily asynchronous operations. In this CASE THELIMITOFTHREADSMIGHTBETOOLOW)MAGINEASCENARIOYOULLPROBABLYWORKWITH!JAX enabled applications. These applications have fewer page requests but many background tasks CREATEDBY*AVA3CRIPTWEBSERVICEPAIRS4HISISHEAVILYASYNCHRONOUS ANDASINGLEWEBPAGECAN  "EFORETHEAPPEARANCEOF.%430 THESETTINGSCANBEFOUNDINTHE2EGISTRYUNDERTHEPATH (+%9?,/#!,?-!#().%<3/&47!2%<-ICROSOFT
C H A P T E R 2 N W O R K E R A N D T H R E A D S

send large numbers of such requests. If you look into browser-based Outlook clients or Word-like TEXTPROCESSINGINTERFACES YOULLSEETHATALOTOFBACKGROUNDWORKHAPPENSEVENWHENTHEUSER MERELYMOVESTHEMOUSEPOINTER3ETTINGSOFUPTOSEVERALTHOUSANDAREPOSSIBLEINORDERTOHANDLE MANYSIMPLEREQUESTS ISTHELIMIT WITHOUTMAKINGCHANGESELSEWHERE in the system.

Server Too Busy You might beWONDERINGWHENANDWHYTHEh3ERVER4OO"USYvSTATUSISSENTTOTHECLIENT4HISIS (440STATUSERRORANDAPPEARSAMONGOTHERREASONSWHENTHELIMITOFCONCURRENTREQUESTS EXCEEDSTHEDEFAULTVALUEOF  WHICHCOULDBECHANGESBYTHEnamqaopMqaqaHeiep parameter MENTIONEDBEFORE4HEACTUALVALUEISEXPOSEDBYTHEh!30.%42EQUESTS#URRENTvPERFORMANCE counter. 3EETHESECTIONh)NSTALLA0ERFORMANCE#OUNTERvFORDETAILSONHOWTOMONITORANDLOGSUCHVALues and discover what is happening to your server at any given moment.

Tune the Threading The previous explanations might discourage you from changing theSETTINGS(OWEVER THEYRE worth exploring when performance issues arise or strange errors occur. This section shows some solutions for the following error messages:

s !PROCESSSERVINGAPPLICATIONPOOLhNAMEvEXCEEDSTIMELIMITSDURINGSHUTDOWN



s 3YSTEM)NVALID/PERATION%XCEPTION4HEREARENOTENOUGHFREETHREADSINTHE4HREAD0OOL object to complete the operation.



s (TTP%XCEPTIONX 2EQUESTTIMEDOUT To solve the preceding problems, try the following:



s ,IMITTHENUMBEROFREQUESTSTHATCANEXECUTEATTHESAMETIMETOAPPROXIMATELYPER #054HISLIMITWORKSWELLFORMOSTAPPLICATIONS



s 0ERMIT7EB3ERVICECALLBACKSTOFREELYUSETHREADSINTHE4HREAD0OOL



s 3ELECTANAPPROPRIATEVALUEFORTHEi]t_kjja_pekjoATTRIBUTE"ASEYOURSELECTIONONTHE NUMBEROF)0ADDRESSESAND!PP$OMAINSTHAT are used (more details follow in the section h3ETMAXCONNECTIONv 

Tuning Task by Task This section gives some examples of how and when to change the default settings of the following values:

s MAX7ORKER4HREADS



s MIN7ORKER4HREADS



s MAX)O4HREADS



s MIN&REE4HREADS



s MIN,OCAL2EQUEST&REE4HREADS



s MAXCONNECTION



s EXECUTION4IMEOUT

Download at WoweBook.Com

73

74

CH APT ER 2 N W OR K ER A ND THR EA DS

Set maxWorkerThreads and maxIoThreads !30.%4USES the following two configuration settings to limit the number of worker threads and completion threads used: 8lnk_aooIk`ahi]tSknganPdna]`o9.,i]tEkPdna]`o9.,: The i]tSknganPdna]`o attribute and the i]tEkPdna]`o attribute are implicitly multiplied by THENUMBEROF#05S)NTHEEXAMPLE THEMAXIMUMNUMBEROFWORKERTHREADSISIFYOUHAVE a dual-core processor.

Set minFreeThreads and minLocalRequestFreeThreads !30.%4ALSO contains the following configuration settings, which determine how many worker threads and completion port threads must be available to start a remote request or a local request: 8dpplNqjpeiaiejBnaaPdna]`o94iejHk_]hNamqaopBnaaPdna]`o94: If there are insufficient threads available, the request is queued until sufficient threads are FREETOHANDLETHEREQUEST4HEREFORE !30.%4WILLNOTEXECUTEMORETHANTHEFOLLOWINGNUMBEROF requests at the same time: $i]tSknganPdna]`o&jqi?LQo%)iejBnaaPdna]`o The iejBnaaPdna]`o parameter and the iejHk_]hNamqaopBnaaPdna]`o attributes are not implicITLYMULTIPLIEDBYTHENUMBEROF#05S!SSUMINGYOUHAVEFOUR#05S THEFORMULAGIVENEQUALS PARALLELREQUESTS n 

Set minWorkerThreads !30.%4ALSO contains a configuration setting for the number of worker threads to be made available immediately to service a remote request. 8lnk_aooIk`ahiejSknganPdna]`o9-: The specified number of threads that are controlled by this setting can be created at a much FASTERRATETHANWORKERTHREADSTHATARECREATEDFROMTHE#,2SDEFAULTCAPABILITIES4HESEARESTILL regular threads, but they are prepared and ready to use anytime. Requests may suddenly fill the request queue due to a slow-down on a back-end server, a sudden burst of requests from the client end, or something similar that would cause a sudden rise in the number of requests in the queue. The default value for the iejSknganPdna]`o parameter is 1. Microsoft recommends that you set the value for the iejSknganPdna]`o parameter to half of the i]tSknganPdna]`oVALUE"YDEFAULT THE iejSknganPdna]`o parameter is implicitly multiplied byTHENUMBEROF#05S

Set maxconnection The i]t_kjja_pekj attributeDETERMINESHOWMANYCONNECTIONSCANBEMADETOASPECIFIC)0 address. The setting was mentioned before, but here is a more complex scenario: 8_kjja_pekjI]j]caiajp: 8]``]``naoo9&i]t_kjja_pekj9.: 8]``]``naoo9-,*2*.,1*40i]t_kjja_pekj9.,: 8+_kjja_pekjI]j]caiajp: The i]t_kjja_pekjSETTINGAPPLIESATTHE!PP$OMAINLEVEL#ONSEQUENTLY ONLYTWOCONNECTIONSBYDEFAULT CANBEMADETOASPECIFIC)0ADDRESSFROMEACH!PP$OMAININYOURPROCESS

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

)NTHISEXAMPLE ALL)0ADDRESSESACCEPTTWOCONNECTIONS EXCEPTFORTHESPECIFIEDONEAT  WHICHACCEPTS

Set executionTimeout !30.%4USES the following configuration setting to limit the request execution time (in seconds): 8dpplNqjpeiaata_qpekjPeiakqp95,+: This refers to the Oanran*O_nelpPeiakqp property exposed by the DpplOanran object. If you increase the value of the ata_qpekjPeiakqp attribute, you may have to also modify the naolkjoa@a]`hk_gEjpanr]h attribute of the 8lnk_aooIk`ah: tag.

Install a Performance Counter To monitor theCURRENTWORKLOAD YOUCANUSEA0ERFORMANCE#OUNTER. Open the Reliability and Performance Monitor TOOL0ERF-ON BYENTERINGPerfMon in the Run window. Install the counter using these steps: 1. #LICKON0ERFORMANCE-ONITORINTHETREEVIEW 2. 2IGHT CLICKANDCHOOSE.EWANDTHEN$ATA#OLLECTOR3ET 3. 'IVETHECOLLECTIONANAPPROPRIATENAMESUCHASh-ONITOR))3v ANDCLICK.EXTSEE &IGURE  

Figure 2-6. Install new data collection using the Performance Monitor tool. 4. Choose a directory in which the data is to be saved. The default path is SYSTEMDRIVE<0ERF,OGS
Download at WoweBook.Com

75

76

CH APT ER 2 N W OR K ER A ND THR EA DS

9OUCANNOWOPENYOURCOLLECTIONWITHINTHEOBJECTSTREEVIEWATTHELEFTANDNAVIGATETHE PATHTO2ELIABILITYAND0ERFORMANCE°$ATA#OLLECTOR3ETS°5SER$EFINED°-ONITOR))34HEREIS ADEFAULTENTRYHERENAMEDh3YSTEM-ONITOR,OGv9OUCANMODIFYTHISORADDANEWDATACOLLECTOR,ETSADDANEWONETODEMONSTRATETHEPROCESS2IGHT CLICKONTHELEAFENTRYINTHETREENAMED -ONITOR))3ANDCHOOSE.EW°$ATA#OLLECTOR!WIZARDLAUNCHESANDASKSFORANAMEANDCOLLECTIONTYPE.AMEITh))32EQUESTvANDCHOOSE0ERFORMANCECOUNTERDATACOLLECTORASTHETYPESEE &IGURE  

Figure 2-7. Add a new Data Collector. #LICKON.EXTTOADDTHECOUNTER/NTHEWIZARDSNEXTSCREEN CHOOSE!DDANDSEARCHFOR THECOUNTER)NTHELEFT HANDAREAYOULLFINDTHE!VAILABLECOUNTERSGROUP3EARCHFORTHESECTION h!30.%4!PPLICATIONvANDEXPANDIT4HELISTISSORTEDALPHABETICALLY3CROLLDOWNTOh2EQUESTS)N !PPLICATION1UEUEv)NTHEh)NSTANCESOFSELECTEDOBJECTvGROUP YOULLFINDALLAPPLICATIONS!CCEPT THEDEFAULTSELECTION??4OTAL??TOVIEWALLREQUESTS#LICK!DDAND/+4HEMONITORBEGINSTO watch the counter and saves the results in the file chosen after the counter is started. 4OVIEWTHERESULTS OPENTHEPATH2ELIABILITYAND0ERFORMANCE° Reports °5SER$EFINED° -ONITOR))3°))32EQUEST)TMIGHTTAKESOMETIMETOLOADTHERESULTS DEPENDINGONWORKLOADAND settings. There are several ways to modify the counter to bind it to specific events. For example, you could add a scheduler to run the counter at a specific time. For instance, if you experience problems BETWEENANDAMONYOURSERVER ITDOESNTMAKESENSETORUNTHETOOLTHEWHOLEDAYANDCOLLECT an unnecessarily large amount of data.

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

9OUCANDEFINESTOPCONDITIONSBASEDONTIMEFRAMEORTHESIZEOFTHELOGFILE9OUCANALSO launch a task when the scheduler stops. Depending on the resources of the server, you could run an APPLICATIONTHATAUTOMATICALLYANALYZESTHECONTENT SENDINGTHELOGFILETOANEMAILADDRESS ORJUST copying it to another location. 4HISSHORTDESCRIPTIONDOESNOTCOVERTHE2ELIABILITYAND0ERFORMANCE-ONITORTOOLINALLITS GLORY)TSJUSTAhTEASERvSOTHATYOUKNOWTHEREAREPOWERFULTOOLSAVAILABLETOMONITORASERVERAND find bottlenecks, failures, and performance loss easily. You can also gather hard data to confirm a problem, find a solution, and validate that your solution fixes the PROBLEM3TARTHERE reading more about the toolREGARDING7INDOWS3ERVEROPERATINGSYSTEM dppl6++pa_djap*ie_nkokbp*_ki+ aj)qo+he^n]nu+__311,4-*]opx.

Threading and Asynchronous Operations For most scenarios, the internal thread handling is well-designed and functional. However, there are situations where you reach the limits of the default settings. In particular, if a site comes under pressure from too many requests, the internal thread pool can run out of threads and the server will NOLONGERRESPONDASEXPECTED)LLDISCUSSSEVERALTECHNIQUESFOROVERCOMINGTHIS)LLCONSIDERHOW THECOMMONLANGUAGERUNTIMETHREADPOOLISUSEDBY!30.%4TOSERVICEREQUESTS ASWELLASLOOKing into the pooling mechanisms used for handlers, modules, and applications. )LLALSOSHOWTHETHREADINGUSAGEINDEPENDENTOFOTHERTECHNIQUESANDTHEASYNCHRONOUSPROcessing of requests using internal features to solve common issues.

Threading in ASP.NET To efficientlySERVICEMULTIPLECLIENTREQUESTS 7EB3ERVERSMAKEEXTENSIVEUSEOFCONCURRENCYBY launching multiple processes and spawning multiple threads to service requests. Considering the CONSTRUCTIONANDBEHAVIOROFTHE!30.%4ENGINE ITSEEMSTHATDEVELOPERSNEEDNOTCONCERNTHEMselves with threading at all, as the challenging aspects are handled internally. This is correct for most scenarios; page requests are serviced on the same thread, and a separate instance is created to service each new request. However, there are scenarios where you reach the limits of this model—as every model has limits—and need to extend the behavior. &IRSTOFALL ACLEARUNDERSTANDINGOFTHEINTERNALBEHAVIORISREQUIRED3OMEPARTSHAVEBEEN explained in the previous sections but I will repeat it from the perspective of threading. The processWIDE#,2THREADPOOLSERVICESREQUESTS4HETHREADPOOLSIZEISSETTOWORKERTHREADSAND)/ threads by default. Recall the 8lnk_aooIk`ah: settings explained already: 8lnk_aooIk`ahaj]^ha9pnqa i]tSknganPdna]`o9.1 i]tEkPdna]`o9.1+: !SEXPLAINEDIN#HAPTER FOREACHINCOMINGREQUESTANINSTANCEOFTHETYPEDppl=llhe_]pekj is CREATED4OAVOIDREALLOCATINGAPPLICATIONSANDMODULES EACH!PP$OMAINHOLDSAPOOLOFAPPLICATIONINSTANCESAND(440MODULES4HESIZEOFTHISPOOLISALSOˆTHATMEANSTHATREQUESTSCAN be handled per worker process.

Download at WoweBook.Com

77

78

CH APT ER 2 N W OR K ER A ND THR EA DS

The Need for Asynchrony )MAGINETHATYOUNEEDTOEXCLUSIVELYREQUESTARESOURCE!SLONGASONEPERSONISUSINGANAPPLIcation, this is not a problem. However, web applications are typically employed by many, if not thousands, of concurrent users. The thread pool and thread handling design allows several requests TOBEEXECUTEDINPARALLELTOIMPROVETHEUSERSEXPERIENCEWHENUSINGAWEBAPPLICATION,IMITING THENUMBEROFTHREADSISIMPORTANTINORDERTOALLOWMORETHANONEREQUESTPER#05ORCORE#REATing a vast number of threads can cause a system to a grind to a halt. (OWEVER AREQUESTCANLAUNCHDIFFERENTKINDSOFTASKS0ROCESSINGAPAGEANDSENDING RESOURCESTOTHECLIENTISTHEMOSTCOMMONACTION2EQUESTINGDATAFROMADATABASE 233FEED OR 7EB3ERVICEISANOTHER2EQUESTINGDATACANBETIMECONSUMING RATHERTHANPROCESSORINTENSIVE 7HATHAPPENSTHEN4HENUMBEROFTHREADSINTHETHREADPOOLQUICKLYREACHESITSLIMITANDSUBSEQUENTREQUESTSARENOTHANDLEDASEXPECTED$ESPITETHIS THE#05ISONLYIDLING!SYOULEARNEDIN THEPREVIOUSSECTIONS THESETTINGSALLOWYOUTOCHANGETHENUMBEROFCONCURRENTTHREADS"UTTHIS is not a solution either, as your system has to handle both kinds of requests: short-lived requests for resources and long-running queries against other servers. 4OMAKETHINGSCLEARER LOOKAT,ISTING )TDELAYSAREQUESTWHILEDEMANDINGLITTLEFROMTHE #05)TDISPLAYSTHETHREAD)$TOSHOWWHETHERORNOTANEWTHREADISCREATEDTOHANDLETHEREQUEST Listing 2-7. A Simple Page That Slows Down a Request 8!<L]caH]jcq]ca9?!: 8!<EilknpJ]iaol]_a9Ouopai*Nabha_pekj!: 8!<EilknpJ]iaol]_a9Ouopai*Pdna]`ejc!: 8o_nelpnqj]p9oanran: lnkpa_pa`rke`L]ca[Hk]`$k^fa_pon_(Arajp=ncoa% w Pdna]`*Ohaal$/,,,%7 Naolkjoa*Kqplqp*Snepa$OhksNaolkjoa(Pdna]`E@9w,y(± =ll@ki]ej*Cap?qnnajpPdna]`E`$%%7 y 8+o_nelp: To test it, open the page in a browser. Open the page in more browser windows and refresh all THEPAGESWITHINTHETHREE SECONDMILLISECOND PERIOD9OULLSEETHATTHETHREAD)$EXPOSED by the script changes for each request. Once the period is over, the next request receives a recycled THREADFROMAPREVIOUSREQUEST3EVERALLONG RUNNINGREQUESTSCANFILLTHETHREADPOOLANDEASILY REACHTHELIMITOFCONCURRENTTHREADS Removing the OhaalCALL,ISTING  WILLRESULTINAFASTERRUNNINGPAGE9OUWONTBEABLETO request the page again while the server is handling the previous one. The thread IDs demonstrate that ALLREQUESTSRUNONTHESAMETHREADANDTHETHREADPOOLISNEVERFILLEDUPTOITSLIMITSEE,ISTING   Listing 2-8. A Simple Page That Performs Well (Threading/FastThread.aspx) 8!<L]caH]jcq]ca9?!: 8!<EilknpJ]iaol]_a9Ouopai*Nabha_pekj!: 8o_nelpnqj]p9oanran: lnkpa_pa`rke`L]ca[Hk]`$k^fa_pon_(Arajp=ncoa% w Naolkjoa*Kqplqp*Snepa$B]opNaolkjoa(Pdna]`E@9w,y( =ll@ki]ej*Cap?qnnajpPdna]`E`$%%7 y 8+o_nelp:

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

Microsoft offers a stress test tool for simulating multiple concurrent requests even in the develOPMENTENVIRONMENT3EETHESIDEBARABOUTTHE7EB3TRESS4OOLFORMOREINFORMATION

WEB STRESS TOOL The web application stress tool can be downloaded from: dppl6++sss*ie_nkokbp*_ki+`ksjhk]`o+`ap]eho* ]olt;b]iehue`9a._,141]),2.])0/5a)]23`)31]45]]/2051"`eolh]uh]jc9aj. Unfortunately, the tool is quite old and Microsoft has not refreshed it to support newer environments. So if you run it on Vista, a DLL named msvcp50.dll is missing. You may find the file on the Web or you can safely copy it from the support files section provided with this book. Perform these steps to install the stress test tool: s $OWNLOADTHESETUPEXEFROMTHEADDRESSPREVIOUSLYSHOWN s $OWNLOADMSVCPDLLFROMTHE!PRESSSUPPORT7EBSITE s #OPYTHEUNZIPPEDFILETOFOLDER7IN$IR<SYSTEMYOUMUSTRUNWITHHIGHERPRIVILEGESTODOTHIS .OTETHAT this is really system, not system32! s )NSTALLTHESTRESSTESTTOOL s 2UNITONCETOCHECKTHATITSWORKING3TARTITASAN!DMINISTRATOR Now you can use the tool as outlined in the following sections. 4HEREAREFEWALTERNATIVETOOLSOUTTHEREYOUMIGHTCONSIDERFORYOUROWNSTRESSTESTING3EE!LIK,EVINS7#!4 at dppl6++^hkco*io`j*_ki+]hegh+]n_dera+.,,4+,/+,5+opnaoo)paop)]ol)jap)sa^)]llhe_]pekj)sepd) bnaa)s_]p)pkkh*]oltknpdaBe``han=``)ejjaTlanp(]r]eh]^ha]pdppl6++sss*ie_nkokbp*_ki+ `ksjhk]`o+`ap]eho*]olt;b]iehue`91531`]1.)4_a2)04^`)5^/_)312]2.1,.0^^"`eolh]uh]jc9aj.

Working with the Stress Test Tool !STRESSTEST is what the name implies—your application is forced to handle as many requests as NECESSARYTOFEELSTRESSED4OWALKTHROUGHTHISSTRESSTEST YOULLNEEDTOSETUPTHEPAGESPREVIOUSLY SHOWNSEE,ISTINGS AND LATERINTHISCHAPTER WITHINYOUR))3ENVIRONMENT WHICHYOUREABLE to run from a browser manually. Follow these steps to set up the script in the stress test tool. I have SET))3TOUSETHISPATH dppl6++hk_]hdkop+Pdna]`ejc+OhksPdna]`*]olt dppl6++hk_]hdkop+Pdna]`ejc+B]opPdna]`*]olt First, set up the script by adding the content tree—the pages requested from the tool (see &IGURE   4HECONTENTTREEALLOWSYOUTOSETTHEACTIONSTHETOOLPERFORMSSEVERALTIMES!LTERNATIVELY you can record a session to save the page load action. However, in this script, only one page is called USINGA'%4COMMAND SORECORDINGISNOTNECESSARY 4HESETTINGSDEFINEHOWTHETOOLOPERATESONTHESERVER)N&IGURE  )SETTHREADS WHICH CREATECONCURRENTREQUESTS4HISRUNSFORSECONDSASQUICKLYASPOSSIBLE4HEREISNOTHROTTLING ANDNOOTHEROPTIONSAREUSED4HISISTHECONFIGURATIONTHATSHOULDCAUSETHESERVERTOCREATE threads and bring the thread pool to its limit.

Download at WoweBook.Com

79

80

CH APT ER 2 N W OR K ER A ND THR EA DS

Figure 2-8. Set the content for a stress test.

Figure 2-9. Settings used to force the test

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

4ABLE SHOWSTHERESULTSOFSOMESTRESSTESTS2EMEMBERTHATTHEREISAWIDERANGEOFPOSsible values for response time, depending on your machine, its configuration, and what other APPLICATIONSANDSERVICESARECURRENTLYRUNNING)TSTHERELATIVEVALUESTHATARESIGNIFICANTHERE Table 2-2. Test Results Using a Web Stress Test Tool

Threads

File

Hits

Average Response Time



&AST4HREADASPX



MS



&AST4HREADASPX



MS



3LOW4HREADASPX



 MS



3LOW4HREADASPX



 MS



"OTHSEETHEFOLLOWING



 MS&AST4HREADASPX

These results are not surprising. The server is less able to handle the requests as the number OFPARALLELTHREADSINCREASES"ECAUSEWEREFORCING))3TOQUEUETHEREQUESTS THISCAUSESADDITIONALOVERHEAD2UNNINGTHECLIENTAGAINSTBOTH&AST4HREADASPXAND3LOW4HREADASPX HOWEVER INCREASESTHEAVERAGERESPONSETIMEFOR&AST4HREADASPXREQUESTSTOSECONDSANDONLYHITS BEINGHANDLED&OR3LOW4HREADASPX THENUMBEROFTHREADSMAKESNOSIGNIFICANTDIFFERENCE4HISIS the worst case—because of long-running requests, fast ones are not served quickly. Increasing the #05POWERWILLNOTHELP4HESLOWPAGEDOESNOTCONSUMEANY#05POWERBECAUSETHEREISNOTHING TOCALCULATE4HEDELAYYOUSEEISDUETOTHESATURATIONOFTHETHREADPOOL%VENTHEFASTREQUESTSARE queued until a thread is released. This demonstrates that some pages can influence the performance of other requests even if THEYHAVENOTHINGTODOWITHEACHOTHER7HATISTHESOLUTION )DISCUSSEDPREVIOUSLYTHEVARIOUSSETTINGSAVAILABLEFORIMPROVINGTHESYSTEMSBEHAVIOR)NTHE STRESSTEST)USEDTHREADS)NCREASINGTHETHREADPOOLLIMITSMIGHTHELP(OWEVER THEREALWORLD does not have a defined number of requests regularly arriving. Finding the right value is anything but easy. It could change depending on user behavior, server settings, network connection, and application code—which means that there is no right answer. 4HESOLUTIONWERELOOKINGFORSHOULDFREETHETHREADSINTHETHREADPOOLTOHOLDTHEUTILIZATION low and have enough threads available at any time. In other words, each page should behave like a fast-running page. This brings us to asynchronous handlers.

NNote

Chapter 3 is dedicated to the world of handlers and modules. Here I discuss only the portion directly related to threading issues. For more information about handlers, refer to the next chapter.

Custom Thread Pool and Asynchronous Handlers 7HILEMOST!30.%4PAGESANDHANDLERSARESERVICEDSYNCHRONOUSLYON threads drawn from the thread pool, it is possible to create handlers and pages that service requests asynchronously. !SYNCHRONOUSHANDLERSIMPLEMENTTHEEDppl=ouj_D]j`han interface, which derives from EDpplD]j`hanSEE,ISTING  

Download at WoweBook.Com

81

82

CH APT ER 2 N W OR K ER A ND THR EA DS

Listing 2-9. Definition of the IHttpAsynchHandler Interface lq^he_ejpanb]_aEDppl=ouj_D]j`han6EDpplD]j`han w E=ouj_Naoqhp>acejLnk_aooNamqaop$Dppl?kjpatp_pt( =ouj_?]hh^]_g_^( k^fa_pk^f%7 rke`Aj`Lnk_aooNamqaop$E=ouj_Naoqhp]n%7 y The interface follows the typical pattern for asynchronous actions—it has a method for indicating the beginning and one for indicating the end of a process. Handlers must have a method named Lnk_aooNamqaop due to the implemented EDpplD]j`han interface. Instead of calling this method, the asynchronous handler calls the >acejLnk_aooNamqaop method. In this method, you launch a new thread and manage things, which can take some time. The method returns immediately, providing a reference to an E=ouj_NaoqhpINSTANCE4HISFREESTHETHREADFROMTHETHREADPOOL!NEWTHREAD is then used to perform the long-running action. When the internal (or private) thread returns, the Aj`Lnk_aooNamqaop method is called. The E=ouj_Naoqhp instance is handed over in order to paramETERIZETHECALL#LEANUPACTIONS SUCHASCLOSINGADATABASECONNECTION AREBESTPLACEDHERE

Asynchronous Handler with a Delegate Creating an asynchronous handler with a delegate is the most common approach. Delegates called with >acejEjrkgaIMPLICITLYCREATEANEWTHREADSEE,ISTING   Listing 2-10. A Handler Using IHttpAsyncHandler 8!<Sa^D]j`hanH]jcq]ca9??h]oo9=lnaoo*Pdna]`ejc*=ouj_D]j`hano*=ouj_D]j`han!: qoejcOuopai7 qoejcOuopai*Sa^7 qoejcOuopai*Pdna]`ejc7 qoejcOuopai*@e]cjkope_o7 qoejcOuopai*Nabha_pekj7 j]iaol]_a=lnaoo*Pdna]`ejc*=ouj_D]j`hano w lq^he_`ahac]parke`Lnk_aooNamqaop@ahac]pa$Dppl?kjpatp_pt%7 lq^he__h]oo=ouj_D]j`han6EDppl=ouj_D]j`han w lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_pt% w Ouopai*Pdna]`ejc*Pdna]`*Ohaal$.,,,%7 _pt*Naolkjoa*Kqplqp*Snepa$ =ouj_@ahac]pa(Pdna]`E@9w,y( =ll@ki]ej*Cap?qnnajpPdna]`E`$%%7 y lq^he_^kkhEoNaqo]^ha w capwnapqnjpnqa7y y

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

lq^he_E=ouj_Naoqhp>acejLnk_aooNamqaop$Dppl?kjpatp_pt(± =ouj_?]hh^]_g_^(± k^fa_pk^f% w Lnk_aooNamqaop@ahac]palnc9jasLnk_aooNamqaop@ahac]pa$Lnk_aooNamqaop%7 napqnjlnc*>acejEjrkga$_pt(_^(k^f%7 y lq^he_rke`Aj`Lnk_aooNamqaop$E=ouj_Naoqhp]n% w y y y #ALLTHISHANDLERBYUSINGABROWSER ASBEFORE TOTESTTHATITSRUNNINGPROPERLY4HEFOLLOWING 52,ASSUMESTHATYOUHAVETHEPROJECTCONFIGUREDIN))3USINGAVIRTUALDIRECTORYNAMEDh4HREADing”: dppl6++hk_]hdkop+Pdna]`ejc+=ouj_Pdna]`@ahac]pa*]odt The process starts with the method >acejLnk_aooNamqaop5SINGTHEDELEGATEANDITS >acejEjrkga method, the method Lnk_aooNamqaop is called. Then the Ohaal method simulates SOMETHINGLONGRUNNINGWITHOUTPERFORMINGANYTHINGONTHE#05"ECAUSETHEREISNOTHINGTO clean up, no code is required in Aj`Lnk_aooNamqaop. .OWITSTIMETOSEEWHATTHESTRESSTESTTOOLISREPORTING If you run the test as before, you can see that the results are nearly identical. What is going on HERE7HYWRITEASYNCHRONOUSDELEGATESIFTHEREISNOSPEEDIMPROVEMENTATALL4HEREASONISIN THEWAY!30.%4INTERNALLYHANDLESTHETHREADING Recall that when I first introduced the term “thread pool,” it was called a “process wide thread pool.” The asynchronous handler still runs in the very same process, which leads to a lack of improvement. The original thread is freed, but the new one is taken from the same thread pool. The same thing would happen if you used Pdna]`Lkkh*MqaqaQoanSkngEpai from the Ouopai*Pdna]`ejc namespace. You need to find from what other thread source you can get a new thread.

Asynchronous Handler with Custom Threads "EFOREYOUCANIMPLEMENTTHEWHOLESOLUTION ANOTHERINTERFACEISREQUIREDˆE=ouj_dNaoqhp—as the RETURNRESULTISNOWESSENTIAL4HEDEFINITIONISSHORTˆJUSTFOURPROPERTIESSEE,ISTING   Listing 2-11. The Definition of IAsyncResult lq^he_ejpanb]_aE=ouj_Naoqhp w lq^he_k^fa_p=ouj_Op]pawcap7y lq^he_^kkh?kilhapa`Ouj_dnkjkqohuwcap7y lq^he_^kkhEo?kilhapa`wcap7y lq^he_S]epD]j`ha=ouj_S]epD]j`hawcap7y y Our actual implementation of the E=ouj_dNaoqhp interface,ISTING  HASTWOADDITIONAL properties: a reference to the Dppl?kjpatp object, and a reference to the callback object. The callback method is invoked later, when processing is complete. The =ouj_Op]pa object is optional; you can use it to store private data. =ouj_S]epD]j`ha returns a S]epD]j`ha object, which is used to signal WHENTHEREQUESTISCOMPLETE5SINGTHE?kilhapaNamqaop method implemented additionally to the requirements of the interface, the calling class can execute the Aj`Lnk_aooNamqaop method. In this

Download at WoweBook.Com

83

84

CH APT ER 2 N W OR K ER A ND THR EA DS

routine, the S]epD]j`haOBJECTISTRIGGERED%ITHERWAY THEEo?kilhapa` property shows that the object has reached the completed state. Listing 2-12. The Implementation of IAsyncResult (from AsyncThreadCallback.ashx) _h]oo=ouj_NamqaopOp]pa6E=ouj_Naoqhp w ejpanj]hDppl?kjpatp[_pt7 ejpanj]h=ouj_?]hh^]_g[_^7 ejpanj]hk^fa_p[`]p]7 lner]pa^kkh[eo?kilhapa`7 lner]paI]jq]hNaoapArajp[_kilhapaArajp7 lq^he_=ouj_NamqaopOp]pa$Dppl?kjpatp_pt(± =ouj_?]hh^]_g_^(± k^fa_p`]p]% w [_pt9_pt7 [_^9_^7 [`]p]9`]p]7 y ejpanj]hDppl?kjpatp?qnnajp?kjpatp w cap w napqnj[_pt7 y y ejpanj]hrke`Aj`Namqaop$% w [eo?kilhapa`9pnqa7 hk_g$pdeo% w eb$[_kilhapaArajp9jqhh% [_kilhapaArajp*Oap$%7 y ++ejrkganaceopana`_]hh^]_g(eb]ju eb$[_^9jqhh% [_^$pdeo%7 y lq^he_k^fa_p=ouj_Op]pa w cap w napqnj$[`]p]%7 y y  lq^he_^kkh?kilhapa`Ouj_dnkjkqohu w cap w napqnj$b]hoa%7 Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

y y  lq^he_^kkhEo?kilhapa` w cap w napqnj$[eo?kilhapa`%7 y y  lq^he_S]epD]j`ha=ouj_S]epD]j`ha w cap w hk_g$pdeo% w eb$[_kilhapaArajp99jqhh% [_kilhapaArajp9jasI]jq]hNaoapArajp$b]hoa%7 napqnj[_kilhapaArajp7 y y y y The next step is to spawn a new thread to process the request. The method called on this new thread will need access to the state cached in the =ouj_NamqaopOp]pa class previously shown. To pass NECESSARYDATATOTHISOBJECT APARAMETERIZEDTHREADISUSED BASEDONL]n]iapaneva`Pdna]`Op]np class. The handler itself is similar to the one already introduced. The definition for the ashx page looks like this: 8!<Sa^D]j`hanH]jcq]ca9?± ?h]oo9=lnaoo*Pdna]`ejc*=ouj_D]j`hano*?qopki=ouj_D]j`han!: The Lnk_aooNamqaop method must be present, as it is required by the interface EDppl=ouj_D]j`han, BUTYOUDONTUSEIT4HEWHOLEWORKISSPLITBETWEENTHE>acejLnk_aooNamqaop and Aj`Lnk_aooNamqaop methods. In the >acejLnk_aooNamqaop method the =ouj_NamqaopOp]pa object is created, along with the REFERENCETOTHECONTEXTANDCALLBACKSEE,ISTING   Listing 2-13. The Implementation of AsyncResult (AsyncThreadCallback.ashx) lq^he__h]oo?qopki=ouj_D]j`han6EDppl=ouj_D]j`han w lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_pt% w ++jkpqoa` y lq^he_^kkhEoNaqo]^ha w capwnapqnjb]hoa7y y lq^he_E=ouj_Naoqhp>acejLnk_aooNamqaop$Dppl?kjpatp_pt(± =ouj_?]hh^]_g_^(± k^fa_pk^f% Download at WoweBook.Com

85

86

CH APT ER 2 N W OR K ER A ND THR EA DS

w =ouj_NamqaopOp]panamOp]pa9± jas=ouj_NamqaopOp]pa$_pt(_^(k^f%7 L]n]iapaneva`Pdna]`Op]nppo9jasL]n]iapaneva`Pdna]`Op]np$Lnk_aooPdna]`%7 Pdna]`p9jasPdna]`$po%7 p*Op]np$namOp]pa%7 napqnjnamOp]pa7 y lq^he_rke`Aj`Lnk_aooNamqaop$E=ouj_Naoqhp]n% w =ouj_NamqaopOp]pa]no9]n]o=ouj_NamqaopOp]pa7 eb$]no9jqhh% w ]no*?qnnajp?kjpatp*Naolkjoa*Snepa$Aj`Namqaopna]_da`%7 y y lner]parke`Lnk_aooPdna]`$k^fa_pk^f% w Pdna]`*Ohaal$.,,,%7 =ouj_NamqaopOp]pa]on9k^f]o=ouj_NamqaopOp]pa7 ]on*?qnnajp?kjpatp*Naolkjoa*Kqplqp*Snepa$± =ouj_Pdna]`(Pdna]`E@9w,y(± =ll@ki]ej*Cap?qnnajpPdna]`E`$%%7 ++oecj]haj`kblnk_aooejc ]on*Aj`Namqaop$%7 y y ,ETSLOOKATTHECODETOUNDERSTANDHOWITSWORKING&IGURE SHOWSTHETHREADUSAGEDURing internal processing. Initiated by the request, the process starts by calling the >acejLnk_aooNamqaop method. The =ouj_D]j`han creates the helper objects required and launches the new custom thread independent of the thread pool. The custom thread runs and the thread pool thread is released. Once the process is completed, the end is signaled via the callback method and the request is finished. The response held in memory is waiting for the thread to complete. This might seem disapPOINTING BECAUSEITDOESNTMAKEANYTHINGFASTER4HEPAGEISSTILLWAITINGFORTHESLOWOPERATION to finish, and so is the user. Remember the thread pool issue, however; once the pool runs out of threads, the performance of the whole server is reduced and no more requests are handled properly. The advantage of custom threads is not a faster response for one user but for all users. )NSTEP ASSHOWNIN&IGURE  THECALLTOAj`Namqaop indicates the end of the process and terminates the request. Once called, the response is complete and sent to the browser. This means that you can add content to the response at any time before the Aj`Lnk_aooNamqaop method is called. )NTHEEXAMPLECODE,ISTING  THENaolkjoa*Kqplqp*Snepa method demonstrates this. 2UNTHESTRESSTESTAGAINTOSEEWHETHERYOUFINDANIMPROVEMENT5NDERPRESSUREITPERFORMS better, and the thread pool no longer runs out of threads. This allows the site to accept incoming REQUESTSATANYTIME ANDTHEWHOLESERVERAPPEARSTOBEMORERESPONSIVE!GAIN THE processing time for a single page is the same.

Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

Figure 2-10. First step of the processing using an asynchronous handler

Figure 2-11. Second step of the processing using an asynchronous handler

Creating a Custom Thread Pool This techniqueISUSEFULFORMANYEXTENSIBILITYPROJECTS)N#HAPTER )LLSHOWMOREEXAMPLES OFPRACTICALIMPLEMENTATIONSTHATSOLVECOMMONISSUES!LLHANDLERSEXPLAINEDTHEREUSESIMPLE synchronous operations. You can implement them all as asynchronous counterparts using the TECHNIQUESDESCRIBEDHERE5SINGASYNCHRONOUSHANDLERS YOULLSEEHOWTOIMPROVETHEOVERALLPERFORMANCEOFAN!30.%4SITEDRASTICALLY4HETHREADISSUESANDHANDLERSTHAT)DISCUSSHEREAREJUST one solution. There is another issue that can be found easily using the stress test tool. In one of the previous paragraphs I wrote “accept incoming requests at any time.” This is quite a claim, as it assumes that the server will respond no matter how many requests arrive, just by creating new threads. However,

Download at WoweBook.Com

87

88

CH APT ER 2 N W OR K ER A ND THR EA DS

THEOPERATINGSYSTEM #05POWER AVAILABLEMEMORY ANDARCHITECTURALRESTRICTIONSOFTHEHARDWARE may stop the code from creating new threads. It is possible for too many threads to be created, in which case they will block each other and make the system slow and unresponsive. 9OUMIGHTASKh7HYNOTUSEATHREADPOOLv5NFORTUNATELY .%4HASONLYONETHREADPOOL INTERNALLYANDITISUSEDBY!30.%44HATSWHYUSINGPdna]`Lkkh*MqaqaQoanSkngEpai does not WORK/URTASKNOWISTHECREATIONOFOUROWNTHREADPOOL3EVERALPEOPLEHAVEDONETHISSUCcessfully. Mike Woodring wrote a version which is useful and fits our needs, using the code in an asynchronous handler. The original version can be found on his page: dppl6++sss*^a]n_]jukj*_ki+. I have adapted his code to suit our needs for a handler. There are several clever aspects to this code. The usage of Dppl?kjpatp is much simpler. In the previous example, a reference to the context object was stored and the use of Dppl?kjpatp*?qnnajp was forbidden. It is not good programMINGPRACTICETOCHANGEWELL KNOWNMETHODCALLS!PARTFROMTHISEXAMPLETHEREARESEVERALOTHER IMPLEMENTATIONSOUTTHERETHATMIGHTHELPASWELL!LTERNATIVELYYOUMAYHAVEALOOKAT*ON3KEETS #USTOM4HREAD0OOLTHATSPARTOFHISh-ISCELLANEOUS5TILITY,IBRARYvdppl6++sss*uk`]*]n]_douo*_ki+ _od]nl+ieo_qpeh+ (OWEVER THECUSTOMTHREADPOOLEXPLAINEDHEREISJUSTANEXAMPLEOFWHERE!30.%4EXTENSIbility approaches can go and how to deal with very specific conditions.

Overview !CUSTOMTHREADPOOLISNOTATRIVIALPIECEOFCODE)TCONSISTSOFSEVERALCLASSES DELEGATES ANDAN interface as well. First, have a look at the types defined in the project:

s #USTOM4HREAD0OOL



s )7ORK2EQUEST



s 7ORK2EQUEST



s 4HREAD)NFO



s 4HREAD7RAPPER

4HE#USTOM4HREAD0OOLCLASS is the core implementation. It supports a bunch of characterisTICS!PARTFROMTHEFEATURESPROVIDEDBYTHE#,2STHREADPOOL THOSEARETHECRUCIALONES

s )TCANBEEXPLICITLYSTARTEDANDSTOPPEDANDRESTARTED 



s )THASCONFIGURABLETHREADPRIORITY



s )THASCONFIGURABLEFOREGROUNDBACKGROUNDCHARACTERISTIC



s )THASCONFIGURABLEMINIMUMTHREADCOUNTCALLEDhSTATICvORhPERMANENTvTHREADS 



s )THASCONFIGURABLEMAXIMUMTHREADCOUNTTHREADSADDEDOVERTHEMINIMUMARECALLED “dynamic” threads).



s )THASCONFIGURABLEDYNAMICTHREADCREATIONTRIGGERTHEPOINTATWHICHTHEPOOLDECIDESTO add new threads).



s )THASCONFIGURABLEDYNAMICTHREADDECAYINTERVALTHETIMEPERIODAFTERWHICHANIDLE dynamic thread will exit).



s )TSUPPORTSCONFIGURABLELIMITOPTIONAL TOTHEREQUESTQUEUESIZEBYDEFAULTUNBOUNDED 



s 4HEPOOLEXTENDS7AIT(ANDLETHATBECOMESSIGNALEDWHENLASTTHREADEXITS



s /PERATIONSENQUEUEDTOTHEPOOLARECANCELLABLE



s %NQUEUEOPERATIONSUPPORTSEARLYBOUNDAPPROACHLIKETHEPdna]`Lkkh*MqaqaQoanSkngEpai type) as well as late bound approach (like the ?kjpnkh*Ejrkga/>acejEjrkga approach) to posting work requests. Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S



s /PTIONALPROPAGATIONOFCALLINGTHREADCALLCONTEXTTOTARGET



s /PTIONALPROPAGATIONOFCALLINGTHREADPRINCIPALTOTARGET



s /PTIONALPROPAGATIONOFCALLINGTHREADDppl?kjpatp to target.



s )THASSUPPORTFORSTARTEDSTOPPEDEVENTSUBSCRIPTIONANDNOTIFICATION This all makes it a well-designed tool to extend the thread pool behavior where necessary.

The Implementation of the Custom Thread Pool The next code listings show the implementation in several steps. The core functionality is explained IN LINESEE,ISTING   Listing 2-14. The Basic Thread Pool Implementation lq^he_oa]ha`_h]oo?qopkiPdna]`Lkkh6S]epD]j`ha w ++@ab]qhpl]n]iapano ++@a_]upeiaejioi]`akbiejqpao&oa_&io _kjopejp@AB=QHP[@UJ=IE?[PDNA=@[@A?=U[PEIA91&2,&-,,,7 ++iehheoa_kj`o _kjopejp@AB=QHP[JAS[PDNA=@[PNECCAN[PEIA91,,7 _kjopPdna]`Lneknepu@AB=QHP[PDNA=@[LNEKNEPU9Pdna]`Lneknepu*Jkni]h7 ++qj^kqj`a` _kjopejp@AB=QHP[NAMQAOP[MQAQA[HEIEP9)-7 lq^he_?qopkiPdna]`Lkkh$ejpejepe]hPdna]`?kqjp(ejpi]tPdna]`?kqjp(± opnejclkkhJ]ia% 6pdeo$ejepe]hPdna]`?kqjp(i]tPdna]`?kqjp(lkkhJ]ia( @AB=QHP[JAS[PDNA=@[PNECCAN[PEIA( @AB=QHP[@UJ=IE?[PDNA=@[@A?=U[PEIA( @AB=QHP[PDNA=@[LNEKNEPU( @AB=QHP[NAMQAOP[MQAQA[HEIEP% w y lq^he_?qopkiPdna]`Lkkh$ejpejepe]hPdna]`?kqjp(ejpi]tPdna]`?kqjp(± opnejclkkhJ]ia(± ejpjasPdna]`Pneccan(ejp`uj]ie_Pdna]`@a_]uPeia(± Pdna]`Lneknepupdna]`Lneknepu(ejpnamqaopMqaqaHeiep% w D]j`ha9opkl?kilhapaArajp*D]j`ha7 eb$i]tPdna]`?kqjp8ejepe]hPdna]`?kqjp% w pdnksjas=ncqiajpAt_alpekj$I]teiqipdna]`_kqjpiqop^a:9 ejepe]hpdna]`_kqjp*(i]tPdna]`?kqjp%7 y eb$`uj]ie_Pdna]`@a_]uPeia89,% w pdnksjas=ncqiajpAt_alpekj$@uj]ie_pdna]``a_]upeia_]jjkp^a89,*( `uj]ie_Pdna]`@a_]uPeia%7 y eb$jasPdna]`Pneccan89,% w pdnksjas=ncqiajpAt_alpekj$Jaspdna]`pneccanpeia_]jjkp^a89,*( jasPdna]`Pneccan%7 Download at WoweBook.Com

89

90

CH APT ER 2 N W OR K ER A ND THR EA DS

y pdeo*ejepe]hPdna]`?kqjp9ejepe]hPdna]`?kqjp7 pdeo*i]tPdna]`?kqjp9i]tPdna]`?kqjp7 pdeo*namqaopMqaqaHeiep9$namqaopMqaqaHeiep8,; @AB=QHP[NAMQAOP[MQAQA[HEIEP6namqaopMqaqaHeiep%7 pdeo*`a_]uPeia9`uj]ie_Pdna]`@a_]uPeia7 pdeo*jasPdna]`Pneccan9jasPeiaOl]j$± PeiaOl]j*Pe_goLanIehheoa_kj`&jasPdna]`Pneccan%7 pdeo*pdna]`Lneknepu9pdna]`Lneknepu7 pdeo*namqaopMqaqa9jasMqaqa$± namqaopMqaqaHeiep8,;0,526namqaopMqaqaHeiep%7  eb$lkkhJ]ia99jqhh% w pdnksjas=ncqiajpJqhhAt_alpekj$lkkhJ]ia(± Pdna]`lkkhj]ia_]jjkp^ajqhh%7 y ahoa w pdeo*pdna]`LkkhJ]ia9lkkhJ]ia7 y y ++PdaLneknepu"@uj]ie_Pdna]`@a_]ulnklanpeao]najkppdna]`o]ba ++]j`_]jkjhu^aoap^abknaOp]npeo_]hha`* lq^he_Pdna]`LneknepuLneknepu w capwnapqnj$pdna]`Lneknepu%7y  oap w eb$d]o>aajOp]npa`% w pdnksjasEjr]he`Klan]pekjAt_alpekj$?]jjkp]`fqoppdna]`± lneknepu]bpanlkkhd]o^aajop]npa`*%7 y pdna]`Lneknepu9r]hqa7 y y lq^he_ejp@uj]ie_Pdna]`@a_]u w capwnapqnj$`a_]uPeia%7y  oap w eb$d]o>aajOp]npa`% w pdnksjasEjr]he`Klan]pekjAt_alpekj$?]jjkp]`fqop`uj]ie_± pdna]``a_]upeia]bpanlkkhd]o^aajop]npa`*%7 y eb$r]hqa89,% w pdnksjas=ncqiajpAt_alpekj$@uj]ie_pdna]``a_]upeia± _]jjkp^a89,*(r]hqa%7 y Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

`a_]uPeia9r]hqa7 y y lq^he_ejpJasPdna]`Pneccan w capwnapqnj$$ejp%jasPdna]`Pneccan*Pkp]hIehheoa_kj`o%7y  oap w eb$r]hqa89,% w pdnksjas=ncqiajpAt_alpekj$Jaspdna]`pneccanpeia_]jjkp± ^a89,*(r]hqa%7 y hk_g$pdeo% w jasPdna]`Pneccan9jasPeiaOl]j$± PeiaOl]j*Pe_goLanIehheoa_kj`&r]hqa%7 y y y lq^he_ejpNamqaopMqaqaHeiep w capwnapqnj$namqaopMqaqaHeiep%7y oapwnamqaopMqaqaHeiep9$r]hqa8,;@AB=QHP[NAMQAOP[MQAQA[HEIEP6r]hqa%7y y lq^he_ejp=r]eh]^haPdna]`o w capwnapqnj$i]tPdna]`?kqjp)_qnnajpPdna]`?kqjp%7y y lq^he_ejpI]tPdna]`o w capwnapqnj$i]tPdna]`?kqjp%7y oap w eb$r]hqa8ejepe]hPdna]`?kqjp% w pdnksjas=ncqiajpAt_alpekj$I]teiqipdna]`_kqjpiqop± ^a:9ejepe]hpdna]`_kqjp*(I]tPdna]`o%7 y i]tPdna]`?kqjp9r]hqa7 y y lq^he_^kkhEoOp]npa` w capwnapqnj$d]o>aajOp]npa`%7y y lq^he_^kkhLnklkc]paPdna]`Lnej_el]h w Download at WoweBook.Com

91

92

CH APT ER 2 N W OR K ER A ND THR EA DS

capwnapqnj$lnklkc]paPdna]`Lnej_el]h%7y oapwlnklkc]paPdna]`Lnej_el]h9r]hqa7y y lq^he_^kkhLnklkc]pa?]hh?kjpatp w capwnapqnj$lnklkc]pa?]hh?kjpatp%7y oapwlnklkc]pa?]hh?kjpatp9r]hqa7y y lq^he_^kkhLnklkc]paDppl?kjpatp w capwnapqnj$lnklkc]paDppl?kjpatp%7y oapwlnklkc]paDppl?kjpatp9r]hqa7y y lq^he_^kkhLnklkc]pa?=OI]ngano w capwnapqnj$lnklkc]pa?=OI]ngano%7y y lq^he_^kkhEo>]_gcnkqj` w capwnapqnj$qoa>]_gcnkqj`Pdna]`o%7y  oap w eb$d]o>aajOp]npa`% w pdnksjasEjr]he`Klan]pekjAt_alpekj$?]jjkp]`fqop^]_gcnkqj`± op]pqo]bpanlkkhd]o^aajop]npa`*%7 y qoa>]_gcnkqj`Pdna]`o9r]hqa7 y y lq^he_arajpPdna]`Lkkh@ahac]paOp]npa`7 lq^he_arajpPdna]`Lkkh@ahac]paOpklla`7 lq^he_rke`KjOpklla`$% w eb$pdeo*Opklla`9jqhh% w pdeo*Opklla`$%7 y y lq^he_rke`KjOp]npa`$% w eb$pdeo*Op]npa`9jqhh% w pdeo*Op]npa`$%7 y y lq^he_rke`Op]np$% Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

w hk_g$pdeo% w eb$d]o>aajOp]npa`% w pdnksjasEjr]he`Klan]pekjAt_alpekj$Lkkhd]o]hna]`u± ^aajop]npa`*%7 y d]o>aajOp]npa`9pnqa7 ++?da_gpkoaaebpdanasana]hna]`uepaiolkopa`pkpdamqaqa ++^abknaOp]nps]o_]hha`*Ebok(naoappdaenpeiaop]ilopk ++pda_qnnajppeia* eb$namqaopMqaqa*?kqjp:,% w NaoapSkngNamqaopPeiao$%7 y bkn$ejpj9,7j8ejepe]hPdna]`?kqjp7j''% w Pdna]`Sn]llanpdna]`9± jasPdna]`Sn]llan$pdeo(pnqa(pdna]`Lneknepu(± opnejc*Bkni]p$w,y$op]pe_%(pdna]`LkkhJ]ia%%7 pdna]`*Op]np$%7 y KjOp]npa`$%7 y y  lq^he_rke`Opkl$% w Ejpanj]hOpkl$b]hoa(Peiakqp*Ejbejepa%7 y lq^he_rke`Opkl=j`S]ep$% w Ejpanj]hOpkl$pnqa(Peiakqp*Ejbejepa%7 y lq^he_^kkhOpkl=j`S]ep$ejppeiakqp% w napqnjEjpanj]hOpkl$pnqa(peiakqp%7 y lner]pa^kkhEjpanj]hOpkl$^kkhs]ep(ejppeiakqp% w eb$d]o>aajOp]npa`% w pdnksjasEjr]he`Klan]pekjAt_alpekj$?]jjkpopkl]pdna]`lkkh± pd]pd]ojkp^aajop]npa`uap*%7 y hk_g$pdeo% w opklEjLnkcnaoo9pnqa7 Ikjepkn*Lqhoa=hh$pdeo%7 y Download at WoweBook.Com

93

94

CH APT ER 2 N W OR K ER A ND THR EA DS

eb$s]ep% w ^kkhopkl?kilhapa9S]epKja$peiakqp(pnqa%7 eb$opkl?kilhapa% w ++Ebpdaopkls]ooq__aoobqh(sa_]joqllknp^aejc ++naop]npa`*Ebpdaopkls]onamqaopa`(^qpjkp ++s]epa`kj(pdajsa`kj#poqllknpnaop]npejc* d]o>aajOp]npa`9b]hoa7 opklEjLnkcnaoo9b]hoa7 namqaopMqaqa*?ha]n$%7 opkl?kilhapaArajp*Naoap$%7 y napqnj$opkl?kilhapa%7 y napqnj$pnqa%7 y ++Kranhk]`obknpdaa]nhu^kqj`SkngNamqaop@ahac]pa)^]oa`p]ncapo* lq^he_^kkhLkopNamqaop$SkngNamqaop@ahac]pa_^% w napqnjLkopNamqaop$_^($k^fa_p%jqhh%7 y lq^he_^kkhLkopNamqaop$SkngNamqaop@ahac]pa_^(k^fa_pop]pa% w ESkngNamqaopjkpQoa`7 napqnjLkopNamqaop$_^(op]pa(kqpjkpQoa`%7 y lq^he_^kkhLkopNamqaop$SkngNamqaop@ahac]pa_^(k^fa_pop]pa(± kqpESkngNamqaopnamOp]pqo% w SkngNamqaopnamqaop9± jasSkngNamqaop$_^(op]pa(± lnklkc]paPdna]`Lnej_el]h(lnklkc]pa?]hh?kjpatp(± lnklkc]paDppl?kjpatp(lnklkc]pa?=OI]ngano%7 namOp]pqo9namqaop7 napqnjLkopNamqaop$namqaop%7 y ++Kranhk]`obknpdah]pa^kqj`@ahac]pa*@uj]ie_Ejrkga)^]oa`p]ncapo* lq^he_^kkhLkopNamqaop$@ahac]pa_^(k^fa_pWY]nco% w ESkngNamqaopjkpQoa`7 napqnjLkopNamqaop$_^(]nco(kqpjkpQoa`%7 y lq^he_^kkhLkopNamqaop$@ahac]pa_^(k^fa_pWY]nco(± kqpESkngNamqaopnamOp]pqo% w SkngNamqaopnamqaop9± jasSkngNamqaop$_^(]nco(± lnklkc]paPdna]`Lnej_el]h(lnklkc]pa?]hh?kjpatp(± lnklkc]paDppl?kjpatp(lnklkc]pa?=OI]ngano%7 namOp]pqo9namqaop7 Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

napqnjLkopNamqaop$namqaop%7 y ++Pda]_pq]heilhaiajp]pekjkbLkopNamqaop* ^kkhLkopNamqaop$SkngNamqaopnamqaop% w hk_g$pdeo% w ++=namqaopMqaqaHeiepkb)-ia]jopdamqaqaeoqj^kqj`a` ++$oq^fa_ppk]r]eh]^hanaokqn_ao%*EKS(jk]npebe_e]hheiep ++d]o^aajlh]_a`kjpdai]teiqikbnamqaopopd]p_]j^a ++lh]_a`ejpkpdamqaqa* eb$$namqaopMqaqaHeiep99)-%xx± $namqaopMqaqa*?kqjp8namqaopMqaqaHeiep%% w pnu w namqaopMqaqa*Ajmqaqa$namqaop%7 Ikjepkn*Lqhoa$pdeo%7 napqnj$pnqa%7 y _]p_d w y y y napqnj$b]hoa%7 y ejpanj]hrke`NaoapSkngNamqaopPeiao$% w hk_g$pdeo% w @]paPeiajasPeia9@]paPeia*Jks7 bkna]_d$SkngNamqaopsnejnamqaopMqaqa% w sn*skngejcPeia9jasPeia7 y y y  lner]pa^kkhd]o>aajOp]npa`9b]hoa7 lner]pa^kkhopklEjLnkcnaoo9b]hoa7 ejpanj]h^kkhOpklEjLnkcnaoo w capwnapqnjopklEjLnkcnaoo7y y lner]pana]`kjhuopnejcpdna]`LkkhJ]ia7 lq^he_opnejcPdna]`LkkhJ]ia w capwnapqnjpdna]`LkkhJ]ia7y y ++Ejepe]hkbpdna]`opk_na]pa$_]hha`op]pe_pdna]`oejpdeo_h]oo%* Download at WoweBook.Com

95

96

CH APT ER 2 N W OR K ER A ND THR EA DS

lner]pana]`kjhuejpejepe]hPdna]`?kqjp7 ++?]lbknpdna]`_kqjp* ++Pdna]`o]``a`]^kraejepe]hPdna]`?kqjp]na_]hha``uj]ie_pdna]`o* lner]paejpi]tPdna]`?kqjp7 lq^he_ejpI]tPdna]`?kqjp w capwnapqnji]tPdna]`?kqjp7y y ++?qnnajpkbpdna]`oejpdalkkh$op]pe_'`uj]ie_%* lner]paejp_qnnajpPdna]`?kqjp9,7 lq^he_ejp?qnnajpPdna]`?kqjp w capwnapqnj_qnnajpPdna]`?kqjp7y oapw_qnnajpPdna]`?kqjp9r]hqa7y y ++Eb]`uj]ie_pdna]`eoe`habknpdeolanek`kbpeias+klnk_aooejc ++skngnamqaopo(epsehhatep* lner]paejp`a_]uPeia7 lq^he_ejp@a_]uPeia w capwnapqnj`a_]uPeia7y y ++Eb]skngnamqaopoepoejpdamqaqapdeohkjc^abkna^aejclnk_aooa`( ++]jaspdna]`sehh^a]``a`pkmqaqaqlpkpdai]t* lner]paPeiaOl]jjasPdna]`Pneccan7 lq^he_PeiaOl]jJasPdna]`PneccanPeiaOl]j w capwnapqnjjasPdna]`Pneccan7y oapwjasPdna]`Pneccan9r]hqa7y y lner]paPdna]`Lneknepupdna]`Lneknepu7 ++Oecj]ha`]bpanOpkl_]hha`]j`h]oppdna]`atepo* lner]paI]jq]hNaoapArajpopkl?kilhapaArajp9jasI]jq]hNaoapArajp$b]hoa%7 lq^he_I]jq]hNaoapArajpOpkl?kilhapaArajp w capwnapqnjopkl?kilhapaArajp7y y lner]paMqaqanamqaopMqaqa7 lq^he_MqaqaNamqaopMqaqa w capwnapqnjnamqaopMqaqa7y y ++Pdnkpphabkni]teiqikbskngnamqaopopd]p_]j^a]``a`* lner]paejpnamqaopMqaqaHeiep7 lner]pa^kkhqoa>]_gcnkqj`Pdna]`o9pnqa7 lq^he_^kkhQoa>]_gcnkqj`Pdna]`o w capwnapqnjqoa>]_gcnkqj`Pdna]`o7y y lner]pa^kkhlnklkc]paPdna]`Lnej_el]h9b]hoa7 lner]pa^kkhlnklkc]pa?]hh?kjpatp9b]hoa7 lner]pa^kkhlnklkc]paDppl?kjpatp9b]hoa7 lner]pa^kkhlnklkc]pa?=OI]ngano9b]hoa7  y Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

"EFORELOOKINGINTOTHEIMPLEMENTATIONDETAILSOFTHEUSAGESCENARIO ITISHELPFULTOUNDERSTAND how it works: ?qopkiPdna]`Lkkhpl-9jas?qopkiPdna]`Lkkh$.(2(Lkkh-%7 pl-*Lneknepu9Ouopai*Pdna]`ejc*Pdna]`Lneknepu*>ahksJkni]h7 pl-*JasPdna]`Pneccan90,,7 pl-*@uj]ie_Pdna]`@a_]u91,,,7 pl-*Op]np$%7 This starts a new thread pool using two initial threads and defines a maximum of six with low priority. The decay time is five seconds for testing purposes—the default is five minutes. The new THREADTRIGGERISSETTOMILLISECONDS The code used to test the thread pool requires an interface and a delegate, as defined in ,ISTING  Listing 2-15. Delegates and Base Interface for the Thread Pool lq^he_`ahac]parke`SkngNamqaop@ahac]pa$k^fa_pop]pa(± @]paPeianamqaopAjmqaqaPeia%7 lq^he_`ahac]parke`Pdna]`Lkkh@ahac]pa$%7 nacekjESkngNamqaopejpanb]_a lq^he_ejpanb]_aESkngNamqaop w ^kkh?]j_ah$%7 y aj`nacekj Once the pool is up and running, you can issue requests to get threads out of it. Doing so REQUIRESACALLBACKTHATSRESPONSIBLETOHANDLETHEWORKLOAD SkngNamqaop@ahac]pa_^-9jasSkngNamqaop@ahac]pa$?]hh^]_gKja%7 opnejc]nc97 Then a request internally starts the thread, using the callback to handle the worker method: pl-*LkopNamqaop$_^-(]nc%7 Once the threads are no longer required, the pool can be stopped: pl-*Opkl=j`S]ep$%7 This method call assures that the currently running threads can properly end its work before THETHREADPOOLISGOINGDOWNSEE,ISTING   Listing 2-16. The ThreadInfo Class That Provides the Thread-Specific HttpContext ejpanj]h_h]ooPdna]`Ejbk w lq^he_op]pe_Pdna]`Ejbk?]lpqna$^kkhlnklkc]paPdna]`Lnej_el]h(± ^kkhlnklkc]pa?]hh?kjpatp(± ^kkhlnklkc]paDppl?kjpatp(± ^kkhlnklkc]pa?=OI]ngano% w napqnjjasPdna]`Ejbk$lnklkc]paPdna]`Lnej_el]h(lnklkc]pa?]hh?kjpatp(± lnklkc]paDppl?kjpatp(lnklkc]pa?=OI]ngano%7 y lq^he_op]pe_Pdna]`EjbkEilanokj]pa$Pdna]`Ejbkpe% Download at WoweBook.Com

97

98

CH APT ER 2 N W OR K ER A ND THR EA DS

w eb$pe99jqhh%pdnksjas=ncqiajpJqhhAt_alpekj$pe%7 Pdna]`EjbklnarEjbk9?]lpqna$pnqa(pnqa(pnqa(pnqa%7 Naopkna$pe%7 napqnj$lnarEjbk%7 y lq^he_op]pe_rke`Naopkna$Pdna]`Ejbkpe% w eb$pe99jqhh%pdnksjas=ncqiajpJqhhAt_alpekj$pe%7 ++Naopkna_]hh_kjpatp* eb$ieOapHkce_]h?]hh?kjpatp9jqhh% w ieOapHkce_]h?]hh?kjpatp*Ejrkga$Pdna]`*?qnnajpPdna]`(± jask^fa_pWYwpe*_]hh?kjpatpy%7 y ++NaopknaDppl?kjpatpsepdpdaikn]hamqer]hajpkb ++Dppl?kjpatp*?qnnajp9pe*dppl?kjpatp7 ?]hh?kjpatp*Oap@]p]$Dppl?kjpatpOhkpJ]ia(pe*dppl?kjpatp%7 ++Naopknapdna]`e`ajpepu*Ep#oeilknp]jppd]ppdeo^a`kja]bpan ++naopknejc_]hh_kjpatp]^kra(oej_anaopknejc_]hh_kjpatp]hok ++kransnepaopda_qnnajppdna]`lnej_el]hoappejc*Eb ++lnklkc]pa?]hh?kjpatp ++]j`lnklkc]paPdna]`Lnej_el]h]na^kpdpnqa(pdajpda ++bkhhksejceona`qj`]jp* ++Dksaran(oej_alnklkc]pejc_]hh_kjpatpnamqenaopdaqoa ++kbnabha_pekjpk_]lpqna+naopkna_]hh_kjpatp(Es]jp ++pd]p^ad]reknpk^aej`alaj`ajphu ++osep_d]^haokpd]pep_]j^a`eo]^ha`7sdehaopehh]hhksejc ++pdna]`lnej_el]hpk^alnklkc]pa`* ++Pdeo]hok_kranoqoejpdaarajppd]p_]hh_kjpatp ++lnkl]c]pekj_d]jcaookpd]pepjkhkjcanlnklkc]paopdna]`lnej_el]h* Pdna]`*?qnnajpLnej_el]h9pe*lnej_el]h7 y lner]paPdna]`Ejbk$^kkhlnklkc]paPdna]`Lnej_el]h(^kkhlnklkc]pa?]hh?kjpatp(± ^kkhlnklkc]paDppl?kjpatp(^kkhlnklkc]pa?=OI]ngano% w eb$lnklkc]paPdna]`Lnej_el]h% w lnej_el]h9Pdna]`*?qnnajpLnej_el]h7 y eb$lnklkc]paDppl?kjpatp% w dppl?kjpatp9Dppl?kjpatp*?qnnajp7 y eb$lnklkc]pa?]hh?kjpatp""$ieCapHkce_]h?]hh?kjpatp9jqhh%% w _]hh?kjpatp9$Hkce_]h?]hh?kjpatp%± ieCapHkce_]h?]hh?kjpatp*Ejrkga$Pdna]`*?qnnajpPdna]`(jqhh%7 _]hh?kjpatp9$Hkce_]h?]hh?kjpatp%_]hh?kjpatp*?hkja$%7 Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

y y ELnej_el]hlnej_el]h7 Hkce_]h?]hh?kjpatp_]hh?kjpatp7 ++=hs]uojqhhqjpehCap+Oap?kilnaooa`Op]_g]naklaja`ql* ?kilnaooa`Op]_g_kilnaooa`Op]_g9jqhh7 Dppl?kjpatpdppl?kjpatp7 ++?]_da`pulaejbkni]pekj* _kjop>ej`ejcBh]co^bJkjLq^he_Ejop]j_a9>ej`ejcBh]co*Ejop]j_ax± >ej`ejcBh]co*JkjLq^he_7 _kjop>ej`ejcBh]co^bJkjLq^he_Op]pe_9>ej`ejcBh]co*Op]pe_x± >ej`ejcBh]co*JkjLq^he_7 op]pe_Iapdk`EjbkieCapHkce_]h?]hh?kjpatp9± pulakb$Pdna]`%*CapIapdk`$CapHkce_]h?]hh?kjpatp(^bJkjLq^he_Ejop]j_a%7 op]pe_Iapdk`EjbkieOapHkce_]h?]hh?kjpatp9± pulakb$Pdna]`%*CapIapdk`$OapHkce_]h?]hh?kjpatp(^bJkjLq^he_Ejop]j_a%7 op]pe_opnejcDppl?kjpatpOhkpJ]ia7 op]pe_Pdna]`Ejbk$% w ++Hkkgqlpdar]hqakbDppl?kjpatp*?]hh?kjpatpOhkpJ]ia$ebepateopo% ++pkoaasd]ppdaj]iakbpda_]hh_kjpatpohkpeo ++sdanaDppl?kjpatp*?qnnajp ++eoop]oda`*=o]b]hh^]_g(ebpdeobeah`eoj#plnaoajp]juikna(fqop ++pnubknpdaknecej]hDppl?kjpatpohkpj]ia* Beah`Ejbkbe9pulakb$Dppl?kjpatp%*CapBeah`$?]hh?kjpatpOhkpJ]ia(± ^bJkjLq^he_Op]pe_%7 eb$be9jqhh% w Dppl?kjpatpOhkpJ]ia9$opnejc%be*CapR]hqa$jqhh%7 y ahoa w Dppl?kjpatpOhkpJ]ia9Dppl?kjpatp7 y y y The Pdna]`Ejbk class handles logical information regarding the current thread. This includes the Dppl?kjpatp object of current request. The idea is that several parallel running threads handle different contexts and need to restore the one currently being executed. The data are held in the Hkce_]h?]hh?kjpatpCLASSTHATHOLDSASETOFSERIALIZABLEPROPERTIESSEE,ISTING   Listing 2-17. The ThreadWrapper Class That Wraps the Actual Thread ejpanj]h_h]ooPdna]`Sn]llan w lner]pa?qopkiPdna]`Lkkhlkkh7 lner]pa^kkheoLani]jajp7 lner]paPdna]`Lneknepulneknepu7 lner]paopnejcj]ia7 Download at WoweBook.Com

99

100

CH APT ER 2 N W OR K ER A ND THR EA DS

lq^he_Pdna]`Sn]llan$?qopkiPdna]`Lkkhlkkh(^kkheoLani]jajp(± Pdna]`Lneknepulneknepu(opnejcj]ia% w pdeo*lkkh9lkkh7 pdeo*eoLani]jajp9eoLani]jajp7 pdeo*lneknepu9lneknepu7 pdeo*j]ia9j]ia7 hk_g$lkkh% w ++Ql`]papdapkp]hkbpdna]`oejpdalkkh* lkkh*?qnnajpPdna]`?kqjp''7 y y lq^he_rke`Op]np$% w Pdna]`p9jasPdna]`$jasPdna]`Op]np$Pdna]`Lnk_%%7 p*=l]npiajpOp]pa9=l]npiajpOp]pa*IP=7 p*J]ia9j]ia7 p*Lneknepu9lneknepu7 p*Eo>]_gcnkqj`9lkkh*Qoa>]_gcnkqj`Pdna]`o7 p*Op]np$%7 y rke`Pdna]`Lnk_$% w ^kkh`kja9b]hoa7 sdeha$`kja% w SkngNamqaopsn9jqhh7 Pdna]`Sn]llanjasPdna]`9jqhh7 hk_g$lkkh% w ++=ohkjc]opdanamqaopmqaqaeoailpu]j`]odqp`ksjd]oj#p ++^aajejepe]pa`(s]epbkn]jasskngnamqaoppk]nnera* ^kkhpeia`Kqp9b]hoa7 sdeha$lkkh*OpklEjLnkcnaoo""peia`Kqp""± $lkkh*NamqaopMqaqa*?kqjp99,%% w eb$Ikjepkn*S]ep$lkkh(± $eoLani]jajp;Peiakqp*Ejbejepa6lkkh*@a_]uPeia%%% w ++Peia`kqps]epejcbknokiapdejcpk`k* ++Kjhu`uj]ie_]hhu_na]pa` ++pdna]`osehhcapdana(ok^]ehkqp* peia`Kqp9pnqa7 y y ++Saatepa`pdahkkl]^kra^a_]qoakjakbpda ++bkhhksejc_kj`epekjos]oiap6 ++)Pdna]`Lkkh*Opkls]o_]hha`pkejepe]pa]odqp`ksj* ++)=`uj]ie_pdna]`peia`kqps]epejcbkn]skngnamqaop ++)Pdana]naepaioejpdaskngmqaqapklnk_aoo* ++Ebsaatepa`pdahkkl^a_]qoapdana#oskngpk^a`kja(] Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

++odqp`ksjd]oj#p^aajejepe]pa`(]j`epeoj#p]`uj]ie_pdna]` ++pd]ppeia`kqp(lqhhpdanamqaopkbbpdamqaqa]j`lnal]napk ++lnk_aooep* eb$lkkh*OpklEjLnkcnaoo""peia`Kqp""± $lkkh*NamqaopMqaqa*?kqjp:,%% w sn9$SkngNamqaop%lkkh*NamqaopMqaqa*@amqaqa$%7 @a^qc*=ooanp$sn9jqhh%7 ++?da_gpkoaaebpdeoskngnamqaoph]jcqeoda`ejpdamqaqa ++ranuhkjc*Ebeps]oejpdamqaqa:9pdajaspdna]` ++pneccanpeia(]j`ebsad]raj#pna]_da`pdai]tpdna]` ++_kqjp_]l(]``]jaspdna]`pkpdalkkh* ++Ebpda`a_eoekjeoi]`a(_na]papdajaspdna]`k^fa_p ++$ql`]pejcpda_qnnajpkbpdna]`oejpdalkkh%( ++^qp`abanop]npejcpdajas ++pdna]`qjpehpdahk_geonaha]oa`* PeiaOl]jnamqaopPeiaEjM9@]paPeia*Jks*Oq^pn]_p$sn*skngejcPeia%7 eb$$namqaopPeiaEjM:9lkkh*JasPdna]`PneccanPeiaOl]j%""± $lkkh*?qnnajpPdna]`?kqjp8lkkh*I]tPdna]`?kqjp%% w jasPdna]`9± jasPdna]`Sn]llan$lkkh(b]hoa(lneknepu(± opnejc*Bkni]p$w,y$`uj]ie_%(± lkkh*Pdna]`LkkhJ]ia%%7 ++Oej_apda_qnnajpnamqaopsafqop`amqaqa`eoop]ha( ++aranupdejcahoa^adej`epejpdamqaqaeo]hokop]ha* ++Oknaoappdapeiaop]ilokbpdanai]ejejclaj`ejcskng ++namqaopookpd]psa`kj#pop]np_na]pejcpdna]`o ++bknaranuoq^oamqajpnamqaop* lkkh*NaoapSkngNamqaopPeiao$%7 y y ahoa w ++Odkqh`kjhucapdanaebpdeoeo]`uj]ie_pdna]`pd]p ++peia`kqps]epejcbkn]skngnamqaop(knebpdalkkh ++eoodqppejc`ksj* lkkh*?qnnajpPdna]`?kqjp))7 eb$lkkh*?qnnajpPdna]`?kqjp99,% w ++H]opkjakqppqnjokbbpdahecdpo* lkkh*KjOpklla`$%7 lkkh*Opkl?kilhapaArajp*Oap$%7 y `kja9pnqa7 y y++hk_g ++Jkhkjcandkh`ejclkkhhk_gdana*** eb$`kja""$sn9jqhh%% w Download at WoweBook.Com

101

102

CH APT ER 2 N W OR K ER A ND THR EA DS

++?da_gpkoaaebpdeonamqaopd]o^aaj_]j_ahha`sdeha ++opq_gejpdaskngmqaqa* ++Ebpdaskngnamqaops]olaj`ejc(i]ngeplnk_aooa`]j` ++lnk_aa`pkd]j`ha*Kpdanseoa(pdanamqaopiqopd]ra^aaj ++_]j_ahha`^abknasalhq_ga`epkbbpdanamqaopmqaqa* eb$Ejpanhk_ga`*?kil]naAt_d]jca$nabsn*op]pa(± SkngNamqaop*LNK?AOOA@(± SkngNamqaop*LAJ@EJC%9SkngNamqaop*LAJ@EJC% w ++Namqaops]o_]j_ahha`^abknasa_kqh`capdana* ++>]ehkqp* _kjpejqa7 y eb$jasPdna]`9jqhh% w jasPdna]`*Op]np$%7 y ++@eol]p_dpdaskngnamqaop* Pdna]`Ejbkknecej]hPdna]`Ejbk9jqhh7 pnu w ++Eilanokj]pa$]oiq_d]olkooe^ha%sd]psagjks]^kqp ++pdapdna]`pd]peooqa`pdaskngnamqaop* knecej]hPdna]`Ejbk9Pdna]`Ejbk*Eilanokj]pa$sn*pdna]`Ejbk%7 SkngNamqaop@ahac]pap]ncapLnk_9sn*p]ncapLnk_]o± SkngNamqaop@ahac]pa7 eb$p]ncapLnk_9jqhh% w p]ncapLnk_$sn*lnk_=nc(sn*peiaOp]ilOp]npa`%7 y ahoa w sn*p]ncapLnk_*@uj]ie_Ejrkga$sn*lnk_=nco%7 y y _]p_d$At_alpekja% w y bej]hhu w ++Naopknakqnsknganpdna]`#oe`ajpepu* ++ Pdna]`Ejbk*Naopkna$knecej]hPdna]`Ejbk%7 y y y y y 7HILETHETHREADISTHERETODOTHEWORK ANOTHERPIECEINTHEPUZZLEISREQUIREDˆTHESkngNamqaop. This type contains the reference between the callback method that is handling the workload and the THREAD,ISTING   Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

Listing 2-18. The WorkRequest Class That Associates Request and Thread ejpanj]h_h]ooSkngNamqaop6ESkngNamqaop w ejpanj]h_kjopejpLAJ@EJC9,7 ejpanj]h_kjopejpLNK?AOOA@9-7 ejpanj]h_kjopejp?=J?AHHA@9.7 lq^he_SkngNamqaop$SkngNamqaop@ahac]pa_^(k^fa_p]nc( ^kkhlnklkc]paPdna]`Lnej_el]h(^kkhlnklkc]pa?]hh?kjpatp( ^kkhlnklkc]paDppl?kjpatp(^kkhlnklkc]pa?=OI]ngano% w p]ncapLnk_9_^7 lnk_=nc9]nc7 lnk_=nco9jqhh7 Ejepe]heva$lnklkc]paPdna]`Lnej_el]h(lnklkc]pa?]hh?kjpatp( lnklkc]paDppl?kjpatp(lnklkc]pa?=OI]ngano%7 y lq^he_SkngNamqaop$@ahac]pa_^(k^fa_pWY]nco( ^kkhlnklkc]paPdna]`Lnej_el]h(^kkhlnklkc]pa?]hh?kjpatp( ^kkhlnklkc]paDppl?kjpatp(^kkhlnklkc]pa?=OI]ngano% w p]ncapLnk_9_^7 lnk_=nc9jqhh7 lnk_=nco9]nco7 Ejepe]heva$lnklkc]paPdna]`Lnej_el]h(lnklkc]pa?]hh?kjpatp( lnklkc]paDppl?kjpatp(lnklkc]pa?=OI]ngano%7 y rke`Ejepe]heva$^kkhlnklkc]paPdna]`Lnej_el]h(^kkhlnklkc]pa?]hh?kjpatp( ^kkhlnklkc]paDppl?kjpatp(^kkhlnklkc]pa?=OI]ngano% w skngejcPeia9peiaOp]ilOp]npa`9@]paPeia*Jks7 pdna]`Ejbk9Pdna]`Ejbk*?]lpqna$lnklkc]paPdna]`Lnej_el]h(± lnklkc]pa?]hh?kjpatp(± lnklkc]paDppl?kjpatp(± lnklkc]pa?=OI]ngano%7 y lq^he_^kkh?]j_ah$% w ++Ebpdaskngnamqaops]olaj`ejc(i]ngep_]j_ahha`*Kpdanseoa( ++pdeoiapdk`s]o_]hha`pkkh]pa*Jkpapd]ppdeo_]hh_]j ++_]j_ah]jklan]pekjsepdkqp]jun]_a_kj`epekjo*>qpebpda ++naoqhpkbpdeopaop)]j`)oapej`e_]paopdanamqaopeoejpda ++lnk_aooa`op]pa(epiecdp]_pq]hhu^a]^kqppk^alnk_aooa`* napqnj$Ejpanhk_ga`*?kil]naAt_d]jca$nabop]pa(?=J?AHHA@(LAJ@EJC%± 99LAJ@EJC%7 y ++Bqj_pekjpk_]hh* ejpanj]h@ahac]pap]ncapLnk_7 ++Op]papkl]oopkbqj_pekj* ejpanj]hk^fa_plnk_=nc7 ++Qoa`sepd@ahac]pa*@uj]ie_Ejrkga* Download at WoweBook.Com

103

104

CH APT ER 2 N W OR K ER A ND THR EA DS

ejpanj]hk^fa_pWYlnk_=nco7 ++Peiaskngnamqaops]oknecej]hhuajmqaqa`$dah`_kjop]jp%* ejpanj]h@]paPeiapeiaOp]ilOp]npa`7 ++?qnnajppeiaop]ilqoa`bknpneccanejcjaspdna]`o$ikrejcp]ncap%* ejpanj]h@]paPeiaskngejcPeia7 ++Aranupdejcsagjks]^kqp]pdna]`* ejpanj]hPdna]`Ejbkpdna]`Ejbk7 ++Pdaop]pakbpdeol]npe_qh]nnamqaop* ejpanj]hejpop]pa9LAJ@EJC7 y The goal is the function that contains the worker code stored in p]ncapLnk_. The field lnk_=nco held the particular arguments. The field pdna]`Ejbk contains the associated information, especially the Dppl?kjpatp object. This all creates the necessary functions to have threads ready to be used any time and indepenDENTOFTHEINTERNALTHREADPOOL.OWTHATYOUHAVEACUSTOMTHREADPOOLIMPLEMENTATION ITSTIME to use it.

Using the Custom Thread Pool with ASP.NET’s Asynchronous Handler The following example is simply an extended version of the previous one. Instead of using single threads, however, and risk having too many of them, you can use the custom thread pool and set SOMELIMITATIONSSEE,ISTING   Listing 2-19. Using the Thread Pool 8))Beha6=ouj_Lkkh*]odt)): 8!<Sa^D]j`hanH]jcq]ca9? ?h]oo9=lnaoo*Pdna]`ejc*DpplLelaheja*=ouj_D]j`han!: j]iaol]_a=lnaoo*Pdna]`ejc*DpplLelaheja w  lq^he__h]oo=ouj_D]j`han6EDppl=ouj_D]j`han w op]pe_=lnaoo*Atpajoe^ehepu*Pdna]`ejc*?qopkiPdna]`Lkkh[pdna]`Lkkh7 op]pe_=ouj_D]j`han$% w [pdna]`Lkkh9± jas=lnaoo*Atpajoe^ehepu*Pdna]`ejc*?qopkiPdna]`Lkkh$.(.1(=ouj_Lkkh%7 [pdna]`Lkkh*Lnklkc]pa?]hh?kjpatp9pnqa7 [pdna]`Lkkh*Lnklkc]paPdna]`Lnej_el]h9pnqa7 [pdna]`Lkkh*Lnklkc]paDppl?kjpatp9pnqa7 [pdna]`Lkkh*Op]np$%7 y lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_pt% w ++jkpqoa`(bknouj_kjhu y lq^he_^kkhEoNaqo]^ha w capwnapqnjb]hoa7y y Download at WoweBook.Com

C H A P T E R 2 N W O R K E R A N D T H R E A D S

lq^he_E=ouj_Naoqhp>acejLnk_aooNamqaop$Dppl?kjpatp_pt(± =ouj_?]hh^]_g_^(k^fa_pk^f% w =ouj_NamqaopOp]panamOp]pa9± jas=ouj_NamqaopOp]pa$_pt(_^(k^f%7 [pdna]`Lkkh*LkopNamqaop$jasSkngNamqaop@ahac]pa$Lnk_aooNamqaop%(namOp]pa%7 napqnjnamOp]pa7 y lq^he_rke`Aj`Lnk_aooNamqaop$E=ouj_Naoqhp]n% w y rke`Lnk_aooNamqaop$k^fa_pop]pa(@]paPeianamqaopPeia% w =ouj_NamqaopOp]panamOp]pa9op]pa]o=ouj_NamqaopOp]pa7 ++P]gaokiapeiapk`kep Pdna]`*Ohaal$.,,,%7  namOp]pa*[_pt*Naolkjoa*Kqplqp*Snepa$± =ouj_Pdna]`Lkkh(w,y(± =ll@ki]ej*Cap?qnnajpPdna]`E`%7 ++pahh]ol*japukq]nabejeoda`lnk_aooejcpdeonamqaop namOp]pa*?kilhapaNamqaop$%7 y y y )NTHEORY THISTHREADPOOLWILLNOTRUNOUTOFTHREADSUNLESSITDOESNOTREACHTHELIMITOF  THREADSALLOWED(OWEVER THEREARESOMELIMITATIONS SUCHASAVAILABLEMEMORY #05POWER AND operating system restrictions. This is why the pool was designed, so that you can optionally specify limits. The previous code is a good platform for experimenting with threads and thread pools, and for monitoring the number of threads for your application. If you want to replace the internal thread pool, try out the custom pool toLEARNHOW!30.%4REQUESTSTHREADS, and find out where to improve performance.

Summary This chapter covered in-depth information about the internal request processing and how to tweak the worker process and the threading. You were given an idea of how the thread pool works and how TOEXTENDTHEBEHAVIOR5SINGASYNCHRONOUSPROCESSINGMIGHTINCREASEPERFORMANCEANDHANDLE HIGHWORKLOAD!CUSTOMTHREADPOOLWASINTRODUCEDTODEMONSTRATEHOWTOCHANGEINTERNALPARTS of the processing pipeline transparently. In anticipation of Chapter 3, you had a first look into asynchronous handlers and their usage.

Download at WoweBook.Com

105

Download at WoweBook.Com

CHAPTER

3

Modules and Handlers

I

n this chapter, you will look more closely at the extensibility of ASP.NET through the addition of custom modules and handlers. Handlers and modules are integrated into IIS so that your web applications can perform and scale well. In Chapter 2, you learned how to use asynchronous handlers to handle custom threads. Here, you’ll learn more about how ASP.NET can extend using handlers. This chapter includes:

s 7HATINTERNALMODULESAREFOR



s (OWTOCREATE ACTIVATE ANDDEBUGCUSTOMMODULES



s 4HEHANDLERSINCLUDEDIN!30.%4



s (OWTOEXTEND CUSTOMIZE ANDREPLACEHANDLERS



s 7RITINGYOUROWNHANDLERSWITHBOTHSYNCHRONOUSANDASYNCHRONOUSBEHAVIOR

Module, Handlers, and IIS ))37EB3ERVERFEATURESFITINTOONEOFTWOCATEGORIES

s -ODULES



s (ANDLERS

Similar to the ISAPI filterINPREVIOUS))3VERSIONS AMODULE participates in the processing of each request. Its role is to change or add content to the request. Examples of some out-of-the-box modules in IIS7 include authentication modules, compression modules, and logging modules. The names indicate the function of each module. A module is a .NET class that implements the Ouopai*Sa^*EDpplIk`qha interface and uses APIs in the Ouopai*Sa^ namespace to participate in one or more of ASP.NET’s request-processing stages. I explained the stages of this “pipeline” in Chapter 1. By contrast, a handler, similar to the ISAPI extensionINPREVIOUS))3VERSIONS ISRESPONSIBLEFOR handling requests and creating responses for specific content types. The main difference between modules and handlers is that handlers typically map to a particular request path or extension. They also support the processing of a specific resource to which that path or extension corresponds. (ANDLERSPROVIDEDWITH))3INCLUDE!30.%4SL]caD]j`hanB]_pknu, which processes .aspx pages, among others. This kind of a handler is a .NET class that implements the ASP.NET Ouopai*Sa^* EDpplD]j`han or Ouopai*Sa^*EDppl=ouj_D]j`han interface. It uses APIs in the Ouopai*Sa^ namespace to produce an HTTP response for the specific content it creates. 7HENDEVELOPINGAN))3FEATUREOR!30.%4EXTENSION YOULLNEEDTODECIDEWHETHERAMODule or a handler is appropriate. No common task requires both. If your feature is responsible for SERVINGREQUESTSTOASPECIFIC52,ORFILEEXTENSION LIKE&*ljc, then a handler is the right choice, as 107 Download at WoweBook.Com

108

CH APT ER 3 N MODU L ES A ND HA NDL ER S

HANDLERSAREPRIMARILYFORSPECIFICTASKS!LTERNATIVELY IFYOUWANTTORESPONDTOSOMEORALLREQUESTS a module is appropriate. #REATINGIMAGESONTHEFLYCORRESPONDSTOASPECIFICFILETYPEˆUSEAHANDLERTOACHIEVETHIS Adding footers to all your pages from one location is a good idea—implement a module to do that.

Modules 4HISSECTIONEXPLAINSHOWTOCREATEINTERNALMODULESANDGIVESSOMEEXAMPLESTHATYOUCANUSEIN your own applications.

IIS7 Architecture ASP.NET isTIGHTLYINTEGRATEDWITH))3%VENTHOUGHITISPOSSIBLE to run ASP.NET with any host, thanks to its modular architecture, you should keep in mind that IIS is the best platform “by design.” %XTENDINGANDCUSTOMIZING!30.%4ISONLYPOSSIBLEWITHAGOODUNDERSTANDINGOF))3ANDITSPARTS -ICROSOFTCHANGEDLARGEPARTSOFTHEARCHITECTUREOF))3COMPAREDTOPREVIOUSVERSIONS/NEOF THEMAJORCHANGESWASTHEGREATLYENHANCEDEXTENSIBILITY)NSTEADOFAPOWERFULYETMONOLITHIC7EB 3ERVER ))3NOWHASA7EB3ERVERENGINETOWHICHYOUCANADDORREMOVECOMPONENTS4HESECOMponents are called modules. -ODULESBUILDTHEFEATURESOFFEREDBYTHE7EB3ERVER!LLMODULESHAVEONEPRIMARYTASKˆ PROCESSINGAREQUEST4HISCANBECOMECOMPLICATED HOWEVER ASAREQUESTISNOTJUSTACALLTOSTATIC RESOURCES#ONSIDERREQUESTSINVOLVINGTHEAUTHENTICATIONOFCLIENTCREDENTIALS COMPRESSIONAND decompression, or cache management. Assuming that IIS7 is the primary platform for running ASP.NET, any discussion about extensibility does not make sense without understanding what accompanies IIS7. IIS7 comes with two module types:

s .ATIVE-ODULES



s -ANAGED-ODULES

Native Modules .ATIVEMODULESPERFORMALLTHEBASICTASKSOFA7EB3ERVER(OWEVER NOTALLMODULESMANAGECOMMONREQUESTS)TDEPENDSONYOURINSTALLATIONANDCONFIGURATIONASTOWHETHERAMODULEISAVAILABLE and running. Inside IIS7 are:

s (440-ODULES



s 3ECURITY-ODULES



s #ONTENT-ODULES



s #OMPRESSION-ODULES



s #ACHING-ODULES



s ,OGGINGAND$IAGNOSING-ODULES



s )NTEGRATIONOF-ANAGED-ODULES

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

You can find all modules—apart from those whose full path follow—in the following directory: !Sej@en!XOuopai/.XEjapOnr As shown in Table 3-1, the HTTP modules perform tasks specific to Hypertext Transfer Protocol. Table 3-1. HTTP Modules Module Name

DLL

Description

?qopkiAnnknIk`qha

Custerr.dll

Its purpose is to send default or configured HTTP error messages when the response contains an error status.

DpplNa`ena_pekjIk`qha

2EDIRECTDLL

-ODULESUPPORTSCONFIGURABLEREDIRECTIONFOR HTTP requests.

Lnkpk_khOqllknpIk`qha 

Protsup.dll

This module executes protocol-related actions, such as setting response headers and redirecting headers.

SecurityISESSENTIALFORA7EB3ERVER ASSHOWNBYTHENUMBEROFMODULESIN4ABLE  Table 3-2. Security Modules

Module Name

DLL

Description

=jkjuikqo=qpdajpe_]pekjIk`qha

Authanon.dll

Accomplishes anonymous authentication in case other authentication methods fail.

>]oe_=qpdajpe_]pekjIk`qha

Authbas.dll

Performs Basic authentication.

?anpebe_]paI]llejc=qpdajpe_]pekjIk`qha

Authcert.dll

0ERFORMS#ERTIFICATE-APPING AUTHENTICATIONUSING!CTIVE $IRECTORY

@ecaop=qpdajpe_]pekjIk`qha

Authmd5.dll

0ERFORMS$IGESTAUTHENTICATION

EEO?anpebe_]paI]llejc=qpdajpe_]pekjIk`qha

Authmap.dll

0ERFORMS#ERTIFICATE-APPING authentication using IIS certificate configuration.

NamqaopBehpanejcIk`qha

-ODRQFLTDLL

Performs tasks such as conFIGURINGALLOWEDVERBSANDFILE extensions, setting limits, and scanning for bad character seQUENCESBYSCANNINGTHE52,

Qnh=qpdknev]pekjIk`qha

5RLAUTHZDLL

%XECUTES52,AUTHORIZATION

Sej`kso=qpdajpe_]pekjIk`qha

Authsspi.dll

0ERFORMS.4,-INTEGRATED authentication.

ElNaopne_pekjIk`qha 

iprestr.dll

4HEPURPOSEISTORESTRICT)0V addresses listed in the IpSecurity list.

/NCETHEREQUESTISACCEPTEDANDAUTHORIZED THEREQUESTEDRESOURCESAREHANDLED3EVERAL modules perform these specific tasks. Table 3-3 shows the modules that handle content directly, like static files.

Download at WoweBook.Com

109

110

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Table 3-3. Content Modules

Module Name

DLL

Description

?ceIk`qha

Cgi.dll

Executes Common Gateway Interface (CGI) processes to build response output.

@ab]qhp@k_qiajpIk`qha

$EFDOCDLL

Attempts to return a default document for requests made to the parent directory.

@ena_pknuHeopejcIk`qha

dirlist.dll

,ISTSTHECONTENTSOFADIRECTORYANDBUILDSA(4-, response of the listing.

Eo]leIk`qha

Isapi.dll

4HISMODULESHOSTSOTHER)3!0)EXTENSION$,,S

Eo]leBehpanIk`qha

Filter.dll

4HISMODULESUPPORTS)3!0)FILTER$,,S

OanranOe`aEj_hq`aIk`qha

Iis_ssi.dll

4HISMODULEISRESPONSIBLEFORSERVER SIDEINCLUDE CODE AFORMERMODULARIZATIONTECHNIQUE

Op]pe_BehaIk`qha

Static.dll

4HISMODULESERVESSTATICFILES SUCHASIMAGES

B]op?ceIk`qha 

iisfcgi.dll

3UPPORTS&AST#') WHICHPROVIDESAHIGH PERFORMANCE ALTERNATIVETO#')5SEDTOSUPPORTWEBDEVELOPMENT ENVIRONMENTSLIKE0(0

CompressionISACOMMONWAYTOSAVEBANDWIDTHANDTRANSFERLARGEFILESMOREEFFICIENTLYSEE 4ABLE   Table 3-4. Compression Modules

Module Name

DLL

Description

@uj]ie_?kilnaooekjIk`qha

Compdyn.dll

5SEDTOCOMPRESSRESPONSESUSINGgzip compression transfer coding on the fly

Op]pe_?kilnaooekjIk`qha

Compstat.dll

Performs the pre-compression of static content

CachingISANOTHERWAYTOIMPROVEPERFORMANCE3EVERALMODULESSTOREFILESSOTHATTHEDELIVERY process is either accelerated or eliminated altogether (see Table 3-5). Table 3-5. Caching Modules

Module Name

DLL

Description

Beha?]_daIk`qha

Cachfile.dll

0ROVIDESUSERMODECACHINGFORFILESANDFILEHANDLES

DPPL?]_daIk`qha

Cachhttp.dll

0ROVIDESKERNELMODEANDUSERMODECACHINGIN(440SYS DRIVER

Pkgaj?]_daIk`qha

Cachtokn.dll

0ROVIDESUSERMODECACHINGOFUSERNAMEANDTOKENPAIRSFOR MODULESTHATUSE7INDOWSUSERPRINCIPALS

Qne?]_daIk`qha

Cachuri.dll

0ROVIDESUSERMODECACHINGOF52,INFORMATION

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

+NOWINGWHATISHAPPENINGISESSENTIALFOR7EB3ERVERADMINISTRATORS4HEREARESEVERAL STEPSFROMTHECODEONYOURSERVERˆWHEREYOUPROBABLYHAVEDEBUGCAPABILITIESˆTOTHEBROWSER WHEREYOUMIGHTMISSSEEINGTHEDESIREDOUTPUT%VENPRODUCTIONSYSTEMSDONOTALWAYSBEHAVEAS expected. Table 3-6 shows logging and diagnostic modules, which help you understand the internal processing of requests and responses. Table 3-6. Logging and Diagnostic Modules

Module Name

DLL

Description

?qopkiHkccejcIk`qha

,OGCUSTDLL

,OADSADDITIONALCUSTOMLOGGINGMODULES

B]eha`NamqaopoPn]_ejcIk`qha

Iisfreb.dll

4HISMODULESUPPORTSTHEh&AILED2EQUEST4RACINGv feature.

DpplHkccejcIk`qha

,OGHTTPDLL

This module passes information and processing STATUSTOTHE(440SYSDRIVERFORLOGGINGPURPOSES

NamqaopIkjepknIk`qha

Iisreqs.dll

This module tracks requests currently executing in worker processes and reports information using the 2UNTIME3TATUSAND#ONTROL!PPLICATION0ROGRAMMING)NTERFACE23#! 

Pn]_ejcIk`qha

Iisetw.dll

2EPORTSEVENTSTO-ICROSOFT%VENT4RACINGFOR 7INDOWS%47 

Finally, you need an interface to the managed world. In Chapter 1, you saw how modules interacted. Table 3-7 shows which modules areINVOLVEDINTHISINTERACTION Table 3-7. Integration of Managed Modules

Module Name

DLL/Assembly

Description

I]j]ca`Ajceja

-ICROSOFT.%4<&RAMEWORK< V<WEBENGINEDLL

0ROVIDESINTEGRATIONOFMANaged code modules in the IIS request-processing pipeline. The VERSIONNUMBERMIGHTCHANGE

?kjbecqn]pekjR]he`]pekjIk`qha VALIDCFGDLL    

Validates configuration issues, such as if an application is running in Integrated mode but has handlers or modules declared in the system.web section of web. config file.

Managed Modules 7HILEEXTENDING))3VIANATIVEMODULESISONEMETHODOFWRITINGHIGH PERFORMANCEAPPLICATIONS for most projects, this is not necessary or desirable. Extending ASP.NET using managed modules HASSIGNIFICANTADVANTAGESINDEVELOPMENTTIMEANDRELIABILITY))3INCLUDESSEVERALBUILT IN MANAGEDMODULES WHICHSHOWTHATITISPOSSIBLETOWRITELOW LEVELINFRASTRUCTURECOMPONENTSIN managed code.

Download at WoweBook.Com

111

112

CH APT ER 3 N MODU L ES A ND HA NDL ER S

You can find the definition of security modules in the Ouopai*Sa^*Oa_qnepu namespace (see Table 3-8). Table 3-8. Managed Code Security Modules Shipped with IIS7

Module Name

Class

Description

AnonymousIdentification

=jkjuikqoE`ajpebe_]pekjIk`qha

-ANAGESANONYMOUSIDENTIFIERS which are used by features to support anonymous identification such as the ASP.NET profile.

$EFAULT!UTHENTICATION

@ab]qhp=qpdajpe_]pekjIk`qha

Ensures that a default authentication object is present in the context.

&ILE!UTHORIZATION

Beha=qpdknev]pekjIk`qha

Verifies that a user has permission to access the requested file based on file security.

FormsAuthentication

Bknio=qpdajpe_]pekjIk`qha

Supports authentication using the Forms authentication technique.

2OLE-ANAGER

NkhaI]j]canIk`qha

-ANAGESA2OLE0RINCIPALINSTANCE for the current user and therefore the role management. This is EXTENSIBLETHROUGHPROVIDERS

5RL!UTHORIZATION

Qnh=qpdknev]pekjIk`qha

$ETERMINESWHETHERTHECURRENT user is permitted to access the reQUESTED52, BASEDONTHEUSERS name or his or her membership of a suitable role.

7INDOWS!UTHENTICATION

Sej`kso=qpdajpe_]pekjIk`qha 

Supports the identity of a user WHEN7INDOWSAUTHENTICATIONIS enabled for the application.

Table 3-9 shows some more modules for particular usage. The definition of the cache module is stored in Ouopai*Sa^*?]_dejc. This module is declared as ejpanj]h and is not accessible by user code. The other ones are declared lq^he_. The module for profile handling is in the Ouopai*Sa^* Lnkbeha namespace. For session handling modules, look into the Ouopai*Sa^*OaooekjOp]pa NAMESPACE4HEMODULESFOR52,HANDLINGARESTOREDINTHEROOTNAMESPACEOuopai*Sa^. Table 3-9. Managed Code Modules Shipped with IIS7

Module Name

Class

Description

/UTPUT#ACHE

Kqplqp?]_daIk`qha

This module supports output caching.

Profile

LnkbehaIk`qha

-ANAGESUSERPROFILESBYUSING!30.%4PROFILES WHICHSTOREANDRETRIEVEUSERSETTINGSINADATA source such as a database. This is extensible THROUGHPROVIDERS

Session

OaooekjOp]paIk`qha

Supports the maintenance of the session state, which enables the storage of data specific to a sinGLECLIENTONTHESERVER4HISISEXTENSIBLETHROUGH PROVIDERS

5RL-APPINGS-ODULE

QnhI]llejcoIk`qha

3UPPORTSTHEMAPPINGOFAREAL52,TOAMORE USER FRIENDLYOREVENASEARCH ENGINEFRIENDLY52,

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

'IVENTHISLISTOFMODULES YOUMIGHTFEELTHATTHEREISNONEEDTOWRITECUSTOMMODULESTOPERFORMSTANDARDTASKS4HISISTRUETHEDEVELOPERSOF!30.%4AND))3HAVEDELIVEREDEVERYTHINGYOU NEEDFORCOMMONINFRASTRUCTUREWORK(OWEVER IFYOUDLIKETOPROGRAMANAPPLICATION SPECIFIC task, writing your own module is an excellent way to extend ASP.NET and add sophisticated features of your choice.

The IIS7 Managed Module Starter Kit -ICROSOFTPROVIDES a starter kit to make it easy to write your first module for the new IIS7 managed !0)4HIS6ISUAL3TUDIO#ONTENT)NSTALLERCONTAINSAPROJECTTEMPLATEFORBUILDING))3-ODULES using the .NET Framework.

Get the Starter Kit The Starter Kit isAVAILABLEATNOCOSTFROM-ICROSOFTATTHEsss*eeo*jap7EBSITEdppl6++sss*eeo* jap+`ksjhk]`o+`ab]qhp*]olt;p]^e`9/0"e9-/,."c92. #LICKON$OWNLOAD SAVETHEFILE ANDUNZIPTOACURRENTFOLDER4HEKITISA6ISUAL3TUDIOTEMPLATEINSTALLER PROVIDED as a .roe file.

Benefits of Module Development Kit Since IIS7 supportsDEVELOPMENTUSINGMANAGEDCODE ITMEANSYOUCANPROGRAM(440REQUEST PROCESSINGINMANAGEDCODE4HEENTIREEVENTSTRUCTUREOF))3 WRITTENINNATIVE!0)## ISALSO AVAILABLETOMANAGEDCODEDEVELOPERS&IGURE SHOWSTHESTARTSCREENOFTHEINSTALLATIONWIZARD

Figure 3-1. Installing the template

Download at WoweBook.Com

113

114

CH APT ER 3 N MODU L ES A ND HA NDL ER S

NNote

Using the Starter Kit simplifies the first steps. However, you don’t need it to run the samples provided in this chapter.

/NCEYOUINSTALLTHETEMPLATE YOUCANADDNEWMODULESBYUSINGTHERIGHTITEMFORYOURPROJECT !DDITIONALLY YOUCANUSETHEh))3-ANAGED-ODULEvPROJECTTEMPLATETOCREATEANEWPROJECTWITH APREDEFINEDMODULECLASSALREADYTHERE4HEPROJECTTEMPLATEPROVIDESACOMPREHENSIVEINSTRUCtion, too (see Figure 3-2).

Figure 3-2. Adding a new module code item to a current project 4HISITEMCREATESACLASSSKELETON ASSHOWNIN,ISTING  Listing 3-1. Skeleton of a Module Class qoejcOuopai7 qoejcOuopai*Sa^7 j]iaol]_a=lnaoo*Atpajoe^ehepu*DpplIk`qhao w lq^he__h]ooIuIk`qha6EDpplIk`qha w +++8oqii]nu: +++Ukqsehhjaa`pk_kjbecqnapdeoik`qhaejpdasa^*_kjbecbeha +++]j`naceopanepsepdEEO^abkna^aejc]^hapkqoaep* +++Bkniknaejbkni]pekj +++oaapdabkhhksejchejg6dppl6++ck*ie_nkokbp*_ki+;hejge`94-,-,,3 +++8+oqii]nu: nacekjEDpplIk`qhaIai^ano

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

++@eolkoaokbpdanaokqn_ao$kpdanpd]jiaiknu%qoa`^updaik`qha* lq^he_rke`@eolkoa$% w ++_ha]j)ql_k`adana* y ++Ejepe]hevaopdaik`qha(]j`naceopanobkn]llhe_]pekjarajpo* lq^he_rke`Ejep$Dppl=llhe_]pekj]llhe_]pekj% w ++Sd]pbkhhksoeo]jat]ilhakbdksukq_]jd]j`haHkcNamqaop ++arajp]j`lnkre`a ++_qopkihkccejceilhaiajp]pekjbknep ]llhe_]pekj*HkcNamqaop'9jasArajpD]j`han$KjHkcNamqaop%7 y aj`nacekj lq^he_rke`KjHkcNamqaop$K^fa_pokqn_a(Arajp=ncoa% w ++_qopkihkccejchkce__]jckdana y y y For the sake of clarity and space, I will not repeat this part of the module code in the following sections when examining theVARIOUSEXAMPLES

Building a Module !SREQUESTSMOVETHROUGHTHEPIPELINE ANUMBEROFEVENTSFIRE on the Dppl=llhe_]pekj object. !SYOUVESEENALREADY THESEEVENTSPUBLISHASEVENTMETHODSINGlobal.asax. This approach is application-specific, but not always ideal. If you want to build generic Dppl=llhe_]pekjEVENTHOOKS THATCANPLUGINTOANY7EBAPPLICATION YOUCANUSEDpplIk`qhao. These are reusable and require an entry in web.config instead of application-specific code.

Define the Modules -ODULESALLOWYOUTOHOOKEVENTSFORANYREQUESTTHATPASSESTHROUGHTHE!30.%4Dppl=llhe_]pekj object. These modules are stored as classes in external assemblies configured in web.config, which causes them to load when the application starts. By implementing specific interfaces and methods, the module hooks up to the Dppl=llhe_]pekjEVENTCHAIN-ULTIPLEDpplIk`qhao can hook the same EVENT4HEIRORDERISDETERMINEDBYAPPEARANCEINweb.config,ISTING SHOWSAHANDLERDEFINITION in web.config. Listing 3-2. Register a Module in web.config 8_kjbecqn]pekj: 8ouopai*sa^: 8dpplIk`qhao: 8]``j]ia9IuIk`qha± pula9=lnaoo*Atpajoe^ehepu*DpplIk`qhao*Ik`qhao(IuIk`qha+: 8+dpplIk`qhao: 8+ouopai*sa^: 8+_kjbecqn]pekj:

Download at WoweBook.Com

115

116

CH APT ER 3 N MODU L ES A ND HA NDL ER S

.OTETHATYOUNEEDTOSPECIFYBOTHAFULLTYPENAMEANDANASSEMBLYNAMEWITHOUTTHE$,, extension. -ODULESALLOWYOUTOOBSERVEEACHINCOMINGREQUESTANDPERFORMANACTIONBASEDONTHE EVENTSTHATFIRE-ODULESAREEXCELLENTFORMODIFYINGAREQUESTORRESPONDINGTOPARTICULARCONTENTIN ORDERTOPROVIDECUSTOMAUTHENTICATIONORPRE ORPOST PROCESSINGTOEACHREQUESTTHATARRIVES -ANYOF!30.%4SFEATURES SUCHASTHE!UTHENTICATIONAND3ESSIONENGINES AREIMPLEMENTED AS(440-ODULES7HILEDpplIk`qhao might feel similar to ISAPI FiltersINTHATTHEYEXAMINEEVERY REQUESTTHATARRIVESTHROUGHAN!30.%4APPLICATION INREALITYTHEYARELIMITEDTOSCRUTINIZING REQUESTSMAPPEDTOASINGLESPECIFIC!30.%4APPLICATIONORVIRTUALDIRECTORY Therefore, you can inspect all *]olt pages or any other custom extensions that map to this APPLICATION(OWEVER YOUCANNOTLOOKATSTANDARDHTMLORIMAGEFILESUNLESSYOUEXPLICITLYMAPTHE extension to the ASP.NET ISAPI.dll.

Example—Write a Simple Authentication Module This first example shows how to intercept the authentication procedure of the request pipeline. It also demonstrates how to add your own authentication module to handle tasks independently of the existing code. )MPLEMENTINGAN(440-ODULEISVERYEASY)MPLEMENTTHEEDpplIk`qha interface, which contains two methods: Ejep and @eolkoa.

NNote The Starter Kit item additionally creates a HkcNamqaop handler, if you add the module using the ASP.NET module item. If you use the IIS7 Managed Module project with the first module item predefined, the LnaNamqaopD]j`hanAta_qpa event is already hooked. You can safely remove these handlers and their event assignment if you don’t need them. 4HEEVENTPARAMETERSPASSEDINCLUDEAREFERENCETOTHEDPPL=llhe_]pekj object, which in turn GIVESYOUACCESSTOTHEDppl?kjpatpOBJECT5SINGTHEEjep method, you can hook up to Dppl=llhe_]pekj EVENTS&OREXAMPLE IFYOUWANTTOHOOKTHE=qpdajpe_]paNamqaopEVENTTOAMODULE YOUWOULDDOSOAS SHOWNIN,ISTING  Listing 3-3. Simple Implementation of an HTTP Module lq^he__h]oo>]oe_=qpd?qopkiIk`qha6EDpplIk`qha w lq^he_rke`Ejep$Dppl=llhe_]pekj]llhe_]pekj% w ]llhe_]pekj*=qpdajpe_]paNamqaop'9± jasArajpD]j`han$pdeo*Kj=qpdajpe_]paNamqaop%7 y lq^he_rke`@eolkoa$%wy lq^he_rke`Kj=qpdajpe_]paNamqaop$k^fa_pokqn_a(Araj)p=ncoarajp=nco% w Dppl=llhe_]pekj]ll9$Dppl=llhe_]pekj%okqn_a7 Dppl?kjpatp?kjpatp9Dppl?kjpatp*?qnnajp7 ++]j`]_pekj y

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

2EMEMBERTHATYOURMODULEHASACCESSTOTHEDppl?kjpatp object and from there to all other intrinsic ASP.NET pipeline objects, such as Naolkjoa and Namqaop&ROMHERE YOUCANRETRIEVEINPUT CREATECONTENT ANDSOFORTH(OWEVER KEEPINMINDTHATCERTAINTHINGSMAYNOTBEAVAILABLEUNTIL further down the chain. 9OUCANHOOKASMANYEVENTSASYOULIKEINTHEEjep method so that your module is able to manage multiple operations with different functions. It is tidier to separate differing logic into separate modules. This ensures that the modules are, indeed, modular, as their name implies. In many CASES ANYFUNCTIONALITYTHATYOUIMPLEMENTCOULDREQUIREHOOKINGMULTIPLEEVENTS&OREXAMPLE a logging filter might log the start time of a request in >acejNamqaop and then write the request completion into the log in Aj`Namqaop.

NCaution Modules work deep inside the processing pipeline. Calling certain methods can prevent the pipeline from proceeding to the next step. In particular, Naolkjoa*Aj` and =llhe_]pekj*?kilhapaNamqaop complete the request and force the pipeline to end, thus skipping all subsequent steps. The pipeline will return control to the Web Server and no further modules will be invoked. A better practice is to leave the pipeline running, but use a context variable to inform subsequent modules not to execute. The purpose of the @eolkoa method is to clean up any resources when the module unloads ANDTORELEASEOTHERRESOURCESBEFORETHEGARBAGECOLLECTORFINALIZESTHEMODULEINSTANCE)FTHEREIS NOTHINGTODISPOSE LEAVETHEMETHODBODYBLANK The Ejep methodISTHEMAINMETHODOFINTEREST(ERE YOUCANINITIALIZEYOURMODULEANDWIRE ITUPTOONEORMOREREQUEST PROCESSINGEVENTSAVAILABLEONTHEDppl=llhe_]pekj class. Keep in mind THATEVENTSFIREWHENTHEAPPROPRIATESTEPINTHEPIPELINEISREACHED INADEFINEDORDER ANDINCONJUNCTIONWITHOTHERMODULES7ITHOUTACLEARUNDERSTANDINGOFTHEPIPELINEARCHITECTUREEXPLAINED IN#HAPTER YOULLHAVEDIFFICULTYWRITINGSOPHISTICATEDMODULESTHAT perform well.

Example—Check for a Specific Header The following example checks for a specific header, called a referrer WHICHPROVIDESINFORMATION ABOUTTHEREFERRINGPAGE0ARADOXICALLY THEREFERRERISNAMEDhREFERRERv$ONTWORRYABOUTTHEMISspelled word (the sidebar explains more).

WIKIPEDIA ON THE WORD REFERER Referer is a common misspelling of the word referrer. It is so common, in fact, that it made it into the official specification of HTTP—the communication protocol of the World Wide Web—and has therefore become a widely used industry spelling when discussing HTTP referrers. The misspelling usage is not universal; the correct spelling of “referrer” occurs in some web specifications, such as the Document Object Model. [Source: dppl6++aj*segela`e]*knc+sege+Nabanan]

)ADVISEYOUTOPAYATTENTIONTOWHICHWORDYOUREUSING


Download at WoweBook.Com

117

118

CH APT ER 3 N MODU L ES A ND HA NDL ER S

In this example, you’ll look for a specific referrerORREFERRINGPAGEˆTHE52,OFTHEPREVIOUS page. (It’s the page containing the link to the page you’re currently processing.) The usage of the HEADERISVOLUNTARY ACCORDINGTO(440STANDARDS BUTMOSTSITESUSEITTOTRACKUSERSORMANAGE LOGGING(OWEVER SOMEPAGESARENOTINTENDEDTOBECALLEDFROMOUTSIDEOURSITE)FLINKEDFROM another page within our application, such pages will execute correctly, but if linked from anywhere else, you’ll treat that as an exception. Such external links typically occur when a user bookmarks ASPECIFICPAGEDEEPWITHINYOURAPPLICATION7HENATTEMPTINGTOOPENONEOFTHESEPAGES ITISNOT POSSIBLE BECAUSETHEREARESEVERALPREREQUISITESTEPSTOCOMPLETEBEFOREHAND5SINGAMODULELIKE THEONEIN,ISTING  YOUCANCAPTURETHESEREQUESTSOUTSIDETHECOMMONPAGECODEANDREDIRECT users to a suitable page, such as one that explains appropriate usage of bookmarks. Listing 3-4. An HTTP Module That Looks for the Referer Header lq^he__h]ooNabannanIk`qha6EDpplIk`qha w nacekjEDpplIk`qhaIai^ano lq^he_rke`@eolkoa$% w ++_ha]j)ql_k`adana* y lq^he_rke`Ejep$Dppl=llhe_]pekj_kjpatp% w _kjpatp*LnaNamqaopD]j`hanAta_qpa'9± jasArajpD]j`han$_kjpatp[LnaNamqaopD]j`hanAta_qpa%7 y rke`_kjpatp[LnaNamqaopD]j`hanAta_qpa$k^fa_poaj`an(Arajp=ncoa% w Dppl=llhe_]pekj]ll9$Dppl=llhe_]pekj%oaj`an7 DpplNamqaopnamqaop9]ll*?kjpatp*Namqaop7 eb$namqaop*Qnh*Hk_]hL]pd*Aj`oSepd$@ab]qhp*]olt%% w eb$Opnejc*EoJqhhKnAilpu$namqaop*Da]`anoWNabananY%% w pdnksjasDpplAt_alpekj$0,/(>kkgi]ngejceojkp]hhksa`%7 y y y aj`nacekj y 4HISCODEASSUMESTHATYOUHAVEAPAGECALLEDORATLEASTENDINGWITHh$EFAULTASPXvLINKINGTO another page in your application. The name of the other page doesn’t matter. To test this module: 1. Configure web.configTOACTIVATETHEMODULE 2. #REATETWOPAGES $EFAULTASPXAND2EFERER4ESTASPX$EFAULTASPXHASAHYPERLINKTO 2EFERER4ESTASPX 3. #OMPILEANDSTARTTHEAPPLICATIONBYLAUNCHINGTHE$EFAULTASPXPAGE

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

4. #LICKTHEHYPERLINKON$EFAULTASPXˆTHE2EFERER4ESTASPXPAGEISDISPLAYED 5. "OOKMARKTHE2EFERER4ESTASPXPAGE 6. Close your browser, reopen it, and load the bookmark, then press F5 to force a refresh of the PAGEFROMTHESERVER 7. !NEXCEPTIONOCCURSANDTHEBROWSERSHOWSAERROR 9OUMIGHTINSISTTHATALLOFTHISCANBEACCOMPLISHEDONTHEPAGELEVELUSINGCONVENTIONAL CODE4HISISCORRECT BUTFUNDAMENTALTASKSAREBESTHANDLEDONAFUNDAMENTALLEVEL)NADDITION INTERCEPTINGLOW LEVELEVENTSTOHANDLELOW LEVELACTIONISFASTER MORESECURE ANDMORERELIABLE !DDINGMOREPAGESWITHTHESAMEBEHAVIORDOESNOTREQUIREANYCHANGETOTHECODE)TSIMPLY works because the module tests all pages in the application.

Interaction Between Modules 7RITINGPRIVATEMODULESISAPOWERFULTECHNIQUEFOREXTENDING!30.%4(OWEVER EXTENDINGCAN mean replacing existing functionality. Sometimes a smart solution results simply from using the internal modules and your own module together. To begin, you’ll need access to the internal modules at runtime. You should make connections in the EjepEVENTINORDERTOHAVEACCESSATANEARLYSTAGE,ISTING SHOWSYOUHOWTORETRIEVE information about internal modules, and other kinds of modules, attached to the pipeline so far. Listing 3-5. Retrieving Information About Modules lq^he__h]ooOaooekjHkcIk`qha6EDpplIk`qha w nacekjEDpplIk`qhaIai^ano lq^he_rke`@eolkoa$% w y lq^he_rke`Ejep$Dppl=llhe_]pekj]llhe_]pekj% w Dppl?kjpatp_kjpatp9Dppl?kjpatp*?qnnajp7 bkna]_d$opnejcgauej]llhe_]pekj*Ik`qhao*=hhGauo% w _kjpatp*Naolkjoa*Snepa$Opnejc*Bkni]p$w,y9w-yw.y8^n:( gau( ]llhe_]pekj*Ik`qhaoWgauY*CapPula$%*EoLq^he_;lq^he_6ejpanj]h( ]llhe_]pekj*Ik`qhaoWgauY*CapPula$%*=ooai^huMq]hebea`J]ia%%7 y y aj`nacekj y

Download at WoweBook.Com

119

120

CH APT ER 3 N MODU L ES A ND HA NDL ER S

The current context is used to output the text directly into the current page where the request is handled. You can use the Ik`qhao property to get a list of the modules and where they are defined (see Figure 3-3).

Figure 3-3. Modules already available You probably need to use this method of getting access to an embedded module, as not all MODULESOFFERDIRECTACCESSTOTHEIRSTATESANDEVENTS/NCEYOUKNOWTHENAMEANDTYPEOFASPEcific module, you can cast the type and get the object you need.

Configuration and Deployment Now that the module is implemented, you can compile it into an assembly that ASP.NET is able to load at runtime. This is straightforward as long as the module is in the web application. No SPECIALACTIONISREQUIRED9OUWILLPROBABLYWANTTOCREATESEVERALMODULESANDHAVETHEMINDIFferent assemblies for easy reuse. The assemblies will need to be referenced by your web project. To CONSTRUCTSUCHAMODULE CHOOSEh#LASS,IBRARYvASTHEPROJECTTEMPLATE2EMOVETHEDEFAULTCLASS CREATEDBYTHETEMPLATE ANDADDANOBJECTOFTYPEh!30.%4-ODULEvASSHOWNIN&IGURE 

Figure 3-4. Add a module to current project.

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

Configuring the Default Web Server and Development Environment To test the module, you’ll need to configure the settings in web.config. Place the appropriate lines in the 8ouopai*sa^: section: 8dpplIk`qhao: 8]``j]ia9NabannanIk`qha pula9=lnaoo*Atpajoe^ehepu*DpplIk`qhao*NabannanIk`qha+: 8+dpplIk`qhao: 4HESETTINGSFORTHEDEVELOPMENTENVIRONMENTALSOAPPLYFOR))3 ))3 AND))3INCLASSIC MODE4HEREARESEVERALADVANTAGESTORUNNINGTHE))3INTEGRATEDPIPELINEHOWEVER THATREQUIRES different settings, asSHOWNIN4ABLE  Table 3-10. Options of the httpModule Settings

Attribute

Typical Values

Description

j]ia

any string

The module name that appears in settings dialogs

pula

class, assembly

-ODULETYPE

Configuring IIS7 Settings In the main (web) project, add a reference to the project containing the module. Assuming the namespace of the external project is =lnaoo*Atpajoe^ehepu*DpplD]j`han*IuD]j`han, add the following to web.config: 8ouopai*sa^Oanran: 8ik`qhao: 8]``j]ia9NabannanIk`qha pula9=lnaoo*Atpajoe^ehepu*DpplD]j`han*IuD]j`hannaokqn_aPula9Beha namqena=__aoo9Na]`lna?kj`epekj9ejpacn]pa`Ik`a+: 8+ik`qhao: 8+ouopai*sa^Oanran: Compile both the project containing the module and the web project. Add the mapping in )NTERNET)NFORMATION3ERVICES-ANAGER4HEMAPPINGWILLNOWFUNCTIONPERFECTLYFORBOTHTHEDEVELOPMENTENVIRONMENTANDDIRECTUSAGE from the local IIS7 (see Table 3-11). Table 3-11. Options for the Module Settings for IIS7 Integrated Mode

Attribute

Typical Values

Description

j]ia

any string

The module name that appears in settings dialogs.

lna_kj`epekj

string

Specifies conditions under which the module will run. This is usually the name of another handler or module required to run before this one.

pula

class, assembly

Type information of the handlers definition.

Download at WoweBook.Com

121

122

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Configure Using IIS Management Console 2ATHERTHAN adding the IIS7 integrated mode settings to web.config YOUCANSIMPLYUSETHE))3-ANagement Console. The settings correspond directly. Altering web.config will result in an immediate CHANGETOTHE-ANAGEMENT#ONSOLESETTINGS ANDVICEVERSA4OCONFIGUREUSINGTHE))3-ANAGEment Console: 1. /PEN)NTERNET)NFORMATION3ERVICE-ANAGER 2. /PENTHEWEBYOUWANTTOCHANGE 3. )NTHE))3SECTION DOUBLE CLICKONTHE-ODULESICON 4. #LICKON!DD-ANAGED-ODULEINTHETASKLISTTOTHERIGHT 5. %NTERTHESEVALUESINTHEDIALOGANDCLOSETHEDIALOGBYCLICKING/+ THEN a. 'IVETHEMODULEANAPPROPRIATENAME b. /PENTHETYPEDROP DOWNANDSELECTTHEMODULESTYPE 6. #LOSETHEMAINDIALOGBYPRESSING/+ No restartISREQUIREDTOACTIVATE the new settings.

Handlers This sectionFOCUSESONDEVELOPING(440HANDLERSFOR))3 USING the .NET Framework. You’ll look ATWHENITISAPPROPRIATETODEVELOPAN))3HANDLER rather than a module.

Built-In Handlers ASP.NET offersSEVERALDEFAULT(440HANDLERS

s 0AGE(ANDLERASPX : Handles web pages



s 5SER#ONTROL(ANDLERASCX (ANDLES7EBUSERCONTROLPAGES



s 7EB3ERVICE(ANDLERASMX (ANDLES7EB3ERVICEPAGES



s 4RACE(ANDLERTRACEAXD : Handles trace functionality



s !SSEMBLY2ESOURCE,OADER7EB2ESOURCEAXD : Handles embedded resources in assemblies



s 3CRIPTRESOURCEHANDLER3CRIPT2ESOURCEAXD : Handles the scripting support for AJAXenabled projects



s &ORBIDDEN(ANDLERCONFIG $ENIESACCESSTOFILESTHATCONTAINCONFIDENTIALINFORMATION

The IIS configuration defines the assignments. You will also find other assignments there. Extensions such as .tkih, *nai, *ok]l, and *or_RELATETOTHECAPABILITIESPROVIDEDBY7INDOWS #OMMUNICATION&OUNDATION7#& AND its predecessor, .NET remoting.

Extending ASP.NET Using Http Handlers 7HILEMODULESARELOWLEVEL ANDRUNAGAINSTEVERYINBOUND request to the ASP.NET application, HTTP handlers focus more on a specific request mapping. This is usually a mapping of a file extension.

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

(440HANDLERIMPLEMENTATIONSAREVERYSIMPLEINTHEIRCONCEPT BUTHAVINGACCESS to the Dppl?kjpatpOBJECTENABLESENORMOUSVERSATILITY(ANDLERSAREIMPLEMENTEDTHROUGHTHE EDpplD]j`han interface, or its asynchronous counterpart, EDppl=ouj_D]j`han. The interface consists of a single method, Lnk_aooNamqaop, and a single property, EoNaqo]^ha4HEASYNCHRONOUSVERSION has a pair of methods (>acejLnk_aooNamqaop and Aj`Lnk_aooNamqaop) and the same EoNaqo]^ha propERTY4HEVITALINGREDIENTISLnk_aooNamqaop WHICHRECEIVESANINSTANCEOFTHEDppl?kjpatp object. 4HISSINGLEMETHODISRESPONSIBLEFORHANDLINGA7EBREQUESTFROMSTARTTOFINISH (OWEVER SIMPLEDOESNOTIMPLYSIMPLISTIC!SYOUMAYKNOW THEREGULARPAGEPROCESSINGCODE ANDTHE7EB3ERVICEPROCESSINGCODEAREIMPLEMENTEDASHANDLERS"OTHAREANYTHINGBUTSIMPLE Their power originates from the Dppl?kjpatp object, which has access to both the request informaTIONANDTHERESPONSEDATA4HISMEANSTHAT LIKEA7EB3ERVER AHANDLERCANCONTROLTHEWHOLE PROCESSONITSOWN7HATEVERYOUWANTTOIMPLEMENTONTHELEVELOFSPECIFICMAPPINGISACHIEVABLE using handlers.

Scenarios to Use HTTP Handlers To betterUNDERSTANDTHEPOWEROFHANDLERS LETSTAKEALOOKATWHATOTHERSHAVEIMPLEMENTEDON top of EDpplD]j`han:

s #REATINGDYNAMICIMAGES



s 7ATERMARKINGEXISTINGIMAGES



s h0RETTYPRINTINGvOFTHEPAGESSOURCECODE



s 'ENERATINGDYNAMICCONTENTPULLEDFROMADATABASEOREXTERNALRESOURCE



s 4RANSFORMINGCONTENTFROMOTHERRESOURCES SUCHAS8-,INTO(4-,



s %XTRACTINGRESOURCESFROMASSEMBLIESONTHEFLY



s 2EDIRECTINGTOFROM33,



s )MPLEMENTING0INGBACKAND4RACKBACKCAPABILITIES EVENIFTHESITEISNOTABLOG

!DDITIONALLY YOUCANIMPLEMENTHANDLERSASYNCHRONOUSLY4HISVASTLYEXTENDSTHEPOTENTIAL usage scenarios. Since asynchronous calls are closely related to threading and performance, you looked at threading and how it could benefit from asynchronous programming in Chapter 2. In this section, I will focus more on common usages of basic HTTP handler implementations.

Getting Started For an HTTP handler, all the action occurs through a single call to Lnk_aooNamqaop. This can be as simple as: lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_kjpatp% w _kjpatp*Naolkjoa*Snepa$DahhkSknh`%7 y 5SINGTHEDppl?kjpatpOBJECT YOUHAVEACCESSTOTHENamqaop, Naolkjoa, Oaooekj, and ?]_da OBJECTS9OUHAVEALLTHEKEYFEATURESOFAN!30.%4REQUESTATYOURDISPOSAL ANDYOUCANUSETHISTO DETERMINEWHATUSERSSUBMITTEDANDTORETURNCONTENTBACKTOTHECLIENT2EFERTO#HAPTERTOSEE why Dppl?kjpatp plays such an important role in the request-processing process.)

Download at WoweBook.Com

123

124

CH APT ER 3 N MODU L ES A ND HA NDL ER S

The key operation of the handler is to write output into the Naolkjoa object—or, more specifically, the Naolkjoa object’s KqplqpOpna]i. This output is sent back to the client. Behind the scenes—for IIS6 or classic mode—the EO=LESknganNamqaop sends the KqplqpOpna]i back to the ISAPI a_^*Snepa?heajp METHOD WHICHACTUALLYPERFORMSTHE))3OUTPUTGENERATION&OR))3)NTEGRATED-ODETHEPIPELINEIS responsible to handle the KqplqpOpna]i object. Again, refer to Chapters 1 and 2 to learn more about these steps.

Building a Handler Now, let’s build a simple handler. To do this, you define a class, which implements the Ouopai*Sa^* EDpplD]j`han interface. $ESPITETHEPROMINENCEOFTHELnk_aooNamqaop method, you’ll also need to implement a property—EoNaqo]^ha4HISPROPERTY WHICHRETURNSA"OOLEANVALUE INDICATESWHETHERTHEINSTANCE can be reused for subsequent requests. In some cases, after processing a request, your handler may NOTBEINAVALIDSTATEFORPROCESSINGFURTHERREQUESTSˆESPECIALLYIFDATAABOUTTHEPREVIOUSREQUEST WASSTOREDINMEMBERVARIABLES4HISISBECAUSETHE!30.%4RUNTIMECANHANDLEMANYREQUESTSAT THESAMETIME!SLONGASTHEREARETHREADSAVAILABLEINTHETHREADPOOL ANEWREQUESTWILLBEPROCESSEDEVENIFANOTHERONEISSTILLRUNNING%ACHTHREADREQUIRESANEWINSTANCEOFTHEHANDLER EVEN IFTHEHANDLERISMARKEDhISREUSABLEv7HENAREQUESTISCOMPLETE THECURRENTHANDLERINSTANCEIS RETAINEDINMEMORYANDREUSEDFORTHENEXTREQUEST4HISCANLEADTOODDBEHAVIOR DEPENDINGON the workload and on the existence of other instances of the handler. Such problems can be unpreDICTABLEANDDIFFICULTTOSIMULATEORRECOGNIZEINADEVELOPMENTENVIRONMENT &ORSTABLEANDRELIABLEBEHAVIOR YOUMIGHTASSUMETHATSETTINGTHEEoNaqo]^ha property to b]hoa is the solution. After all, this would create a new instance of the object any time a request is ABOUTTOBEPROCESSED(OWEVER DEPENDINGONHOWhINTENSIVEvYOURCODEIS THISCANLEADTOHIGHER MEMORYCONSUMPTION MORE#05WORKLOAD ANDLESSTHROUGHPUT4HEREISNOSTRICTRULEABOUTIT BUT reusing the instances is the preferred solution. Keep in mind that access to members is not exactly WHATYOUMIGHTEXPECT4HEREFORE ITISADVISABLETOAVOIDPRIVATEMEMBERSTHATHOLDDATA IFPOSSIBLE)FYOUSTILLWISHTOUSEMEMBERVARIABLES REMEMBERTHATTHEYNEEDTOBETHREADSAFE7HEN REPLACINGREGULARMEMBERSWITHSTATICMETHODS YOULLHAVETOIMPLEMENTTHREADSAFECODE)FANY of these requirements cannot be fulfilled, you should set EoNaqo]^ha to b]hoa/THERWISE THEIMPLEmentation will look like the following: lq^he_^kkhEoNaqo]^ha w cap w napqnjpnqa7 y y EoNaqo]^haSHOULDBEACONSTANT#HANGINGTHEVALUEDURINGPROCESSINGWOULDNOTHAVEANY EFFECT ASTHEVALUEISREADONCETHE handler is instantiated.

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

The Entry Point The Lnk_aooNamqaop method is the main entry point for the handler. Its role is to work off the request specified by the DpplNamqaopINSTANCE FROMTHEPROVIDEDDppl?kjpatp instance, and generate an appropriate response using the DpplNaolkjoa instance. The Lnk_aooNamqaopMETHODISINVOKEDBY the .NET runtime during the Ata_qpaNamqaopD]j`han request processing stage, assuming that the mapping is able to route the request to the specific handler. This is in contrast to modules, which RECEIVEALLREQUESTSPASSINGTHROUGHTHEPIPELINE Finally, let’s implement the Lnk_aooNamqaop method, so that our handler has something to do. 4OKEEPTHINGSSIMPLE OURHANDLERWILLRETURNTHECURRENTTIMEOFTHESERVER9OUCANSPECIFYTHE TIMEZONEINTHEQUERYSTRING/URGOALISTOREQUESTA52, SUCHASdppl6++iuoanran+l]ca*peia, and OBTAINTHECURRENTTIMEOFTHESERVER)NADDITION YOUCANGETTHEUNIVERSALCOORDINATEDTIME54# by requesting dppl6++iuoanran+l]ca*peia;qp_9pnqa,ISTING SHOWSTHEIMPLEMENTATION Listing 3-6. Simple Handler Mapped to a New *.time File Extension lq^he__h]ooPeiaD]j`han6EDpplD]j`han w nacekjEDpplD]j`hanIai^ano lq^he_^kkhEoNaqo]^ha w capwnapqnjpnqa7y y lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_kjpatp% w @]paPeia`p7 opnejcqoaQp_9_kjpatp*Namqaop*MqanuOpnejcWqp_Y7 eb$Opnejc*EoJqhhKnAilpu$qoaQp_%""qoaQp_*Amq]ho$pnqa%% w `p9@]paPeia*Qp_Jks7 y ahoa w `p9@]paPeia*Jks7 y _kjpatp*Naolkjoa*Snepa$± Opnejc*Bkni]p$8dpih:8^k`u:8d-:w,y8+d-:8+^k`u:8+dpih:(± `p*PkHkjcPeiaOpnejc$%± %%7 y aj`nacekj y !SYOUASSIGNTHISHANDLERTOASPECIFICEXTENSIONˆTIMEˆYOULLONLYRECEIVEITWHENTHECLIENT USESTHISSPECIFIC52,4HERESPONSEISSIMPLEANDCREATESASMALL(4-,PAGE9OUCOULDEVENTAILOR the response to suit clients that are not browsers.

Download at WoweBook.Com

125

126

CH APT ER 3 N MODU L ES A ND HA NDL ER S

You use the DpplNamqaop*MqanuOpnejcCOLLECTIONTORETRIEVEAQUERYSTRINGVARIABLE AND write the current time in response using the DpplNaolkjoa*Snepa method. I recommend using the KqplqpOpna]i if other handlers are processing the request, or if you want to add to the existing RESPONSE)NTHEPREVIOUSEXAMPLE YOUWRITEACOMPLETERESPONSEINTHEONEHANDLER ANDTHUS the SnepaMETHODISAPPROPRIATE&IGURE SHOWSHOWTOADDAMODULEUSINGTHE))3-ANAGER

Figure 3-5. Setting the mapping of a managed handler in IIS7 ))3DOESNOTREQUIREARESTARTORANYOTHERACTIONINORDERTOACTIVATETHEHANDLER!REQUESTTHAT uses the mapped extension should work immediately.

Example—Image Handler !VERYCOMMON scenario for handlers is the manipulation of images. As with any other resource, a browser obtains an image by sending a GET request. Handling large numbers of images at multiple resolutions can be a challenge. Imagine a web shop with thousands of product images stored at one RESOLUTION(OWEVER DIFFERENTIMAGESIZESAREREQUIREDTHROUGHOUTTHESITE FROMCATALOGTHUMBNAILS TOLARGEPREVIEWPANESANDICONSINTHESHOPPINGBASKET#ONVERTINGALLTHESEIMAGESINTOSEVERALDIFFERENTSIZESCOULDBEEXPENSIVE EVENWITHABATCHSCRIPT)MAGESCHANGEFREQUENTLY ANDMAINTAINING ALLCURRENTPICTURESINMANYDIFFERENTSOURCESIZESISANIMAGEMANAGEMENTHEADACHE!DDITIONALLY a watermark is added to the image to protect the intellectual properties of the image’s owner. 7RITINGCODEANDCREATINGIMAGESDYNAMICALLYISATYPICALTASKFORAHANDLER!TTACHINGREQUESTS TOANIMAGECOULDBEACHIEVEDBYUSINGAPATHFILTERLIKE&*ljc,ISTING SHOWSHOWEASYITISTO manipulate content and send it to a client. Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

Listing 3-7. Adding a Watermark to an Image and Resizing It Using a Handler j]iaol]_a=lnaoo*Atpajoe^ehepu*DpplD]j`han w lq^he__h]ooEi]caD]j`han6EDpplD]j`han w nacekjEDpplD]j`hanIai^ano lner]pa_kjopbhk]pBKJPOEVA93.B7 lner]pa_kjopopnejcBKJP9Ran`]j]7 lner]pa_kjopopnejcPATP9S]pani]ng7 lq^he_^kkhEoNaqo]^ha w capwnapqnjpnqa7y y lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_kjpatp% w ++`apanieja]jei]canamqaop eb$$L]pd*Cap@ena_pknuJ]ia$± _kjpatp*Namqaop*Qnh*=^okhqpaL]pd%%*Aj`oSepd$Ei]cao%% w ++hk]`ei]ca]j`]``s]pani]ng >epi]leic9$>epi]l%>epi]l*BnkiBeha$± _kjpatp*Oanran*I]lL]pd$_kjpatp*Namqaop*Qnh*=^okhqpaL]pd%%7 Cn]lde_oc9Cn]lde_o*BnkiEi]ca$eic%7 >nqod^9jasOkhe`>nqod$?khkn*Oehran%7 Bkjpb9jasBkjp$BKJP(BKJPOEVA%7 OevaBopnejcIa]oqna9c*Ia]oqnaOpnejc$PATP(b%7 ++_]h_qh]papdaopnejclkoepekjpk_ajpankqplqp bhk]pt(u7 t9eic*Se`pd+.)opnejcIa]oqna*Se`pd+.7 u9eic*Daecdp+.)opnejcIa]oqna*Daecdp+.7 c*@n]sOpnejc$PATP(jasBkjp$BKJP(BKJPOEVA%(^(t(u%7 ++naoevapklnkre`a``]p]$bnkiMqanuOpnejc% eb$_kjpatp*Namqaop*MqanuOpnejcWsY9jqhh"" _kjpatp*Namqaop*MqanuOpnejcWdY9jqhh% w ejps(d7 eb$Ejp/.*PnuL]noa$_kjpatp*Namqaop*MqanuOpnejcWsY(kqps%"" Ejp/.*PnuL]noa$_kjpatp*Namqaop*MqanuOpnejcWdY(kqpd%% w eic9$>epi]l%eic*CapPdqi^j]ehEi]ca$s(d(jqhh(EjpLpn*Vank%7 y y ++kqplqppkpdanaolkjoaopna]i eic*O]ra$_kjpatp*Naolkjoa*KqplqpOpna]i(Ei]caBkni]p*Flac%7 eic*@eolkoa$%7 y y y aj`nacekj y y Download at WoweBook.Com

127

128

CH APT ER 3 N MODU L ES A ND HA NDL ER S

4HEHANDLERFIRSTCHECKSTHATITISDEALINGWITHAFILEFROMAPARTICULARDIRECTORYSEE,ISTING   7HILETHEFILEMAPPINGFORCESTHEHANDLERTORUNFOREVERYREQUESTFORANIMAGEWITHTHESPECIFIED extension, this test restricts the special processing to images in the “Images” folder only. The handler LOADSTHEIMAGEFROMDISK RESOLVINGTHELOCALPATHVIAOanran*I]lL]pd. Then it applies the watermark to the image. The Ia]oqnaOpnejc methodMEASURESTHESTRINGSIZEINORDERTOALIGNITWITHTHEIMAGE SOTHATTHETEXTAPPEARSCENTEREDHORIZONTALLYANDVERTICALLY3TREAMSSIMPLIFYTHEOUTPUTOFTHEIMAGE The O]raMETHODSENDSTHEOUTPUTDIRECTLYINTOANOUTPUTSTREAMIN*0%'FORMAT$ISPOSINGOFTHE IMAGEISREQUIRED ASFREQUENTUSEOFAHANDLERONASYSTEMWITHHIGHWORKLOADCOULDPREVENTTHEGARbage collector from freeing the memory often enough. Listing 3-8. The Handler Is As Easy to Use As Any Other Image Resource 8]ol6Ei]canqj]p9oanranE@9eic-Ei]caQnh9z+Ei]cao+Eic-*ljc+:8^n+: 8]ol6Ei]canqj]p9oanranE@9Ei]ca-Ei]caQnh9z+Ei]cao+Eic-*ljc;s9-,,"d9-,,+: Figure 3-6 shows the output of the watermarked and thumbnail images.

Figure 3-6. Add a watermark to an image on the fly or create a thumbnail. $YNAMICIMAGEMANIPULATIONISPOWERFULANDFLEXIBLE ANDTHEREARENUMEROUSPOSSIBILITIESFOR using an image handler in your applications. The final step in creating such a handler is to configure it in web.config0LEASEREFERTOTHESECTIONh#ONFIGURATIONAND$EPLOYMENTvTOREADMOREABOUT the VARIOUSSETTINGS

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

Example—Read Dynamic CSS from Resource )N,ISTING  )DESCRIBEAHANDLERTHATLOADSSTYLESHEETSSTOREDASEMBEDDEDRESOURCESINAN ASSEMBLY)TREPLACESANYCALLTOASTYLESHEETBYDELIVERINGASPECIFICCSSFILE4HEDEFINITIONINTHE web.config looks like this: 8]``ran^9CAPl]pd9&*_oopula9=lnaoo*Atpajoe^ehepu*DpplD]j`han*?ooD]j`han+: 3EETHESECTIONh#ONFIGURATIONAND$EPLOYMENTvFORMOREINFORMATIONABOUTCONFIGURING a handler for the IIS7 integrated mode. 4OOBTAINTHESTYLEFILES THEYMUSTBEMARKEDASANEMBEDDEDRESOURCE4HEREARESEVERALWAYS to handle data from sources other than the file system (see Figure 3-7).

. Figure 3-7. To handle files as embedded resources, use the file’s Property box. 4HECODEITSELFDOESNOTHAVEANYQUIRKS)TPROCESSESWHATEVERITENCOUNTERS ANDDECIDESHOW to proceed from the information in Dppl?kjpatpSEE,ISTING  

Download at WoweBook.Com

129

130

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Listing 3-9. Dynamic Handling of CSS from Embedded Resources lq^he__h]oo?ooD]j`han6EDpplD]j`han w nacekjEDpplD]j`hanIai^ano lq^he_^kkhEoNaqo]^ha w capwnapqnjb]hoa7y y lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_kjpatp% w Qji]j]ca`IaiknuOpna]io7 eb$_kjpatp*Namqaop*Qoan=cajp9jqhh"" _kjpatp*Namqaop*Qoan=cajp*?kjp]ejo$IOEA%% w o9$Qji]j]ca`IaiknuOpna]i%± pdeo*CapPula$%*=ooai^hu*CapI]jebaopNaokqn_aOpna]i$± =lnaoo*DppD]j`han*D]j`han=ooai^hu*?oo*ea*_oo%7 y ahoa w o9$Qji]j]ca`IaiknuOpna]i%± pdeo*CapPula$%*=ooai^hu*CapI]jebaopNaokqn_aOpna]i$± =lnaoo*DppD]j`han*D]j`han=ooai^hu*?oo*bb*_oo%7 y o*Oaag$,(OaagKnecej*>acej%7 qoejc$IaiknuOpna]iio9jasIaiknuOpna]i$$ejp%o*Hajcpd%% w ^upaWY^qbban9jas^upaWo*HajcpdY7 o*Na]`$^qbban(,(^qbban*Hajcpd%7 io*Snepa$^qbban(,(^qbban*Hajcpd%7 io*SnepaPk$_kjpatp*Naolkjoa*KqplqpOpna]i%7 y y aj`nacekj y First, let’s locate the current user agent in this code by using the property Qoan=cajp of the DpplNamqaop object. If the Qoan=cajpISh-3)% vINDICATINGAN)NTERNET%XPLORERBROWSER THENTHE RESOURCENAMEDhIECSSvISRETRIEVEDFROMTHEASSEMBLY&ORANYOTHERQoan=cajpo, “ff.css” is loaded instead. The stream is copied to a IaiknuOpna]i object. The IaiknuOpna]i is helpful, as it is able to copy its own content to another stream by using the SnepaPk method. In the case of a handler, this is THEOUTPUTSTREAMPROVIDEDBYTHEDpplNaolkjoa object through the Naolkjoa property. This technique can be reused. By looking for specific file extensions and for the “user-agent” header, you can block certain clients from reading the content of these resources or supply them WITHAREPLACEMENTRESOURCE!LTERNATIVELY READINGRESOURCESFROMADATABASEINSTEADOFANASSEMBLYGIVESMOREFLEXIBILITYWITHOUTADDINGCODETOTHEPAGESTHEMSELVES

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

USING WEB RESOURCES The example shown in this section is just to explain typical scenarios for HTTP handlers. Especially regarding web resource management, the preferred method for storing and retrieving resources is the embedding of web resources. Using an assembly bound attribute, you can add any kind of data to the assembly: W]ooai^hu6Sa^Naokqn_a$?oo*ea*_oo(patp+_oo%Y W]ooai^hu6Sa^Naokqn_a$?oo*bb*_oo(patp+_oo%Y An embedded handler for the designated *]t` extension retrieves the resources from server. The URL uses two query string values, “d” and “t”. “d” takes an encrypted ID of that value and “t” a time stamp. To retrieve such a resource, you can create the URL, using the following code snippet from a page: ?heajpO_nelpI]j]can_o9L]ca*?heajpO_nelp7 PulanoPula9pdeo*CapPula$%7 DpihHejgdh?oo9jasDpihHejg$%7 dh?oo*Dnab9_o*CapSa^Naokqn_aQnh$noPula(?oo*ea*_oo%7 pdeo*?kjpnkho*=``$dh?oo%7 The call of the CapSa^Naokqn_aQnh method assures that the parameters for query string are set properly.

Example—Handler That Does Not Create Content Handlers usuallyCREATECONTENTˆTYPICALLY(4-,ORDATATHATBUILDSANIMAGE(OWEVER ITSNOT IMPERATIVE(ANDLERSAREPRIMARILYINVOKEDBYTHEASSOCIATEDFILEEXTENSION)MAGINEYOUDEFINE a custom extension named “.counter” and associate it with a handler. Your handler might execute SOMECODE BUTIGNORETHE7RITERANDNOTSENDANYTHINGBACKTOTHECLIENT!NOTHERIDEAISTOONLY WRITEDATATOTHECLIENTWHENYOURUNTHEHANDLERINDEBUGMODEANDSAVEBANDWIDTHWHENRUNNING ONAPRODUCTIONSERVER7HETHERORNOTTHEOUTPUTISREQUIRED YOULLSTILLHAVETOINVOKETHEHANDLER BYISSUINGA'%4OR0/34REQUESTTOTHESERVER4HEREFORE YOULLNEEDANELEMENTTHATCANFORCETHE browser to create such a request. There are only a few ways to do this:

s )MAGEELEMENT



s &ORMELEMENT



s )&RAMEELEMENT



s *AVA3CRIPTCODE

)MUSINGAN)&2!-%ELEMENT in the following example, because I want to show the content WHENINDEBUGMODE ANDLEAVETHECONTENTEMPTY OTHERWISE4HEDEFINITIONOFTHE)&2!-%DEMONSTRATESHOWYOUINVOKETHEHANDLER ASSHOWNIN,ISTING  Listing 3-10. Invoke a Handler Using a Registered Extension 8ebn]iaon_9iu*_kqjpanse`pd9-,,daecdp91,o_nkhhejc9jk:8+ebn]ia: Furthermore, the handler itself shows the processing within the Lnk_aooNamqaop method (see ,ISTING  

Download at WoweBook.Com

131

132

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Listing 3-11. Code of the Handler lq^he__h]oo?kqjpanD]j`han6EDpplD]j`han w nacekjEDpplD]j`hanIai^ano lq^he_^kkhEoNaqo]^ha w capwnapqnjpnqa7y y lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_kjpatp% w opnejcl]pd9_kjpatp*Namqaop*QnhNabannan*Hk_]hL]pd7 opnejcbeha9_kjpatp*Oanran*I]lL]pd$?kqjpan*tih%7 T@k_qiajp_jp@k_9T@k_qiajp*Hk]`$beha%7 r]n_jp9$bnkiaej_jp@k_*Nkkp*Ahaiajpo$l]ca%sdana± a*=ppne^qpa$l]pd%*R]hqa*Amq]ho$l]pd%± oaha_pa%*BenopKn@ab]qhp8TAhaiajp:$%7 eb$@a^qccan*Eo=pp]_da`% w ++Ej`a^qcik`ana]`kjhu]j`_na]pakqplqp ++na]`ejcTIHeopdna]`o]ba _kjpatp*Naolkjoa*Snepa$Opnejc*Bkni]p$?kqjpan9w,y(± _jp*=ppne^qpa$_kqjp%*R]hqa%%7 y ahoa w ++ejlnk`q_pekjfqopopknar]hqao Na]`anSnepanHk_gnsh9jasNa]`anSnepanHk_g$%7 nsh*=_mqenaSnepanHk_g$PeiaOl]j*BnkiOa_kj`o$.%%7 eb$_jp99jqhh% w ++l]ca`kaojkpateopuap TAhaiajpjasL]ca9jasTAhaiajp$l]ca( jasT=ppne^qpa$_kqjp(-%( jasT=ppne^qpa$l]pd(l]pd%%7 _jp@k_*Ahaiajp$L]cao%*=``$jasL]ca%7 y ahoa w ++ej_na]oa_kqjpan(oappeiaop]il ejpe9Ejp/.*L]noa$_jp*=ppne^qpa$_kqjp%*R]hqa%7 _jp*=ppne^qpa$_kqjp%*R]hqa9$''e%*PkOpnejc$%7 y _jp@k_*O]ra$beha%7 nsh*Naha]oaSnepanHk_g$%7 y y aj`nacekj y 4HEHANDLERSTORESTHENUMBEROFPAGEREQUESTSINASINGLE8-,DOCUMENT/THERDEVELOPERSCANADDTHE)&2!-% code to the pages they want included in the counter total. Internally, the file access is shared read mode. The BehaOpna]i class used behind the scenes in T@k_qiajp*Hk]` Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

SUPPORTSREADINGFROMDIFFERENTTHREADS(OWEVER WRITEACCESSREQUIRESANEXCLUSIVELOCK BLOCKINGOTHERTHREADS4OACHIEVETHIS ANa]`anSnepanHk_g class monitors the threads and blocks other THREADSFROMACCESSINGTHEFILEDURINGWRITEMODE4HISISNTAVERYEFFICIENTMETHOD)NAREAL LIFE SCENARIO CONSIDERREPLACINGTHE8-,ACCESSWITHADATABASEOPERATION!FTEROBTAININGACCESSTOTHE 8-, ,).1TO8-,ISUSEDTOEITHERCREATEELEMENTSFORTHEFIRSTTIMEORADDTOTHEEXISTINGCOUNTER when the page is requested again. In the example, you want to distinguish between debug mode and production mode. You can ascertain debug mode by using the @a^qccan*Eo=pp]_da` property. In debug mode, the content OFTHE)&2!-%ISFILLEDWITHTHECOUNTERFORTHECURRENTPAGE4HE,).1STATEMENTPREPAREDATTHE beginning of the Lnk_aooNamqaop method returns either jqhh or the element containing the counter information. Figure 3-8 shows the output in debug mode. The counter does not increase for requests in debug mode. In production mode, the counter increases but no output displays.

Figure 3-8. Output of the handler in debug mode )NTHISEXAMPLE )SHOWEDAHANDLERTHATDOESNTCREATECONTENTWITHEVERYUSE4HECONCEPTS behind this are:

s $EFININGHOWANDWHERETOINVOKETHEHANDLER



s 2EMEMBERINGTHATCONCURRENTTHREADSACCESSTHECODE



s 2ECOGNIZINGTHATCREATING output is not mandatory

Example—Using IHttpHandlerFactory to Perform URL Rewriting In this example, I’ll introduce another interface. For more flexibility with creating handlers on the fly, the EDpplD]j`hanB]_pknuINTERFACEISAVAILABLE!CLOSERLOOKATTHEDEFAULTL]caD]j`hanB]_pknu SHOWSTHATITISNOTDERIVEDFROMEdpplD]j`han, but from EDpplD]j`hanB]_pknu. This class is used to process the regular *]olt pages. 9OUDONTHAVETOCREATEAFACTORY BUTITGIVESMORECONTROLOVERTHECREATIONPROCESS)TCANBE useful in more complex scenarios. First, let’s look into the interface definition: lq^he_ejpanb]_aEDpplD]j`hanB]_pknu w EDpplD]j`hanCapD]j`han$Dppl?kjpatp_kjpatp(± opnejcnamqaopPula(± opnejcqnh(± opnejcl]pdPn]joh]pa`%7 rke`Naha]oaD]j`han$EDpplD]j`hand]j`han%7 y

Download at WoweBook.Com

133

134

CH APT ER 3 N MODU L ES A ND HA NDL ER S

NNote If you decode this using Reflector, you may see another interface named EDpplD]j`hanB]_pknu.. This provides another overload for the CapD]j`han method. You don’t need this at this stage, as you’ll only be using the EDpplD]j`hanB]_pknu. )MAGINEYOUHAVEAPAGEWITHCONTENTSUCHAS 8!9@]paPeia*Jks*PkOpnejc$I%!: 3ETTHECURRENTCULTUREBYADDINGTHECULTURE)$TOTHE52,4YPICAL52,SLOOKLIKETHIS

s dppl6++hk_]hdkop+?d]lpan,/+QnhNasnepaB]_pknuD]j`han+@ab]qhp*]olt



s dppl6++hk_]hdkop+?d]lpan,/+QnhNasnepaB]_pknuD]j`han+aj)qo+@ab]qhp*]olt



s dppl6++hk_]hdkop+?d]lpan,/+QnhNasnepaB]_pknuD]j`han+`a)`a+@ab]qhp*]olt



s dppl6++hk_]hdkop+?d]lpan,/+QnhNasnepaB]_pknuD]j`han+bn)bn+@ab]qhp*]olt

/URGOALISTOFINDAWAYTOEXTRACTTHECULTURECODESUCHAShDE DEvORhEN USv FROMTHE52, set it as the current culture of the thread, and process the page without the culture code, as shown INTHEFIRST52,,ISTING SHOWSAFACTORYTHATCREATESTHEREQUIREDINSTANCES Listing 3-12. Using a Factory to Rewrite a URL lq^he_]^opn]_p_h]ooNasnepaB]_pknuD]j`han6EDpplD]j`hanB]_pknu w lnkpa_pa`NasnepaB]_pknuD]j`han$% 6^]oa$% w y EDpplD]j`hanEDpplD]j`hanB]_pknu*CapD]j`han$Dppl?kjpatp_kjpatp(± opnejcnamqaopPula(± opnejcqnh(± opnejcl]pdPn]joh]pa`% w L]enp]ncap9CapNai]lEjbk$_kjpatp(namqaopPula(qnh(l]pdPn]joh]pa`%7 opnejcbehaj]ia9_kjpatp*Oanran*I]lL]pd$p]ncap*Benop*PkOpnejc$%%7 _kjpatp*NasnepaL]pd$qnh(qnh(p]ncap*Oa_kj`*PkOpnejc$%%7 EDpplD]j`han]llD]j`han9± L]caL]noan*Cap?kileha`L]caEjop]j_a$p]ncap*Benop*PkOpnejc$%(± behaj]ia(_kjpatp%7 napqnj]llD]j`han7 y rke`EDpplD]j`hanB]_pknu*Naha]oaD]j`han$EDpplD]j`hand]j`han% w y lnkpa_pa`]^opn]_pL]enCapNai]lEjbk$Dppl?kjpatp_kjpatp(opnejcnamqaopPula(± opnejcqnh(opnejcl]pdPn]joh]pa`%7 y lq^he__h]oo?qhpqnaNasnepaD]j`han6NasnepaB]_pknuD]j`han w

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

lnkpa_pa`kranne`aL]enCapNai]lEjbk$Dppl?kjpatp_kjpatp(± opnejcnamqaopPula(± opnejcqnh(± opnejcl]pdPn]joh]pa`% w opnejcknecej]hL]pd9Dppl?kjpatp*?qnnajp*Namqaop*L]pd7 opnejcopaiL]pd9+7++At]ilha(nalh]_asepdrenpq]h`ena_pknueb]ju opnejcjasL]pd9knecej]hL]pd*Oq^opnejc$knecej]hL]pd*Ej`atKb$opaiL]pd%'± opaiL]pd*Hajcpd%7 opnejcWYoaciajpo9jasL]pd*Olhep$#+#%7 opnejcmqanuOpnejc9Dppl?kjpatp*?qnnajp*Namqaop*Qnh*Mqanu7 pnu w opnejch]jcq]caL]np9oaciajpoW,Y7 ?qhpqnaEjbk_e9jas?qhpqnaEjbk$h]jcq]caL]np%7 Ouopai*Pdna]`ejc*Pdna]`*?qnnajpPdna]`*?qnnajp?qhpqna9_e7 napqnjjasL]en$+'opaiL]pd'opnejc*Fkej$+(oaciajpo(-(± oaciajpo*Hajcpd)-%(mqanuOpnejc%7 y _]p_d$JqhhNabanaj_aAt_alpekj% w y napqnjjasL]en$knecej]hL]pd(mqanuOpnejc%7 y y The definition in web.config or IIS settings is the same as for any other handler. This means that the ASP.NET engine will accept both EDpplD]j`han and EDpplD]j`hanB]_pknu in order to obtain access to the handler object. The code is simplified for clarity. You can extend the error handling by adding code to handle THESTEMPATH EVENIFITSSETTOAVALUEOTHERTHANTHEROOTPATH4HECOREIMPLEMENTATIONISAROUND the CapD]j`han method, which returns the used handler. If resources are blocked and need to be freed or disposed of, the required code will appear in the Naha]oaD]j`han method. As shown in the example, this is not always necessary. Keep in mind that the memory consumption of the handler MIGHTBEANISSUEIFTHESERVERHASAHIGHWORKLOAD INWHICHCASERELEASINGRESOURCESCOULDHELP &IGURE SHOWSTHEBEHAVIORFORSEVERALLANGUAGES52,REWRITINGISAFLEXIBLE SEARCH ENGINE FRIENDLYMETHODOFMODIFYINGBEHAVIOR

Figure 3-9. Use URL rewriting to set the current culture of a Web application.

Download at WoweBook.Com

135

136

CH APT ER 3 N MODU L ES A ND HA NDL ER S

4HISEXAMPLEDEMONSTRATEDAVERYBASICHANDLERFACTORY)NTHEABSTRACTBASECLASS THECapD]j`han method rewrites using Dppl?kjpatp*NasnepaL]pd4HEDEFAULTPAGEHANDLERISSUBSEQUENTLYRETRIEVEDAND returned. This is required because otherwise, the processing of all *]olt pages is remapped to the new FACTORY2EDEFININGTHEINTERNALHANDLERWITHYOUROWNONEREPLACESTHEMAPPING ASONLYONEHANDLER CANPROCESSASPECIFICREQUEST2EMAPPINGTHEDEFAULTHANDLERREQUIRESEITHERACOMPLETEIMPLEMENTATIONOFAHANDLERWITHSIMILARBEHAVIOR ORCREATINGTHEORIGINALHANDLERANDRETURNINGITUSINGAFACTORY FromTHEPERSPECTIVEOFEXTENSIBILITY THE latter is the better option.

Advanced Usage of Handlers The standardHANDLERSCOVERMOST BUTNOTALL TASKS(TTPHANDLERS can go further. In this section, I’ll DISCUSSADVANCED extensibility topics:

s !CCESSINGTHESESSIONSTATE



s $YNAMICALLYDEALINGWITHHANDLERSINTHEPIPELINE

Handlers and Session State Handlers areLOW LEVELPROGRAMMINGCONSTRUCTS4HEYARECRITICALFOROVERALLPERFORMANCEANDIF BADLYWRITTENORCONFIGURED COULDDEGRADETHESERVERSTHROUGHPUT7HILETHEREAREWAYSTODEAL with long-running threads in the handler code (as you saw in Chapter 2), it’s preferable to write HANDLERSTHATRUNASFASTASPOSSIBLE4OMAXIMIZEHANDLERSPEED -ICROSOFTREMOVEDSESSIONINFORMATIONFROMTHEDEFAULTHANDLERS4HEPREVIOUSEXAMPLESSHOWUSEFULTASKSACCOMPLISHEDWITHOUT needing session information. )FYOUDONEEDTOACCESSSESSIONSTATEINFORMATION ITISAVAILABLEBYIMPLEMENTINGONEOFTHE following two interfaces:

s ENamqena`OaooekjOp]pa



s ENa]`KjhuOaooekjOp]pa

It’s possible to obtain session information with minimal performance loss. If you only require read access to the session data, the ENa]`KjhuOaooekjOp]pa is ideal. ENamqena`OaooekjOp]paGIVESFULL ACCESSTOALLSESSIONDATA7HENADDINGEITHERINTERFACETOYOURCLASS YOULLNOTICETHAT6ISUAL3TUDIO does not attempt to implement any method bodies. Both interfaces are simply marker interfaces that modify the internal processing within the base class. Your class declaration should look like this: lq^he__h]ooPeiaD]j`hanSepdOaooekj6EDpplD]j`han(ENamqena`OaooekjOp]pa 4HESESSIONINFORMATIONISNOWPROVIDEDTOTHEDppl?kjpatpOBJECT ANDAVAILABLETHROUGHTHE _kjpatpPARAMETEROFTHEENTRYMETHOD,ISTING PASSESAVALUETHROUGHASESSIONVARIABLETOTHE handler. Listing 3-13. The Handler Implementation with Session Support lq^he__h]ooPeiaD]j`hanSepdOaooekj6EDpplD]j`han(ENa]`KjhuOaooekjOp]pa w nacekjEDpplD]j`hanIai^ano lq^he_^kkhEoNaqo]^ha w capwnapqnjpnqa7y y Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_kjpatp% w @]paPeia`p7 opnejcqoaQp_9_kjpatp*Namqaop*MqanuOpnejcWqp_Y7 eb$Opnejc*EoJqhhKnAilpu$qoaQp_%""qoaQp_*Amq]ho$pnqa%% w `p9@]paPeia*Qp_Jks7 y ahoa w `p9@]paPeia*Jks7 y _kjpatp*Naolkjoa*Snepa$± Opnejc*Bkni]p$_kjpatp*OaooekjWBkni]pOpnejcY*PkOpnejc$%(± `p*PkHkjcPeiaOpnejc$%± %%7 y aj`nacekj y 4HEONLYDIFFERENCEFROMTHEPREVIOUSEXAMPLEISTHESESSIONVALUENAMEDh&ORMAT3TRINGv RETRIEVEDFROM_kjpatp*OaooekjOBJECT)NTHEAPPLICATION YOUCANSETTHATVERYVALUETOCONTROLTHE BEHAVIOROFTHEHANDLER&ORPERFORMANCEPURPOSES THEENa]`KjhuOaooekjOp]pa interface is used because only read access is required.

Accessing the Pipeline Using the Context You can use these three properties of the Dppl?kjpatpOBJECTTOFURTHERMODIFYTHEBEHAVIOROFTHE HANDLERORTORETRIEVEMOREINFORMATIONABOUTWHATISTAKINGPLACE

s _kjpatp*D]j`han



s _kjpatp*LnarekqoD]j`han



s _kjpatp*Nai]lD]j`han

5SINGTHED]j`han property YOUHAVEACCESSTOTHECURRENTHANDLEREMPLOYEDINTHECURRENT CONTEXT3INCETHECONTEXTISAVAILABLEASASTATICPROPERTY ITSEASYTOACCESSTHEHANDLERINCLASSES defined elsewhere. This also applies to the LnarekqoD]j`han property, a property that is set when the HANDLERISREMAPPED2EMAPPING a handler might occur in complex scenarios where a default hanDLERPROCESSESALLREQUESTS BUTREMAPSTOANOTHERHANDLERUNDERCERTAINCIRCUMSTANCES,ISTING  demonstrates this technique. Listing 3-14. Remapping to Another Handler lq^he__h]ooNai]lD]j`han6EDpplD]j`han w nacekjEDpplD]j`hanIai^ano lq^he_^kkhEoNaqo]^ha w capwnapqnjpnqa7y y

Download at WoweBook.Com

137

138

CH APT ER 3 N MODU L ES A ND HA NDL ER S

lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_kjpatp% w EDpplD]j`hannai]lD]j`han9jqhh7 ++`apanieja]jei]canamqaop]j`d]j`hasepdlner]pad]j`han eb$$L]pd*CapAtpajoekj$_kjpatp*Namqaop*Qnh*=^okhqpaL]pd%%*Amq]ho$*ljc%% w nai]lD]j`han9jasEi]caD]j`han$%7 y ahoa w ++lnk_aoo]jukpdannamqaopsepd`ab]qhpd]j`han opnejcrenpq]hL]pd9_kjpatp*Namqaop*Qnh*=^okhqpaL]pd7 opnejcbehaj]ia9Dppl?kjpatp*?qnnajp*Namqaop*L]pd7 nai]lD]j`han9L]caL]noan*Cap?kileha`L]caEjop]j_a$renpq]hL]pd(± behaj]ia(_kjpatp%7 y _kjpatp*Nai]lD]j`han$nai]lD]j`han%7 y aj`nacekj y In this code, the handler searches for *ljcEXTENSIONSANDASSIGNSPRIVATEHANDLERSTOPROCESS THEM/THERWISE YOUUSETHESTANDARDPAGEPROCESSINGNOOTHERCUSTOMCODEISINVOLVED3IMPLY call _kjpatp*Nai]lD]j`han$nai]lD]j`han% to assign to a different handler. All internal processing is redirected to the new handler from the beginning of the pipeline. As there’s noADDITIONALOVERHEAD there are no performance issues with the handler remapping.

Asynchronous Pages The processing of pages relies on just another kind of built-inHANDLER7HENPROCESSINGPAGES YOU HAVEOFTENLENGTHYOPERATIONSAGAINSTDATABASES 7EB3ERVICES OREXTERNALDATASOURCESTHATCOULD BLOCKYOURWORKERTHREADS(EREYOUMIGHTWONDERWHETHERITSPOSSIBLETOPROCESSEVENREGULAR pages asynchronously. Fortunately, the Framework already implements this for us, and there is nothing to do but set a property.

Prepare Pages for Asynchronous Operation Building asynchronous pages is simple. Begin by including an attribute in the page’s
Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

That’s enough theory for now. The following examples address a common problem. It calls A7EB3ERVICEˆACURRENTEXCHANGERATESERVICETHATCONVERTSBETWEEN53AND%URO0UTTINGTHIS ONA7EB3ITEISAGOODIDEAFORASHOPTHATHASANINTERNATIONALAUDIENCE(OWEVER BLOCKINGTHE SERVERSTHREADDUETOUNPREDICTABLECALLSTOAFOREIGNSERVICEISNOSOLUTION

Figure 3-10. Synchronous vs. asynchronous page processing

Download at WoweBook.Com

139

140

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Using a Public Web Service 5SINGAPUBLIC7EB3ERVICEISBOTHCONVENIENTANDRISKY9OUHAVEAPOWERFULSERVICEAVAILABLEAND CANUSEITASTHETERMSANDCONDITIONSPERMIT(OWEVER BETWEENTHESERVICESHOSTANDYOURSERVER ISALONGDISTANCEANDMANYTHINGSCOULDGOWRONG*USTASSUMETHATTHESERVICEEXPERIENCESHIGH WORKLOAD ANDEITHERRESPONSESAREDELAYEDORTHESERVICESTOPSWORKINGCOMPLETELY"LOCKINGYOUR application’s thread could cause huge performance loss. Just to simplify first steps into the world of ASYNCHRONOUSPAGES THEFOLLOWINGEXAMPLEUSESAPUBLICSERVICETHATAPPEARSTOBEALMOSTRELIABLE 4HEREARESEVERALPUBLICSERVICESAVAILABLETOTESTSUCHANAPPLICATION!TOFTHETIMEOFPUBLISHing, the following works: dppl6++sss*sa^oanre_at*_ki+?qnnaj_u?kjranpkn*]oit.

Prepare a Project to Consume a Service The only stepREQUIREDTOCONSUMEASERVICEISTOREFERENCEIT4HEADDRESSPREVIOUSLYSHOWNISALREADY THESERVICESENDPOINTITSELF4OREFERENCETHESERVICE RIGHT CLICKTHEPROJECTANDCHOOSEh!DD7EB2EFerence” (see Figure 3-11).

Figure 3-11. Add a reference to an external Web Service.

Calling Web Services Asynchronously )FA7EB3ERVICEHAS a method named ?kjranoekjN]pa THENTHE7EB3ERVICEPROXYINCLUDESA method named ?kjranoekjN]pa=ouj_ANDANEVENTNAMED?kjranoekjN]pa?kilhapa`. You can call ?kjranoekjN]paASYNCHRONOUSLYBYREGISTERINGAHANDLERFORTHECOMPLETEDEVENTANDCALLING ?kjranoekjN]pa=ouj_ ASSHOWNIN,ISTING 

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

Listing 3-15. Calling a Web Service from an ASP.NET Page Asynchronously lq^he_l]npe]h_h]oo[@ab]qhp6Ouopai*Sa^*QE*L]ca w ?qnnaj_u?kjranpkn__7 lnkpa_pa`rke`L]ca[Hk]`$k^fa_poaj`an(Arajp=ncoa% w __9jas?qnnaj_u?kjranpkn$%7 y lnkpa_pa`rke`^pjOaj`[?he_g$k^fa_poaj`an(Arajp=ncoa% w __*?kjranoekjN]pa?kilhapa`'9jas± ?kjranoekjN]pa?kilhapa`ArajpD]j`han$__[?kjranoekjN]pa?kilhapa`%7 __*?kjranoekjN]pa=ouj_$?qnnaj_u*QO@(?qnnaj_u*AQN%7 y rke`__[?kjranoekjN]pa?kilhapa`$k^fa_poaj`an(± ?kjranoekjN]pa?kilhapa`Arajp=ncoa% w `kq^ha]ikqjp9@kq^ha*L]noa$ptp=ikqjp*Patp%7 h^hNaoqhp*Patp9$a*Naoqhp&]ikqjp%*PkOpnejc$%7 y y 4HECODEINTHEFOLLOWINGSIDEBARPRESENTSABEHINDCLASSTHATCALLSA7EB3ERVICES ?kjranoekjN]paMETHODASYNCHRONOUSLYUSINGTHEh-ETHOD!SYNCvPATTERN&UNCTIONALLY THIS ISIDENTICALTOTHEONESHOWNIN,ISTING (OWEVER INTERNALLYITISQUITEDIFFERENT!GAIN THE
Download at WoweBook.Com

141

142

CH APT ER 3 N MODU L ES A ND HA NDL ER S

WHERE THE BEGIN-END PATTERN HAS GONE You may have read or heard about the classic Begin/End pattern used to call services asynchronously. However, when referencing a Web Service using the new style Web Project as provided in Visual Studio, the BeginMethod and EndMethod proxy methods are hidden as protected methods. Microsoft recommends using the new pattern as described in this section. However, if you like to use the old pattern, a few more steps are required. First, you can use the old style Web project (use File ° New ° Web Site instead of File ° New ° Project ° Web Project). Secondly, add the reference to the Web Service. The generated proxy will now expose the BeginMethod and EndMethod methods for all the service’s methods. Next, you have to call the =``KjLnaNaj`an?kilhapa=ouj_ method early in the page’s lifetime. For example, in Hk]` this is early enough. Register a >acej method and an Aj` method, as shown in the following code: =``KjLnaNaj`an?kilhapa=ouj_$ jas>acejArajpD]j`han$>acejIapdk`%( jasAj`ArajpD]j`han$Aj`Iapdk`% %7 The page runs through its normal processing life cycle until shortly after the LnaNaj`an event fires. Then ASP.NET calls the >acejIapdk` just registered. The method launches an asynchronous operation and returns immediately. This is the lengthy operation previously mentioned that might require more time. At this point, the thread assigned to the request returns to the thread pool. Furthermore, the method returns an E=ouj_Naoqhp that allows ASP.NET to determine when the asynchronous operation has been completed. ASP.NET then extracts a thread from the thread pool and calls your End method (Aj`Iapdk`). After this returns, it executes the remaining portion of the page’s life cycle. This might sound confusing—getting the thread back from thread pool and blocking the thread again. However, between the time >acej returns and Aj` is called, the request-processing thread is free to serve other requests. Keep in mind that the page processing usually takes only a few milliseconds. The time-consuming operation in the asynchronous handler might run for seconds. The process of freeing the thread pool thread for this time allows ASP.NET to process hundreds, if not thousands, of regular pages on this very same thread. However, until Aj` is called, the rendering of the current asynchronous page is delayed. This is the same as in the previous example. It improves the situation not only for one user, but also for all users. In the sample code, you might look for the E=ouj_Naoqhp implementation. Instead of implementing our own version, you take one that the Framework implements for us. The complete code of such an example would look like the following: lq^he_l]npe]h_h]oo[@ab]qhp6Ouopai*Sa^*QE*L]ca w ?qnnaj_u?kjranpkn__7 lnkpa_pa`rke`L]ca[Hk]`$k^fa_poaj`an(Arajp=ncoa% w y E=ouj_Naoqhp>acej?kjranoekj$k^fa_poaj`an(Arajp=ncoa( =ouj_?]hh^]_g_^(k^fa_pop]pa% w __9jas?qnnaj_u?kjranpkn$%7 napqnj__*>acej?kjranoekjN]pa$?qnnaj_u*QO@(?qnnaj_u*AQN(_^(op]pa%7 y

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

rke`Aj`?kjranoekj$E=ouj_Naoqhp]n% w `kq^hanaoqhp9__*Aj`?kjranoekjN]pa$]n%7 `kq^ha]ikqjp9@kq^ha*L]noa$ptp=ikqjp*Patp%7 h^hNaoqhp*Patp9$naoqhp&]ikqjp%*PkOpnejc$%7 y

lnkpa_pa`rke`^pjOaj`[?he_g$k^fa_poaj`an(Arajp=ncoa% w =``KjLnaNaj`an?kilhapa=ouj_$ jas>acejArajpD]j`han$>acej?kjranoekj%( jasAj`ArajpD]j`han$Aj`?kjranoekj%%7 y y Here the asynchronous methods are registered with the Button’s click event. >acej?kjranoekjN]pa and Aj`?kjranoekjN]pa are the methods used to invoke the service and get the result back.

Configuration and Deployment 4OCREATEAHANDLER YOUCHOSEh#LASS,IBRARYvASTHEPROJECTTEMPLATE REMOVED the default class CREATEDBYTHETEMPLATE ANDADDEDANOBJECTOFTYPEh!30.%4(ANDLERv.OWTHATYOUHAVE implemented the handler, you can compile it into an assembly loaded by ASP.NET at runtime (see Figure 3-12). As long as the handler remains in the web application, this is simple. No special action ISREQUIRED9OULLPROBABLYWANTTOIMPLEMENTSEVERALHANDLERSANDKEEPTHEMINDIFFERENTASSEMblies for easy reuse. Simply reference the assemblies in your web project.

Figure 3-12. Add a handler to the current project

Download at WoweBook.Com

143

144

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Configuring Default Web Server and Development Environment To test the handler, you’ll need to configure the settings in web.config. Place the appropriate settings in the 8ouopai*sa^: section: 8dpplD]j`hano: 8]``ran^9CAPl]pd9&*ljcpula9=lnaoo*DpplD]j`han*Ei]caD]j`han+: 8+dpplD]j`hano: )NCASEYOUHAVEASIMILARHANDLERDEFINITIONINTHEUPSIDECONFIGURATIONPATHYOUMIGHTCONsider using either 8naikra+: or 8_ha]n+:TAGSTOOVERWRITETHEVALUESPROPERLY 4HESETTINGSFORTHEDEVELOPMENTENVIRONMENTALSOAPPLYTO))3 ))3 AND))3INCLASSICMODE 4HEREARESEVERALADVANTAGESˆASEXPLAINEDIN#HAPTERˆTORUNNINGTHE))3INTEGRATEDPIPELINE HOWEVER WHICHINVOLVESTHEDIFFERENTSETTINGS shown in Table 3-12. Table 3-12. Options of the httpHandler Settings

Attribute

Typical Values

Description

ran^

'%4 0/34

4HEHANDLERRESPONDSTOTHE(440VERBSONLY

l]pd

full path or wildcards

The path that defines the requests the handlers responds to.

pula

class, assembly

Type information of the handler’s definition.

Configuring IIS7 Settings In the main (web) project, add a reference to this project. If the namespace of the external project is =lnaoo*DppD]j`han*Ei]caD]j`han, the following addition to web.config will be required: 8ouopai*sa^Oanran: 8d]j`hano: 8]``j]ia9Ei]caD]j`hanl]pd9&*ljcran^9CAP pula9=lnaoo*DpplD]j`han*Ei]caD]j`hannaokqn_aPula9Beha namqena=__aoo9Na]`lna?kj`epekj9ejpacn]pa`Ik`a+: 8+d]j`hano: 8+ouopai*sa^Oanran: Compile both the project containing the handler and the web project. Add the mapping in )NTERNET)NFORMATION3ERVICES-ANAGER ASSHOWNBEFORE4HEMAPPINGWILLNOWFUNCTIONPERFECTLY FORBOTHTHEDEVELOPMENTENVIRONMENTANDDIRECTUSAGEFROMTHELOCAL))3SEE4ABLE   Table 3-13. Handler Settings for IIS7 Integrated Mode

Attribute

Typical Values

Description

ran^

'%4 0/34

The handler responds to the HTTP VERBSONLY/THERVERBSARE$%"5' AND(%!$

l]pd

full path or wildcards

The path that defines the requests the handlers respond to.

naokqn_aPula

File

Expect that the file exists.

o_nelpLnk_aookn

a path

0ATHTOTHEENGINE$,, THATHANDLES the request.

namqena=__aoo

3CRIPT %XECUTE .ONE 2EAD 7RITE

2EQUIREDSETTINGSFORRESOURCEACCESS

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

Attribute

Typical Values

Description

naokqn_aPula

$IRECTORY %ITHER &ILE 5NSPECIFIED

The type of the resource the handler ISMAPPEDTO4HEDEFAULTVALUEIS 5NSPECIFIED

lna?kj`epekj

See following list

Conditions that must be fulfilled to ACTIVATETHEHANDLER)FTHEREQUESTFAILS AN(440ERRORhPRECONDITIONFAILEDv is sent to the client.

]hhksL]pdEjbk

true,false

Specifies whether the handler processes full path information. If set to false, the handler processes the file information part of a path only.

ik`qhao

Names

/PTIONALCOMMASEPARATEDLISTOF modules the extension is mapped to. By default, handler settings map to -ANAGED0IPELINE(ANDLER

pula

class, assembly

The type name of the handler.

TypicalVALUESFORlna?kj`epekj are these:

s ^epjaoo/., ^epjaoo20!CTIVATE BITOR BITMODERESPECTIVELY



s nqjpeiaRanoekj-*-, nqjpeiaRanoekj.*,4HEREQUIREDRUNTIMEONTHESERVER



s _h]ooe_Ik`a, ejpacn]pa`Ik`a-ODETHAT))3ISRUNNINGIN



s i]j]ca`D]j`han2EQUIRESTHEHANDLERTOBEWRITTENINMANAGEDCODE

Configure via IIS Management Console The settings in web.configREQUIREDBY))3INTEGRATEDMODECANBEALTEREDVIATHE))3-ANAGEMENT Console. The settings correspond directly. Altering web.config will result in an immediate change to THE-ANAGEMENT#ONSOLESETTINGS ANDVICEVERSA4OCONFIGUREUSINGTHE))3-ANAGEMENT#ONSOLE 1. /PEN)NTERNET)NFORMATION3ERVICE-ANAGER 2. /PENTHEWEBYOUWANTTOCHANGE 3. )NTHE))3SECTION DOUBLE CLICKONTHE(ANDLER-APPINGS 4. #LICKON!DD-ANAGED(ANDLERINTHETASKLISTTOTHERIGHT 5. %NTERTHESEVALUESINTHEDIALOG,EAVETHEDIALOGBYCLICKING/+ THEN a. 4HE2EQUESTPATH TIME b. Choose the handler from the drop-down list. The handler will appear in the list, as long as you’re in the right web and the project compiles. c. 'IVETHEHANDLERANAPPROPRIATENAME d. #LICKON2EQUEST2ESTRICTIONS e. /PENTHE6ERBSTAB f. #LICKONONEOFTHEFOLLOWINGVERBSANDENTERTHEVALUEh'%4v 6. ,EAVETHEMAINDIALOGBYCLICKING/+

Download at WoweBook.Com

145

146

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Configure Using Generic Handlers The final optionISNOTACONFIGURATIONOPTION BUTAWAYOFINVOKINGHANDLERSWITHOUTCONFIGURING them in web.config. By default, ASP.NET defines handlers using the extension *]odt. Therefore, PLACINGTHECODEFORAHANDLERINAFILEUSINGTHEFOLLOWINGDECLARATIVEFORMISSUFFICIENTTOGETIT working. There is no further need for web.config!NADVANTAGEOFTHISISTHATYOUWONTNEEDTODISTINGUISHBETWEENTHESETTINGSFOR))3INTEGRATEDMODEANDOTHER7EB3ERVERS NORWILLYOUNEEDTO maintain settings in the web.config regarding handlers. #REATINGSUCHAHANDLERINVOLVESTWOSTEPS 1. For each handler required, create a file with the extension *]odt. 2. Add the following declaration at the top of the file: 8!<Sa^D]j`hanH]jcq]ca9??h]oo9=lnaoo*DpplD]j`han*IuD]j`han!: The Sa^D]j`hanDIRECTIVEISSIMILARTOTHE0AGEDIRECTIVE/NLYAFEWOPTIONSAREAVAILABLE HOWEVER ASSHOWNIN4ABLE  Table 3-14. Attributes Supported for WebHandler Directive

Attribute

Available Values

Usage

H]jcq]ca

C#, VB

,ANGUAGEOFTHECODESECTION

?h]oo

Name

Name of the class defined in code, including the namespace.

?k`a>adej`

Name

?kilehanKlpekjo

Name of the file containing the code. /PTIONSFORON THE FLYCOMPILATION

@a^qc

True, False

Compile in debug or release mode. In debug mode, the symbol file (.pdb) is created.

S]njejcHarah

TO

7ARNINGLEVEL

@ao_nelpekj

A description for documentation purposes only. The PAGEPARSERDOESNOTRECOGNIZETHISATTRIBUTE

7HETHERYOUUSETHECONFIGURATIONFILEORTHE*]odt extension is a matter of preference. HowEVER THEREARESOMEBASICGUIDELINESFORSELECTINGTHEBESTOPTION5SINGTHE*]odt file within an APPLICATIONISBETTERFORSMALLPROJECTSORHANDLERSTHATHAVESIMPLE BUTSPECIFIC TASKS)FYOUPLAN TOREUSETHEHANDLERSEVERALTIMES ORINSEVERALPROJECTSONTHESERVER YOUSHOULDSEPARATEITINTOITS own assembly and register it in the Global Assembly Cache (GAC). Storing handlers in assemblies with signing and deployment capabilitiesISFORLARGERPROJECTSINVOLVINGHANDLER reuse.

Testing and Debugging Modules and Handlers (AVINGDEPLOYEDANDCONFIGUREDTHEMODULEORHANDLER DEBUGGING may be required. In Visual Studio, THENORMAL$EBUGMODEWORKSWELLFORDEBUGGINGHANDLERS9OUREPROBABLYALREADYFAMILIARWITHTHE DEBUGGINGCAPABILITIESIN6ISUAL3TUDIO3ETTINGBREAKPOINTSANDVIEWINGVARIABLESVALUESISJUSTAS simple for handlers as for any other type of .NET solution.

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

Debug Using IIS You may occasionally experience trouble with your application when running on IIS. There are no breakpoints, and adding, logging, and tracing capabilities can be tedious. In large projects there are often coding guidelines that require you to add tracing code and to log pertinent messages (such as exceptions). In smaller projects, it might not be appropriate to write more code for logging and tracING3ETTINGASIMPLEBREAKPOINTANDEXAMININGAVALUEORCONDITIONDURINGAREQUESTWOULDBENICE It can be done. To do so, you can attach a debugger to a running application. In the case of an !30.%4APPLICATIONRUNNINGON))3 THISISTHEWORKERPROCESSˆWWPEXE,ETSCONSIDERTHECASE WHEREYOUHAVENOTPUBLISHEDYOURPROJECT BUTSIMPLYCOMPILEDONTHEFLY ANDYOURSOURCESˆTHE *_oFILESˆARESTILLAVAILABLEBESIDETHE*]olt files. (I’ll discuss techniques for attaching to a precomPILEDPROJECTLATERINTHESECTIONh0ROBLEMS$EBUGGINGTHE7ORKER0ROCESSv (ERE THE6ISUAL3TUDIO debugger attaches automatically to the current process when you hit F5 and start a debug session. 4HISCURRENTPROCESSISTHEINTERNAL7EB3ERVERINCLUDEDIN6ISUAL3TUDIO9OUCANACHIEVETHESAME thing simply by attaching the debugger to the worker process. If the worker process is not running, FORCEITBYREQUESTINGTHEFIRSTPAGEANDINVOKINGTHEMODULESORHANDLERSCONFIGUREDFORYOURAPPLIcation. It doesn’t matter whether it is running properly or not. Here is a brief summary of the pre-conditions so far:

s ))3ISCONFIGUREDTORUNTHE7EBDIRECTLYFROMPROJECTFILES



s 6ISUAL3TUDIOISRUNNINGANDHASTHEPROJECTLOADEDHOWEVER THEREISNODEBUGSESSIONSO far).



s 4HE7ORKERPROCESSISUPANDRUNNINGSEE&IGURE  

NTip You can force the worker process to start by invoking a first request to the application. To check whether it is available, open Task Manager, switch to the Processes tab, check the box (Windows Server 2008) or click the button (Windows Vista) Show Processes From All Users, and search for w3wp.exe in the list. Now open Visual Studio and attach the debugger to the worker process: 1. /PENDebug ° Attach to Process . . . 2. In the subsequent dialog, check these settings: s Transport: default. s Qualifier4HENAMEOFTHESERVERORWORKSTATION s )NTHEAttached toSECTION YOUSHOULDATLEASTHAVETHEOPTION-ANAGED#ODESELECTED 5SETHE3ELECTBUTTONTOCHANGESETTINGS 3. )NTHELISTOF!VAILABLE0ROCESSES LOOKFORTHEWORKERPROCESS)FITSNOTTHERE TICKTHECHECKbox Show processes from all users4HISISSAMEOPTIONASINTHE4ASK-ANAGER 4. 5SETHE2EFRESHBUTTONTORELOADTHELISTOFPROCESSESDURINGTHESESSIONWITHOUTCLOSINGTHE dialog. 5. -ARKAVAILABLEWORKERPROCESSESANDCLICKAttach, ASSHOWNIN&IGURE 

Download at WoweBook.Com

147

148

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Figure 3-13. Use the Task Manager to check for the worker process.

$EPENDINGONYOURSERVERCONDITIONS YOUMAYFINDTHATSEVERALWORKERPROCESSESAPPEARINTHE list. If you’re not sure which process is the one handling the current request, you can attach to all of THEM!LTERNATIVELY USE4ASK-ANAGERTOKILLALLTHEWORKERPROCESSES ISSUEANEWREQUESTTOYOUR APPLICATION ANDREFRESHTHELIST)FNOONEELSEISUSINGTHESERVER ONEWORKERPROCESSWILLAPPEAR /FCOURSE THEUSAGEOFWORKERPROCESSESˆASEXPLAINEDIN#HAPTERˆDEPENDSONTHETHREADS REQUIRED5NDERRARECIRCUMSTANCES THEAPPLICATIONNEEDSMOREPOWERANDSPLITSTHEREQUESTSINTO MULTIPLEWORKERPROCESSES(OWEVER ATTACHINGSEVERALINSTANCESOFTHEWORKERPROCESSTOTHESAME debugger session is quite easy.

Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

7ITH6ISUAL3TUDIORUNNINGINDEBUGMODE ASITISWHENYOUHITTHE&KEY YOUCANSETBREAKPOINTSWITHINTHEMODULEORHANDLERCODEANDINVOKEAREQUESTTOHITTHEBREAKPOINT9OUCANEVEN watch the debug and trace information in the output window.

Figure 3-14. Attaching the debugger to the worker process

Problems Debugging the Worker Process 3OMETIMESTHEBEHAVIOROFTHEDEBUGGERDOESNOTMATCHYOUREXPECTATIONS1UITEFREQUENTLYTHE BREAKPOINTSAPPEARINACTIVE ORTHEYCANTBEhHIT vAS6ISUAL3TUDIOCALLSITSEE&IGURE  

Figure 3-15. The breakpoint will not currently be hit. 5SUALLYTHISISBECAUSETHEPAGEHASNOTYETBEENLOADED3INCEYOUDECIDEDTOLET!30.%4 COMPILEPAGESONTHEFLY THECURRENTPAGEMIGHTNOTYETBEAVAILABLEANDTHEREFORETHESYMBOLSARE not built. To check this, use the Modules dialog in Visual Studio as shown in Figure 3-16.

Download at WoweBook.Com

149

150

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Figure 3-16. Use the Modules window to retrieve information about loaded symbols. )NTHE-ODULESWINDOW LOOKFORTHEASSEMBLYYOUBUILTFORYOURMODULEORHANDLER)NTHECONtext menu of each entry, use the Symbol load informationITEMTORETRIEVEMOREINFORMATION%ITHER you’ll obtain the full path, or the symbol file (*l`^) is loaded from the list of paths Visual Studio has tried so far (see Figure 3-17).

NTip To debug parts of the operating system or .NET Framework, use the Modules dialog to attach foreign pdb files. Additionally, it can be a good idea to set up a symbol server in your company in order to have common symbol files ready, or, alternatively, attach to Microsoft’s public symbol server.

Figure 3-17. Use the symbols settings in Visual Studio to optimize access to public pdbs. Download at WoweBook.Com

C H A P T E R 3 N M O D U LE S A N D H A N D LE R S

/NCEEVERYTHINGISFUNCTIONINGNORMALLYANDTHEATTACHEDSYMBOLSAREAVAILABLE THEBREAKpoints should function as expected and be “hit” when the code execution reaches them (see Figure 3-18).

Figure 3-18. Everything is ready to go if the breakpoint is active.

Set Up Tracing for Handlers Aspx pagesHAVEAPOWERFULANDPOPULARTRACINGFEATURE7HENYOUSETTHEFOLLOWINGPAGEDIRECTIVE the page’s content will be replaced by a complete analysis of the request: 8!<L]caPn]_a9pnqa*** (OWEVER THE<Sa^D]j`hanDIRECTIVE does not support this. If you write your module or handler INASEPARATEASSEMBLY USINGPLAINCODE THEREISNODIRECTIVEATALL !NEXAMPLEOFAHANDLERINVOKEDBYFILEEXTENSIONISTHETrace.axd file used for debugging. In ORDERTOINVOKETHETrace.axdHANDLER CONFIGURETHE7EBSITEFORTRACINGBYADDINGATRACESECTIONTO web.config like this: 8_kjbecqn]pekj: 8ouopai*sa^: 8pn]_aaj]^ha`9pnqa+: 8+ouopai*sa^: 8+_kjbecqn]pekj: Call the trace.axdFILEFROMTHEROOTOFTHE7EBSITEFOREXAMPLE dppl6++hk_]hdkop+pn]_a*]t`. The output starts with information similar to the one in Figure 3-19.

Figure 3-19. Part of the trace information output

Download at WoweBook.Com

151

152

CH APT ER 3 N MODU L ES A ND HA NDL ER S

Summary In this chapter, you learned how to extend the pipeline by creating your own modules and handlers. !MODULEPROVIDESLOW LEVELPROCESSINGANDISINVOKEDTWICEWHENTHEREQUESTBUBBLESUPTHE PIPELINE ANDAGAINAFTERALLINTERNALPROCESSINGBYTHEDESIGNATEDHANDLERISCOMPLETE5SINGAHANdler, you can add your own processing code either assigned to your own file extension or using the generic *]odt extension. Handlers process requests and create the output sent to the client. Asynchronous handlers help to process long-running requests—such as database queries or 7EB3ERVICESˆWITHOUTFILLINGTHETHREADPOOLWITHTHREADS4HISTECHNIQUEIMPROVESTHEOVERALL PERFORMANCEOFA7EBAPPLICATIONANDLEADSTOACONSISTENTLYSMOOTHUSEREXPERIENCE

Download at WoweBook.Com

CHAPTER

4

Providers and Configuration

I

n the previous chapters, you learned how to extend ASP.NET at a low level. For daily tasks, however, you typically work at a higher level. A core concept of the ASP.NET extensibility paradigm is the provider model: a software module that provides a uniform interface to a service. ASP.NET incorporates several common providers that allow developers to replace functionality with their own modules, without breaking compatibility with existing modules. This chapter includes:

s 4HEPROVIDERMODELCONCEPT



s (OWPROVIDERSWORKINTERNALLYANDHOWTOCONFIGURETHEMPROPERLY



s 4HEBUILT INPROVIDERS



s (OWTODEVELOPYOUROWNCUSTOMPROVIDERMODELTOALLOWOTHERSTOEXTENDYOURAPPLICATION



s (OWTOEXTENDTHECONFIGURATIONMODEL



s (OWTOUSEEXPRESSIONSYNTAXANDEXPRESSIONGENERATORSTOACCESSCONFIGURATIONFROM markup

At the end of this chapter, you’ll be able to create and extend your own providers. You’ll also know how to integrate them with existing ASP.NET applications so that other developers can extend your application. The extensibility of built-in providers is covered in more detail in Chapters 5 to 8.

The Provider Model Providers are software modules built on top of interfaces or abstract classes that define the façade for the application. The interfaces constitute a “seam” in the architecture, which allows you to replace providers without affecting other modules. For instance, the data access provider enables ACCESSTOANYKINDOFSTORAGEFORDATAINCLUDINGDATABASESFROMDIFFERENTVENDORS(ENCE THEPROvider model encapsulates the functionality and isolates it from the rest of the application. Since almost all the major parts of ASP.NET are built on top of providers, there are multiple ways of modifying the internal behavior. Providers are responsible for the extensibility of ASP.NET. Creating your own providers gives you the ability to construct a sophisticated architecture that others might use—and to alter its behavior without disturbing internal processing. Consider an application such as Microsoft Office SharePoint Server 2007 (MOSS), which is an ASP.NET application and a framework that others use as a foundation for their applications. A similar extensibility concept is supplied on this level. Providers build the core technology that all of this is based on.

153 Download at WoweBook.Com

154

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

Goals of the Provider Model When you work with providers for the first time, you may find that writing or extending a provider can be a complicated task. Due to the constraints of compatibility and transparency towards other modules, there is often no other option but extending internal interfaces. You may still need to decide whether or not to write your own provider model. This chapter gives you the information you need for making that decision. Recall what the provider model was designed for:

s )TMAKES!30.%4BOTHFLEXIBLEANDEXTENSIBLE



s )TSROBUSTANDWELLDOCUMENTED



s )TPROVIDESACOMMONANDMODERNARCHITECTUREFORYOURAPPLICATION



s )TSPARTOFAMULTI TIERARCHITECTURE

The provider model does not consist only of simple provider modules. At the top level of the model are services. “Services” in ASP.NET is a generic term for separate modules, such as Membership, site maps, or Profiles. These all are high-level components that make your life as a developer easier. Almost all of these services need some kind of data storage or at least a communication channel. From the perspective of a multi-tier application, the service should be independent of the particulars of data persistence. The Provider sits between these two layers: the Service and the Data Store (see Figure 4-1). Modifying the Provider allows the Service to use a different Data Store or communication channel without changing the Service functionality. From the perspective of the user, this architecture is transparent. Additionally, the Provider is a readily configurable module. You can usually change the Provider by editing the web.config file or by setting properties in base classes.

Figure 4-1. Provider as part of a multi-tier architecture

Default Provider ASP.NET comes with several built-in providers. As long as they perform their function for you, they NEEDNOMODIFICATION(OWEVER CIRCUMSTANCESCHANGE ANDATSOMEPOINTYOUMIGHTFINDITNECESsary to create your own provider. Before commencing, though, it’s illuminating to learn about the existing providers and how they enhance their associated services.

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

NNote

In this book, I do not supply a full description of all the built-in providers. Please refer to the documentation on MSDN to learn more about usage and configuration scenarios. Start at dppl6++io`j*ie_nkokbp*_ki+ aj)qo+he^n]nu+ouopai*_kjbecqn]pekj*lnkre`an*]olt to find the official documentation for the underlying types.

Before looking into the provider model, let’s differentiate between the two levels, services and providers, as mentioned before. Table 4-1 shows all the services in ASP.NET and the provider associated with each service. Table 4-1. ASP.NET Services Using Providers

Service

Default Provider

Membership

Ouopai*Sa^*Oa_qnepu*OmhIai^anodelLnkre`an

Roles

Ouopai*Sa^*Oa_qnepu*OmhNkhaLnkre`an

Site Map

Ouopai*Sa^*TihOepai]lLnkre`an

Profile

Ouopai*Sa^*Lnkbeha*OmhLnkbehaLnkre`an

Session State

Ouopai*Sa^*OaooekjOp]pa*EjLnk_OaooekjOp]paOpkna

Web Parts

Ouopai*Sa^*QE*Sa^?kjpnkho*Sa^l]npo*OmhLanokj]hev]pekjLnkre`an

You can deduce the storage location from the naming scheme. Membership, Role Management, Profile, and Web Parts services use SQL Server by default, while the Site Map service defaults to a XML file, the web.sitemapFILE3ESSIONVARIABLESAREHELDINMEMORYWITHINTHE))3PROCESS 4WOSERVICESDONOTINCLUDEPRECONFIGUREDBUILT INPROVIDERS)NFACT THESESERVICESDOHAVE default providers, but you need to configure them explicitly before you can use them. See Table 4-2 for more information. Table 4-2. ASP.NET Services with Unconfigured Default Providers

Service

Recommended Provider (Not Assigned By Default)

Web Events

Ouopai*Sa^*I]j]caiajp*ArajpHkcSa^ArajpLnkre`an

Protected Configuration

Ouopai*?kjbecqn]pekj*No]Lnkpa_pa`?kjbecqn]pekjLnkre`an

Web events are events that monitor ASP.NET. They are normally off and must be configured in the 8da]hpdIkjepknejc: section of web.config. By default, configuration data is saved in plain text. The No]Lnkpa_pa`?kjbecqn]pekjLnkre`an enables encryption of sensitive configuration data—particularly useful if your application is hosted on external servers where unvetted administrators could read the files. The providers shown in the preceding tables are merely recommendations—there are alternatives. Table 4-3 gives the full list of providers included with ASP.NET.

Download at WoweBook.Com

155

156

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

Built-In Providers Some of the built-in ASP.NET services have multiple provider options (see Table 4-3): Table 4-3. Built-In Providers—The Complete List

Service

Available Providers

Membership

Ouopai*Sa^*Oa_qnepu*OmhIai^anodelLnkre`an Ouopai*Sa^*Oa_qnepu*=_pera@ena_pknuIai^anodelLnkre`an Ouopai*Sa^*Oa_qnepu*OmhNkhaLnkre`an

Roles

Ouopai*Sa^*Oa_qnepu*=qpdknev]pekjOpknaNkhaLnkre`an 

Ouopai*Sa^*Oa_qnepu*Sej`ksoPkgajNkhaLnkre`an

Site Map

Ouopai*Sa^*TihOepai]lLnkre`an

Profile

Ouopai*Sa^*Lnkbeha*OmhLnkbehaLnkre`an

Session State

Ouopai*Sa^*OaooekjOp]pa*EjLnk_OaooekjOp]paOpkna Ouopai*Sa^*OaooekjOp]pa*KqpKbLnk_OaooekjOp]paOpkna Ouopai*Sa^*OaooekjOp]pa*OmhOaooekjOp]paOpkna

Web Parts

Ouopai*Sa^*QE*Sa^?kjpnkho*Sa^l]npo*OmhLanokj]hev]pekjLnkre`an

Protected Configuration

Ouopai*?kjbecqn]pekj*NO=Lnkpa_pa`?kjbecqn]pekjLnkre`an Ouopai*?kjbecqn]pekj*@L=LELnkpa_pa`?kjbecqn]pekjLnkre`an

)FNONEOFTHEPROVIDERSAVAILABLEFORASPECIFICSERVICEFITYOURNEEDS YOUMIGHTCONSIDERWRITing your own provider. There are two ways to accomplish this:

s %XTENDANEXISTINGPROVIDERINORDERTOCHANGEITSBEHAVIORSLIGHTLY



s 7RITEYOUROWNPROVIDERONTOPOFTHEPROVIDERSBASECLASS

As you can imagine, extending an existing provider is the easier option. Whenever you keep the EXISTINGDATASTOREBUTWISHTOCHANGETHEBEHAVIOR ITSBETTERTOEXTENDANEXISTINGPROVIDER)FYOU want to use a different data store, it is preferable to write your own provider. Third-party developers might also appear as a source of providers for distinct tasks. The next sections of this chapter will provide the necessary information to build your own.

Extending Built-In Providers Extending the built-in providers is an important feature. Several sections of this book describe extensibility methods based on extending providers. Please refer to related parts in:

s #HAPTER%XTENDINGRESOURCEMANAGEMENTTHROUGHRESOURCEPROVIDERSINTHESECTION “Programming a Custom Resource Provider”



s #HAPTER%XTENDINGPAGEPERSISTENCETHROUGHSESSIONSTATEPROVIDERSINTHESECTIONSh$EVELOPINGA#USTOM0AGE3TATE0ROVIDERvANDh)MPLEMENTINGTHE3ESSION3TATE3TORE0ROVIDERv



s #HAPTER%XTENDINGTHEMEMBERSHIPANDROLEPROVIDERSINTHESECTIONh%XTENDING Membership and Role Providers” and profile provider extensibility features in section h)MPLEMENTINGA#USTOM0ROFILE0ROVIDERv



s #HAPTER%XTENDINGTHESITEMAPPROVIDERINTHESECTIONh7RITINGA#USTOM3ITEMAP Provider”

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

Extensibility for all the providers is supplied by the same base class, as explained in the next section, while the section “Creating a Custom Provider-Based Service” later in this chapter shows the basic techniques for custom provider implementation. Read these first before proceeding with any of the chapters previously mentioned.

The Anatomy of a Provider Both custom and built-in providers inherit from the Lnkre`an>]oa base class. The full definition looks like this: qoejcOuopai7 qoejcOuopai*?khha_pekjo*Ola_e]heva`7 j]iaol]_aOuopai*?kjbecqn]pekj*Lnkre`an w lq^he_]^opn]_p_h]ooLnkre`an>]oa w lnkpa_pa`Lnkre`an>]oa$%7 lq^he_renpq]hopnejc@ao_nelpekjwcap7y lq^he_renpq]hopnejcJ]iawcap7y lq^he_renpq]hrke`Ejepe]heva$opnejcj]ia(J]iaR]hqa?khha_pekj_kjbec%7 y y There is nothing specific to providers here so far. The properties J]ia and @ao_nelpekj are for descriptive purposes only. J]ia is the internal name used in configuration settings, and @ao_nelpekj SUPPORTSGRAPHICALTOOLS)FTHEDESCRIPTIONISNOTSET THEPROPERTYRETURNSTHENAMEINSTEAD4HE name is mandatory within the configuration collection. lq^he_renpq]hopnejc@ao_nelpekj w cap w eb$opnejc*EoJqhhKnAilpu$pdeo*[@ao_nelpekj%% w napqnjpdeo*[@ao_nelpekj7 y napqnjpdeo*J]ia7 y y The only method to put the provider in operation is Ejepe]heva. The _kjbec parameter passes the configuration settings. The j]ia parameter is required because you can name the provider in the configuration file, while the call to Ejepe]heva transfers this name for further reference. As you can see from this code snippet, the base class does not do anything useful. This is what MAKESITHARDTODEVELOPYOUROWNPROVIDERFROMSCRATCH)FYOUWANTTOMODIFYTHEBEHAVIOR ITS much easier to develop one of the existing classes and override the properties or methods that don’t FITYOURNEEDS(OWEVER INTHISCHAPTER)LLEXPLAINHOWTOWRITEACUSTOMPROVIDERFROM scratch.

Download at WoweBook.Com

157

158

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

Making the Provider Available To make thePROVIDERAVAILABLE YOULLNEEDASERVICETHATUSESTHEPROVIDER(OWEVER THEREARENO one-to-one relationships between services and their providers. The provider model exists to enable the substitution of one provider with another. To create a custom provider, you’ll need a custom service and one or more custom providers. The service itself does not have a base class, but it does hold several references to other types discussed in this section:

s 4HECOLLECTIONOFCONFIGUREDPROVIDERS



s 4HEPARTICULARPROVIDERCURRENTLYASSOCIATEDWITHTHESERVICE



s 4HECONFIGURATIONPARAMETERSASSIGNEDTOTHECURRENTPROVIDER



s 4HECODETOINSTANTIATEANDINITIALIZETHEPROVIDER

Somewhere in your application, there will be a consumer of this service. Consider the service from the perspective of this consumer. The consumer code needs the service in order to obtain data or do something useful. The consumer is not concerned with how the service is configured or how it stores or retrieves data. Even the service itself does not care about this, but handles it using a custom definition of the provider. With both of these abstraction tiers, it’s possible to replace the provider without altering anything within either the service or its consumers.

Configuring the Provider A providerSERVESASALAYERBETWEENANUPPER LEVELTIERANDADATATIER)TCANBESIMPLEORCOMplex, but there’s nothing specific to providers except for the Ejepe]heva method. The uniqueness of providers is in the special way you can configure and attach them using the web.config file. This MAKESAPROVIDERACCESSIBLETOTHOSEWHOCONFIGUREANDMAINTAINA7EB3ERVER)NCIDENTALLY THE namespace for the provider’s base class indicates that providers are all about configuration.) All provider configurations follow the following pattern: 8_kjbecqn]pekj: 8ouopai*sa^: 8oanre_aJ]ia: 8lnkre`ano: 8_ha]n+: 8]``j]ia9iuLnkre`an+: 8+lnkre`ano: 8+oanre_aJ]ia: 8+ouopai*sa^: 8+_kjbecqn]pekj: Notice that there is not one provider but a collection of them. Usually there will be only one, but the configuration schema allows you to configure several. The configuration classes, as explained later in the section “Extending the Configuration,” manage the typical pattern in the XML file based on the instructions 8_ha]n+:, 8naikra:, and 8]``:. This is necessary because the web.config files form a hierarchy from machine level down to the specific subfolder in the application. As long as you have permission, you can override the inherited settings, remove one or all entries, and add your own. Since you have to handle a collection of providers even if only one is needed, a collection class is required. As for the provider’s base class, there is a base class for collections, too. j]iaol]_aOuopai*?kjbecqn]pekj*Lnkre`an w lq^he__h]ooLnkre`an?khha_pekj6E?khha_pekj(EAjqian]^ha w lq^he_Lnkre`an?khha_pekj$%7 Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

lq^he_^kkhEoOuj_dnkjeva`wcap7y lq^he_k^fa_pOuj_Nkkpwcap7y lq^he_Lnkre`an>]oapdeoWopnejcj]iaYwcap7y lq^he_renpq]hrke`=``$Lnkre`an>]oalnkre`an%7 lq^he_rke`?kluPk$Lnkre`an>]oaWY]nn]u(ejpej`at%7 lq^he_EAjqian]pknCapAjqian]pkn$%7 lq^he_rke`Naikra$opnejcj]ia%7 lq^he_rke`OapNa]`Kjhu$%7 y y Using the Lnkre`an>]oa type, it’s easy to handle the custom provider as well as any of the default built-in ones using this collection. You can also specify one of the providers to be the default provider. This links the service to a provider in the absence of any other selection criteria. So far, you have a service supplying the consumers, a provider as a late-bound component that hides the details of the data or communication tier, and finally a storage location for a collection of PROVIDERDEFINITIONS(OWEVER THEFORMATOFTHECONFIGURATIONALSOREQUIRESASECTIONDEFINITION Configuration sections are defined at the beginning of the web.config file and extend the conFIGURATIONBYSPECIFYINGWHERETHEACTUALDEFINITIONSARESTORED)NITIALLY )ASSUMEDTHATPROVIDER configurations are stored in the 8_kjbecqn]pekj:8ouopai*sa^: hive. This is the default setting for BUILT INPROVIDERSBUTNOTCOMPULSORYFORCUSTOMPROVIDERS)NFACT YOUCANUSEANYPATHWITHIN the 8_kjbecqn]pekj:TOP LEVELELEMENT)TSGOODPRACTICETOSTAYWITHTHISMODELANDPLACECUSTOM providers there, too. The configuration sections are defined within the 8_kjbecOa_pekjo: element. Beneath this element, you’ll find a hierarchy of 8oa_pekjCnkql: and 8oa_pekj: elements in no particular order. The hierarchy of configuration elements is the exact representation of the sections used below the 8_kjbecqn]pekj: part in the web.config(OWEVER THEDEFAULTweb.config has more sections than the 8_kjbecOa_pekj: section does. The reason is that your current web.config inherits from the global, machine-wide definition. You can find the configuration file that contains all possible section definitions within the following path: !ouopai!XIe_nkokbp*JAPXBn]iaskngXr.*,*1,3.3X?KJBECXi]_deja*_kjbec To add your own configuration section to support a specific location for your custom provider definition, you’ll need to add a section definition. First, a custom section definition class has to be implemented. The following base class is the final step in obtaining a complete definition for custom providers: j]iaol]_aOuopai*?kjbecqn]pekj w lq^he_]^opn]_p_h]oo?kjbecqn]pekjOa_pekj6?kjbecqn]pekjAhaiajp w lnkpa_pa`?kjbecqn]pekjOa_pekj$%7 lq^he_Oa_pekjEjbkni]pekjOa_pekjEjbkni]pekjwcap7y lnkpa_pa`ejpanj]hrenpq]hrke`@aoane]hevaOa_pekj$TihNa]`anna]`an%7 lnkpa_pa`ejpanj]hrenpq]hk^fa_pCapNqjpeiaK^fa_p$%7 lnkpa_pa`ejpanj]hkranne`a^kkhEoIk`ebea`$%7 lnkpa_pa`ejpanj]hkranne`arke`NaoapIk`ebea`$%7 lnkpa_pa`ejpanj]hrenpq]hopnejcOane]hevaOa_pekj$ ?kjbecqn]pekjAhaiajpl]najpAhaiajp( opnejcj]ia( ?kjbecqn]pekjO]raIk`ao]raIk`a%7 y y Download at WoweBook.Com

159

160

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

From this declaration, you can see that ?kjbecqn]pekjOa_pekj in turn inherits from the ?kjbecqn]pekjAhaiajp class. This is the reason why you can mix 8oa_pekjCnkql: and 8oa_pekj: elements easily. The class contains several implemented methods and others that you must override to obtain the required behavior. The Oane]hev]pekjOa_pekj and @aoane]hev]pekjOa_pekj methods convert the settings to and from XML.

General Considerations All providers have certain characteristics in common. The base class, as already explained, forces few typical usage scenarios only. You should know some of the best practices for creating providers that fit well into the framework under all circumstances.

Initialization Procedure of a Provider All providers derive from Lnkre`an>]oa. Therefore, they inherit the Ejepe]heva method, which is declared renpq]h)N# THISINDICATESAMETHODTHATYOUNEEDTOOVERRIDE$OINGSOTRANSFERSAFEW critical tasks over to you. Most providers need specific permissions to run. Requesting permissions is the way you let the runtime know what your code needs to be allowed to do. This is required by access to a SQL database or local file system, for instance. The best way to implement permission checks is to add the appropriate attributes from the Ouopai*Oa_qnepu*LanieooekjoNAMESPACE)MAGINETHATAPROVIDER ISAPLUGGABLEMODULETHATOTHERSMAYREUSE EVENIFITDOESNOTOPERATEWELL)NSTEADOFEVENTUALLY FAILINGINCUSTOMCODE THEINITIALIZATIONPROCEDURESHOULDIMMEDIATELYREPORTANEXCEPTIONINDICATing what went wrong. This is precisely the purpose of such permission attributes. Next, the _kjbec parameter passed to the Ejepe]hevaMETHODISIMPORTANT)FITISNULL ITMEANS THATSOMETHINGWENTWRONGWITHINTHECONFIGURATION)NTHATCASE THROWAN=ncqiajpJqhhAt_alpekj, even if there are no configuration parameters required. The error indicates an unexpected condition and must be reported to the calling method. The base class’s Ejepe]heva methodISNOTABSTRACT)TCONTAINSCODEANDMUSTBECALLEDTO ensure that basic requirements are met. As shown in the last section, the code validates the name and description settings. Even if you intend to change this, and you replace the name and descripTIONVALUESINYOURCODE CALLTHEBASEMETHOD)FAFUTUREVERSIONOFTHE.%4FRAMEWORKADDSCODE here to ensure required functionality, then failing to call the base class could break your provider. 2EADINGTHECONFIGURATIONISANIMPORTANTPART(OWEVER TEXTUALDEFINITIONS EVENIFMADEIN XML, can be error-prone. Use the J]iaR]hqa?khha_pekj class and its indexer to access the configuRATIONVALUES)FAREQUIREDPARAMETERISMISSING THROWALnkre`anAt_alpekj. Make sure you call Naikra each time you read a parameter. That clears the _kjbec objects one by one. After all required parameters are processed, nothing should be left in the _kjbecOBJECT)F_kjbec*?kqjp:, is still pnqa, throw a Lnkre`anAt_alpekj. This ensures that you have all the required parameters and that the user has no other elements in the configuration that can’t be processed. You might wonder why you can’t just ignore these values. This is because the user’s intention was probably not to add priVATEVALUESTOSTOREADDITIONALINFORMATIONTHERE(EORSHEHASPROBABLYMISTYPEDANATTRIBUTE4HE EXCEPTIONHELPSTORECOGNIZETHESETYPOSINSTEADOFSEARCHINGFORTHEERRORINEVENTLOGS There are also best practices regarding provider code. First, the service and the provider are two different things. Even if you develop them together in one project, with nothing else in mind, they should stay independent. Second, never call a method of the service from the provider. This could lead to infinite, recursive loops, or a break in modularity. Exchanging the provider would be impossible because it is tightly bound to the service.

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

Lifetime Providers are loaded dynamically the first time the service requires them. This ensures that PROVIDERSARENOTHELDINMEMORYWHENTHEYARENOTNEEDED(OWEVER LOADINGACOMPLEXPROVIDER could be a time-consuming task—clearly not desirable when you’re trying to improve the responsiveness of a site. You can force the provider to load by calling certain methods of the services in the =llhe_]pekj[Op]np event. This assumes that the provider has a lifetime equaling the lifetime of the application and that the provider has a global state. A provider should not depend on the current session or the context. (OWEVER Dppl?kjpatp and all subsequent classes can be used at any point to retrieve data. This MAKESITSAFETOUSEPRIVATEFIELDSTOSTOREVALUES)TSAVESMEMORYANDSPEEDSUPTHEPROVIDER(OWever, you must remember to write thread-safe code.

Thread Safety Threads in ASP.NET are explained in depth in Chapter 2. Web applications are multi-user applications—as with mainframe computer software, you can consider web applications as massively parallel applications. Consequently, when dealing with providers, you must handle threads with care. Providers are instantiated only once and shared across all requests. This speeds them up and causes them to consume less memory, which is necessary for basic tasks. Since threads run in parallel—that’s what threads are for—one provider might be called at the same time by multiple threads. This means that you must always code a provider to be thread-safe. Otherwise, you risk throwing exceptions or creating garbage on any request. There are subtle differences that might appear under heavy workload only. The only exception is the Ejepe]heva method. Since it’s only called once, thread safety isn’t an ISSUE!SLONGASTHESERVICEINITIALIZESIN=llhe_]pekj[Op]np THISISALWAYSTRUE)FYOUCANNOTBESURE of this, the code that calls the method in the service has to be locked, as shown in the following code snippet: eb$[lnkre`an99jqhh% w hk_g$[hk_g% w eb$[lnkre`an99jqhh% w This ensures that the provider is not loaded twice. The hk_g statement blocks other threads. (OWEVER ANOTHERTHREADMIGHTHAVEPASSEDTHELOCKANDALREADYBERUNNINGINSIDETHEMETHOD That’s why you must check the existence of the provider again after getting the lock. For property access, a similar technique is appropriate. Usually, you write your properties like this: lner]paQjep[oeva7 lq^he_QjepOeva w capwnapqnj[oeva7y oapw[oeva9r]hqa7y y

Download at WoweBook.Com

161

162

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

)MAGINETHATTWOTHREADSACCESSTHISMETHOD4HEREISONLYONEINSTANCEOFTHISCLASSINTHE MEMORY ANDHENCEONESTORAGEMEMORYPLACE FORTHEVALUE)FONETHREADWRITESTHEVALUEAND the other reads the value at the same time, you’ll receive an incorrect value back. The hk_g statementISAGAINTHESOLUTION)TSASHORTCUTTOTHEOuopai*Pdna]`ejc*Ikjepkn class of the framework the compiler creates for us. The code should look like the following snippet: lner]paQjep[oeva7 lner]pak^fa_p[ouj_d lq^he_QjepOeva w capwhk_g$[ouj_d%wnapqnj[oeva7yy oapwhk_g$[ouj_d%w[oeva9r]hqa7yy y The Ikjepkn methodISAVERYBASICLOCK)TBLOCKSALLTHREADS EVENIFTHEYAREBEINGACCESSEDFOR reading only. This could slow down an application under heavy load. 4HEREARESEVERALOTHERWAYSTOOPTIMIZETHEBEHAVIOR4HENa]`anSnepanHk_g class improves behavior by allowing shared reads but preventing overlapping write and read access to the property. This improves performance if the values are mostly read rather than written. Another method uses the Ouopai*Nqjpeia*?kilehanOanre_ao*Iapdk`Eilh=ppne^qpa. See the following code for a usage scenario: lner]paQjep[oeva7 WIapdk`Eilh$Iapdk`EilhKlpekjo*Ouj_dnkjeva`%Y lq^he_QjepCapOeva$% w napqnj[oeva7 y WIapdk`Eilh$Iapdk`EilhKlpekjo*Ouj_dnkjeva`%Y lq^he_rke`OapOeva$Qjepoeva% w [oeva9oeva7 y (OWEVER THISREPLACESPROPERTIESWITHMETHODS WHICHISNTTHEBESTCODINGSTYLE4HELOCKING experience isn’t any better. The compiler also uses the Ikjepkn method. As you can see from the code snippet, there is no object for storing the locking state. The compiler selects an object at the best level, like hk_g$pdeo%. This could be an object on either the type or application level, which is a higher level than within the method. Usually this means that the locking phase is enduring, and this causes the threads to last longer. Unless locking on type level is required, this attribute is not appropriate for providers. Which method is best will depend on the specific conditions. Generally, you have to ensure THREAD SAFEACCESSTOALLINSTANCEDATA INCLUDINGPRIVATEFIELDS(OWEVER WHENYOUWRITECONfiguration data in the Ejepe]heva method (thread-safe because it’s only called once) and provide read-only access, no action is required to ensure thread safety. The cap statement of the property shown in the last code snippets might omit the lock statement, then. Calls to access all stack-based data and local variables within a property or method should not be locked.

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

Creating a Custom Provider-Based Service )MAGESARE an essential part of almost all web applications. Powerful image management makes YOURLIFEANDYOURUSERSLIVESEASIER)MAGINETHATYOURFINALSTORAGESOLUTIONISNTCLEARLYDEFINED SO you want to create a flexible and extensible image management solution. Other developers in your ORGANIZATIONSHOULDBEABLETOADOPTYOURCODEANDREPLACEPARTSOFITTOSUITTHEIRNEEDSWITHOUT KNOWINGTHEINTERNALDETAILSOFTHEIMAGECREATIONANDDELIVERYPROCESS)NSUCHASITUATION YOU could consider a custom provider-based service. Again, the multi-tier model points to a solution: 1. You need to create a service that is able to retrieve and send image data. 2. You need a provider interface that makes data storage access replaceable. 3. You need a specific provider to put it into operation. 4. You need a configuration definition to handle the configuration in web.config. Following the model of the provider as previously described in the section “The Anatomy of a Provider,” you should create these classes:

s !NIMPLEMENTATIONOFACONFIGURATIONSECTIONDEFINITIONCLASS



s !NABSTRACTBASECLASSTHATDESCRIBESTHEPROVIDER



s !NIMPLEMENTATIONOFTHISBASECLASSTHATCREATESTHEPROVIDERTHATSERVESASACONCRETE implementation against data storage



s !CLASSTHATIMPLEMENTSTHESERVICETODOANYTHINGUSEFULUSINGTHEPROVIDER



s !PROVIDERCOLLECTIONCLASSTHATSTORESMULTIPLEPROVIDERS

!DDITIONALLY DATASTORAGEMUSTBEPROVIDED"ECAUSEITSCOMMONTOUSE31,3ERVER )LLCREATE the image service’s default provider using a SQL Server database. You can build such a solution from the bottom up, beginning with the configuration, followed by the provider and finally the service. This is fine if you have a design and planning phase in your PROJECTANDCLEARLYDEFINEDREQUIREMENTS(OWEVER FORLEARNINGPURPOSES YOULLCREATEAPROVIDER from the top down and start with the last step—the service. This clarifies the purpose of the provider and makes the next steps easier to understand.

Limitations of the Code Samples Depending on real-life requirements, creating a provider-based solution might require a little more effort. Remember that, for the sake of clarity, all the code snippets here lack error handling, UNITTESTING ANDLOGGINGFEATURES)NADDITION NOCODESNIPPETSHEREFEATURELOCALIZATION4HEBEST PRACTICEISTOSTORERESOURCESINRESOURCEFILESANDTOLOCALIZEIFTHEAPPLICATIONISUSEDINMULTIPLE countries. See Chapter 5 for more information about resources. #ERTAINSAMPLES LIKEINTHESECTIONh)MPLEMENTINGAN%XPRESSION"UILDERWITH$ESIGN 4IME3UPPORTvINTHISCHAPTER ACCESSDATABASES)FYOUAREWRITINGMORESOPHISTICATEDPROVIDERS YOUMAYHAVE multiple database operations for one action. When the database supports transactions, use transactions to ensure the atomicity of updates. Transactions ensure a rollback if one of the database operations fails. )FTHEDATABASEDOESNOTINHERENTLYSUPPORTTRANSACTIONS YOUMUSTENSURETHEATOMICITYWITHINYOUROWN code. Add pnu/_]p_d blocks and check conditions to the code shown here. Some sample code regarding providers in this and all remaining chapters shows only one part of the provider to explain specific techniques. Any methods or properties that are not implemented HAVEBEENOMITTEDFORTHESAKEOFCLARITYANDSIMPLICITY(OWEVER FORPRODUCTIONCODEYOUSHOULD add a JkpEilhaiajpa`At_alpekj to redundant methods. This verifies that users of the provider only IMPLEMENTTHEFEATURESYOUINTENDED)FCOMPLETENESSISNOTREQUIRED DONTFORGETTOEXPLAINTHISIN the documentation as well. Download at WoweBook.Com

163

164

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

Creating a Service The purpose of the sample service is to retrieve an image via the NapnearaEi]ca method. All the other service properties and methods are required to set up the provider. The provider allows other developers using the service to replace the default provider with their own version. For instance, you could choose to use the file system on a file server to store images instead of the database. No change would be required in the application or the service implementation. Let’s take a look at the class itself, as shown in Listing 4-1. Listing 4-1. The Service Itself Is Able to Retrieve an Image qoejcOuopai*Sa^*?kjbecqn]pekj7 qoejcOuopai*?kjbecqn]pekj7 qoejcOuopai*?kjbecqn]pekj*Lnkre`an7 qoejcOuopai*@n]sejc7 j]iaol]_a=lnaoo*Atpajoe^ehepu*?qopkiLnkre`an w lq^he__h]ooEi]caOanre_a w lner]paop]pe_Ei]caLnkre`an[lnkre`an9jqhh7 lner]paop]pe_Ei]caLnkre`an?khha_pekj[lnkre`ano9jqhh7 lner]paop]pe_k^fa_p[hk_g9jask^fa_p$%7 lq^he_Ei]caLnkre`anLnkre`an w capwnapqnj[lnkre`an7y y lq^he_Ei]caLnkre`an?khha_pekjLnkre`ano w capwnapqnj[lnkre`ano7y y lq^he_op]pe_Ei]caNapnearaEi]ca$ejpei]caE@% w Hk]`Lnkre`ano$%7 napqnj[lnkre`an*NapnearaEi]ca$ei]caE@%7 y lner]paop]pe_rke`Hk]`Lnkre`ano$% w eb$[lnkre`an99jqhh% w hk_g$[hk_g% w eb$[lnkre`an99jqhh% w k^fa_pWY]ppne^qpao9± pulakb$Ei]caLnkre`anOa_pekj%*Cap?qopki=ppne^qpao$± pulakb$Oa_pekj=ppne^qpa%(b]hoa%7 eb$]ppne^qpao*Hajcpd9-% pdnksjas?kjbecqn]pekjAt_alpekj$Oa_pekj=ppne^qpajkpoap%7 Oa_pekj=ppne^qpao]9$Oa_pekj=ppne^qpa%]ppne^qpaoW,Y7 Ei]caLnkre`anOa_pekjoa_pekj9± $Ei]caLnkre`anOa_pekj%± Sa^?kjbecqn]pekjI]j]can*CapOa_pekj$o]*Oa_pekjJ]ia%7 Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

[lnkre`ano9jasEi]caLnkre`an?khha_pekj$%7 Lnkre`anoDahlan*Ejop]jpe]paLnkre`ano$oa_pekj*Lnkre`ano(± [lnkre`ano(± pulakb$Ei]caLnkre`an%%7 [lnkre`an9[lnkre`anoWoa_pekj*@ab]qhpLnkre`anY7 eb$[lnkre`an99jqhh% pdnksjasLnkre`anAt_alpekj$Qj]^hapkhk]``ab]qhpEi]caLnkre`an%7 y y y y y y The NapnearaEi]ca method is static, because you don’t need to handle multiple instances of the service. Although the configuration allows multiple providers, only one can act as the current proVIDER4HEOTHERPARTSOFTHECODEINTERACTWITHTHISCURRENTPROVIDER)NTHISAPPLICATION THESERVICE class is created once and starts working when the Hk]`Lnkre`ano method is called. Each method launches with a call to the Hk]`Lnkre`ano method to ensure that a provider is present when retrieving data. Loading the provider is a one-time operation. To avoid claiming the lock if providers are already loaded, the first action is checking the _provider variable. After claiming the lock, this test is made again to ensure the provider is still not loaded. This is required, as parallel running requests might invoke the service and start a duplicate procedure. Changing the _provider variable afterwards could change the conditions, and you’re supposed to recheck the state again. )NTHENEXTSTEP THENAMEOFTHESECTIONISRETRIEVEDBYREADINGAPRIVATEATTRIBUTE4HEREARE several ways to do this. Using an attribute allows a single location definition. The section configuration, which provides the necessary information, is the only class where the definition is used. Using data from the Oa_pekj=ppne^qpa attribute, it’s possible to get a reference to the 8ei]caOanre_a: section you use to define the current provider. Then the code loads all the registered providers and points _provider to the default provider to make it the current one. Lnkre`anDahlan is a static class in the Ouopai*Sa^*?kjbecqn]pekj namespace that simplifies the process. )FANYTHINGGOESWRONG ANEXCEPTIONISRAISEDTOINFORMTHECALLINGCODE)FEVERYTHINGISFINE the Ei]caOanre_a class will be ready to serve images.

Creating the Provider The provider consists of two classes. One is an abstract base class that extends the Lnkre`an>]oa class with the required additional methods. The other is the implementation of that class. Again, this provider is just one implementation to bring the whole solution into operation. Other developers could replace this provider with their own creation and extend the behavior of the service at will (Listing 4-2). Listing 4-2. Base Class for the Provider qoejcOuopai*?kjbecqn]pekj*Lnkre`an7 qoejcOuopai*@n]sejc7 j]iaol]_a=lnaoo*Atpajoe^ehepu*?qopkiLnkre`an w lq^he_]^opn]_p_h]ooEi]caLnkre`an6Lnkre`an>]oa w lq^he_]^opn]_popnejc=llhe_]pekjJ]iawcap7oap7y lq^he_]^opn]_pEi]caNapnearaEi]ca$ejpe`%7 y y Download at WoweBook.Com

165

166

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

4HISCLASSHASTWOCHARACTERISTICS)TMUSTINHERITTHELnkre`an>]oaINORDERTOBERECOGNIZEDAS APROVIDERINOTHERPARTSOFTHEAPPLICATION)TMUSTALSODEFINETHEMETHODSTHATSERVETHESERVICE)N this case, NapnearaEi]ca is such a method. The service knows that it can call this method to get an image, and the provider completes the process. Now the implementation is required. Since you want to pull the images from a database, some preparation are needed. Assuming you have local database, aspnetdb, with integrated security, add the table shown in Figure 4-2.

Figure 4-2. The table that stores the images (see Listing 4-2 for corresponding T-SQL script) )NTERNALLY YOUUSE,).1TO31,TORETRIEVETHEIMAGEINFORMATIONFROMTHESPECIFIEDTABLE4HE TABLEDOESNOTACTUALLYCONTAINTHEIMAGES)TCONTAINSPATHSTOTHEIMAGEFOLDERSANDALLOWSFURTHER management of the relationship between resources requesting the images. The data storage method LEADSTOTHEFIRSTREQUIREMENTOFTHEPROVIDERITMUSTSTOREACONNECTIONSTRING)TSAGOODIDEATO use the predefined 8_kjja_pekjOpnejc: section in web.config and only handle the name that references it. Next, look into the provider code (see Listing 4-3). Listing 4-3. Implementation of the Provider qoejcOuopai7 qoejcOuopai*?khha_pekjo*Ola_e]heva`7 qoejcOuopai*?kjbecqn]pekj*Lnkre`an7 qoejcOuopai*@]p]*Omh?heajp7 qoejcOuopai*@n]sejc7 qoejcOuopai*Hejm7 qoejcOuopai*Oa_qnepu*Lanieooekjo7 qoejcOuopai*Sa^7 qoejcOuopai*Sa^*?kjbecqn]pekj7 j]iaol]_a=lnaoo*Atpajoe^ehepu*?qopkiLnkre`an w WOmh?heajpLanieooekj$Oa_qnepu=_pekj*@ai]j`(Qjnaopne_pa`9pnqa%Y lq^he__h]ooOmhEi]caLnkre`an6Ei]caLnkre`an w lq^he_kranne`aopnejc=llhe_]pekjJ]ia w cap7 oap7 y lq^he_opnejc?kjja_pekjOpnejc Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

w cap7 oap7 y lq^he_kranne`arke`Ejepe]heva$opnejcj]ia(J]iaR]hqa?khha_pekj_kjbec% w eb$_kjbec99jqhh% pdnksjas=ncqiajpJqhhAt_alpekj$_kjbec%7 eb$Opnejc*EoJqhhKnAilpu$j]ia%% j]ia9OmhEi]caLnkre`an7 eb$opnejc*EoJqhhKnAilpu$_kjbecW`ao_nelpekjY%% w _kjbec*Naikra$`ao_nelpekj%7 _kjbec*=``$`ao_nelpekj( OMHei]calnkre`an%7 y ^]oa*Ejepe]heva$j]ia(_kjbec%7 =llhe_]pekjJ]ia9_kjbecW]llhe_]pekjJ]iaY7 eb$opnejc*EoJqhhKnAilpu$=llhe_]pekjJ]ia%% =llhe_]pekjJ]ia9+7 _kjbec*Naikra$]llhe_]pekjJ]ia%7 opnejc_kjja_p9_kjbecW_kjja_pekjOpnejcJ]iaY7 eb$Opnejc*EoJqhhKnAilpu$_kjja_p%% pdnksjasLnkre`anAt_alpekj $Ailpuknieooejc_kjja_pekjOpnejcJ]ia%7 _kjbec*Naikra$_kjja_pekjOpnejcJ]ia%7 eb$Sa^?kjbecqn]pekjI]j]can*?kjja_pekjOpnejcoW_kjja_pY99jqhh% pdnksjasLnkre`anAt_alpekj$Ieooejc_kjja_pekjOpnejcJ]ia%7 ?kjja_pekjOpnejc9Sa^?kjbecqn]pekjI]j]can*± ?kjja_pekjOpnejcoW_kjja_pY*?kjja_pekjOpnejc7 eb$Opnejc*EoJqhhKnAilpu$?kjja_pekjOpnejc%% pdnksjasLnkre`anAt_alpekj$Ailpu_kjja_pekjopnejc%7 eb$_kjbec*?kqjp:,% w opnejc]ppn9_kjbec*=hhGauo*Benop$%7 eb$Opnejc*EoJqhhKnAilpu$]ppn%% pdnksjasLnkre`anAt_alpekj $Qjna_kcjeva`]ppne^qpa6']ppn%7 y y lq^he_kranne`aEi]caNapnearaEi]ca$ejpe`% w Ei]ca@]p]@]p]?kjpatp_pt9jas± Ei]ca@]p]@]p]?kjpatp$?kjja_pekjOpnejc%7 r]nmn9bnkieej_pt*]oljap[?kjbecqn]pekjo sdanae*_bc[_]packnu99Ei]caLnkre`an± ""e*_bc[e`99e`± ""e*_bc[pula99ei]ca oaha_pe*_bc[_kjpajp7 opnejc`]p]9mn*BenopKn@ab]qhp8opnejc:$%7 Ei]caeic9Ei]ca*BnkiBeha$Dppl?kjpatp*?qnnajp*Oanran*I]lL]pd$`]p]%%7 napqnjeic7 y y y Download at WoweBook.Com

167

168

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

The life of a provider begins with the call to its Ejepe]heva method. The first step is to verify that _kjbec is not jqhh)FSO ANEXCEPTIONISTHROWN2EMEMBERTHATCONFIGURATIONISESSENTIALFORTHE provider model. As other parts of the configuration might reference the provider, it needs a name. !SSIGNTHEPROVIDERADEFAULTNAMEIFITDOESNTHAVEONE)NTHEEXAMPLE ITSCALLEDh3QL)MAGE0ROVIDERv)TSTHESAMEFORTHEDESCRIPTION%VENIFTHEDESCRIPTIONISOPTIONAL ITSHOULDBESETPROPERLY 3EVERALGRAPHICALTOOLSMIGHTREFERTOTHEDESCRIPTION)FTHEATTRIBUTEhDESCRIPTIONvDOESNTEXIST THE code creates one. Next, the base class’s Ejepe]heva method is called. The provider retrieves the ]llhe_]pekjJ]ia and _kjja_pekjOpnejcJ]iaATTRIBUTESFROMTHECONFIGURATIONFILE)FTHE]llhe_]pekjJ]ia doesn’t exist, assume it is the root application “/”. The connection string is mandatory, and the lack of it throws an exception. Now, the provider instance should have all the information required to operate. The code checks for the remaining configuration attributes. As explained in the best practice section “General Considerations,” the check—eb$_kjbec*?kqjp:,%ˆENSURESTHATUNRECOGNIZED attributes are reported to the user in order to avoid typos. Next, the NapnearaEi]ca method must be implemented. The Ei]ca@]p]@]p]?kjpatp is a class CREATEDWITHTHE,).1TO31,WIZARD4OCREATETHISCLASS FOLLOWTHESESTEPS 1. )N6ISUAL3TUDIO CHOOSEAdd ° New Item in the context menu of the solution. 2. )NTHESECTIONData of the Add New Item dialog choose LINQ to SQL Classes item. 3. Give the item a common name, such as ImageData.dbml (see Figure 4-3).

Figure 4-3. Add a LINQ to SQL item to the provider project. #LOSETHEDIALOGANDANEMPTYDESIGNERSURFACEWILLAPPEAR/PENTHE3ERVER%XPLORER6IEW° Server Explorer, or press Ctrl+Alt+S instead) and add a connection to your database. Either it will already be present or you’ll have to add the database and the appropriate tables. The full script for the table is shown in Listing 4-4. Listing 4-4. SQL Table Definition for the Provider Project ?NA=PAP=>HAW`^kY*W]oljap[?kjbecqn]pekjY$ W_bc[e`YWejpYE@AJPEPU$-(-%JKPJQHH( W_bc[gauYWr]n_d]nY$1,%JKPJQHH( W_bc[_]packnuYWr]n_d]nY$1,%JKPJQHH( Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

W_bc[pulaYWr]n_d]nY$-,%JKPJQHH( W_bc[_kjpajpYWr]n_d]nY$i]t%JQHH( ?KJOPN=EJPWLG[]oljap[?kjbecqn]pekjYLNEI=NUGAU?HQOPANA@ $ W_bc[e`Y=O? %SEPD$L=@[EJ@AT9KBB(± OP=PEOPE?O[JKNA?KILQPA9KBB(± ECJKNA[@QL[GAU9KBB(± =HHKS[NKS[HK?GO9KJ(± =HHKS[L=CA[HK?GO9KJ %KJWLNEI=NUY This is just a simple example of a storage method. Real-life projects tend to be more sophisticated. Once the table exists, and the Server Explorer shows the server, you can add a connection. Choose the icon Data Connections and Add Connection from the context menu; then, in the followINGDIALOG CHOOSETHESERVER)FYOUUSEALOCAL31,%XPRESS%DITION THENAMEMIGHTLOOKLIKEh SQLEXPRESS”. Select the database where you have created the table. Test the connection and close the dialog to add the connection, as shown in Figure 4-4.

Figure 4-4. Adding a connection to the current project Download at WoweBook.Com

169

170

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

9OUCANNOWDRAGANDDROPTHETABLEONTOTHEDESIGNERSURFACEOFTHE,).1TO31,CLASS The result should look like the image already shown in Figure 4-2. Based on the class’s name, THEDESIGNERWILLCREATEACONTEXTFILE)FTHENAMEISImageData, the data context is called ImageDataDataContext (DataContext is the suffix). The context contains a property called ]oljap[ ?kjbecqn]pekjo WHICHREPRESENTSTHETABLE)FYOUHAVENAMEDTHETABLEDIFFERENTLY THEPROPERTY WILLHAVETHATNAME5SINGTHECONTEXT YOUCANUSESIMPLE,).1STATEMENTSTOQUERYTHEDATABASE as shown in the NapnearaEi]ca method. )NTHEEXAMPLE THEIMAGEISRETRIEVEDBASEDONITS)D THECATEGORYh)MAGE0ROVIDER vANDTHE type “image.” This is only a suggestion. Based on the retrieved name, the Oanran*I]lL]pd method is used to obtain the full path to the image. The Ei]ca*BnkiBeha creates the image in memory for further processing. )MAGINEANOTHERPROVIDERTHATSIMPLYTAKESTHEIMAGEANDCREATESATHUMBNAILOFIT)N a derived class, you could override the NapnearaEi]ca method, call the base class, get the image, and manipulate it to create a thumbnail. The configuration is already able to change the provider. This shows once more the power of the provider architecture.

Configuring Providers The next step is to implement the configuration support. Because many providers can serve a single service, a collection is appropriate. Listing 4-5 shows a simple implementation based on the abstract base class, Lnkre`an?khha_pekj. Listing 4-5. Provider Collections Represent All Configured Providers qoejcOuopai7 qoejcOuopai*?kjbecqn]pekj*Lnkre`an7 j]iaol]_a=lnaoo*Atpajoe^ehepu*?qopkiLnkre`an w lq^he__h]ooEi]caLnkre`an?khha_pekj6Lnkre`an?khha_pekj w lq^he_Ei]caLnkre`anpdeoWopnejcj]iaY w cap w napqnj^]oaWj]iaY]oEi]caLnkre`an7 y y lq^he_kranne`arke`=``$Lnkre`an>]oalnkre`an% w eb$lnkre`an99jqhh% pdnksjas=ncqiajpJqhhAt_alpekj$lnkre`an%7 eb$$lnkre`aneoEi]caLnkre`an%% pdnksjas=ncqiajpAt_alpekj $Ejr]he`lnkre`anpula(lnkre`an%7 ^]oa*=``$lnkre`an%7 y y y

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

There are only two features. You can add providers of the Ei]caLnkre`an type and retrieve them using an indexer. The base class handles all the other features. The method and property previously shown ensure the integrity of the base class type. This means that you won’t be able to add a provider to the configuration section that does not serve the service. The last step required in order to operate the service is to define the configuration section, as SHOWNIN,ISTING  Listing 4-6. The Configuration Section and the Supporting Custom Attribute qoejcOuopai7 qoejcOuopai*?kjbecqn]pekj7 j]iaol]_a=lnaoo*Atpajoe^ehepu*?qopkiLnkre`an w W=ppne^qpaQo]ca$=ppne^qpaP]ncapo*?h]oo%Y lq^he__h]ooOa_pekj=ppne^qpa6=ppne^qpa w lq^he_Oa_pekj=ppne^qpa$opnejcoa_pekjJ]ia% 6^]oa$% w Oa_pekjJ]ia9oa_pekjJ]ia7 y lq^he_opnejcOa_pekjJ]ia w cap7 oap7 y y WOa_pekj$ouopai*sa^+ei]caOanre_a%Y lq^he__h]ooEi]caLnkre`anOa_pekj6?kjbecqn]pekjOa_pekj w W?kjbecqn]pekjLnklanpu$lnkre`ano%Y lq^he_Lnkre`anOappejco?khha_pekjLnkre`ano w capwnapqnj$Lnkre`anOappejco?khha_pekj%^]oaWlnkre`anoY7y y WOpnejcR]he`]pkn$IejHajcpd9-%Y W?kjbecqn]pekjLnklanpu$`ab]qhpLnkre`an(± @ab]qhpR]hqa9OmhEi]caLnkre`an%Y lq^he_opnejc@ab]qhpLnkre`an w capwnapqnj$opnejc%^]oaW`ab]qhpLnkre`anY7y oapw^]oaW`ab]qhpLnkre`anY9r]hqa7y y y y

Download at WoweBook.Com

171

172

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

As suggested before, a custom attribute helps to get a single location definition of the configuration path—like “system.web/imageService” in this example. The custom Oa_pekj=ppne^qpa attributeDOESNOTINVOLVEANYTHINGSPECIAL)TISUSEDTODECORATETHEEi]caLnkre`anOa_pekj class, which contains two properties, a collection of providers, and the name of the default provider. This results in configuration code that could look like this: 8ouopai*sa^: 8ei]caOanre_a`ab]qhpLnkre`an9: 8lnkre`ano: 8_ha]n+: 8]``***+: 8+lnkre`ano: 8+ei]caoanre_a: 8+ouopai*sa^: The ?kjbecqn]pekjLnklanpu attribute declares the elements in the web.config file. Although it follows the pattern of all provider-based definitions in the configuration, you’re free to choose difFERENTDEFINITIONS(OWEVER THEBESTPRACTICEISTOFOLLOWTHISPATTERN This is all you need to know in order to write your own provider configuration sections.

Using the Service This serviceCANBEUSEDBYANYCODEINTHEAPPLICATION)N#HAPTER YOUSAWHOWTOUSEHANDLERS to manage images. Let’s create a handler which uses our ImageService. Start with a simple *]olt page that uses a handler, as shown in Listing 4-7. Listing 4-7. A Simple Page That Calls the Handler 8!<L]caH]jcq]ca9?=qpkArajpSenaql9pnqa± ?k`aBeha9@ab]qhp*]olt*_oEjdanepo9[@ab]qhp!: 8@K?PULAdpihLQ>HE?)++S/?++@P@TDPIH-*,Pn]joepekj]h++AJ± dppl6++sss*s/*knc+PN+tdpih-+@P@+tdpih-)pn]joepekj]h*`p`: 8dpihtihjo9dppl6++sss*s/*knc+-555+tdpih: 8da]`nqj]p9oanran: 8pepha:8+pepha: 8+da]`: 8^k`u: 8bknie`9bkni-nqj]p9oanran: 8`er: 8]ol6Ei]canqj]p9oanranE@9Ei]ca.Ei]caQnh9z+Ei]caD]j`han*]odt;e`90+: 8^n+: 8]ol6Ei]canqj]p9oanranE@9Ei]ca-Ei]caQnh9z+Ei]caD]j`han*]odt;e`95+: 8+`er: 8+bkni: 8+^k`u: 8+dpih: The ImageHandler.ashxFILEISAGENERICHANDLERTHATDOESNTNEEDTOBEASSIGNEDIN))34HE parameter e`CORRESPONDSTOTHE)DCOLUMNINTHEIMAGERESOURCETABLE4HISISASIMPLIFIEDSCENARIO)NREAL LIFEAPPLICATIONS ITWOULDBEBETTERTOUSEREADABLESTRINGSTODEFINETHERESOURCES (OWEVER FORLEARNINGPURPOSES THESECODESNIPPETSAREASSHORTANDEASYASPOSSIBLE The handler calls the service’s static method to retrieve the image and adds the Ei]ca object to the output stream (see Listing 4-8).

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

Listing 4-8. The Image Handler That Uses the Configurable Service 8!<Sa^D]j`hanH]jcq]ca9??h]oo9Ei]caD]j`han!: qoejcOuopai7 qoejcOuopai*Sa^7 qoejcOuopai*@n]sejc7 qoejcOuopai*@n]sejc*Ei]cejc7 qoejc=lnaoo*Atpajoe^ehepu*?qopkiLnkre`an7 lq^he__h]ooEi]caD]j`han6EDpplD]j`han w lq^he_rke`Lnk_aooNamqaop$Dppl?kjpatp_kjpatp% w ejpe`7 eb$_kjpatp*Namqaop*MqanuOpnejcWe`Y9jqhh% w eb$Ejp/.*PnuL]noa$_kjpatp*Namqaop*MqanuOpnejcWe`Y(kqpe`%% w Ei]caeic9Ei]caOanre_a*NapnearaEi]ca$e`%7 _kjpatp*Naolkjoa*?kjpajpPula9ei]ca+flc7 eic*O]ra$_kjpatp*Naolkjoa*KqplqpOpna]i(Ei]caBkni]p*Flac%7 y y y lq^he_^kkhEoNaqo]^ha w cap w napqnjpnqa7 y y y Within the Lnk_aooNamqaop method, the handler attempts to retrieve the id from the MqanuOpnejcPROPERTY)FTHEIDISPRESENTANDISANUMBER THESERVICECLASSEi]caOanre_a retrieves the image using the NapnearaEi]ca method. Finally, the right content type is set and the image is streamed into the KqplqpOpna]i property using the O]ra method. The last step—the handler—is our target usage scenario. This is why we’ve written the configuration, the service, and the provider. Any developer can use the handler to retrieve images. They only need to know how to use one specific parameter (the image id). They don’t need to know how the image is created. This is part of the service. Moreover, they don’t need to know how the image is stored. This is the role of the provider. These three parts form a multi-tier model:

s 4IERONETHEUSERINTERFACESUPPORTLAYER ISCREATEDBYTHEHANDLER



s 4IERTWOTHEBUSINESSLOGIC ISCONTAINEDINTHESERVICE



s 4IERTHREETHEDATASTORAGE ISHANDLEDBYTHEPROVIDER

The provider model is a distinct way of creating a multi-tier architecture within your appliCATION)TMAKESTHEAPPLICATIONFLEXIBLEANDEXTENSIBLE ANDITSIMPLIFIESTHEWRITINGOFUNITTESTS logging, and supervision by splitting a monolithic block of code into smaller chunks.

Download at WoweBook.Com

173

174

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

Extending the Configuration )NTHE previous sections, you learned how to extend the provider model and configure the provider using the web.config file. The extensibility of parts of the web.config is not limited to configuring providers. Using the base classes within the Ouopai*?kjbecqn]pekj namespace, you can create cusTOMSECTIONSANDHANDLETHEMDIRECTLY)FTHESETTINGSDEFINEDIN8=llOappejco: are too limited for your application’s needs, you can extend them.

How to Scaffold a Configuration Section The first step is to add a reference to the System.Configuration.dll assembly and the Ouopai* ?kjbecqn]pekj namespace. Creating a new project of type class library for the new configuration definition is not required, but recommended. This makes the code reusable and easier to test and deploy. Before you start creating a section like this, it’s worth examining the anatomy of a configuration section.

Anatomy of a Configuration Section The configuration section is based on the implementation of two abstract classes, ?kjbecqn]pekjOa_pekj and ?kjbecqn]pekjAhaiajp. ?kjbecqn]pekjOa_pekj is a successor of ?kjbecqn]pekjAhaiajp that makes it easy to create hierarchies of sections that contain elements on each level. The concrete ?kjbecqn]pekjOa_pekj is defined at the top of the web.config file, as shown in Listing 4-9. Listing 4-9. Definition of Private Configuration Sections 8_kjbecOa_pekjo: 8oa_pekjCnkqlj]ia9ouopai*sa^*atpajoekjopula9***: 8oa_pekjCnkqlj]ia9o_nelpejcpula9***: 8oa_pekjj]ia9o_nelpNaokqn_aD]j`hanpula9*** namqenaLanieooekj9b]hoa]hhks@abejepekj9I]_dejaPk=llhe_]pekj+: 8oa_pekjCnkqlj]ia9sa^Oanre_aopula9***: 8oa_pekjj]ia9fokjOane]hev]pekjpula9***namqenaLanieooekj9b]hoa ]hhks@abejepekj9Aranusdana+: 8oa_pekjj]ia9lnkbehaOanre_apula9***namqenaLanieooekj9b]hoa ]hhks@abejepekj9I]_dejaPk=llhe_]pekj+: 8oa_pekjj]ia9***namqenaLanieooekj9b]hoa ]hhks@abejepekj9I]_dejaPk=llhe_]pekj+: 8oa_pekjj]ia9nkhaOanre_apula9***namqenaLanieooekj9b]hoa ]hhks@abejepekj9I]_dejaPk=llhe_]pekj+: 8+oa_pekjCnkql: 8+oa_pekjCnkql: 8+oa_pekjCnkql: 8+_kjbecOa_pekjo: The pula attributes are empty for the sake of clarity. They contain the fully qualified assembly names of the type that holds the configuration definition. The top-level element, 8oa_pekjCnkql:, defines in which group the new element appears: 8oa_pekjCnkqlj]ia9ouopai*sa^*atpajoekjo: The section 8ouopai*sa^*atpajoekjo: is thus defined as the location for all subsequent groups, elements, or any combinations of groups and elements. You can define exactly what appears there simply by implementing the base classes previously mentioned.

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

The Class Model Figure 4-5 shows the complete class model behind the configuration classes. To create a private configuration section, you’ll need to implement these abstract classes.

Figure 4-5. Base classes for a custom configuration The ?kjbecqn]pekjOa_pekj and ?kjbecqn]pekjAhaiajp classes are the most important. Many elements will allow collections. Collections define tags such as 8]``:, 8naikra:, and 8_ha]n: to handle multiple elements in XML. The corresponding definition in this code is based on the ?kjbecqn]pekjAhaiajp?khha_pekj class. These classes form the structure of the configuration elements. You can refine their behavior by adding attributes. Attributes not only decorate the properties that define elements, but also add features in order to:

s 6ALIDATESCALARDATA



s $EFINECUSTOMVALIDATIONMETHODS



s 3ETADEFAULTIFTHEVALUEISNOTSET



s $EFINEASUBCLASSSTYPETO refine the elements hierarchy.

Download at WoweBook.Com

175

176

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

Attributes to Control Elements’ Behaviors Table 4-4 shows all the attributes available to define the behavior of properties. Table 4-4. Validator Attributes That Control the Elements’ Behaviors

Validator

Purpose of this Attribute

EjpacanR]he`]pkn

Checks whether the element’s value is of type Ejp/..

HkjcR]he`]pkn

Checks whether the element’s value is of type Ejp20.

OpnejcR]he`]pkn

Checks specific string conditions, such as minimum and maximum Hajcpd)TSEVENPOSSIBLETODEFINEFORBIDDENCHARACTERLIKEPATHS for instance).

NacatOpnejcR]he`]pkn

Defines a regular expression the element’s value must match.

?]hh^]_gR]he`]pkn

Defines a callback method that is responsible for checking the value.

Peiaol]jR]he`]pkn

Checks time conditions, declares usually a valid range.

LkoeperaPeiaol]jR]he`]pkn

Checks time conditions, usually a positive range (ahead in time).

Oq^_h]ooPulaR]he`]pkn

Defines the Type of a class this element must derive from.

The following attributes refine the configuration element properties at a Meta level. They can be used together and with the R]he`]pkn attributes in any combination (see Table 4-5). Table 4-5. Attributes to Refine the Configuration Elements’ Behavior

Attribute

Description

@ab]qhpR]hqa

4HEDEFAULTVALUE)FDEFINED THISVALUEISUSEDIFNOOTHERVALUEIS assigned.

Eo@ab]qhp?khha_pekj

True, if this element represents a collection.

EoNamqena`

True, if the element is mandatory.

EoGau

True, if this is the key element of a collection. Applies only if it is a collection.

Klpekjo

A combination of the EoGau, EoNamqena`, and Eo@ab]qhp?khha_pekj elements as a flagged enum.

Definition of a Simple Configuration Section Now thatYOUHAVEALLTHEPARTSOFTHEPUZZLEHANDY YOUCANSTARTCREATINGAREAL LIFEEXAMPLE THATDEFINESACUSTOMIZEDCONFIGURATIONSECTION&IRST LETSTAKEALOOKATTHESECTIONDEFINITION Listing 4-10 defines a section with two new elements. Listing 4-10. A Section with Two Elements qoejcOuopai7 qoejcOuopai*?khha_pekjo7 qoejcOuopai*Patp7 qoejcOuopai*?kjbecqn]pekj7 qoejcOuopai*Tih7 j]iaol]_a=lnaoo*Atpajoe^ehepu*?kjbecqn]pekj w Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

lq^he__h]ooL]ca=lla]n]j_aOa_pekj6?kjbecqn]pekjOa_pekj w W?kjbecqn]pekjLnklanpu$naikpaKjhu(@ab]qhpR]hqa9b]hoa(± EoNamqena`9b]hoa%Y lq^he_>kkha]jNaikpaKjhu w cap w napqnj$>kkha]j%pdeoWnaikpaKjhuY7 y oap w pdeoWnaikpaKjhuY9r]hqa7 y y W?kjbecqn]pekjLnklanpu$bkjp%Y lq^he_BkjpAhaiajpBkjp w cap w napqnj$BkjpAhaiajp%pdeoWbkjpY7 y oap wpdeoWbkjpY9r]hqa7y y W?kjbecqn]pekjLnklanpu$_khkn%Y lq^he_?khknAhaiajp?khkn w cap w napqnj$?khknAhaiajp%pdeoW_khknY7 y oap wpdeoW_khknY9r]hqa7y y y y This class defines three allowed properties. The property NaikpaKjhu is of type Boolean and doesn’t need any additional definition, beyond declaring it as a ?kjbecqn]pekjLnklanpu. )FYOUHAVEAMORECOMPLEXCLASSANDWISHTODISTINGUISHBETWEENPRIVATEPROPERTIESANDTHOSE exposed to the configuration manager, this requires an additional attribute. The two named properties set in the attribute’s constructor (@ab]qhpR]hqa and EoNamqena`) are explained in Table 4-5. For the other elements (Bkjp and ?khkn), you’ll need to create your own structures. This means that an element of type 8bkjp: should contain specific attributes, just as for 8_khkn:. The definition of the BkjpAhaiajp class demonstrates this, as shown in Listing 4-11. Listing 4-11. The FontElement Class Defines a Single Element That Represents a Font lq^he__h]ooBkjpAhaiajp6?kjbecqn]pekjAhaiajp w W?kjbecqn]pekjLnklanpu$j]ia(@ab]qhpR]hqa9=ne]h(EoNamqena`9pnqa%Y WOpnejcR]he`]pkn$Ejr]he`?d]n]_pano9z< !Z"&$%WYwy+7#XxXX(± IejHajcpd9-(I]tHajcpd92,%Y lq^he_OpnejcJ]ia Download at WoweBook.Com

177

178

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

w cap w napqnj$Opnejc%pdeoWj]iaY7 y oap w pdeoWj]iaY9r]hqa7 y y W?kjbecqn]pekjLnklanpu$oeva(@ab]qhpR]hqa9-.(EoNamqena`9b]hoa%Y WEjpacanR]he`]pkn$At_hq`aN]jca9b]hoa(I]tR]hqa9.0(IejR]hqa92%Y lq^he_ejpOeva w cap wnapqnj$ejp%pdeoWoevaY7y oap wpdeoWoevaY9r]hqa7y y y For the font’s name, a OpnejcR]he`]pknISUSED)TLIMITSTHELENGTHTOBETWEENAND 4HENAMEISNOTALLOWEDTOCONTAINSEVERALCHARACTERS4HEFONTSSIZEISLIMITEDWITHAN EjpacanR]he`]pkn. At_hq`aN]jca defines whether the values provided as I]tR]hqa and IejR]hqa AREPARTOFTHERANGEORNOT(ERE THERANGEISBETWEENAND INCLUDINGTHEVALUEShvANDhv respectively. The access to the underlying configuration element is through an indexer. The code behind this SERIALIZESANDDESERIALIZESTHEVALUESTOCREATEALINKBETWEENTHEELEMENTSNAMEANDITSATTRIBUTE in code. This means that the values used as keys for the indexer (oeva and j]ia respectively) ARERESPONSIBLEFORRETRIEVINGTHECONFIGURATIONS8-,)NTHESTRING8bkjpoeva9-.:( the name of THEATTRIBUTEhSIZEvISDEFINEDBYpdeoWoevaY and made accessible in the code via the Oeva property. Although it’s highly recommended to use the same names, there is no technical restriction on changing them. The color element operates similarly, as shown in Listing 4-12. Listing 4-12. The ColorElement Class Defines a Single Element That Represents a Color Value lq^he__h]oo?khknAhaiajp6?kjbecqn]pekjAhaiajp w W?kjbecqn]pekjLnklanpu$^]_gcnkqj`(@ab]qhpR]hqa9BBBBBB(EoNamqena`9pnqa%Y WOpnejcR]he`]pkn$± Ejr]he`?d]n]_pano9z< !Z"&$%WYwy+7#XxXXCDEFGHIJKLMNOPQRSTUV(± IejHajcpd92(I]tHajcpd92%Y lq^he_Opnejc>]_gcnkqj` w cap w napqnj$Opnejc%pdeoW^]_gcnkqj`Y7 y oap w pdeoW^]_gcnkqj`Y9r]hqa7 y y

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

W?kjbecqn]pekjLnklanpu$bknacnkqj`(@ab]qhpR]hqa9,,,,,,(EoNamqena`9pnqa%Y WNacatOpnejcR]he`]pkn$L]ppanj9W,)5=)B])bYw2yY lq^he_OpnejcBknacnkqj` w cap w napqnj$Opnejc%pdeoWbknacnkqj`Y7 y oap w pdeoWbknacnkqj`Y9r]hqa7 y y y The OpnejcR]he`]pkn is again used to constrain the >]_gcnkqj` property. The NacatOpnejcR]he`]pkn has the same effect by using a regular expression. As you can see, the values have the same constraint. (OWEVER THEREGULAREXPRESSIONISSHORTER CLEARER ANDEASIERTOREAD5SINGREGULAREXPRESSIONSIS a good style and allows better control when searching, restricting, or replacing strings. To understand what all this creates, see the following valid web.config section. First, the custom configuration itself has to be registered (see Listing 4-13). Listing 4-13. The Configuration Definition Must Be Registered Using This Code 8_kjbecOa_pekjo: 8oa_pekjCnkqlj]ia9l]ca=lla]n]j_aCnkql: 8oa_pekj j]ia9l]ca=lla]n]j_a pula9=lnaoo*Atpajoe^ehepu*?kjbecqn]pekj*L]ca=lla]n]j_aOa_pekj ]hhksHk_]pekj9pnqa ]hhks@abejepekj9Aranusdana+: 8+oa_pekjCnkql: *** 8+_kjbecOa_pekjo: Second, the configuration section can be used (see Listing 4-14). Listing 4-14. The Configuration Definition Allows the Following Usage Scenario 8l]ca=lla]n]j_aCnkql: 8l]ca=lla]n]j_anaikpaKjhu9pnqa: 8bkjpj]ia9PeiaoJasNki]joeva9-4+: 8_khkn^]_gcnkqj`9,,,,,,bknacnkqj`9BBBBBB+: 8+l]ca=lla]n]j_a: 8+l]ca=lla]n]j_aCnkql: (OWEVER THISDOESNOTMAKESENSEIFTHEVALUESARENOTUSED$EFININGVALUESISONEISSUE using them in custom code is another. Recall the point of this chapter: providers and their configuration should assist other developers to easily replace parts of your application, simply by defining another provider. On the user interface SIDE !30.%4USESPOWERFULSERVERCONTROLSASMUCHASPOSSIBLETOCONSTRUCTTHE(4-,MARKUP/N the code side, anything that’s configurable in any way should be placed in the web.config file, another configuration file, or a database. Custom configuration is a part of the extensibility model.

Download at WoweBook.Com

179

180

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

Usage of a Custom Configuration Section Assuming the configuration section is defined, present, and filled with data, it’s time to access its values at runtime from your own code. Listing 4-15 shows how to achieve this. Listing 4-15. Access the Configuration Data 8!<L]caH]jcq]ca9?!: 8@K?PULAdpihLQ>HE?)++S/?++@P@TDPIH-*,Pn]joepekj]h++AJ± dppl6++sss*s/*knc+PN+tdpih-+@P@+tdpih-)pn]joepekj]h*`p`: 8o_nelpnqj]p9oanran: lnkpa_pa`rke`L]ca[Hk]`$k^fa_poaj`an(Arajp=ncoa% w r]n_kjbec9± $=lnaoo*Atpajoe^ehepu*?kjbecqn]pekj*L]ca=lla]n]j_aOa_pekj%± Ouopai*?kjbecqn]pekj*?kjbecqn]pekjI]j]can*CapOa_pekj$± l]ca=lla]n]j_aCnkql+l]ca=lla]n]j_a%7 Opnejc>qeh`ano^9jasOpnejc>qeh`an$%7 o^*=llaj`$8d.:OappejcoejpdaL]ca=lla]n]j_aOa_pekj68+d.:%7 o^*=llaj`$Opnejc*Bkni]p$NaikpaKjhu6w,y8^n:(_kjbec*NaikpaKjhu%%7 o^*=llaj`$Opnejc*Bkni]p$Bkjpj]ia]j`oeva6w,yw-y8^n:(± _kjbec*Bkjp*J]ia(_kjbec*Bkjp*Oeva%%7 o^*=llaj`$± Opnejc*Bkni]p$>]_gcnkqj`]j`bknacnkqj`_khkn6w,yw-y8^n:(± _kjbec*?khkn*>]_gcnkqj`(_kjbec*?khkn*Bknacnkqj`%%7 h^h?kjbec*Patp9o^*PkOpnejc$%7 y 8+o_nelp: 8dpih: 8da]`e`9Da]`-nqj]p9oanran: 8pepha:?qopki?kjbecqn]pekjOa_pekjAt]ilha8+pepha: 8+da]`: 8^k`u: 8bknie`9bkni-nqj]p9oanran: 8`er: 8]ol6H]^ahnqj]p9oanranE@9h^h?kjbec:8+]ol6H]^ah: 8+`er: 8+bkni: 8+^k`u: 8+dpih: The ?kjbecqn]pekjI]j]can class is the entry point into the configuration. You can address any section here by giving the full path or, at least, a distinct part of the leaf path. As shown in the section about providers, “The Provider Model,” there are several ways to handle these strings. Consider attributes, constant literals, and helper classes. Once you have the section, and the section is a private type, you can cast as shown in the listing. The properties will represent the current values in the configuration. This will not only handle private data but also give fully typed access to the elements. 4HECONFIGURATIONISBASEDONTHESERIALIZATIONANDDESERIALIZATIONFEATURESTHATTHEBASECLASS provides. This could make it difficult to read or to modify the values in the web.configFILE)FYOU UNDERSTANDHOWTHESERIALIZERWORKSANDCANCREATESIMILARSTRINGS by hand, your configuration class should function correctly as is.

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

Accessing the Configuration Declaratively You now have an extended configuration model allowing the storage of complex values in a clearly DEFINEDWAY4HEPROGRAMMATICACCESSISEASY(OWEVER !30.%4FAVORSDECLARATIVETECHNIQUES Making the configuration accessible from markup would be ideal.

Extending the Expression Binding Syntax )NTEGRATEDEXPRESSIONS play an important role in accessing data dynamically. You probably work with data binding expressions following the 8!!: pattern. A different declarative syntax is available, with this pattern: 8! !: This is also an extensible model, allowing the creation of your own syntax in order to access data within the markup: 8]ol6hepan]hpatp98! Iu?kjbec6Cap@]p]!:nqj]p9oanran+: Read this as an enhancement to the configuration extension described in the section “ExtendINGTHE#ONFIGURATIONv)TTRANSFERSACCESSTOTHEMARKUP$EVELOPERSCANACCESSDATAWITHOUT writing explicit code. Now page designers working with .aspx pages can add specific formatting options without doing any coding tasks.

Introduction to Expression Syntax Expression builders process expressions. These build code from expressions during the pageprocessing phase—the parsing procedure. Expressions have this distinct pattern: 8! WlnabetY6W`a_h]n]pekjY!: The first part, the prefix, maps to a type that handles the expression. Any string will do for the prefix. The colon is mandatory, but you can enter whatever you like in the declaration part. Anything from the colon to the end of the expression is treated as a Opnejc and processed at once. One common usage is the accessing of the =llOappejco section in web.config)TFOLLOWSTHISPATTERN 8! =llOappejco6GauJ]ia!: 4HEPREFIXISh!PP3ETTINGSv)TDETERMINESTHEEXPRESSIONBUILDERVIAAMAPPINGEXPLAINED in the “Declare the Prefix” section) to a built-in class called =llOappejcoAtlnaooekj>qeh`an. The expression builder must be able to handle the remaining part, “KeyName” in the example. &ORLOCALIZEDRESOURCESTHEREISANOTHERBUILT INCLASS 8! Naokqn_ao6Naokqn_a?]packnu(J]ia!: The prefix is now “Resources”. The expression builder used behind the scenes is the Naokqn_aAtlnaooekj>qeh`an. There is also another, ?kjja_pekjOpnejcoAtlnaooekj>qeh`an, which makes connection strings available in markup. All expression builders derive from the abstract base class Atlnaooekj>qeh`an. The extensibility concept follows the common pattern. By implementing this base class, you can build your own expression builder.

How It Works Internally )NTERNALLY THE expression builder creates a code snippet. This code is inserted into the page during the parsing step. The compiler treats this code as part of your custom code and creates the page object. This requires the code snippet to follow specific rules. Essentially, the code is an assignment. Download at WoweBook.Com

181

182

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

)TASSIGNSAVALUETOAPROPERTYOFACONTROL7HERETHEVALUECOMESFROMMIGHTREQUIRECOMPLEX code, but the assignment is simple and limits the usage of such expressions. The most evident limitation is that usage without a control is not allowed. The following code will not function: 8`er: 8! Iu?kjbec6R]hqa-!: 8+`er: )NSTEAD YOUMUSTUSEACONTROL 8`er: 8]ol6h]^ahnqj]p9oanranPatp98! Iu?kjbec6R]hqa-!:+: 8+`er: (OWEVER USINGTHEPREFIXISNOTENOUGHTOPUTITINTOOPERATION&IRST YOUMUSTMAPTHEPREFIX to a specific type.

Declare the Prefix The declaration of the prefix takes place in the web.config file. The path to the configuration element is 8ouopai*sa^:8_kileh]pekj:8atlnaooekj>qeh`ano:. The 8atlnaooekj>qeh`ano: element is usually absent. Add the following element to define a new mapping between a prefix and a type: 8atlnaooekj>qeh`ano: 8]``atlnaooekjLnabet9lnabetpula9pula(]ooai^hu+: 8+atlnaooekj>qeh`ano: The pula follows the common schema of an assembly reference:

s .AMESPACE#LASS !SSEMBLY 6ERSION #ULTURE 0UBLIC+EY4OKEN



s .AMESPACE#LASS !SSEMBLY



s .AMESPACE#LASS ??CODE

The first form defines the fully qualified name of an assembly. The last references the App_Code FOLDER IFTHEAPPROPRIATEPROJECTTYPEISUSEDIN6ISUAL3TUDIO.OTETHETWOUNDERSCORESBEFORETHE word “code” here.) An example could look like this:

s !PRESS%XTENSIONS-Y"UILDER !PRESS%XTENSIONS Now you need to create the type. As mentioned, the abstract base class is where you start.

How the Expression Builder Works The expression builder has only a few methods. Using these methods, it can parse the expression and generate the required code. Parsing is initiated using the L]noaAtlnaooekj method)FTHISSTEP is successful, the Cap?k`aAtlnaooekj method generates a code snippet. The only condition is that the compiler must be able to assign the snippet to a property. Therefore, the snippet must form the right-hand side of an assignment: _kjpnkh*Lnklanpu98pdeoeopda_k`aatlnaooekj:7 While the right-hand side is merely a method call, this method can contain any amount of code (meaning that even the most complex operations are possible). )FTHEPARSINGFAILS YOUSHOULDTHROWANEXCEPTION/THERWISE THECap?k`aAtlnaooekj method is invoked to create the code using the Code Document Object Model (CodeDOM). Although a short explanation follows, this book does not teach CodeDOM in depth. Refer to the MSDN documentation to learn more about source code generation: dppl6++io`j*ie_nkokbp*_ki+aj)qo+he^n]nu+ ouopai*_k`a`ki*]opx. Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

4ABLE LISTSTHEMETHODSYOUHAVETOIMPLEMENTTOADDANEXPRESSIONBUILDERTOANOPERATION Table 4-6. Methods of an Expression Builder

Method

Description

Ar]hq]paAtlnaooekj

Returns the value for non-compiled pages (see the section “Accessing Settings for Non-Compiled Pages” in this chapter for details)

Cap?k`aAtlnaooekj

Creates the code snippet to insert into the page

L]noaAtlnaooekj

Parses the syntax of the expression

OqllknpoAr]hq]pa

)NDICATESWHETHERTHISEXPRESSIONBUILDERSUPPORTSNON COMPILEDPAGES

These methods are sufficient for creating our own expression builder.

Creating an Expression Builder )NTHEFIRST example, you need direct access to values stored in a SQL Server database. You are using the same database and table you created earlier in the section “Creating a Custom ProviderBased Service.” Please also refer to Figure 4-2. Specific criteria are used to retrieve the right values. The prefix is called “Cfg” and the syntax of the expressions looks like this: 8! ?bc6GauBNKI_]packnuSDANApula!: The syntax is similar to SQL, which makes it more readable. The type refers to the type of data, SUCHAShIMAGEvORhLABELv)NTHEMARKUPPORTION THISWOULDLOOKLIKETHEFOLLOWING 8]ol6H]^ahE@9h^hDa]`annqj]p9oanran± Patp98! ?bc6Da]`anBNKIL]ca@]p]SDANAh]^ah!::8+]ol6H]^ah: The following code is the same for an image: 8]ol6Ei]caE@9eicDa]`annqj]p9oanran± Ei]caQnh98! ?bc6Da]`anBNKIL]ca@]p]SDANAei]ca!::8+]ol6Ei]ca: 4HECREATEDCODEFORTHEIMAGEEXAMPLELOOKSLIKEhIMAGESHEADERPNGv/NCEDEFINED 6ISUAL 3TUDIORECOGNIZESTHEEXPRESSIONSYNTAX ASSHOWNIN&IGURE 

Figure 4-6. The private expression builder appears in Visual Studio’s expression dialog. /NESOLUTIONISSHOWNIN,ISTING 

Download at WoweBook.Com

183

184

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

Listing 4-16. Using Expressions for Retrieving Configuration Data from a Database qoejcOuopai7 qoejcOuopai*Sa^*?kileh]pekj7 qoejcOuopai*?k`a@ki7 j]iaol]_a=lnaoo*Atpajoe^ehepu*Atlnaooekjo w lq^he__h]oo?bcAtlnaooekj6Atlnaooekj>qeh`an w lner]paop]pe_?kjbec@]p]@]p]?kjpatp_pt7 lner]paop]pe_rke`Ajoqna?bc?kjpatp$% w _pt9jas?kjbec@]p]@]p]?kjpatp$%7 y lq^he_op]pe_opnejcCap?bc$opnejcgau(opnejc_]packnu(opnejcpula% w Ajoqna?bc?kjpatp$%7 r]nnao9bnkinksej_pt*]oljap[?kjbecqn]pekjo± sdananks*_bc[gau99gau± ""nks*_bc[_]packnu99_]packnu± ""nks*_bc[pula99pula± oaha_pnks*_bc[_kjpajp7 napqnjnao*BenopKn@ab]qhp8opnejc:$%7 y lq^he_kranne`a?k`aAtlnaooekjCap?k`aAtlnaooekj$± Ouopai*Sa^*QE*>kqj`LnklanpuAjpnuajpnu(± k^fa_pl]noa`@]p](± Atlnaooekj>qeh`an?kjpatp_kjpatp% w AtlnaooekjR]hqao_bcR]hqao9l]noa`@]p]]oAtlnaooekjR]hqao7 eb$_bcR]hqao99jqhh%pdnksjas=ncqiajpAt_alpekj$l]noa`@]p]%7 ?k`aLneieperaAtlnaooekjWY_=nc9jas?k`aLneieperaAtlnaooekjWY w jas?k`aLneieperaAtlnaooekj$_bcR]hqao*Gau%( jas?k`aLneieperaAtlnaooekj$_bcR]hqao*?]packnu%( jas?k`aLneieperaAtlnaooekj$_bcR]hqao*Pula% y7 ?k`aPulaNabanaj_aAtlnaooekjp9jas?k`aPulaNabanaj_aAtlnaooekj$± pulakb$?bcAtlnaooekj%%7 ?k`aIapdk`EjrkgaAtlnaooekjatl9jas?k`aIapdk`EjrkgaAtlnaooekj$p(± Cap?bc(_=nc%7 napqnjatl7 y lq^he_kranne`ak^fa_pL]noaAtlnaooekj$opnejcatlnaooekj(± PulalnklanpuPula(± Atlnaooekj>qeh`an?kjpatp_kjpatp% w napqnjPkgajL]noan*L]noa$atlnaooekj%7 y

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

lq^he_kranne`a^kkhOqllknpoAr]hq]pa w cap w napqnjb]hoa7 y y lq^he_kranne`ak^fa_pAr]hq]paAtlnaooekj$k^fa_pp]ncap(± Ouopai*Sa^*QE*>kqj`LnklanpuAjpnuajpnu( k^fa_pl]noa`@]p](± Atlnaooekj>qeh`an?kjpatp_kjpatp% w napqnj^]oa*Ar]hq]paAtlnaooekj$p]ncap(ajpnu(l]noa`@]p](_kjpatp%7 y nacekj?kjbecR]hqao _h]ooAtlnaooekjR]hqao w lq^he_opnejcGauwcap7oap7y lq^he_opnejc?]packnuwcap7oap7y lq^he_opnejcPulawcap7oap7y y aj`nacekj nacekjOeilhaPkgajL]noan op]pe__h]ooPkgajL]noan w op]pe_AtlnaooekjR]hqaor]hqao7 op]pe_PkgajL]noan$% w r]hqao9jasAtlnaooekjR]hqao$%7 y ejpanj]hop]pe_AtlnaooekjR]hqaoL]noa$opnejcpkL]noa% w eb$Opnejc*EoJqhhKnAilpu$pkL]noa%% pdnksjas=ncqiajpJqhhAt_alpekj$pkL]noa%7 ejpe9,7 opnejc_qnnajpPkgaj9Opnejc*Ailpu7 ++r]hqaBNKI_]pSDANApula sdeha$pnqa% w _d]n_9pkL]noaWeY7 osep_d$_% w _]oa#B#6 eb$pkL]noa*Oq^opnejc$e(1%*Amq]ho$BNKI%% w r]hqao*Gau9_qnnajpPkgaj*Pnei$%7 _qnnajpPkgaj9Opnejc*Ailpu7 e'907 Download at WoweBook.Com

185

186

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

y ^na]g7 _]oa#S#6 eb$pkL]noa*Oq^opnejc$e(2%*Amq]ho$SDANA%% w r]hqao*?]packnu9_qnnajpPkgaj*Pnei$%7 _qnnajpPkgaj9Opnejc*Ailpu7 e'917 y ^na]g7 `ab]qhp6 _qnnajpPkgaj'9_7 ^na]g7 y eb$''e8pkL]noa*Hajcpd%_kjpejqa7 r]hqao*Pula9_qnnajpPkgaj7 ^na]g7++aj`sdeha y napqnjr]hqao7 y y aj`nacekj y y 4HECREATIONOFDYNAMICCODEISTHEMOSTIMPORTANTPART(OWEVER ITDOESNTMAKESENSE to do everything dynamically. This is why the code for retrieving data is moved to the static method, Cap?bc. The dynamic portion calls that method, which leads to generated code, such as the following: h^hDa]`an*Patp9Cap?bc$***%7 4HEMETHODISSTATICBECAUSETHEPRIVATEEXPRESSIONBUILDERISNOTINSTANTIATEDATRUNTIME)TS ADESIGN TIMETOOLWHICHSUPPORTSTHEPAGEPARSERANDDESIGN TIMEEXPERIENCEIN6ISUAL3TUDIO Only the assignment remains in the page’s code after compilation. The procedure commences with the L]noaAtlnaooekj method. The object created here appears later as the l]noa`@]p] parameter of the Cap?k`aAtlnaooekj method. The PkgajL]noan class in the EXAMPLEDEMONSTRATESHOWTOPARSECUSTOMSTRINGS)TANALYSESTHESTRINGAFTERTHEEXPRESSIONSCOLON and creates three required parameters from it. The private class, AtlnaooekjR]hqao, stores the values, while the Cap?k`aAtlnaooekj methodBUILDSTHENECESSARYCODE)TMUSTRETURNANOBJECTOFTYPEOuopai* ?k`a@ki*?k`aAtlnaooekj, which will contain a code fragment assignable to the right-hand side of an ASSIGNMENTSTATEMENT2EFERTOTHENEXTTABLETOVIEWTHEMOSTIMPORTANT#ODE$/-FUNCTIONS)NTHIS EXAMPLE )USEASIMPLECALLTOASTATICMETHODSOTHATTHECODEGENERATIONISASSIMPLEASPOSSIBLE4HE core element is the method invocation: jas?k`aIapdk`EjrkgaAtlnaooekj$p(Cap?bc(_=nc% The argument cArg is the collection of private parameters (see Table 4-7).

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

Table 4-7. Important CodeDOM Methods

Method

Description

?k`aAtlnaooekj

An abstract base class for all CodeDOM types

?k`aPulaNabanaj_aAtlnaooekj

A type reference, such as a type used in code

?k`aLneieperaAtlnaooekj

Any code expression, which does not fit into other categories

?k`aIapdk`EjrkgaAtlnaooekj

A method call which requires, as parameters, the type where the method is defined, the name of the method, and an array of code fragments used as parameters for the method

The Cap?bc method follows the same pattern used in the configuration example earlier in the section “Extending the Expression Binding Syntax.” This draws from the @]p]?kjpatp class and ,).1TO31,TORETRIEVETHEVALUES4HENAMEOFTHECONTEXT ?kjbec@]p]@]p]?kjpatp, is based on the definition in ConfigData.dbml.

Accessing Settings for Non-Compiled Pages )FPAGESCONTAIN mainly static content, the compilation step can be suppressed. Code expressions and expression builders will still function. Moreover, expression builders which support non-compiled pages offer a different way of handling the code creation. You can suppress the compilation by setting the following attribute in the
Download at WoweBook.Com

187

188

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

j]iaol]_a=lnaoo*Atpajoe^ehepu*Atlnaooekjo w lq^he__h]oo?bcAtlnaooekj6Atlnaooekj>qeh`an w lner]paop]pe_?kjbec@]p]@]p]?kjpatp_pt7 lner]paop]pe_rke`Ajoqna?bc?kjpatp$% w _pt9jas?kjbec@]p]@]p]?kjpatp$%7 y lq^he_op]pe_opnejcCap?bc$opnejcgau(opnejc_]packnu(opnejcpula% w Ajoqna?bc?kjpatp$%7 r]nnao9bnkinksej_pt*]oljap[?kjbecqn]pekjo± sdananks*_bc[gau99gau± ""nks*_bc[_]packnu99_]packnu± ""nks*_bc[pula99pula± oaha_pnks*_bc[_kjpajp7 napqnjnao*BenopKn@ab]qhp8opnejc:$%7 y lq^he_kranne`a^kkhOqllknpoAr]hq]pa w cap w napqnjpnqa7 y y lq^he_kranne`ak^fa_pAr]hq]paAtlnaooekj$k^fa_pp]ncap(± Ouopai*Sa^*QE*>kqj`LnklanpuAjpnuajpnu(± k^fa_pl]noa`@]p](Atlnaooekj>qeh`an?kjpatp_kjpatp% w AtlnaooekjR]hqao_bcR]hqao9l]noa`@]p]]oAtlnaooekjR]hqao7 napqnjCap?bc$_bcR]hqao*Gau(_bcR]hqao*?]packnu(_bcR]hqao*Pula%7 y y Read the Ar]hq]paAtlnaooekj method as a combination of the L]noaAtlnaooekj and Cap?k`aAtlnaooekj methods. The database access is the same as in the last example (see ,ISTING  

Beyond Simple Expressions This expressionMODELSUPPORTSSEVERALOTHERFEATURES(OWEVER ASTHEYAREBEYONDTHESCOPEOF THISBOOK )LLONLYGIVEASHORTOVERVIEWOFTHEM0LEASEREFERTOTHEOFFICIALDOCUMENTATIONFORMORE usage scenarios. The L]noaAtlnaooekj method has another parameter named _kjpatp)TSNOTUSEDIN the example, as it’s intended for more advanced scenarios. This parameter is of the type Atlnaooekj>qeh`an?kjpatp)TSPURPOSEISTOSUPPORTTEMPLATE BASEDCONTROLS ANDITCONTAINSTHE virtual path to the page or user control that contains the control. The expression builder refers to the control and is able to support different code-generation strategies, depending on the requirements of the template-based control.

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

Another parameter, lnklanpuPula, refers to the type of the property. Usually, this is Opnejc, but it can be modified to any type that suits your needs. For instance, when using a very limited set of options, an ajqiWOULDBEAPPROPRIATE4HISWOULDCREATEADROPDOWNELEMENTIN6ISUAL3TUDIOS expression builder for an advanced design-time experience. The last parameter named ajpnu is of the >kqj`LnklanpuAjpnu type. This allows access to the control itself, its ?kjpnkhE@ property, and the control’s type. Finally, the parameter AtlnaooekjLnabet retrieves the currently used prefix. This assumes that you can assign the same expression builder multiple times and create complex and sophisticated frameworks on top of expression builders.

Design-Time Support As demonstratedEARLIER 6ISUAL3TUDIOSUPPORTSEXPRESSIONSTHROUGHSIMPLE%XPRESSIONDIALOGS4HESE can be invoked using the Expression section of the property browser. Simply select a control on the designer surface, open the property browser (F4), and click on the ellipses in the Expressions element in the Data section. The dialog contains a mapping tool, which assigns properties to expressions. (ERE THEPROPERTYGRIDUSESATTRIBUTESREADBYREFLECTIONTOMODIFYITSBEHAVIOR&IGURE  

Figure 4-7. Invoke the Expression dialog using the ellipses button. Bound properties appear with a small icon in the name column.

Download at WoweBook.Com

189

190

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

To support this, decorate the class of the expression builder with an AtlnaooekjA`epkn=ppne^qpa, defined in the Ouopai*Sa^*QE*@aoecj namespace of the Ouopai*@aoecj assembly: WAtlnaooekjA`epkn$pulakb$?bcAtlnaooekjA`epkn%%Y The type ?bcAtlnaooekjA`epkn implements the abstract base class AtlnaooekjA`epkn. The only required step is to implement the CapAtlnaooekjA`epknOdaap method: lq^he_kranne`aAtlnaooekjA`epknOdaapCapAtlnaooekjA`epknOdaap$± opnejcatlnaooekj(± EOanre_aLnkre`anoanre_aLnkre`an% w napqnjjas?bcAtlnaooekjA`epknOdaap$atlnaooekj(oanre_aLnkre`an%7 y The ?bcAtlnaooekjA`epknOdaap type results from the implementation of the base class AtlnaooekjA`epknOdaap. This type defines the properties in the property grid of the expression BUILDERDIALOGTHAT6ISUAL3TUDIODISPLAYS2EGARDINGOTHERTYPES YOUCANUSETHECLASSES A`epkn=ppne^qpa and Pula?kjranpan=ppne^qpa to change the data the property grid reads via reflection. You can find both types in the Ouopai*?kilkjajpIk`ah)NTHEEXAMPLE ITWOULDBEHELPFULTO have three properties, such as “Key,” “Category,” and “Type.” The A`epkn=ppne^qpa defines the editor used in one entry of the property grid. This can be a dropdown list, or another dialog opened by clicking on the ellipses.

NNote

Dialogs and controls that are used in Visual Studio to extend the design-time experience must be WinForm controls. You cannot use web controls here. Some familiarity with Windows Forms Control programming is highly recommended before you begin extending Visual Studio’s design-time environment.

Implementing an Expression Builder with Design-Time Support The next example shows the complete implementation of an expression builder with design-time support. The purpose is the output of current data or time including variations like yesterday, tomorrow, and so on. The current value should appear in design-time view. Additionally, it is selectable in the Expressions dialog using a dropdown. The usage in markup could look like this: 8]ol6H]^ahnqj]p9oanranE@9h^hDa]`anPatp9#8! Peia6Uaopan@]u!:#± Bkjp)>kh`9pnqa:8+]ol6H]^ah: )NDESIGN TIMEVIEW &IGURE SHOWSTHECURRENTVALUE

Figure 4-8. Design-time view with real values ,ISTING ISTHEBASICIMPLEMENTATIONOFTHE%XPRESSIONBUILDERITSELF)NTHEREMAININGPART OFTHESECTION )WILLSHOWHOWTOEXTENDTHISTOGETTHEFULLDESIGN TIMESUPPORT

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

Listing 4-18. The Complete Definition of the Design-Time Environment qoejcOuopai7 qoejcOuopai*?k`a@ki7 qoejcOuopai*Sa^*?kileh]pekj7 qoejcOuopai*Sa^*QE7 qoejcOuopai*Sa^*QE*@aoecj7 j]iaol]_a=lnaoo*Atpajoe^ehepu*Atlnaooekjo*Peia w WAtlnaooekjLnabet$Peia%Y WAtlnaooekjA`epkn$pulakb$PeiaAtlnaooekjA`epkn%%Y lq^he__h]ooPeiaAtlnaooekj6Atlnaooekj>qeh`an w lq^he_kranne`a?k`aAtlnaooekjCap?k`aAtlnaooekj$>kqj`LnklanpuAjpnuajpnu(± k^fa_pl]noa`@]p](± Atlnaooekj>qeh`an?kjpatp_kjpatp% w PeiaKlpekjopk9$PeiaKlpekjo%Ajqi*L]noa$pulakb$PeiaKlpekjo%(± ajpnu*Atlnaooekj(pnqa%7 osep_d$pk% w _]oaPeiaKlpekjo*Pk`]u6 ++Ouopai*@]paPeia*Jks napqnjjas?k`aLnklanpuNabanaj_aAtlnaooekj$± jas?k`aPulaNabanaj_aAtlnaooekj$pulakb$@]paPeia%%(Jks%7 _]oaPeiaKlpekjo*Uaopan`]u6 ++Ouopai*@]paPeia*Jks*=``@]uo$)-% napqnjjas?k`aIapdk`EjrkgaAtlnaooekj$± jas?k`aLnklanpuNabanaj_aAtlnaooekj$± jas?k`aPulaNabanaj_aAtlnaooekj$pulakb$@]paPeia%%(± Jks%(± =``@]uo(± jas?k`aLneieperaAtlnaooekj$)-%%7 _]oaPeiaKlpekjo*Pkiknnks6 ++Ouopai*@]paPeia*Jks*=``@]uo$-% napqnjjas?k`aIapdk`EjrkgaAtlnaooekj$± jas?k`aLnklanpuNabanaj_aAtlnaooekj$± jas?k`aPulaNabanaj_aAtlnaooekj$pulakb$@]paPeia%%(± Jks%(± =``@]uo(± jas?k`aLneieperaAtlnaooekj$-%%7 _]oaPeiaKlpekjo*JatpSaag6 ++Ouopai*@]paPeia*Jks*=``@]uo$3% napqnjjas?k`aIapdk`EjrkgaAtlnaooekj$± jas?k`aLnklanpuNabanaj_aAtlnaooekj$± jas?k`aPulaNabanaj_aAtlnaooekj$pulakb$@]paPeia%%(± Jks%(± =``@]uo(± jas?k`aLneieperaAtlnaooekj$3%%7 `ab]qhp6 pdnksjasEjr]he`Klan]pekjAt_alpekj$Pdaatlnaooekj± r]hqaodkqh`^akjakb6± Pk`]u(Uaopan`]u(Pkiknnks(JatpSaag*%7 y y y y Download at WoweBook.Com

191

192

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

This expression builder takes an enumeration value (see Listing 4-19) and creates code snippets that return a date value based on the current time and date. Note the attribute at the top of the class: WAtlnaooekjA`epkn$pulakb$PeiaAtlnaooekjA`epkn%%Y This assigns the PeiaAtlnaooekjA`epkn type to modify the design-time environment. Listing 4-19. A Supporting Enumeration j]iaol]_a=lnaoo*Atpajoe^ehepu*Atlnaooekjo*Peia w lq^he_ajqiPeiaKlpekjo w Uaopan`]u( Pk`]u( Pkiknnks( JatpSaag y y The PeiaAtlnaooekjA`epkn type derives from the AtlnaooekjA`epkn)TSPURPOSEISTWOFOLD&IRST ITALLOWSTHEOUTPUTOFVALUESINTHEDESIGNER)FAUSEROPENSTHEDESIGNERSURFACEEDITINGAPAGE ORUSERCONTROL THEEXPRESSIONSCANBEUSEDJUSTLIKEANYOTHEREXPRESSION)NSTEADOFSHOWINGTHE expression’s code, such as Time:Today, it shows the calculated value, March 20, 2009. This results in a more realistic design-time experience (see Listing 4-20). Listing 4-20. Code That Supports a Custom Editor at Design-Time qoejcOuopai7 qoejcOuopai*Sa^*QE*@aoecj7 j]iaol]_a=lnaoo*Atpajoe^ehepu*Atlnaooekjo*Peia w lq^he__h]ooPeiaAtlnaooekjA`epkn6AtlnaooekjA`epkn w ++Ar]hq]pao]jatlnaooekj]p`aoecj)peiabknlnareaslqnlkoao lq^he_kranne`ak^fa_pAr]hq]paAtlnaooekj$opnejcatlnaooekj(± k^fa_pl]noaPeia@]p](± PulalnklanpuPula(± EOanre_aLnkre`anoanre_aLnkre`an% w PeiaKlpekjopk9$PeiaKlpekjo%Ajqi*L]noa$pulakb$PeiaKlpekjo%(± atlnaooekj(pnqa%7 osep_d$pk% w _]oaPeiaKlpekjo*Pk`]u6 napqnj@]paPeia*Jks*PkOpnejc$%7 _]oaPeiaKlpekjo*Uaopan`]u6 napqnj@]paPeia*Jks*=``@]uo$)-%*PkOpnejc$%7 _]oaPeiaKlpekjo*Pkiknnks6 napqnj@]paPeia*Jks*=``@]uo$-%*PkOpnejc$%7 _]oaPeiaKlpekjo*JatpSaag6 napqnj@]paPeia*Jks*=``@]uo$3%*PkOpnejc$%7 `ab]qhp6 pdnksjasEjr]he`Klan]pekjAt_alpekj$Pdaatlnaooekjr]hqa± odkqh`^akjakb6Pk`]u(Uaopan`]u(Pkiknnks(JatpSaag*%7 y Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

y lq^he_kranne`aAtlnaooekjA`epknOdaapCapAtlnaooekjA`epknOdaap$± opnejcatlnaooekj(EOanre_aLnkre`anoanre_aLnkre`an% w napqnjjasPeiaAtlnaooekjA`epknOdaap$atlnaooekj(oanre_aLnkre`an%7 y y y The code demonstrates how to define the editor sheet using the CapAtlnaooekjA`epknOdaap method. The PeiaAtlnaooekjA`epknOdaap type used here is shown in Listing 4-21. Listing 4-21. Code That Supports the Propertysheet at Design-Time qoejcOuopai7 qoejcOuopai*?kilkjajpIk`ah7 qoejcOuopai*Sa^*QE*@aoecj7 j]iaol]_a=lnaoo*Atpajoe^ehepu*Atlnaooekjo*Peia w lq^he_oa]ha`_h]ooPeiaAtlnaooekjA`epknOdaap6AtlnaooekjA`epknOdaap w lner]paopnejc[`]u7 lq^he_PeiaAtlnaooekjA`epknOdaap$opnejc`]u(± EOanre_aLnkre`anoanre_aLnkre`an% 6^]oa$oanre_aLnkre`an% w @]u9`]u7 y WPula?kjranpan$pulakb$Peia?kjranpan%%Y lq^he_opnejc@]u w cap w napqnj[`]u7 y oap w [`]u9r]hqa7 y y lq^he_kranne`aopnejcCapAtlnaooekj$% w napqnj@]u7 y ++Pula?kjranpanpklnkre`a`nkl`ksjkbr]he`r]hqao lner]paoa]ha`_h]ooPeia?kjranpan6Opnejc?kjranpan w lq^he_kranne`a^kkhCapOp]j`]n`R]hqaoAt_hqoera$± EPula@ao_nelpkn?kjpatp_kjpatp% w Download at WoweBook.Com

193

194

CH APT ER 4 N P R OVIDER S A ND C ONFIG U R A TI O N

napqnjpnqa7 y lq^he_kranne`a^kkhCapOp]j`]n`R]hqaoOqllknpa`$± EPula@ao_nelpkn?kjpatp_kjpatp% w napqnjpnqa7 y lq^he_kranne`aPula?kjranpan*Op]j`]n`R]hqao?khha_pekj± CapOp]j`]n`R]hqao$EPula@ao_nelpkn?kjpatp_kjpatp% w opnejcWYop]j`]n`R]hqao9Ajqi*CapJ]iao$pulakb$PeiaKlpekjo%%7 napqnjjasOp]j`]n`R]hqao?khha_pekj$op]j`]n`R]hqao%7 y y y y 4HESEARETHEPROPERTIESSHOWNINTHEEXPRESSIONBUILDERDIALOGIN6ISUAL3TUDIO4HE WPula?kjranpan$pulakb$Peia?kjranpan%%Y attribute converts values from the property grid into the enumeration. This is necessary, as the property grid transforms a type internally into a string REPRESENTATION WHICHALLOWSYOUTOSELECTIT)NTHISCASE THEDROPDOWNWILLRETURNSINGLESTRINGSLIKE “Today” or “Tomorrow.” These values must be converted back and forth by the PeiaKlpekjo enumeration. )NTHEPROPERTYGRID YOUHANDLETHEENUMERATIONASADROPDOWN9OUCANFORCETHISBYRETURNING pnqa in the CapOp]j`]n`R]hqaoOqllknpa` method. The CapOp]j`]n`R]hqao method must return the array of elements presented in the dropdown. Ajqi*CapJ]iaoPERFORMSTHISFUNCTION)FTHEENUMERATION values do not fit your needs, you may decorate them with @ao_nelpekj=ppne^qpa attributes (Ouopai* ?kilkjajpIk`ah namespace) and obtain the final strings from this attribute instead of using the enum values. lq^he_ajqiPeiaKlpekjo w W@ao_nelpekj$Pda`]u^abknapk`]u%Y Uaopan`]u( W@ao_nelpekj$Jks%Y Pk`]u( W@ao_nelpekj$Pda`]u]bpanpk`]u%Y Pkiknnks( W@ao_nelpekj$Okiapeiaejpdabqpqna%Y JatpSaag y This is just one of the many options you have in extending the design-time environment. (OWEVER THEMORECODEYOUADD THEHARDERITWILLBETODEBUG4HENEXTSECTIONCOVERSTHEBASIC principles of design-time debugging.

Debugging Design-Time Extensions Design-timeSUPPORTSHOULDBEPARTOFANYEXTENSIONMODEL(OWEVER ITSDIFFICULTTODEBUGTHESE extensions, and this is probably why developers avoid adding design-time support to their applications. There is no debugger attached to design-time code. This means that you cannot add breakpoints easily or step into the code to view its internal operations. Using smart exceptions and try/catch blocks might help, but this is not a good debugging experience.

Download at WoweBook.Com

C H A P T E R 4 N P R O V I D E R S A N D C O N F I G U R A T I O N

4ODEBUGWITHINTHE6ISUAL3TUDIODESIGN TIMEENVIRONMENT YOUMUSTLAUNCHANOTHERINSTANCE OF6ISUAL3TUDIOANDDEBUGTHESAMECODETHERE4OACCOMPLISHTHIS OPENTHEPROPERTYPAGESOFTHE Web project and select the option Start external program (see Figure 4-9).

Figure 4-9. Start another instance of Visual Studio to debug at design-time. #HOOSETHE6ISUAL3TUDIOEXECUTABLEdevenv.exe as the external program. When you start DEBUGGINGTHEPROJECTBYHITTING& ANOTHERINSTANCEOF6ISUAL3TUDIOWILLAPPEAR)NTHISINSTANCE YOULOADTHESAMEPROJECTANDSTARTUSINGTHEDESIGN TIMEENVIRONMENT)NTHEFIRSTINSTANCEOF 6ISUAL3TUDIO YOUCANNOWSETBREAKPOINTSANDDEBUGASYOUWOULDDOATRUNTIME4O reach specific code sections, just start using the code within the second instance.

Summary )NTHISCHAPTER YOUSAWANOVERVIEWOFPROVIDERSANDHOWTHEYCANBEUSEDTOCREATEMODERN multi-tier architecture. Providers result in highly configurable and extensible applications that don’t require additional code when changes to basic features are made. The configuration of providers is AMAJORPARTOFTHISENVIRONMENT)NADDITIONTOPROVIDERS THEWHOLECONFIGURATIONCANBEEXTENDED through web.config. This chapter showed the extensibility of web.config in defining private sections and elements. Lastly, the configuration settings were made available in the declarative part of the web pages, the markup, by supporting private expression builders. Expression builders form a final extensibility feature that improves the design-time experience.

Download at WoweBook.Com

195

Download at WoweBook.Com

CHAPTER

5

Extending the Resource Model

W

eb sites consist of both pure HTML and resources. Resources are everything not directly embedded into the page’s source, such as images, JavaScript, ActiveX controls, Flash, and Silverlight code. Resources can also be used more widely. You can structure a page’s content by moving parts of it into resources, thus changing its content dynamically based on different resource sources. This technique is primarily used to create localized applications able to display different languages and formats for a global market. In this chapter, I’ll explain how to extend the resource model in ASP.NET. In particular, this chapter includes:

s (OWTHERESOURCEMODELWORKS



s %XTENDINGTHEPROVIDER BASEDRESOURCEMANAGEMENT



s #REATINGCUSTOMRESOURCEPROVIDERS



s %DITINGRESOURCES online at runtime

Principles of Resource Management Resource files are usually stored in XML format and located in special folders called either App_ GlobalResources for global resources or App_LocalResourcesFORPAGE ORCONTROL SPECIFICONES App_LocalResources is created on a per folder basis. This means that, within your application, there will normally be several such folders available. Each resource file has a defined file name format: L]caJ]ia*?qhpqna*naot However, for fallback reasons, a common base resource is required. The first resource file has the default name Pagename.resx. Whenever ASP.NET isn’t able to find a particular resource file, it will load the default resource file. It’s a good idea to define all your resources there in order to avoid users seeing strange results. At compile time, the resource compiler takes all these files and compiles them into a binary format. This improves the speed of reading the content and reduces the file size.

The Fallback Strategy If you think in terms of cultures, you’ll see a very straightforward model. A culture is a combination of a language and a country. In many countries around the world, people speak more than one language. You define the country to receive information regarding currency format or calendar, for instance, and you define the language to obtain the correct format of numbers, and names of months and weekdays. Even if several countries only define one such combination, others are much more complex. In some 197 Download at WoweBook.Com

198

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

cases, you’ll also find information about the script; for example, certain languages can be written in EITHER#YRILLICOR,ATINLETTERS7ELL GLOBALIZEDPAGESWILLSUPPORTTHISSITUATION For most applications, it may be unwarranted to distinguish between countries—a simple language definition will suffice. A good example is the usage of German in Germany, Austria, and Switzerland. As long as you don’t deal with currency, it’s almost the same (the differences are subtle). Defining German as the final language will drastically reduce the development effort and STILLHAVEAGREATIMPACTONINTERNATIONALIZATION)NREAL LIFESCENARIOS BROWSERSWILLUSUALLYTRANSMIT preferred culture information, which consists of language and country details. If one sends “Ger man, Austria” and your systems only support German globally, the fallback mechanism must find the appropriate resource information.

Using Global Resources It’s much the same approach for global resources, except that there is no need to bind resources to a specific page. This opens the possibility of holding resources for any situation, with or without add ing support for cultures, languages, and fallback behavior. Such resources are called shared resources. It’s easy to handle any kind of resource file embedded within an assembly by accessing the resource manager. The access is enabled via implicit definition in the page’s markup, using the expression: 8! Naokqn_ao6Naokqn_aGau(P]c!: Alternatively, you can call the L]ca class’s CapChk^]hNaokqn_a method.

Limitations of the Existing Provider The only drawback is that the internal resource provider has a single method of accessing resources—based on resx files&ILE BASEDOPERATIONSARENOTUNUSUAL BUTTHEYLIMITUSTOJUSTONE WAYOFACCESSINGRESOURCESATDESIGN TIMEANDRUNTIME,ARGEAPPLICATIONSWITHFREQUENTLYCHANGING resources might need a different behavior, either with better runtime support or with using a differ ent storage location for the resource information.

Programming a Custom Resource Provider The system of .resx filesPROVIDEDOUT OF THE BOXHASSOME limitations. While it’s well supported in 6ISUAL3TUDIOATDESIGN TIMEANDWORKSATRUNTIMEWITHOUTANYCODINGEFFORT THEREISALMOSTNOWAY of parameterizing or configuring the behavior. Imagine that you have different themes and want to manage different resources for each theme. Even if the resource management fits your needs (apart from wishing to store the data in a database instead of in XML files), you can’t use the default resource provider. Developers often discard the whole default resource handling approach and implement their own solution. However, resource management is based on providers and, as shown in the previous chapter, the model is extensible. It is not easy, but it can be done, and this chapter will explain how.

Extending the Provider Model Whenever you depart from the default resource model, you’ll need to manage some specific require ments. Leaving the default resource model and creating an independent solution has serious drawbacks. .OTONLYDOYOULOSETHEABILITYTOASSIGNACONTROLSPROPERTYARESOURCE BASEDVALUE BUTYOUALSOLOSE THEWHOLEWORLDOFDESIGN TIMESUPPORT RUNTIMEBEHAVIOR ANDCERTAINOPTIMIZATIONS4HEREFORE INSTEAD of implementing a completely isolated solution, the extension of the provider model is a highly recom mended alternative. Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

To understand the resource model, we’ll look first at the classes involved. The classes support three phases:

s 4HEDESIGN TIMESTEP



s 4HECOMPILATIONPHASE



s 4HERUNTIMESTEP

5SUALLYWEDISTINGUISHBETWEENRUNTIMEANDDESIGN TIMEPHASESONLY)TMIGHTLOOKASTHOUGH the compilation step has a special meaning. As you’ll see later in the section “Edit Resources at Runtime,” this is a quirk of the resource man agement. The .resx files used by default to store resources are compiled into binary resource files. %VENIFNOTFILE BASED THERESOURCESMUSTBEEMBEDDEDINTOEACHPAGEBEFOREBEINGDELIVEREDTOTHE BROWSER4HERUNTIMETHENHANDLESTHERESOURCESANDTRANSFORMSTHEPRE COMPILEDDATAINTOVALUES read by the controls on the fly. 4HEDESIGN TIMESTAGE is mostly for local resources. Visual Studio provides a feature in the Tools menu to create local resources for all the controls on a page. This assigns the meta:resourcekey ATTRIBUTEWITHAKEYTHATPOINTSTOTHERESOURCEFILE4HISFILEISASIMPLEKEY VALUELISTTHATISABLETO return the right data. The same approach occurs with any explicit call to the resources, using the 8! Naokqn_a6Gau!: expression. Several .resx filesCO EXISTANDHOLDDATAFOREACHCULTURESUPPORTED)MPLEMENTINGTHE DESIGN TIMEFEATUREISESSENTIALFORSUPPLYINGFULLSUPPORTTO6ISUAL3TUDIO!TCOMPILETIME THESE expressions are translated into calls to the methods CapHk_]hNaokqn_a and CapChk^]hNaokqn_a. At runtime, these methods return values from the compiled resources. The two tiers—the call to resources at the UI level and the access to the data layer—are separate, and the replacement of the data access is quite easy. It’s not unusual to change both the behavior and the data source. The following example extends the default behavior by reading the current theme and man aging as many resource file structures as you have themes. It is still using the .resx file model. !DDITIONALLY YOULLSEEA7EB3ERVICEnBASEDCLIENTAPPLICATIONIN&IGURE WHICHDEMONSTRATES how to handle resources at runtime and allow users to change formerly static content.

Figure 5-1. Bindable properties in the Expression editor in Visual Studio Download at WoweBook.Com

199

200

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

Prerequisites There are good examples in the MSDN documentation of how to implement the various interfaces and abstract base classes to create a usable resource provider. The problem is that it doesn’t give you the whole picture, or explain how the isolated examples fit together and fill in the gaps. Nor mally, you’ll need the following:

s !FACTORYCLASSTHATCREATESTHEPROVIDERATDESIGN TIME



s !FACTORYCLASSTHATCREATESTHEPROVIDERATRUNTIME



s )MPLEMENTATIONSOFBOTHPROVIDERS

The providers are responsible for using specific reader and writer classes to access the resources. These implementations need:

s !CLASSTOREADTHEGLOBALRESOURCES



s !CLASSTOWRITETHEGLOBALRESOURCES



s !CLASSTOREADTHELOCALRESOURCES



s !CLASSTOWRITETHELOCALRESOURCES

You don’t have to completely implement all classes. For instance, if your application does not write resources because you manage all resources outside the application, you don’t need to imple ment the writer classes fully. )N&IGURE  YOUCANSEETHEBASE classes and their dependencies.

Figure 5-2. Class diagram of the base classes and interfaces Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

Implementing the Custom Provider The implementation of a custom resource provider starts with the Naokqn_aLnkre`anB]_pknu class. There are two methods required in order to access both global and local resources. Each method returns the configured provider that is responsible for requesting resources from resource storage. Implementing the factory allows some customization features. In the following examples, I cus tomize by adding support for the current theme. Storing the active theme in the factory allows the factory to pass the information to the provider via a parameter. The provider can then modify the storage using this additional information. )NTHEEXAMPLESHOWNLATERIN,ISTING  THE?qopkiNaokqn_aLnkre`an is based on ENaokqn_a)Lnkre`an, and our particular interest is in Naokqn_aNa]`an. This is the class that implements the reader. The main method is CapK^fa_p, which returns the resource value based on the conditions obtained from the factory and the current conditions, such as the culture, passed via parameters. ?qopkiNaokqn_aNa]`an implements the ENaokqn_aNa]`an interface to make the custom imple mentation available. That means the Naokqn_aNa]`an*CapK^fa_pMETHODRETURNSANOBJECTOFTYPE ENaokqn_aNa]`an4HEOBJECTISOFTHETYPETHATCONTAINSTHEACTUALIMPLEMENTATION In a similar manner, to get the resource writer classes, you can use the CapNaokqn_aSnepan method to return a type that implements ENaokqn_aSnepan4HEIMPLEMENTATIONIN,ISTING IS called ?qopkiNaokqn_aSnepan. As mentioned before, the implementation is only required if you plan to support resource writing at runtime. 4HEWHOLESCHEMAMUSTBEIMPLEMENTEDASECONDTIMETOSUPPORTTHEDESIGN TIMEENVIRON MENT6ISUAL3TUDIOSDESIGN TIMESUPPORTCREATESRESOURCEFILES ANDREADSANDWRITESRESOURCES IF you use the designer view. Visual Studio writes .resxFILESBYDEFAULT)MPLEMENTINGTHEDESIGN TIME support allows your custom resource provider to work inside Visual Studio and still support differ ent storage or schema. To implement the custom resource provider, begin with the factory class. Listing 5-1. The Entry Point Is a Simple Factory Class qoejcOuopai*Sa^*?kileh]pekj7 lq^he_oa]ha`_h]oo?qopkiNaokqn_aLnkre`anB]_pknu6Naokqn_aLnkre`anB]_pknu w lner]paopnejcpdaia7 lq^he_opnejcPdaia w capwnapqnjpdaia7y oapwpdaia9r]hqa7y y

lq^he_kranne`aENaokqn_aLnkre`an?na]paChk^]hNaokqn_aLnkre`an$opnejc_h]ooGau% w napqnjjas?qopkiNaokqn_aLnkre`an$jqhh(_h]ooGau(pdaia%7 y

lq^he_kranne`aENaokqn_aLnkre`an?na]paHk_]hNaokqn_aLnkre`an$opnejcrenpq]hL]pd% w napqnjjas?qopkiNaokqn_aLnkre`an$renpq]hL]pd(jqhh(pdaia%7 y y

Download at WoweBook.Com

201

202

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

This code shows how simple the factory is. It returns a custom resource provider for local and FORGLOBALRESOURCEACCESS)N,ISTING  THESAMEPROVIDERISUSEDFORBOTH ANDITDISTINGUISHES between access methods by supplying either the renpq]hL]pd or _h]ooGau parameter. Listing 5-2. The Provider with Theme-Based resx Support lq^he__h]oo?qopkiNaokqn_aLnkre`an6ENaokqn_aLnkre`an w _h]ooNaokqn_aPqlha w lq^he_Naokqn_aPqlha$ENaokqn_aNa]`anna]`an(ENaokqn_aSnepansnepan% w pdeo*Na]`an9na]`an7 pdeo*Snepan9snepan7 pdeo*?qhpqna9_e7 y lq^he_ENaokqn_aNa]`anNa]`an w cap7 oap7 y lq^he_ENaokqn_aSnepanSnepan w cap7 oap7 y y lner]paopnejcrenpq]hL]pd7 lner]paopnejcpdaia7 lner]pa^kkheoChk^]h7 lner]paop]pe_@e_pekj]nu8opnejc(± @e_pekj]nu8?qhpqnaEjbk(Naokqn_aPqlha::naokqn_a?]_da7 lq^he_?qopkiNaokqn_aLnkre`an$opnejcrenpq]hL]pd(opnejc_h]ooJ]ia(± opnejcpdaia% w eb$pdaia99jqhh%pdaia9@ab]qhp7 eb$Opnejc*EoJqhhKnAilpu$_h]ooJ]ia%% w pdeo*renpq]hL]pd9renpq]hL]pd7 eoChk^]h9b]hoa7 y ahoa w pdeo*renpq]hL]pd9_h]ooJ]ia7 eoChk^]h9pnqa7 y pdeo*pdaia9pdaia7 CapNaokqn_ao$%7 y lner]pa?qhpqnaEjbkCapJ]pera?qhpqna$?qhpqnaEjbk_qhpqna% w Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

eb$_qhpqna99jqhh% w _qhpqna9Ouopai*Pdna]`ejc*Pdna]`*?qnnajpPdna]`*?qnnajpQE?qhpqna7 y ++osep_dpk_kqjpnujaqpn]hl]najppkd]j`hah]jcq]caokjhu eb$_qhpqna*L]najp9?qhpqnaEjbk*Ejr]ne]jp?qhpqna% w _qhpqna9_qhpqna*L]najp7 y napqnj_qhpqna7 y lner]parke`CapNaokqn_ao$% w pnu w eb$naokqn_a?]_da99jqhh% w naokqn_a?]_da9jas@e_pekj]nu8opnejc(± @e_pekj]nu8?qhpqnaEjbk(Naokqn_aPqlha::$%7 y opnejcnacL]pd7 eb$eoChk^]h% w ++chk^]h nacL]pd97 y ahoa w ++hk_]h(TihNaokqn_aDahlaneoatlh]eja`ejjatpheopejc nacL]pd9TihNaokqn_aDahlan*CapHk_]hNaot>]oaL]pd$renpq]hL]pd(± pdaia%7 y ++jk_kjpatpia]jopd]pep#o_kilehapeia]j`sa`kj#poqllknppdeo eb$Dppl?kjpatp*?qnnajp99jqhh%napqnj7 ++na]`]hhnaokqn_aobkn]hh_qhpqnaobknpdeobeha opnejcbehpan9L]pd*CapBehaJ]ia$renpq]hL]pd%'&*naot7 eb$naokqn_a?]_da*?kjp]ejoGau$renpq]hL]pd%% w naokqn_a?]_daWrenpq]hL]pdY9jas@e_pekj]nu8?qhpqnaEjbk(± Naokqn_aPqlha:$%7 y bkna]_d$opnejcbehaej@ena_pknu*CapBehao$± L]pd*Cap@ena_pknuJ]ia$nacL]pd%(behpan%% w opnejcWYl]pdL]npo9L]pd*CapBehaJ]ia$beha%*Olhep$± **Pk?d]n=nn]u$%%7 ?qhpqnaEjbk_e9?qhpqnaEjbk*Ejr]ne]jp?qhpqna7 eb$l]pdL]npo*Hajcpd990% w ++At]ilha6Ej@ab]qhp*]olt*`a*naot9:W.Yeo`a _e9jas?qhpqnaEjbk$l]pdL]npoW.Y%7 y ++lanl]pd]j`lan_qhpqnasaopkna]na]`an]j`]snepan naokqn_a?]_daWrenpq]hL]pdY*=``$_e(± jasNaokqn_aPqlha$jas?qopkiNaokqn_aNa]`an$beha%(± jas?qopkiNaokqn_aSnepan$beha%%%7 Download at WoweBook.Com

203

204

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

y y _]p_d$At_alpekjat% w pdnksjas=llhe_]pekjAt_alpekj$at*Iaoo]ca(at%7 y y k^fa_pENaokqn_aLnkre`an*CapK^fa_p$opnejcnaokqn_aGau(?qhpqnaEjbk_qhpqna% w ENaokqn_aNa]`anna]`an9jqhh7 eb$_qhpqna99jqhh% w ++ebjkpatlhe_ephu`abeja`p]gakranl]ca#oQE_qhpqna _qhpqna9?qhpqnaEjbk*?qnnajpQE?qhpqna7 y `k w eb$naokqn_a?]_daWrenpq]hL]pdY*?kjp]ejoGau$_qhpqna%% w ++bkqj`ep ^na]g7 y ahoa w ++pnuj]pera_qhpqna _qhpqna9CapJ]pera?qhpqna$_qhpqna%7 y ++aj`kbb]hh^]_gl]pd eb$_qhpqna99?qhpqnaEjbk*Ejr]ne]jp?qhpqna%^na]g7 ysdeha$na]`an99jqhh%7 na]`an9naokqn_a?]_daWrenpq]hL]pdYW_qhpqnaY*Na]`an7 eb$na]`an9jqhh% w k^fa_pr]hqa9$$?qopkiNaokqn_aNa]`an%na]`an%*CapK^fa_p$naokqn_aGau%7 IeooD]j`han$nabr]hqa(naokqn_aGau%7 napqnjr]hqa7 y napqnjjqhh7 y ++capk^fa_pbnkigau]j`_qhpqna lq^he_k^fa_pCapNaotK^fa_p$opnejcnaokqn_aGau(?qhpqnaEjbk_qhpqna% w _qhpqna9CapJ]pera?qhpqna$_qhpqna%7 opnejcqjemqaGau9renpq]hL]pd7 NaoTNaokqn_aNa]`annn9jqhh7 k^fa_pr]hqa9jqhh7 ++cappda_]_da`k^fa_pkn_na]paep eb$Dppl?kjpatp*?qnnajp*?]_daWqjemqaGauY99jqhh% w qjemqaGau9TihNaokqn_aDahlan*CapNaotL]pd$qjemqaGau(pdaia(± renpq]hL]pd99jqhh(_qhpqna%7 eb$Opnejc*EoJqhhKnAilpu$qjemqaGau%%napqnjNAOT7 nn9jasNaoTNaokqn_aNa]`an$qjemqaGau%7 Dppl?kjpatp*?qnnajp*?]_daWqjemqaGauY9nn7 y Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

++Qoanaokqn_ana]`anpknapnearapdar]hqa nn9$NaoTNaokqn_aNa]`an%Dppl?kjpatp*?qnnajp*?]_daWqjemqaGauY7 E@e_pekj]nuAjqian]pkne`9nn*CapAjqian]pkn$%7 sdeha$e`*IkraJatp$%% w eb$Opnejc*?kil]na$e`*Gau*PkOpnejc$%(naokqn_aGau(pnqa%99,% w r]hqa9e`*R]hqa7 ^na]g7 y y ++_da_gsdapdanjkpdejcd]o^aajbkqj` IeooD]j`han$nabr]hqa(naokqn_aGau%7 ++napqnj napqnjr]hqa7 y lner]parke`IeooD]j`han$nabk^fa_pr]hqa(opnejcnaokqn_aGau% w ++?na]pa]cajane_r]hqaebnaokqn_ak^fa_peoieooejc eb$r]hqa99jqhh% w eb$naokqn_aGau*?kjp]ejo$*%% w r]hqa9Opnejc*Bkni]p$Ieooejc6w,y(naokqn_aGau%7 y ahoa w osep_d$naokqn_aGau*Oq^opnejc$naokqn_aGau*H]opEj`atKb$*%%% w _]oa*Reoe^ha6 r]hqa9pnqa7 ^na]g7 _]oa*Pkkhpel6 _]oa*PkkhPel6 r]hqa97 ^na]g7 `ab]qhp6 _]oa*Patp6 r]hqa9Opnejc*Bkni]p$Ieooejc6w,y(naokqn_aGau%7 ^na]g7 y y y eb$r]hqa99jqhh%pdnksjas=ncqiajpAt_alpekj$Qjatla_p]`hubkqj`± ]jqjnaokhr]^haieooejcnaokqn_a6'naokqn_aGau%7 y ENaokqn_aNa]`anENaokqn_aLnkre`an*Naokqn_aNa]`an w cap w eb$naokqn_a?]_da*?kjp]ejoGau$renpq]hL]pd%% w napqnjnaokqn_a?]_daWrenpq]hL]pdY± W?qhpqnaEjbk*Ejr]ne]jp?qhpqnaY*Na]`an7 y Download at WoweBook.Com

205

206

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

napqnjjqhh7 y y lq^he_ENaokqn_aSnepanNaokqn_aSnepan w cap w eb$naokqn_a?]_da*?kjp]ejoGau$renpq]hL]pd%% w napqnjnaokqn_a?]_daWrenpq]hL]pdY± W?qhpqnaEjbk*Ejr]ne]jp?qhpqnaY*Snepan7 y napqnjjqhh7 y y y The provider itself is not so simple. First, we need to define the storage location and storage handling. The solution used is based on .resx files. To improve performance, the provider retains a copy of the resources in an internal cache. This is global and therefore can be defined as static: op]pe_@e_pekj]nu8opnejc(@e_pekj]nu8?qhpqnaEjbk(Naokqn_aPqlha::naokqn_a?]_da7 This is a nested @e_pekj]nu. The key to the outer dictionary is the resource key, which is either the renpq]hL]pd to a local resource or the _h]ooJ]ia of a global one. For each resource, we need to handle multiple resource containers. There is one container per culture. The inner @e_pekj]nu contains these containers and employs the ?qhpqnaEjbk as the index to a particular container. The @e_pekj]nu value (the container) holds the appropriate reader and writer OBJECTS WHICHAREOFTYPE?qopkiNaokqn_aNa]`an and ?qopkiNaokqn_aSnepan. The Naokqn_aPqlha class ISANINNERHELPERCLASSTHATSTORESTHEREADERANDWRITEROBJECTSANDALLOWSTYPE SAFEACCESSTOTHEM The provider is instantiated on a per file basis. Each local resource (]olt as well as ]o_t files) creates one provider. The same happens for each global resource. In the CapNaokqn_ao method, the provider immediately constructs the cache. The Dppl?kjpatp*?qnnajp99jqhh check ensures that the provider is not active at both design and compile time. The provider searches a designated directory from the CapHk_]hNaot>]oaL]pd. This is a helper method specific to the required behavior. It creates the path to the *naot file based on both theme and local resource. In the example, the full path conforms to the pattern: =ll[@]p]+Naot+8Pdaia:+renpq]hL]pd+Naokqn_aBeha*8?qhpqna:*Naokqn_aPula The App_Data folder is defined as the storage location. The Resx subfolder ensures that there is no conflict with other data stored there. The part is a placeholder for the named theme. At a minimum, the default theme named “Default” must exist. The virtualPath is the path to the FILETHATUSESTHERESOURCEWITHINYOURPROJECTResourceFile is the name of the ]olt or ]o_t file, and these extensions define the ResourceType. A full path could look like this: =ll[@]p]+Naot+IuPdaia+opknaBnkjp+>]ogap*aj)qo*]olt =ll[@]p]+Naot+@ab]qhp+opknaBnkjp+>]ogap*aj)qo*]olt =ll[@]p]+Naot+IuPdaia+opknaBnkjp+>]ogap*`a*]olt =ll[@]p]+Naot+@ab]qhp+opknaBnkjp+>]ogap*`a*]olt These examples show how to store different resources for one file (>]ogap*]olt) for different themes and cultures. The fallback resource file—the one without any culture information—is han dled with the ?qhpqnaEjbk*Ejr]ne]jp?qhpqna key.

Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

Once the cache is populated and the provider is loaded, the runtime requests the provider for ASPECIFICRESOURCEOBJECTUSINGTHECapK^fa_p method. This method is passed a key and the culture. Since each resource store has its own provider (based on the renpq]hL]pd member), this is sufficient information to retrieve the correct value. The goal of this method is to implement the fallback strat egy. A `o)sdeha loop ascends the path of cultures to obtain an existing definition. Either it finds the invariant culture, or, as a final fallback, the default definition is used. You will need to create at least a default resource definition to avoid an exception being thrown if no resource is found. If the stored resources have been located, the CapK^fa_p method of the ?qopkiNaokqn_aNa]`an TYPEISCALLEDTOOBTAINTHERESOURCEREADERFORTHECURRENTCULTURE2EMEMBERTHATSUCHANOBJECT exists per culture. The resource reader does not know anything about cultures; it only returns the value based on the resource key. During the process of resource creation, translation, and storing, some values may get lost. In this case, the resource reader would return jqhh. The IeooD]j`han method checks the value to assure valid content. Depending on the property retrieved (“.Text,” “.Tooltip,” etc.), the method adds the prefix “Missing:”. This leads to a page that is shown without any exceptions, but with several text PORTIONSSUCHASh-ISSING,ABEL4EXTv!UTHORSCANRECOGNIZETHEMISSINGVALUESANDTHENAMEOF the corresponding control, including the property that’s not properly set. So far there is nothing unusual about this code. The final step is to implement the resource readerSEE,ISTING   Listing 5-3. The Resource Reader Used to Retrieve a Specific Resource Object lq^he__h]oo?qopkiNaokqn_aNa]`an6ENaokqn_aNa]`an w lner]paD]odp]^hanaokqn_ao7 lq^he_?qopkiNaokqn_aNa]`an$opnejcbehaJ]ia% w qoejc$NaoTNaokqn_aNa]`annn9jasNaoTNaokqn_aNa]`an$behaJ]ia%% w naokqn_ao9jasD]odp]^ha$%7 EAjqian]pknajq9nn*CapAjqian]pkn$%7 ajq*Naoap$%7 ++?]_daepej]D]odp]^ha sdeha$ajq*IkraJatp$%% w naokqn_ao*=``$$$@e_pekj]nuAjpnu%ajq*?qnnajp%*Gau*PkOpnejc$%(± $$@e_pekj]nuAjpnu%ajq*?qnnajp%*R]hqa%7 y y y E@e_pekj]nuAjqian]pknENaokqn_aNa]`an*CapAjqian]pkn$% w napqnjnaokqn_ao*CapAjqian]pkn$%7 y rke`ENaokqn_aNa]`an*?hkoa$%wy EAjqian]pknEAjqian]^ha*CapAjqian]pkn$% w napqnjnaokqn_ao*CapAjqian]pkn$%7 y rke`E@eolko]^ha*@eolkoa$% Download at WoweBook.Com

207

208

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

w y ejpanj]hk^fa_pCapK^fa_p$opnejcnaokqn_aGau% w napqnjnaokqn_aoWnaokqn_aGauY7 y y The resource reader is easy to implement because it still uses .resx files. The NaoTNaokqn_aNa]`an class from the Ouopai*Naokqn_a namespace provides almost everything we need. The only addition ISANOTHERINTERNALCACHE TOPROVIDERAPIDREAD WRITEACCESSTOTHEUNDERLYINGRESOURCESATRUNTIME This means that the resource reader must have read and write access to the .resx files. In the code, the NaoTNaokqn_aNa]`an loads each XML file, reads all the content, and copies it into the D]odp]^ha. (A D]odp]^ha is appropriate because the values are of type k^fa_p and a generic Heop would not have any advantages.) The class returns an enumerator used by the runtime to find keys. It also implements a CapK^fa_p method which retrieves the correct resource value using the D]odp]^ha indexer. At this point, the resource provider could start working if any required resource is present in the appropriate files. The following sections describe the usage scenarios. Refer to the section h)MPLEMENTING$ESIGN 4IME3UPPORTvFORMOREINFORMATIONABOUTADDITIONALTASKS SUCHAS

s %XTENDINGTHEPROVIDERBYIMPLEMENTINGAWRITER



s !DDINGSUPPORTFORTHEDESIGN TIMEEXPERIENCE



s !DDINGSUPPORTFORHANDLINGRESOURCESATBOTHDESIGN TIMEANDRUNTIME



s 2EPLACINGTHEPROVIDERTOACCESSADATABASETHATSTORESTHERESOURCES However, first we’ll put this into operation by starting the configuration step.

Configure the Resource Provider Since the provider is instantiated and called from a factory, registering the factory is a necessary step. This is a setting in the web.config file. In the 8ouopai*sa^: section, the following tag registers the custom factory: 8chk^]hev]pekjnaokqn_aLnkre`anB]_pknuPula9?qopkiNaokqn_aLnkre`anB]_pknu+: 7HETHERTOUSEJUSTTHECLASSNAMEORTHEFULLY QUALIFIEDASSEMBLYNAMEDEPENDSONTHEIMPLE MENTATION)FYOUWRITETHECLASSINASEPARATE6ISUAL3TUDIOPROJECT THEFULLY QUALIFIEDNAMEIS required.

Using the Custom Resource Provider Now that everything is implemented and configured, you can start using the resources at runtime. As you can see in the implementation, classes distinguish between local and global resources. For local resources, the key is the name of either the *]olt or *]o_t file. Internally, the renpq]hL]pd parameter retains this data. For global resources, the _h]ooGau parameter is used. To refer to these resources in your web pages, use the following expression format: 8! _h]ooGau6Naokqn_a!:

Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

Implementing Design-Time Support ImplementingDESIGN TIMESUPPORTISREQUIREDFORONEFEATUREONLY)N Visual Studio, you can add a resource’s meta attributes through the following:

s /PENAN]olt page or ]o_t control in the designer view.



s )NTHEh4OOLSvMENU CLICKTHEh'ENERATE,OCAL2ESOURCEvITEM

This will create a iap]6naokqn_agau attribute for each localizable element. The provider is responsible for creating the corresponding entry in the resource file and writing the current values there. However, our current provider supports runtime operations only, and therefore we need an additional provider forDESIGN TIMESUPPORT

NNote

If you’re sure that the Visual Studio design-time support option will never be used, you should not bother to implement the design-time support classes. But it won’t harm your code if you do build it.

Register the Design-Time Support First, you’llNEEDTOREGISTERTHEDESIGN TIMESUPPORT4HEREISNO such option in the web.config file; INSTEAD ANATTRIBUTEISREQUIRED9OUCANREGISTERYOURDESIGN TIMECLASSESBYDECORATINGTHEFACTORY class like this: W@aoecjPeiaNaokqn_aLnkre`anB]_pknu$± pulakb$?qopki@aoecjPeiaNaokqn_aLnkre`anB]_pknu%%Y lq^he_oa]ha`_h]oo?qopkiNaokqn_aLnkre`anB]_pknu6Naokqn_aLnkre`anB]_pknu The ?qopki@aoecjPeiaNaokqn_aLnkre`anB]_pknu type defines another factory used at ESIGN TIME4HISFACTORYISVERYSIMILARTOTHEONESHOWNEARLIER THEDIFFERENCEBEINGTHATTHE D DESIGN TIMESUPPORTREQUIRESSEVERALSPECIFICACTIONS

s 9OUDONTHAVEACURRENTTHEMEATDESIGN TIMEONLYONEPREDEFINEDTHEMECANBESUP ported (the default theme in the example code).



s 9OUDONTHAVEACCESSTODppl?kjpatp to resolve paths.



s 9OUDONTHAVEACURRENTCULTURE SOANYTHINGCREATEDATDESIGN TIMEISWRITTENINTOTHEFALL back resource file.

The factory derives from the @aoecjPeiaNaokqn_aLnkre`anB]_pknu base class. This abstract base class is defined as: lq^he_]^opn]_p_h]oo@aoecjPeiaNaokqn_aLnkre`anB]_pknu w lnkpa_pa`@aoecjPeiaNaokqn_aLnkre`anB]_pknu$%7 lq^he_]^opn]_pENaokqn_aLnkre`an?na]pa@aoecjPeiaChk^]hNaokqn_aLnkre`an$± EOanre_aLnkre`anoanre_aLnkre`an(opnejc_h]ooGau%7 lq^he_]^opn]_pENaokqn_aLnkre`an?na]pa@aoecjPeiaHk_]hNaokqn_aLnkre`an$± EOanre_aLnkre`anoanre_aLnkre`an%7 lq^he_]^opn]_pE@aoecjPeiaNaokqn_aSnepan?na]pa@aoecjPeiaHk_]hNaokqn_aSnepan$± EOanre_aLnkre`anoanre_aLnkre`an%7 y

Download at WoweBook.Com

209

210

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

As you can see, there are three methods and a constructor only. Two methods are similar to the runtime factory. They create and return the appropriate provider. The third method returns a resource writer. This writer explicitly supports the Visual Studio resource creation option available through the Tools menu. All these methods obtain the oanre_aLnkre`anPARAMETER4HEDESIGN TIMEENVIRONMENTISALSO highly extensible. Visual Studio doesn’t know anything about the various controls handled within THEDESIGNER)FITWERETOKNOW THENEVERYNEWORTHIRD PARTYCONTROLWOULDHAVETOBEINSTALLED and registered in Visual Studio. To avoid such a dependency, the control or the provider itself sup plies all features required by Visual Studio to operate well. To determine whether a specific feature is supported, a service provider pattern is used. The EOanre_aLnkre`an interface, implemented by Visual Studio, delivers a collection of services using its CapOanre_a method. The attached module or PLUG INREQUIRINGTHESESERVICESREQUESTSTHECapOanre_a method for a specific implementation. Finally, we’ll need access to the currently designed document. Visual Studio acts as a Designer Host, represented by the E@aoecjanDkop interface. To access it, request the service in this manner: E@aoecjanDkopdkop7 dkop9$E@aoecjanDkop%[oanre_aLnkre`an*CapOanre_a$pulakb$E@aoecjanDkop%%7 The idea behind this technique is that there is no direct dependency between the provider and the host. If you use another host—not Visual Studio—that is well implemented, your provider should still work. These methods also break the dependency on specific assemblies deployed with Visual Studio. Otherwise, when your code runs on a server, it would require Visual Studio to be installed there—a completely unreasonable prospect. Once you have the designer host, you can ask for the current root document. Sa^BknioNkkp@aoecjannkkp@aoecjan7 nkkp@aoecjan9dkop*Cap@aoecjan$dkop*Nkkp?kilkjajp%]oSa^BknioNkkp@aoecjan7 This type is from Ouopai*Sa^*QE*@aoecj and does not depend on Visual Studio. Using the @k_qiajpQnh property, you have the full name of the file currently open in the designer view without any direct access to Visual Studio. 7ITHALLTHESETECHNIQUESINMIND ITSTIMETOCREATETHEDESIGN TIMEFACTORY ASSHOWNIN ,ISTING  Listing 5-4. The Design-Time Factory Implementation lq^he_oa]ha`_h]oo?qopki@aoecjPeiaNaokqn_aLnkre`anB]_pknu6± @aoecjPeiaNaokqn_aLnkre`anB]_pknu w lner]pa@aoecjPeiaNaokqn_aLnkre`anchk^]hNaokqn_aLnkre`an7 lner]pa@aoecjPeiaNaokqn_aLnkre`anhk_]hNaokqn_aLnkre`an7 lner]pa?qopki@aoecjPeiaNaokqn_aSnepanhk_]hNaokqn_aSnepan7 lner]paopnejc[nkkp@k_qiajp7 lq^he_kranne`aENaokqn_aLnkre`an?na]pa@aoecjPeiaChk^]hNaokqn_aLnkre`an$± EOanre_aLnkre`anoanre_aLnkre`an(opnejc_h]ooGau% w ++Napqnj]jENaokqn_aLnkre`an* eb$chk^]hNaokqn_aLnkre`an99jqhh% w chk^]hNaokqn_aLnkre`an9jas@aoecjPeiaNaokqn_aLnkre`an$_h]ooGau(± oanre_aLnkre`an%7 y [nkkp@k_qiajp9chk^]hNaokqn_aLnkre`an*Nkkp@k_qiajp7 napqnjchk^]hNaokqn_aLnkre`an7 y Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

lq^he_kranne`aENaokqn_aLnkre`an?na]pa@aoecjPeiaHk_]hNaokqn_aLnkre`an$± EOanre_aLnkre`anoanre_aLnkre`an% w ++Napqnj]jENaokqn_aLnkre`an eb$hk_]hNaokqn_aLnkre`an99jqhh% w hk_]hNaokqn_aLnkre`an9jas@aoecjPeiaNaokqn_aLnkre`an$oanre_aLnkre`an%7 y napqnjhk_]hNaokqn_aLnkre`an7 y lq^he_kranne`aE@aoecjPeiaNaokqn_aSnepan?na]pa@aoecjPeiaHk_]hNaokqn_aSnepan$± EOanre_aLnkre`anoanre_aLnkre`an% w eb$hk_]hNaokqn_aSnepan99jqhh% w ++Cappdadkop(qoq]hhuReoq]hOpq`ek E@aoecjanDkopdkop9$E@aoecjanDkop%± oanre_aLnkre`an*CapOanre_a$pulakb$E@aoecjanDkop%%7 ++Cappda`aoecjan_qnnajphunalnaoajpopda`aoecjreas Sa^BknioNkkp@aoecjannkkp@aoecjan9dkop*Cap@aoecjan$dkop*Nkkp?kilkjajp%± ]oSa^BknioNkkp@aoecjan7 ++Napnearapdahk_]hQNHkbpdabeha_qnnajphuklaja`ejpda`aoecjan [nkkp@k_qiajp9nkkp@aoecjan*@k_qiajpQnh7 eb$[nkkp@k_qiajp9jqhh% w ++?na]papdanaokqn_asnepanbknpdeobeha hk_]hNaokqn_aSnepan9± jas?qopki@aoecjPeiaNaokqn_aSnepan$[nkkp@k_qiajp%7 y y napqnjhk_]hNaokqn_aSnepan7 y y 4HEFACTORYRETURNSBOTHAGLOBALANDALOCALDESIGN TIMERESOURCEPROVIDER3INCEWECANT access global resources in the Visual Studio environment, it’s the same provider class in both cases. Future versions or other applications might behave differently, and the class design is ready for this. However, the ?na]pa@aoecjPeiaHk_]hNaokqn_aSnepan method is of more interest to us. This method has a oanre_aLnkre`an parameter containing the current designer host. As shown before, retrieving the URL of the current document is easy with the right services. If you’d like to extend the behavior, it’s a good idea to investigate the options by looking into THEPROVIDEROBJECTS Ouopai*?kilkjajpIk`ah*@aoecj*@aoecjanDkopPROVIDESTHEFOLLOWINGPROPERTIESOUT OF THE BOX

s Pn]jo]_pekj@ao_nelpekj: This returns the transaction invoked from the user’s action, which is usually the “Generate Local Resource” string. That means that you can determine exactly what led to the call.



s Nkkp?kilkjajp4HEROOTSFORTHECURRENTTRANSACTION WHETHERITS0AGEOR#ONTROLORANY derived type currently open in the designer surface. You might modify your action after recognizing the type.

Download at WoweBook.Com

211

212

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L



s ?qnnajp?qhpqna4HECULTURERUNBYTHEDESIGN TIMEHOST WHICHISUSUALLYTHECULTUREOFTHE operating system. You might decide not to write a default fallback resource but instead write THESPECIFIEDCULTURE6ISUAL3TUDIOCURRENTLYHASNOOPTIONTOSETTHECULTURE BUTLATER versions might support this.



s Eo@aoecjanReasHk_ga`: Returns either pnqa or b]hoaDEPENDINGONIFTHEDESIGN TIMESURFACE is actually writeable.



s EoHk]`ejc: Must return b]hoa; otherwise, the control is not completely loaded.



s Nabanaj_aI]j]can: Returns the Ie_nkokbp*Sa^*@aoecj*Nabanaj_aI]j]can type. This type allows access to the
There are several methods to modify a document file by accessing the controls in it. However, these are beyond the scope of this chapter and left for you to investigate further. Another access method is more valuable to us. Besides the EOanre_aLnkre`an interface, the PARAMETEROBJECTALSOIMPLEMENTSOuopai*Sa^*QE*@aoecj*ESa^Bknio@k_qiajpOanre_a: lq^he_ejpanb]_aESa^Bknio@k_qiajpOanre_a w opnejc@k_qiajpQnhwcap7y ^kkhEoHk]`ejcwcap7y arajpArajpD]j`hanHk]`?kilhapa7 k^fa_p?na]pa@eo_]n`]^haQj`kQjep$%7 rke`@eo_]n`Qj`kQjep$k^fa_p`eo_]n`]^haQj`kQjep%7 rke`Aj]^haQj`k$^kkhaj]^ha%7 rke`Ql`]paOaha_pekj$%7 y Direct access to the @k_qiajpQnh is the most important feature. In fact, this property does not RETURNTHE52,BUTTHEFULLLOCALPATHATDESIGN TIME4HISISEXACTLYWHATWENEED4HEINTERFACEALSO allows some interaction with undo management.

NCaution

The ESa^Bknio@k_qiajpOanre_a interface is marked as obsolete. Presumably Microsoft is going to transform the interface into its designated successor Sa^BknioNkkp@aoecjan. Actually, there is no information available as to when and with what consequences this will happen, but keep an eye on it.

4HEDESIGN TIMERESOURCEPROVIDERHASSUPPORTFORBOTHREADINGTHECURRENTRESOURCEAT ESIGN TIMEASWELLASWRITINGFROMTHEDESIGNERSURFACEUSINGTHEAPPROPRIATECOMMAND)TTHERE D fore implements two interfaces, ENaokqn_aLnkre`an and E@aoecjPeiaNaokqn_aSnepan,ISTING  shows the whole implementation. Listing 5-5. The Complete Implementation of the Design-Time Resource Provider ejpanj]hoa]ha`_h]oo@aoecjPeiaNaokqn_aLnkre`an6± ENaokqn_aLnkre`an(E@aoecjPeiaNaokqn_aSnepan w lner]paNaoTNaokqn_aSnepan[snepan9jqhh7 lner]paNaoTNaokqn_aNa]`an[na]`an9jqhh7 lner]paopnejc[nkkp@k_qiajp7

Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

ejpanj]hopnejcNkkp@k_qiajp w capwnapqnj[nkkp@k_qiajp7y y lq^he_@aoecjPeiaNaokqn_aLnkre`an$EOanre_aLnkre`anoanre_aLnkre`an%6± pdeo$jqhh(oanre_aLnkre`an% w y lq^he_@aoecjPeiaNaokqn_aLnkre`an$opnejc_h]ooGau(± EOanre_aLnkre`anoanre_aLnkre`an% w ++Cappdabknio`aoecjanlnkre`a`^uReoq]hOpq`ek ESa^Bknio@k_qiajpOanre_abknio@aoecjan9± oanre_aLnkre`an*CapOanre_a$pulakb$ESa^Bknio@k_qiajpOanre_a%%± ]oESa^Bknio@k_qiajpOanre_a7 eb$bknio@aoecjan99jqhh% w pdnksjasJqhhNabanaj_aAt_alpekj$ESa^Bknio@k_qiajpOanre_aeojqhh%7 y [nkkp@k_qiajp9bknio@aoecjan*@k_qiajpQnh7 y k^fa_pENaokqn_aLnkre`an*CapK^fa_p$opnejcnaokqn_aGau(?qhpqnaEjbk_qhpqna% w eb$[na]`an99jqhh% w pdnks± jasJqhhNabanaj_aAt_alpekj$ENaokqn_aLnkre`an66Naokqn_aNa]`an66JQHH%7 y k^fa_pk9jqhh7 E@e_pekj]nuAjqian]pkne`a9[na]`an*CapAjqian]pkn$%7 sdeha$e`a*IkraJatp$%% w eb$e`a*Gau*PkOpnejc$%*PkHksanEjr]ne]jp$%*Amq]ho$± naokqn_aGau*PkHksanEjr]ne]jp$%%% w k9e`a*R]hqa7 ^na]g7 y y napqnjk7 y ENaokqn_aNa]`anENaokqn_aLnkre`an*Naokqn_aNa]`an w cap w eb$[na]`an99jqhh% w [na]`an9jasNaoTNaokqn_aNa]`an$± TihNaokqn_aDahlan*CapEjr]ne]jpNaotL]pd=p@aoecjPeia$± [nkkp@k_qiajp%%7 ++lnal]nao]iabknsnepejc [snepan9jasNaoTNaokqn_aSnepan$± TihNaokqn_aDahlan*CapEjr]ne]jpNaotL]pd=p@aoecjPeia$± [nkkp@k_qiajp%%7 Download at WoweBook.Com

213

214

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

y eb$[na]`an9jqhh% w napqnj[na]`an7 y ahoa w pdnksjasAt_alpekj$ENaokqn_aLnkre`an66Naokqn_aNa]`an66JQHH%7 y y y opnejcE@aoecjPeiaNaokqn_aSnepan*?na]paNaokqn_aGau$opnejcnaokqn_aJ]ia(± k^fa_pk^f% w $$ENaokqn_aSnepan%pdeo%*=``Naokqn_a$naokqn_aJ]ia(k^f%7 napqnjnaokqn_aJ]ia7 y rke`ENaokqn_aSnepan*=``Naokqn_a$opnejcj]ia(^upaWYr]hqa% w [snepan*=``Naokqn_a$j]ia(r]hqa%7 y rke`ENaokqn_aSnepan*=``Naokqn_a$opnejcj]ia(k^fa_pr]hqa% w [snepan*=``Naokqn_a$j]ia(r]hqa%7 y rke`ENaokqn_aSnepan*=``Naokqn_a$opnejcj]ia(opnejcr]hqa% w [snepan*=``Naokqn_a$j]ia(r]hqa%7 y rke`ENaokqn_aSnepan*Cajan]pa$% w [snepan*Cajan]pa$%7 y rke`ENaokqn_aSnepan*?hkoa$% w [snepan*?hkoa$%7 y rke`E@eolko]^ha*@eolkoa$% w [snepan*?hkoa$%7 [snepan*@eolkoa$%7 y y This implementation must support both the writing of resources when the user generates the local resource file as well as the reading of current resources when the file is opened for the first time in the designer surface. The full path to the currently loaded file is retrieved in the constructor by obtaining the ESa^Bknio@k_qiajpOanre_a interface: oanre_aLnkre`an*CapOanre_a$pulakb$ESa^Bknio@k_qiajpOanre_a%% Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

The @k_qiajpQnhPROPERTYWILLRETURNWHATYOUNEED4HEDESIGN TIMEENVIRONMENTWILLUSETHE ENaokqn_aLnkre`an*Naokqn_aNa]`an property first to retrieve the current values. In previous code, I cre ated the reader as well as the writer because the function’s intention is to retrieve and write the values back. The helper class TihNaokqn_aDahlan is a private implementation that collects several methods NEEDEDINBOTHTHEDESIGN TIMEANDRUNTIMEPROVIDER)VECALLEDCapEjr]ne]jpNaotL]pd=p@aoecjPeia to obtain the full path of the .resx file. As mentioned, the provider only supports the Default theme. 4HEMETHODPOINTSTOTHEPATHSSHOWNATTHEBEGINNINGOFTHESECTIONINAHARD CODEDMANNER9OU CANFINDTHEFULLIMPLEMENTATIONOFTHECLASSIN,ISTING  Listing 5-6. Helper Class to Simplify Developers’ Life ejpanj]hop]pe__h]ooTihNaokqn_aDahlan w lner]pa_kjopopnejc@AOECJPEIA[PDAIA9@ab]qhp7 lner]paop]pe_na]`kjhu_d]nWYPNEI?D=NO9+*Pk?d]n=nn]u$%7 ++Pda^]oal]pd]__kn`ejcpkpdaat]ilha#onamqenaiajpo lner]paop]pe_opnejc>]oaL]pd w cap w eb$Dppl?kjpatp*?qnnajp99jqhh% w napqnj+=ll[@]p]+Naot+7 y ahoa w napqnjDppl?kjpatp*?qnnajp*Oanran*I]lL]pd$z+=ll[@]p]+Naot%'± L]pd*@ena_pknuOal]n]pkn?d]n7 y y y ++bqhhl]pd]p`aoecj)peia]j`nqjpeia lq^he_op]pe_opnejcCapBqhhL]pd$opnejcnacqh]nL]pd(opnejcpdaia(^kkhchk^]h% w eb$Opnejc*EoJqhhKnAilpu$pdaia%%pdnksjas=ncqiajpJqhhAt_alpekj$pdaia%7 opnejcl]pd97 eb$Dppl?kjpatp*?qnnajp99jqhh% w ++]ooqia_kilehapeia l]pd9CapEjr]ne]jpNaotL]pd=p@aoecjPeia$nacqh]nL]pd%7 y ahoa w pnu w ++Pneipdal]pd nacqh]nL]pd9Nacat*Nalh]_a$nacqh]nL]pd(± Dppl?kjpatp*?qnnajp*Namqaop*± =llhe_]pekjL]pd*PneiOp]np$PNEI?D=NO%(± (± NacatKlpekjo*Ecjkna?]oa%7 eb$chk^]h% w Download at WoweBook.Com

215

216

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

l]pd9Opnejc*Bkni]p$w,yw-y[Chk^]h(>]oaL]pd(pdaia(± nacqh]nL]pd%7 y ahoa w l]pd9Opnejc*Bkni]p$w,yw-yw.y(>]oaL]pd(pdaia(nacqh]nL]pd%7 y y _]p_d$At_alpekjat% w pdnksjasAt_alpekj$at*Iaoo]ca'at*Op]_gPn]_a%7 y y napqnjl]pd7 y ++Cappdahk_]hl]pdpkbehabknpdaia`l]canaokqn_ao lq^he_op]pe_opnejcCapHk_]hNaot>]oaL]pd$opnejcl]caE`(opnejcpdaia% w eb$Opnejc*EoJqhhKnAilpu$l]caE`%% w l]caE`97 y ahoa w l]caE`9Nacat*Nalh]_a$l]caE`(± DpplNqjpeia*=ll@ki]ej=llRenpq]hL]pd*PneiOp]np$PNEI?D=NO%((± NacatKlpekjo*Ecjkna?]oa%7 y l]caE`9l]caE`*Nalh]_a$**(*%*PneiOp]np$PNEI?D=NO%*Nalh]_a$#+#(± L]pd*@ena_pknuOal]n]pkn?d]n%7 ++i]_dejaj]ia`alaj`]jp]^okhqpal]pd opnejcbeha9Opnejc*?kj_]p$>]oaL]pd(Opnejc*Bkni]p$w,yw.yw-y(pdaia(± l]caE`(L]pd*@ena_pknuOal]n]pkn?d]n%%7 napqnjbeha7 y ++O_]bbkh`behaj]iapknaotbehabnkicerajejbkni]pekj lq^he_op]pe_opnejcCapNaotL]pd$opnejcl]caE`(opnejcpdaia(^kkhchk^]h% w l]caE`9Nacat*Nalh]_a$l]caE`(± DpplNqjpeia*=ll@ki]ej=llRenpq]hL]pd*PneiOp]np$PNEI?D=NO%((± NacatKlpekjo*Ecjkna?]oa%7 opnejcbeha9L]pd*?ki^eja$>]oaL]pd(Opnejc*Bkni]p$w,yw.yw/yw-y*naot(± pdaia(l]caE`($chk^]h%;[Chk^]h6(± L]pd*@ena_pknuOal]n]pkn?d]n%%7 eb$Beha*Ateopo$beha%% w pdnksjasBehaJkpBkqj`At_alpekj$Pdanaotbeha`kaojkp± ateopoWCapEjr]ne]jpNaotL]pdY(beha%7 y napqnjbeha7 y lq^he_op]pe_opnejcCapNaotL]pd$opnejcl]caE`(opnejcpdaia(^kkhchk^]h(± ?qhpqnaEjbk_e% w Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

l]caE`9Nacat*Nalh]_a$l]caE`(± DpplNqjpeia*=ll@ki]ej=llRenpq]hL]pd*PneiOp]np$PNEI?D=NO%((± NacatKlpekjo*Ecjkna?]oa%7 opnejcbeha9L]pd*?ki^eja$>]oaL]pd(Opnejc*Bkni]p$w,yw.yw/yw-y*w0y*naot( pdaia(± l]caE`(± $chk^]h%;[Chk^]h6(± L]pd*@ena_pknuOal]n]pkn?d]n(± _e*J]ia%%7 eb$Beha*Ateopo$beha%% w pdnksjasBehaJkpBkqj`At_alpekj$Pdanaotbeha`kaojkp± ateopoWCapEjr]ne]jpNaotL]pdY(beha%7 ++?na]paBehaEbJkpAteopo$beha%7 y napqnjbeha7 y ++O_]bbkh`pdab]hh^]_gnaokqn_abehaj]iahk_]hhu]p`aoecj)peia lq^he_op]pe_opnejcCapEjr]ne]jpNaotL]pd=p@aoecjPeia$opnejcl]caL]pd% w ++bqhhl]pdpkbeha(jaa`pkcapnaotpkejr]ne]jpbnkipdeo Qneqne9jasQne$l]caL]pd%7 opnejcl]pd9qne*Hk_]hL]pd7 opnejcbeha9Opnejc*Bkni]p$w,yw.yw/yw0yw.yw-y*naot( L]pd*Cap@ena_pknuJ]ia$l]pd%( L]pd*CapBehaJ]ia$l]pd%( L]pd*@ena_pknuOal]n]pkn?d]n( >]oaL]pd( @AOECJPEIA[PDAIA%7++]p`aoecj)peia=ll[@]p]+Naot+@ab]qhp eb$Beha*Ateopo$beha%% w ?na]paBehaEbJkpAteopo$beha%7 y napqnjbeha7 y ++?na]pabehaebkjajkpateopo lner]paop]pe_rke`?na]paBehaEbJkpAteopo$opnejcl]pd% w eb$@ena_pknu*Ateopo$L]pd*Cap@ena_pknuJ]ia$l]pd%%% w @ena_pknu*?na]pa@ena_pknu$L]pd*Cap@ena_pknuJ]ia$l]pd%%7 y ++QoaNaoTNaokqn_anSnepanpk_na]papda`ab]qhpnaotbkni]p Ouopai*Naokqn_ao*NaoTNaokqn_aSnepanNsT9± jasOuopai*Naokqn_ao*NaoTNaokqn_aSnepan$l]pd%7 NsT*Cajan]pa$%7 NsT*?hkoa$%7 y aj`nacekj y 4HEVARIOUSPATHOPERATIONSAREADRAWBACKOFTHEFILE BASEDSOLUTION(OWEVER ADATABASE DRIVENPROJECTMIGHTNEEDADDITIONALWORKTOSUPPORTDATABASEACCESSATDESIGN TIME&ORTHE DESIGN TIMEPORTION THECapEjr]ne]jpNaotL]pd=p@aoecjPeia method is required. Because the Qne Download at WoweBook.Com

217

218

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

is built like any web Qne, it must be resolved and converted into a local file path. A bit of string con catenation will do the trick. If the file is not present, it will be created on the fly; this is the default behavior of Visual Studio. The creation of resource files is simple. The NaoTNaokqn_aSnepan class provides a Cajan]pa METHODTHATCREATESAFILEWITHUNPLEASANTCOMMENTSANDSCHEMACODES#ALLING?hkoa flushes the CONTENTBACKTODISKSEE&IGURE  

Figure 5-3. Resx files contain a comment (closed) and a full schema description. The CapNaotL]pd method is called at compile time. The compiler needs to resolve the implicit expressions that define resources. To determine what values are required to be placed in the page, use the resource provider again. Since neither the Dppl?kjpatpNORTHEDESIGN TIMEHOSTEXISTATTHIS point, instead use the DpplNqjpeia*=ll@ki]ej=llRenpq]hL]pd property. The virtual path is defined at this stage and enables file paths to be resolved. The helper class is used to change the format slightly to meet our needs.

Debugging Design-Time Extensions $ESIGN TIMESUPPORT should be part of any extension model. However, the difficulty of debugging THESEEXTENSIONSISPROBABLYTHEREASONWHYDEVELOPERSAVOIDADDINGDESIGN TIMESUPPORTTOTHEIR Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

APPLICATIONS!TDESIGN TIME THEREISNODEBUGGERATTACHED4HEREFORE YOUCANNOTEASILYADDBREAK points or step into the code to see the internal processes. Using smart exceptions and try/catch blocks might help, but this is not a good debugging experience. 4ODEBUGWITHINTHE6ISUAL3TUDIODESIGN TIMEENVIRONMENT YOUMUSTOPENANOTHERINSTANCE OF6ISUAL3TUDIOANDDEBUGTHECODETHERE4ODOTHIS OPENTHEPROPERTYPAGESOFTHE7EBPROJECT and activate the option Start external programSEE&IGURE  

Figure 5-4. Start another instance of Visual Studio to debug at design-time. As the external program, choose the Visual Studio executable, devenv.exe. When you start DEBUGGINGTHEPROJECTBYHITTING& ANOTHERINSTANCEOF6ISUAL3TUDIOAPPEARS,OADTHESAMEPROJ ECTINTHISINSTANCEANDLAUNCHTHEDESIGN TIMEENVIRONMENT9OUCANNOWSETBREAKPOINTSINTHE first instance and debug as you would do at runtime. To get to specific code sections,JUSTSTARTUSING the code within the second instance.

Edit Resources at Runtime Now that we have flexible access to the resources, it is easy to implement additional options. Imag ine a complex site that contains hundreds or thousands of resources. Several authors add content, CHANGECONTENT ANDADDNEWLANGUAGES$OINGSOIN8-,FILESISVERYINEFFICIENT#ONSIDERALSOTHE way translators usually work. Good translators might handle the content well, but dealing with XML is not their area of proficiency. Deploying a separate application to support their translation work introduces additional complications. Text portions often require a different translation depending on the context in which they appear. This context is lost when translating fragments of a sentence or single words. Editing content online would be a better option. However, handling resources the standard way (in files) and compiling them into binary resources precludes the saving of new content into the resources. In this section, I demonstrate how to use an extended resource provider model to access resource files online—anytime.

How It Works In the previous sections, we looked at a different storage model. The provider still relays the files, but the file structure and availability is much more flexible. Most importantly, we have total con trol over it. To have access at runtime, a service must be able to open each .resx file, write new or changed content into it, and close the file.

Download at WoweBook.Com

219

220

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

The only disadvantage with the provider reading the data directly from the .resx files is: how can we continue to use caching to improve performance? There are several options. For example, you could recognize the editing mode and suppress caching while editing. Alternatively, you could add a refresh button or link that forces the cache to be destroyed. Both options are easy to implement, but beyond the scope of this chapter. To access the resources from the client, we must find a way of communicating between the browser and the server. A Web Service and JavaScript could achieve this. As you only need JavaScript when editing pages—not when merely viewing pages—it’s a good idea to have a special master page containing all the JavaScript functions. From the perspective of the application, you’ll need to create the following functions:

s 2ETRIEVESUPPORTEDLANGUAGESANDDELIVERASA7EB3ERVICE



s 2ETRIEVERESOURCESFORTHECURRENTPAGEANDLANGUAGEFROMTHE7EB3ERVICE



s 7RITEDATABACKTOTHE7EB3ERVICETOSTOREINTHEAPPROPRIATE.resx file.



s %XTENDTHEPAGETOSUPPORTTHEEDITINGOFTHEELEMENTSONACONTROL BY CONTROLBASIS



s #REATEANEDITORTOALLOWEDITINGTHECONTROLSCONTENTONTHECLIENT The client portion is written in JavaScript, which has several functions:



s #REATEANEDITORTOEDITPARTSOFAPAGE



s ,OADCURRENTRESOURCEDATAFROMTHESERVER



s 3AVECHANGEDCONTENTBACKTOTHESERVER



s #HANGETHECURRENTLYEDITEDLANGUAGE )N,ISTING  )STORETHESUPPORTEDLANGUAGESINANOTHER8-,FILE CALLEDCultures.xml.

Listing 5-7. The Supported Cultures Stored As XML 8;tihranoekj9-*,aj_k`ejc9qpb)4;: 8?qhpqnao: 8?qhpqnaEjbkj]ia9Ajcheode`9aj)Qo+: 8?qhpqnaEjbkj]ia9@aqpo_de`9`a)@a+: 8?qhpqnaEjbkj]ia9Ep]he]jke`9ep)Ep+: 8+?qhpqnao: The Web Service method exposes this content to the client. To cache this information, I store THEDATADURINGTHEAPPLICATIONSTARTSEE,ISTING   Listing 5-8. Retrieve Supported Cultures on Application Start rke`=llhe_]pekj[Op]np$k^fa_poaj`an(Arajp=ncoa% w T@k_qiajptih@k_9T@k_qiajp*Hk]`$L]pd*?ki^eja$Oanran*I]lL]pd$z+=ll[@]p]%(± ?qhpqnao*tih%%7 r]n_qhpqnao9bnki_ejtih@k_*@ao_aj`]jpo$?qhpqnaEjbk%± oaha_pjas?qhpqnaEjbk$_*=ppne^qpa$e`%*R]hqa%7 =llhe_]pekjW_qhpqnaoY9_qhpqnao*PkHeop8?qhpqnaEjbk:$%7 y 4HESERVICESMETHODTRANSFORMSTHISINTOASERIALIZABLEOBJECTTHATISEASYTOREADONTHECLIENT &IRST WENEEDA7EB3ERVICECLASSWITHTHEFOLLOWINGDEFINITIONSEE,ISTING  

Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

Listing 5-9. The Web Service’s Class Head WO_nelpOanre_a$%Y WSa^Oanre_a$J]iaol]_a9dppl6++sss*]lnaoo*_ki+so%Y WCajan]paO_nelpPula$pulakb$?qhpqnao%%Y WSa^Oanre_a>ej`ejc$?kjbknioPk9SoeLnkbehao*>]oe_Lnkbeha-[-%Y lq^he__h]ooNaokqn_aOanre_a6Ouopai*Sa^*Oanre_ao*Sa^Oanre_a w ?qopkiNaokqn_aLnkre`anB]_pknunb7 lq^he_Naokqn_aOanre_a$% w nb9jas?qopkiNaokqn_aLnkre`anB]_pknu$%7 y *** y This definition makes the code available for JavaScript pages and defines a private data type, ?qhpqnao ASSHOWNIN,ISTING !DDITIONALLY THECONSTRUCTORPREPARESTHEFACTORYWECREATED EARLIERINTHESECTIONh)MPLEMENTINGTHE#USTOM0ROVIDERvTOOBTAINACCESSTOTHERESOURCES4HIS MEANSTHATTHEMAJORITYOFCODEISINTHEEXISTINGCLASSES ANDLEAVESUSWITHONLYAFEWTASKS Listing 5-10. The Supported Cultures Exposed Via a Service WSa^Iapdk`$%Y lq^he_?qhpqnaoCap=hhH]jcq]cao$% w Heop8?qhpqnaEjbk:_Heop9$Heop8?qhpqnaEjbk:%=llhe_]pekjW_qhpqnaoY7 ?qhpqnao_9jas?qhpqnao$_Heop*?kqjp%7 bkn$ejpe9,7e8_Heop*?kqjp7e''% w _*_qhpqnaJ]iaWeY9_HeopWeY*@eolh]uJ]ia7 _*_qhpqnaE@WeY9_HeopWeY*J]ia7 y napqnj_7 y WOane]hev]^ha$%Y lq^he__h]oo?qhpqnao w lq^he_?qhpqnao$%6pdeo$.% w y lq^he_?qhpqnao$ejphaj% w pdeo*haj9haj7 _qhpqnaJ]ia9jasopnejcWhajY7 _qhpqnaE@9jasopnejcWhajY7 y lq^he_opnejcWY_qhpqnaJ]ia7 lq^he_opnejcWY_qhpqnaE@7 lq^he_ejphaj7 y

Download at WoweBook.Com

221

222

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

The remaining tasks required of the Web Service are coded in two methods—Hk]`Naokqn_a and O]raNaokqn_a. Both receive four parameters:

s l]caE`: The name of the resource file, which names the ]olt or ]o_t file.



s _pnhE`: The Id of the control requesting the resource. This includes the property name, such as Label1Resource1.Text.



s _qhpqna4HEIDOFTHECULTURE SUCHAShEN USvORhDE DEv



s pdaia: The current theme that the resource is written to or read from. This is the special exten sion, as explained at the beginning of the chapter in the section “Extending the Provider Model.” If themed resources are not a requirement, you can safely remove this parameter.

,ISTING ILLUSTRATESTHEMETHODS4HEO]raNaokqn_a method has one additional parameter called _kjpajp that contains the data to be written into the resource file. The Hk]`Naokqn_a method returns exactly that value using the same parameters. Listing 5-11. Web Methods to Load and Save Resources Directly from the Client WSa^Iapdk`$%Y lq^he_opnejcHk]`Naokqn_a$opnejcl]caE`(opnejc_pnhE`(± opnejc_qhpqna(opnejcpdaia% w l]caE`9l]caE`*Nalh]_a$z(%7 nb*Pdaia9pdaia7 ENaokqn_aLnkre`annl9nb*?na]paHk_]hNaokqn_aLnkre`an$l]caE`%7 k^fa_pr]hqa9$$?qopkiNaokqn_aLnkre`an%nl%*CapNaotK^fa_p$± _pnhE`(jas?qhpqnaEjbk$_qhpqna%%7 napqnj$r]hqa99jqhh%;Opnejc*Ailpu6r]hqa*PkOpnejc$%7 y WSa^Iapdk`$%Y lq^he_rke`O]raNaokqn_a$opnejcl]caE`(opnejc_pnhE`(± opnejc_kjpajp(opnejc_qhpqna(opnejcpdaia% w l]caE`9l]caE`*Nalh]_a$z(%7 nb*Pdaia9pdaia7 ENaokqn_aLnkre`annl9nb*?na]paHk_]hNaokqn_aLnkre`an$l]caE`%7 ?qhpqnaEjbk_e9jas?qhpqnaEjbk$_qhpqna%7 $$?qopkiNaokqn_aLnkre`an%nl%*CapNaokqn_aSnepan$_e%*=``Naokqn_a$_pnhE`(± _kjpajp%7 y There are some additional steps required. To display and enable the editor, you’ll need to pre pare the page. To avoid including all the JavaScript in the page, another master page is used. With two different master pages, you can decide which one to use, depending on whether the page is DISPLAYEDINEDITMODEORNOT#HANGINGTHEMASTERPAGEDYNAMICALLYREQUIRESACCESSTOTHEPAGES LnaEjep eventSEE,ISTING   Listing 5-12. Changing the Master Page and Theme Programmatically lq^he_l]npe]h_h]oo[@ab]qhp6>]oaL]ca lnkpa_pa`kranne`arke`KjLnaEjep$Arajp=ncoa% w ^]oa*KjLnaEjep$a%7 ++OapA`epkn$ola_e]hd]j`hejc^aukj`pda`ki]ejo_kla% Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

eb$Namqaop*MqanuOpnejcWaY9jqhh""Namqaop*MqanuOpnejcWaY99kj% w OaooekjWA`epknY9pnqa7 y eb$Namqaop*MqanuOpnejcWaY9jqhh""Namqaop*MqanuOpnejcWaY99kbb% w OaooekjWA`epknY9jqhh7 y opnejc`ki]ej9Namqaop*Qnh*Dkop7 ++Oap@uj]ie_Pdaiejc]j`I]opanL]cao eb$OaooekjWA`epknY9jqhh% w I]opan*I]opanL]caBeha9a`epkn*i]opan7 y ahoa w I]opan*I]opanL]caBeha9`ab]qhp*i]opan7 y eb$OaooekjWpdaiaY9jqhh% w Pdaia9OaooekjWpdaiaY]oopnejc7 y y As you can see from the code, a MqanuOpnejc parameter is used to switch between the master pages with editing capabilities enabled or disabled. Just append ;a9kj to the URL, and the editor will appear. Once enabled, a session variable retains the state. To switch the editor off on the fly, add ;a9kbb. This is only a suggestion—you may find smarter ways of achieving this. Now we need to build the master page to support the necessary features.

Creating an Online Editor For the online editor to function, the JavaScript on the page must handle all controls and call the Web Service’s methods with the right parameters. The first step is preparation. Each control on the page must be tested for the presence of the iap]6naokqn_agau attribute. If this exists, then a connected resource is available, and the editor should handle this control. To achieve this, the Na]`?kjpnkho method loops through all the controls. The Ejep event is the right place in the pipeline for this method call, as the controls are ready to go at that stage. Later, in the LnaNaj`an event, the code uses the data collected here to add the JavaScript calls. To test for the attribute, a regular expression is used. This may seem strange, since we have an OBJECTMODELWHICHWECOULDACCESSDIRECTLY(OWEVER ALTHOUGHTHEOBJECTMODELISPRESENT THE implicit resource expressions have already been replaced by code snippets at the page parser stage. The iap]6naokqn_agau attributesDONOTEXISTINTHEOBJECTMODEL9OURONLYOPTIONISTOPARSETHE source code of the page directly and to virtually add another parser cycle after the internal one.

NNote The page must exist at runtime with full markup available. Pre-compiled sites with hidden source will not work with this example. ,ISTING SHOWSTHEMETHODSTHATPARSETHEPAGE COLLECTTHECONTROLS ANDADDTHEREQUIRED JavaScript. Since the scripting is a little tricky, it’s explained afterwards in more depth.

Download at WoweBook.Com

223

224

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

Listing 5-13. The Master Page with the Default Setting for Regular Expression lq^he_l]npe]h_h]ooA`epknI]opanL]ca6Ouopai*Sa^*QE*I]opanL]ca w lner]paop]pe_Nacatnt7 lner]pa@e_pekj]nu8opnejc(@e_pekj]nu8opnejc(opnejc::l]cao7 op]pe_A`epknI]opanL]ca$% w nt9jasNacat$<X8$;8p]cJ]ia:Xs'$6Xs'%w,(-y%$;8]ppn:WZ:Y&%;:(± NacatKlpekjo*Atlhe_ep?]lpqnax± NacatKlpekjo*Iqhpehejax± NacatKlpekjo*Ecjkna?]oax± NacatKlpekjo*EcjknaL]ppanjSdepaol]_a%7 y The regular expression simply addresses a tag with several attributes and returns the matching element as a collection of named arrays. This array contains all tags on the page captured with the key 8p]cJ]ia: and the attributes block—the remaining part of the element—with the key 8]ppn:. An element like 8]ol6^qppkjnqj]p9oanraniap]6naokqn_agau9>qppkjNao-+: would be divided into the ]ol6^qppkj part and the nqj]p9oanraniap]6naokqn_agau9>qppkjNao- part in the first step. Regular expressions are beyond the scope of this book; please refer to the documentation if you have difficulties reading this expression. For the moment, it’s sufficient to know that the string frag ments recognized by the expression are collected in named arrays, whereas the names are defined in 8]jcha^n]_gapo:. The attributes are split into single ones by using the space as a divider (see ,ISTING   Listing 5-14. Analyzing the Controls Regarding the meta:resourcekey Attribute lnkpa_pa`kranne`arke`KjEjep$Arajp=ncoa% w l]cao9jas@e_pekj]nu8opnejc(@e_pekj]nu8opnejc(opnejc::$%7 Na]`?kjpnkho$pdeo*L]ca*=llNah]peraRenpq]hL]pd%7 ^]oa*KjEjep$a%7 y lner]prke`Na]`?kjpnkho$opnejcl]pd%w eb$l]cao*?kjp]ejoGau$l]pd%% w Opna]iNa]`anon9jasOpna]iNa]`an$Oanran*I]lL]pd$l]pd%%7 opnejco9on*Na]`PkAj`$%7 on*?hkoa$%7 l]cao*=``$l]pd(jas@e_pekj]nu8opnejc(opnejc:$%%7 I]p_d?khha_pekji_9nt*I]p_dao$o%7 bkna]_d$I]p_dieji_% w Cnkqlc9i*CnkqloW]ppnY7 eb$c9jqhh% w opnejcWY]ppne^qpao9c*R]hqa*Olhep$*Pk?d]n=nn]u$%(± OpnejcOlhepKlpekjo*NaikraAilpuAjpneao%7 opnejcgau9jqhh(e`9jqhh7 bkna]_d$opnejc]ppnej]ppne^qpao% w eb$]ppn*Op]npoSepd$iap]6naokqn_agau%% w Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

opnejcl]n]i9]ppn*Olhep$9*Pk?d]n=nn]u$%%W-Y*Pnei$%7 gau9l]n]i*Oq^opnejc$-(l]n]i*Hajcpd).%7 y eb$]ppn*Op]npoSepd$e`(Opnejc?kil]neokj*Ejr]ne]jp?qhpqnaEcjkna?]oa%% w opnejcWYbn]ciajpo9]ppn*Olhep$9*Pk?d]n=nn]u$%%7 eb$bn]ciajpo*Hajcpd99.%w opnejcl]n]i9bn]ciajpoW-Y*Pnei$%7 e`9l]n]i*Oq^opnejc$-(l]n]i*Hajcpd).%7 y y y eb$Opnejc*EoJqhhKnAilpu$e`%""$Opnejc*EoJqhhKnAilpu$gau%%% w ++jaa`pkoqllknpoanranpn]joban eb$l]caoWl]pdY*?kjp]ejoGau$e`%% w l]caoWl]pdY*=``$e`(gau%7 y y y y y y The collection pages contain data from all the files scanned so far. Remember that a page can contain several user controls, and that these controls must become available at the same time. For each page, we store the control’s id and resource key. This makes it possible to access the control, based on its id, and the resource, based on its key. Once all the data has been collected, the page is processed normally. In LnaNaj`an, the information is used to add the JavaScript calls, as shown in ,ISTING  Listing 5-15. Add Editing Capability to the Collected Controls lnkpa_pa`kranne`arke`KjLnaNaj`an$Arajp=ncoa% w bkna]_d$opnejcj]iaejpdeo*?kjpajpLh]_aDkh`ano% w ?kjpajpLh]_aDkh`an_ld9$?kjpajpLh]_aDkh`an%Bej`?kjpnkh$j]ia%7 ?kjpnkh?khha_pekj__9_ld*?kjpnkho7 pdeo*J]rec]pa?kjpnkho$__%7 y ^]oa*KjLnaNaj`an$a%7 y This is only the first part—the entry point. Assuming we’re operating on a page that uses a master page—a prerequisite for this solution—we’ll need to handle the ?kjpajpLh]_aDkh`ano. Each control is processed as its own container. The J]rec]pa?kjpnkh method works recursively SEE,ISTING   Listing 5-16. Navigating All Controls and Adding the Required Script (the Next Listing) lner]parke`J]rec]pa?kjpnkho$?kjpnkh?khha_pekj__% w opnejcl]pd9Opnejc*Ailpu7 bkn$ejpe9,7e8__*?kqjp7e''% w Download at WoweBook.Com

225

226

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

?kjpnkh_ph9__WeY7 ++ql`]pal]jah_kjp]ejaniecdpd]rajke`(^qp_deh`naj eb$_ph9jqhh""$_ph*E@9jqhhxx_ph*D]o?kjpnkho$%%% w eb$_ph*D]o?kjpnkho$%% w eb$_pheoQoan?kjpnkh""± $_ph*CapPula$%*J]ia*?kjp]ejo$_khh]loahepan]h%%""± $_ph*CapPula$%*J]ia*?kjp]ejo$l]cada]`an%%% w l]pd9_ph*Pailh]pa?kjpnkh*=llNah]peraRenpq]hL]pd7 y ahoa w l]pd9_ph*L]ca*=llNah]peraRenpq]hL]pd7 y Na]`?kjpnkho$l]pd%7 pdeo*J]rec]pa?kjpnkho$_ph*?kjpnkho%7 eb$l]cao*?kjp]ejoGau$l]pd%%_kjpejqa7 eb$_ph*E@99jqhh%_kjpejqa7 eb$l]caoWl]pdY*?kjp]ejoGau$_ph*E@%%_kjpejqa7 opnejc_phGau9l]caoWl]pdYW_ph*E@Y7 eb$_phGau9jqhh% w eb$_pheoQoan?kjpnkh% w =``A`epkn?kjpnkh$_ph(l]pd(_phGau(e%7 y y y ahoa w l]pd9_ph*Pailh]pa?kjpnkh*=llNah]peraRenpq]hL]pd7 eb$l]cao*?kjp]ejoGau$l]pd%%_kjpejqa7 eb$l]caoWl]pdY*?kjp]ejoGau$_ph*E@%%_kjpejqa7 opnejc_phGau9l]caoWl]pdYW_ph*E@Y7 eb$_phGau9jqhh% w osep_d$_ph*CapPula$%*J]ia% w _]oaR]he`]pekjOqii]nu6 _kjpejqa7 _]oaSa^L]npVkja6 ++]__aoopdasa^l]npo(sde_d]najkpl]np ++kbpda_kjpnkh_khha_pekj bkna]_d$?kjpnkhl]npej$$Sa^L]npVkja%_ph%*Sa^L]npo% w l]pd9l]np*?kjpnkhoW,Y*Pailh]pa?kjpnkh*± =llNah]peraRenpq]hL]pd7 =``A`epkn?kjpnkh$l]np(l]pd(_phGau(e%7 y ^na]g7 `ab]qhp6 =``A`epkn?kjpnkh$_ph(l]pd(_phGau(e%7 ^na]g7 y __9_ph*L]najp*?kjpnkho7 Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

y y y y y The final step for each valid control located is to call the =``A`epkn?kjpnkh method. The meth ODSADDASMALLIMAGEPIXEL WHICHAPPEARSNEARTHECONTROL ALLOWINGTHEUSERTOCLICKTHERE and open the editor. Different images express different states:

s validator.gif: The control is a validator. The control itself might be invisible depending on the page’s validation state. However, the editor control is present.



s webpart.gif: Webparts do not handle resources, but they have additional content that might contain resources.



s resx.gif: Regular control with previously added resources.



s edit.gif: Regular control with no attached resources.

Additionally, a tooltip is created in order to inform the user about the control beneath the mouse pointer. This is helpful, as on complex pages it isn’t always possible to align the image exactly SEE,ISTING   Listing 5-17. Adding the Script Code lner]parke`=``A`epkn?kjpnkh$?kjpnkh_ph(opnejcl]pd(opnejc_phGau(ejpe% w ^kkhD]oNao9b]hoa7 opnejcWY]ppne^qpaHeop9CapLkooe^haNaokqn_aHeop$_ph%7 D]oNao9pdeo*CapHk_]hNaokqn_a$l]pd(_phGau(]ppne^qpaHeop%7 Opnejc>qeh`ano^9jasOpnejc>qeh`an$%7 qoejc$OpnejcSnepanos9jasOpnejcSnepan$o^%% w DpihPatpSnepandp9jasDpihPatpSnepan$os%7 dp*=``Opuha=ppne^qpa$DpihPatpSnepanOpuha*@eolh]u(ejheja%7 dp*=``Opuha=ppne^qpa$DpihPatpSnepanOpuha*?qnokn(d]j`%7 dp*=``Opuha=ppne^qpa$DpihPatpSnepanOpuha*Lkoepekj(nah]pera%7 dp*=``Opuha=ppne^qpa$DpihPatpSnepanOpuha*Habp()4%7 dp*=``Opuha=ppne^qpa$DpihPatpSnepanOpuha*Pkl()4%7 dp*=``Opuha=ppne^qpa$DpihPatpSnepanOpuha*VEj`at(-,,,,,%7 eb$D]oNao% w eb$_pheoER]he`]pkn% w dp*=``=ppne^qpa$on_(Namqaop*=llhe_]pekjL]pd'± +ei]cao+Naota`epkn+r]he`]pkn*ceb%7 y ahoaeb$_pheoESa^L]np% w dp*=``=ppne^qpa$on_(Namqaop*=llhe_]pekjL]pd'± +ei]cao+Naota`epkn+sa^l]np*ceb%7 y ahoa w dp*=``=ppne^qpa$on_(Namqaop*=llhe_]pekjL]pd'± +ei]cao+Naota`epkn+naot*ceb%7 y y Download at WoweBook.Com

227

228

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

ahoa w dp*=``=ppne^qpa$on_(Namqaop*=llhe_]pekjL]pd'± +ei]cao+Naota`epkn+A`ep*ljc%7 y dp*=``=ppne^qpa$se`pd(Qjep*Letah$4%*PkOpnejc$%%7 dp*=``=ppne^qpa$daecdp(Qjep*Letah$4%*PkOpnejc$%%7 ++=``]hhnamqena``]p]]o]ppne^qpaopkhaphk]`ejcpdaibnkiFO_nelp ^kkh]hhksDpih9$_pheoHepan]h%xx$_pheoHepan]h?kjpnkh%xx± $_pheoDpihCajane_?kjpnkh%xx± $_ph*CapPula$%*J]ia*?kjp]ejo$_khh]loahepan]h%%7 dp*=``=ppne^qpa$]hhksDpih($]hhksDpih%;pnqa6b]hoa%7 dp*=``=ppne^qpa$l]caE@(l]pd%7 dp*=``=ppne^qpa$_pnh?heajpE@(_ph*?heajpE@%7 dp*=``=ppne^qpa$_pnhE@(_phGau%7 dp*=``=ppne^qpa$]ppne^qpao(Opnejc*Fkej$((]ppne^qpaHeop%%7 dp*=``=ppne^qpa$]hp(Opnejc*Bkni]p$Pula$Sd]p;%6w,yXj± J]ia$Sdk;%6w-yXj± ?kjpajp$Sdu;%6w.yXj± ?kjp]ejan$Sdana;%6w/yXj± Op]pa$Dks;%6w0y(± _ph*CapPula$%*J]ia(± _phGau(± $]hhksDpih%;DPIH6Patp(± l]pd(± $_ph*Reoe^ha%;Reoe^ha6De``aj^u@ab]qhp%%7 ++i]gapdae_kj_he_g]^ha dp*=``=ppne^qpa$kj_he_g(± Opnejc*Bkni]p$odksA`epkn$w,y(pdeo%7napqnjb]hoa7($]hhksDpih%;-6,%%7 dp*Naj`an>acejP]c$DpihPatpSnepanP]c*Eic%7 dp*Naj`anAj`P]c$%7 Hepan]h?kjpnkhh^9jasHepan]h?kjpnkh$o^*PkOpnejc$%%7 _ph*L]najp*?kjpnkho*=``=p$e'-(h^%7 y y ++?da_gbknateopaj_akb]hk_]hnaokqn_apkik`ebue_kj lner]pa^kkhCapHk_]hNaokqn_a$opnejcl]pd(opnejc_pnhE`(opnejcWYnaoheop% w ^kkhd]oNao9b]hoa7 bkn$ejpe9,7e8naoheop*Hajcpd7e''% w pnu w eb$naoheopWeY9jqhh% w opnejcnaoE`9Opnejc*Bkni]p$w,y*w-y(_pnhE`(naoheopWeY%7 k^fa_pkR]hqa9Dppl?kjpatp*CapHk_]hNaokqn_aK^fa_p$l]pd(naoE`(± Pdna]`*?qnnajpPdna]`*?qnnajp?qhpqna%7 eb$kR]hqa9jqhh% w d]oNao9pnqa7 ^na]g7 y y ahoa w Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

^na]g7 y y _]p_dwy y napqnjd]oNao7 y ++Napqnj]heopkboqllknpa`lnklanpeao^updeoa`epkn$atpaj`]pukqnsehh% lner]paopnejcWYCapLkooe^haNaokqn_aHeop$?kjpnkh[?kjpnkh% w Heop8opnejc:nao9jasHeop8opnejc:$%7 osep_d$[?kjpnkh*CapPula$%*PkOpnejc$%% w _]oaOuopai*Sa^*QE*Sa^?kjpnkho*Hepan]h6 nao*=``$Patp%7 ^na]g7 _]oaOuopai*Sa^*QE*Sa^?kjpnkho*@nkl@ksjHeop6 nao*=``$PkkhPel%7 ^na]g7 _]oaOuopai*Sa^*QE*Sa^?kjpnkho*Iajq6 nao*=``$O_nkhh@ksjPatp%7 nao*=``$PkkhPel%7 nao*=``$O_nkhhQlPatp%7 nao*=``$OgelHejgPatp%7 ^na]g7 _]oaOuopai*Sa^*QE*Sa^?kjpnkho*Patp>kt6 nao*=``$PkkhPel%7 nao*=``$Patp%7 ^na]g7 `ab]qhp6 eb$?kjpnkheoESa^L]np% w ++ejpanj]hhuoappepha nao*=``$Patp%7 y ahoaeb$[?kjpnkheoER]he`]pkn% w nao*=``$Patp%7 nao*=``$PkkhPel%7 nao*=``$AnnknIaoo]ca%7 yahoaw nao*=``$Patp%7 nao*=``$PkkhPel%7 y ^na]g7 y napqnjnao*Pk=nn]u$%7 y ++Naokhralh]_adkh`anoej_]oakbi]opanl]ca`nerajsa^oepa lner]pa?kjpnkhCap=j`Bej`EjLh]_aDkh`an$opnejc_kjpnkhJ]ia% w I]opanL]cail9$I]opanL]ca%pdeo*L]ca*I]opan7 Download at WoweBook.Com

229

230

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

LnklanpuEjbkle9il*CapPula$%*CapLnklanpu$?kjpajpLh]_aDkh`ano(± Ouopai*Nabha_pekj*>ej`ejcBh]co*Ejop]j_ax± Ouopai*Nabha_pekj*>ej`ejcBh]co*JkjLq^he_%7 EHeopj]iao9$EHeop%le*CapR]hqa$il(jqhh%7 bkna]_d$opnejcj]iaejj]iao% w ?kjpajpLh]_aDkh`an_ld9$?kjpajpLh]_aDkh`an%I]ej?kjpajp*Bej`?kjpnkh$j]ia%7 eb$_ld9jqhh% w ?kjpnkh_9_ld*Bej`?kjpnkh$_kjpnkhJ]ia%7 eb$_9jqhh% w napqnj_7 y y y napqnjjqhh7 y The CapLkooe^haNaokqn_aHeop methodCONTAINSAHARD CODEDSEQUENCEOFSUPPORTEDATTRIBUTES This solution, therefore, does not support all the possible properties of a control. Extending the METHODISTRIVIAL)TTAKESMUCHMOREEFFORTTOCREATETHE*AVA3CRIPT BASEDEDITORTOADDTHECONTENT As long as it’s text, simple controls will achieve this. However, editing image paths or colors would require more work. 4OUNDERSTANDTHEENTIRECODE AGLANCEATTHERESULTMIGHTHELPSEE,ISTING   Listing 5-18. A Typical JavaScript Sequence Created with the Previous Code 8eicon_9+@aik=llhe_]pekj+ei]cao+Naota`epkn+naot*ceb se`pd94ltdaecdp94lt ]hhksDpih9b]hoa l]caE@9z+@ab]qhp*]olt _pnh?heajpE@9_ph,,[_ph,,[I]ej?kjpajp[I]ej?kjpajp[Hejg>qppkjPdaia- _pnhE@9Hejg>qppkjPdaia-Naokqn_a- ]ppne^qpao9Patp(PkkhPel]hp9Pkkhpel kj_he_g9odksA`epkn$,(pdeo%7napqnjb]hoa7 opuha9`eolh]u6ejheja7_qnokn6d]j`7lkoepekj6nah]pera7habp6)47pkl6)47v)ej`at6-,,,,,7+: "EFOREDEFININGTHE*AVA3CRIPTEDITORITSELF HEREISTHEWORKINGEDITORSEE&IGURE  

Figure 5-5. The page in edit mode Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

After clicking on one of the small icons, which represents a resource, the editor appears (see &IGURE  

Figure 5-6. The editor in action The editor needs access to the Web Service method we defined earlier. To achieve this, a O_nelpI]j]can controlISHELPFUL,ISTING REFERENCESTHE7EB3ERVICEDEFINITION Listing 5-19. The Supported Cultures Exposed Via a Service 8]ol6O_nelpI]j]canE@9O_nelpI]j]can-nqj]p9oanran Aj]^haL]npe]hNaj`anejc9B]hoa: 8oanre_ao: 8]ol6Oanre_aNabanaj_al]pd9z+NaotA`epkn+Naokqn_aOanre_a*]oit+: 8+oanre_ao: 8+]ol6O_nelpI]j]can: More code is required for the editor itself. This is accomplished via a user control on the editor MASTERPAGE4HEFIRSTBLOCKOFCODEISSOURCEDFROM#ODE,IFTERCOMˆITCREATESADRAGGABLEPOPUP window. As it’s helpful to view the resources in the context of the page, let the user move the win DOWAROUNDANDMAKEHIDDENPARTSOFTHESURFACEACCESSIBLESEE,ISTING   Download at WoweBook.Com

231

232

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

Listing 5-20. Part 1: The JavaScript Editor Defined in the edit.ascx control: the Drag Window 8!<?kjpnkhH]jcq]ca9?=qpkArajpSenaql9b]hoa?k`aBeha9a`ep*]o_t*_oEjdanepo9a`ep !: 8o_nelph]jcq]ca9F]r]O_nelp-*.pula9patp+f]r]o_nelp: ++O_nelpOkqn_a6?k`aHebpan*_ki ++?klunecdp.,,/ ++@kjkpnaikrapdeoda]`an eoEA9`k_qiajp*]hh7 eoJJ9`k_qiajp*]hh""`k_qiajp*capAhaiajp>uE`7 eoDkp9b]hoa7 bqj_pekj``Ejep$a%w pkl@kc9eoEA;>K@U6DPIH7 dkp@kc9eoEA;arajp*on_Ahaiajp6a*p]ncap7 sdeha$dkp@kc*e`9pepha>]n""dkp@kc*p]cJ]ia9pkl@kc%w dkp@kc9eoEA;dkp@kc*l]najpAhaiajp6dkp@kc*l]najpJk`a7 eb$dkp@kc99jqhhxxdkp@kc*e`99jqhhxxdkp@kc*p]cJ]ia99jqhh% napqnj7 y eb$dkp@kc*e`99pepha>]n%w kbboapt9eoEA;arajp*_heajpT6a*_heajpT7 kbboapu9eoEA;arajp*_heajpU6a*_heajpU7 jksT9l]noaEjp$sde_d@kc*opuha*habp%7 jksU9l]noaEjp$sde_d@kc*opuha*pkl%7 ``Aj]^ha`9pnqa7 `k_qiajp*kjikqoaikra9``7 y y bqj_pekj``$a%w eb$``Aj]^ha`%napqnj7 sde_d@kc*opuha*habp9eoEA;± jksT'arajp*_heajpT)kbboapt6jksT'a*_heajpT)kbboapt7 sde_d@kc*opuha*pkl9eoEA;± jksU'arajp*_heajpU)kbboapu6jksU'a*_heajpU)kbboapu7 napqnjb]hoa7 y bqj_pekjde`aIa$%w sde_d@kc*opuha*reoe^ehepu9de``aj7 y bqj_pekjodksIa$%w sde_d@kc*opuha*reoe^ehepu9reoe^ha7 y `k_qiajp*kjikqoa`ksj9``Ejep7 `k_qiajp*kjikqoaql9Bqj_pekj$``Aj]^ha`9b]hoa%7 8+o_nelp: This code portion is shown for completeness. It is used to move the editor window around. When editing the page, it’s helpful to see the page, which might be partly hidden by the overlaid WINDOWSEE,ISTING  

Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

Listing 5-21. Part 2: The JavaScript Editor Defined in the edit.ascx Control: the Resource Access 8o_nelph]jcq]ca9f]r]o_nelppula9patp+f]r]o_nelp: r]nl]najpK^f7 bqj_pekjodksIaoo]ca$ioc%w r]nh]^ah9`k_qiajp*capAhaiajp>uE`$#Iaoo]caH]^ah#% h]^ah*ejjanPatp9ioc7 h]^ah*opuha*`eolh]u9$ioc*hajcpd99,%;#jkja#6#^hk_g#7 h]^ah*opuha*_khkn9,,BB//7 y bqj_pekjodksAnnkn$ioc%w r]nh]^ah9`k_qiajp*capAhaiajp>uE`$#Iaoo]caH]^ah#% h]^ah*ejjanPatp9ioc7 h]^ah*opuha*`eolh]u9$ioc*hajcpd99,%;#jkja#6#^hk_g#7 h]^ah*opuha*_khkn9BB,,,,7 y ++Pdaoabqj_pekjo_]hhpdaSa^Oanre_aiapdk`* bqj_pekjejepH]jcq]cao$%w odksIaoo]ca$?]hhejcOanran***%7 NaotA`epkn*Naokqn_aOanre_a*Cap=hhH]jcq]cao$ejepH]jcq]cao?]hh^]_g(± ejepH]jcq]caoAnnkn%7 y bqj_pekjejepH]jcq]cao?]hh^]_g$naoqhp%w r]noahHk]`9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 r]noah?klu9`k_qiajp*capAhaiajp>uE`$#Naot?kluOaha_pkn#%7 oahHk]`*klpekjo*hajcpd9,7 oah?klu*klpekjo*hajcpd9,7 bkn$e9,7e8naoqhp*haj7e''%w oahHk]`*klpekjoWeY9jasKlpekj$naoqhp*_qhpqnaJ]iaWeY(± naoqhp*_qhpqnaE@WeY%7 oah?klu*klpekjoWeY9jasKlpekj$naoqhp*_qhpqnaJ]iaWeY(± naoqhp*_qhpqnaE@WeY%7 y odksIaoo]ca$%7 `k_qiajp*capAhaiajp>uE`$#pda?kjpajp?kjp]ejan#%*oap=ppne^qpa$`eo]^ha`(± b]hoa%7 y bqj_pekjejepH]jcq]caoAnnkn$annkn%w odksAnnkn$annkn*cap[iaoo]ca$%%7 y bqj_pekjo]raIa$%w odksIaoo]ca$O]rapda`]p]***%7 r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]npdaia9#8!9Pdaia!:#7 r]np^9`k_qiajp*capAhaiajp>uE`$#8!9A`epPatp>kt*?heajpE@!:#%*ejjanPatp7 r]noah9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 Download at WoweBook.Com

233

234

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

++Patp NaotA`epkn*Naokqn_aOanre_a*O]raNaokqn_a$l]caE`(_pnhE`'*Patp(± p^(_qhpqna(pdaia(± o]raIa?]hh^]_gPatp(± o]raIaAnnkn%7 y ++_hkoa]bpano]raeo`kja eb$`k_qiajp*capAhaiajp>uE`$#o]raIa?hkoa?da_g^kt#%*_da_ga`99pnqa%w de`aA`epkn$%7 y y ++Pdeoeopda_]hh^]_gbqj_pekjpd]plnk_aooaopdaSa^Oanre_anapqnjr]hqa bqj_pekjo]raIa?]hh^]_gPatp$naoqhp(arajp=nco%w eb$l]najpK^f*cap=ppne^qpa$]ppne^qpao%*oa]n_d$+PkkhPel+%9)-%w odksIaoo]ca$O]rapda`]p]****%7 ++Pkkhpel r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]npdaia9#8!9Pdaia!:#7 r]noah9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 r]np^9± `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*r]hqa7 NaotA`epkn*Naokqn_aOanre_a*O]raNaokqn_a$l]caE`(± _pnhE`'*PkkhPel(± p^(_qhpqna(pdaia(± o]raIa?]hh^]_gPkkhpel(± o]raIaAnnkn%7 y yahoaw o]raIa?]hh^]_gPkkhpel$jqhh(jqhh%7 y y bqj_pekjo]raIa?]hh^]_gPkkhpel$naoqhp(arajp=nco%w eb$l]najpK^f*cap=ppne^qpa$]ppne^qpao%*oa]n_d$+AnnknIaoo]ca+%9)-%w odksIaoo]ca$O]rapda`]p]*****%7 ++Pkkhpel r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]npdaia9#8!9Pdaia!:#7 r]noah9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 r]np^9± `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktAnnknIaoo]ca*?heajpE@!:#%*r]hqa7 NaotA`epkn*Naokqn_aOanre_a*O]raNaokqn_a$l]caE`(± _pnhE`'*AnnknIaoo]ca(± p^(_qhpqna(pdaia(± o]raIa?]hh^]_gReoe^ehepu(± o]raIaAnnkn%7 y yahoaw o]raIa?]hh^]_gReoe^ehepu$jqhh(jqhh%7 y Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

y bqj_pekjo]raIa?]hh^]_gReoe^ehepu$naoqhp(arajp=nco%w ++Lnklanpeao66Reoe^ha r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]npdaia9#8!9Pdaia!:#7 r]noah9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 r]n_^9`k_qiajp*capAhaiajp>uE`$#8!9?dg>ktReoe^ha*?heajpE@!:#%7 eb$_^*_da_ga`99b]hoa%w NaotA`epkn*Naokqn_aOanre_a*O]raNaokqn_a$l]caE`(± _pnhE`'*Reoe^ha(± B]hoa(_qhpqna(pdaia(± o]raIa?]hh^]_gAnnknIaoo]ca(± o]raIaAnnkn%7 yahoaw NaotA`epkn*Naokqn_aOanre_a*O]raNaokqn_a$l]caE`(± _pnhE`'*Reoe^ha(± Pnqa(_qhpqna(pdaia(± o]raIa?]hh^]_gAnnknIaoo]ca(± o]raIaAnnkn%7 y y y bqj_pekjo]raIa?]hh^]_gAnnknIaoo]ca$naoqhp(arajp=nco%w odksIaoo]ca$%7 y bqj_pekjo]raIaAnnkn$ann%w odksAnnkn$ann*cap[iaoo]ca$%%7 y bqj_pekjhk]`Ia$%w odksIaoo]ca$Hk]`Naokqn_aobnkiOanran***%7 r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]npdaia9#8!9Pdaia!:#7 r]noah9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 `k_qiajp*capAhaiajp>uE`$#H]^ah?kjpnkhE`#%*ejjanPatp9_pnhE`7 `k_qiajp*capAhaiajp>uE`$#H]^ahL]caE`#%*ejjanPatp9l]caE`7 ++Patp NaotA`epkn*Naokqn_aOanre_a*Hk]`Naokqn_a$l]caE`(± _pnhE`'*Patp(± _qhpqna(pdaia(± hk]`Ia?]hh^]_gPatp(± hk]`IaAnnkn%7 y y bqj_pekjhk]`Ia?]hh^]_gPatp$naoqhp(arajp=nco%w `k_qiajp*capAhaiajp>uE`$#8!9A`epPatp>kt*?heajpE@!:#%*ejjanPatp9naoqhp7 eb$l]najpK^f*cap=ppne^qpa$]ppne^qpao%*oa]n_d$+PkkhPel+%9)-%w Download at WoweBook.Com

235

236

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

odksIaoo]ca$Hk]`Naokqn_aobnkiOanran****%7 ++Pkkhpel r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]npdaia9#8!9Pdaia!:#7 r]noah9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 NaotA`epkn*Naokqn_aOanre_a*Hk]`Naokqn_a$l]caE`(± _pnhE`'*Pkkhpel(± _qhpqna(pdaia(± hk]`Ia?]hh^]_gPkkhpel(± hk]`IaAnnkn%7 `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*± `eo]^ha`9b]hoa7 `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*± opuha*^]_gcnkqj`?khkn9sdepa7 y yahoaw `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*± `eo]^ha`9pnqa7 `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*± opuha*^]_gcnkqj`?khkn9oehran7 capAnnknIaoo]ca$%7 y y

bqj_pekjhk]`Ia?]hh^]_gPkkhpel$naoqhp(arajp=nco%w `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*± ejjanPatp9naoqhp7 capAnnknIaoo]ca$%7 y bqj_pekjcapAnnknIaoo]ca$%w eb$l]najpK^f*cap=ppne^qpa$]ppne^qpao%*oa]n_d$+AnnknIaoo]ca+%9)-%w odksIaoo]ca$Hk]`Naokqn_aobnkiOanran*****%7 ++AnnknIaoo]ca r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]npdaia9#8!9Pdaia!:#7 r]noah9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 NaotA`epkn*Naokqn_aOanre_a*Hk]`Naokqn_a$l]caE`(± _pnhE`'*AnnknIaoo]ca(± _qhpqna(pdaia(± hk]`Ia?]hh^]_gAnnknIaoo]ca(± hk]`IaAnnkn%7 y yahoaw ++Lnk_aa`sepdjatp capReoe^ehepu$%7 y y bqj_pekjhk]`Ia?]hh^]_gAnnknIaoo]ca$naoqhp(arajp=nco%w Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

++O]ranaoqhp `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktAnnknIaoo]ca*?heajpE@!:#%*± ejjanPatp9naoqhp7 ++Lnk_aa`sepdjatp capReoe^ehepu$%7 y bqj_pekjcapReoe^ehepu$%w r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]noah9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 r]npdaia9#8!9Pdaia!:#7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 NaotA`epkn*Naokqn_aOanre_a*Hk]`Naokqn_a$l]caE`(± _pnhE`'*Reoe^ha(± _qhpqna(pdaia(± hk]`Ia?]hh^]_gReoe^ha(± hk]`IaAnnkn%7 y y bqj_pekjhk]`Ia?]hh^]_gReoe^ha$naoqhp(arajp=nco%w ++O]ranaoqhp eb$naoqhp99jqhhxxnaoqhp99pnqaxxnaoqhp99Pnqa%w `k_qiajp*capAhaiajp>uE`$#8!9?dg>ktReoe^ha*?heajpE@!:#%*_da_ga`9± pnqa7 yahoaw `k_qiajp*capAhaiajp>uE`$#8!9?dg>ktReoe^ha*?heajpE@!:#%*_da_ga`9± b]hoa7 y ++@kja(_ha]niaoo]ca odksIaoo]ca$%7 y

bqj_pekjhk]`IaAnnkn$ann%w odksAnnkn$ann*cap[iaoo]ca$%%7 y bqj_pekj_kluIa$%w odksIaoo]ca$Hk]`Naokqn_aobnkiOanran***%7 r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]noah9`k_qiajp*capAhaiajp>uE`$#Naot?kluOaha_pkn#%7 r]npdaia9#8!9Pdaia!:#7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 ++Patp NaotA`epkn*Naokqn_aOanre_a*Hk]`Naokqn_a$l]caE`(± _pnhE`'*Patp(± _qhpqna(pdaia(± _kluIa?]hh^]_gPatp(± hk]`IaAnnkn%7 y y

Download at WoweBook.Com

237

238

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

bqj_pekj_kluIa?]hh^]_gPatp$naoqhp(arajp=nco%w `k_qiajp*capAhaiajp>uE`$#8!9A`epPatp>kt*?heajpE@!:#%*ejjanPatp9naoqhp7 odksIaoo]ca$Hk]`Naokqn_aobnkiOanran****%7 ++Pkkhpel r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]noah9`k_qiajp*capAhaiajp>uE`$#Naot?kluOaha_pkn#%7 r]npdaia9#8!9Pdaia!:#7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 NaotA`epkn*Naokqn_aOanre_a*Hk]`Naokqn_a$l]caE`(± _pnhE`'*Pkkhpel(± _qhpqna(pdaia(± _kluIa?]hh^]_gPkkhpel(± hk]`IaAnnkn%7 y y bqj_pekj_kluIa?]hh^]_gPkkhpel$naoqhp(arajp=nco%w odksIaoo]ca$Hk]`Naokqn_aobnkiOanran*****%7 ++Pkkhpel r]nl]caE`9l]najpK^f*cap=ppne^qpa$l]caE@%7 r]n_pnhE`9l]najpK^f*cap=ppne^qpa$_pnhE@%7 r]noah9`k_qiajp*capAhaiajp>uE`$#Naot?kluOaha_pkn#%7 r]npdaia9#8!9Pdaia!:#7 eb$oah*klpekjo*hajcpd:,%w r]n_qhpqna9oah*klpekjoWoah*oaha_pa`Ej`atY*r]hqa7 NaotA`epkn*Naokqn_aOanre_a*Hk]`Naokqn_a$l]caE`(± _pnhE`'*AnnknIaoo]ca(± _qhpqna(pdaia(± _kluIa?]hh^]_gAnnknIaoo]ca(± hk]`IaAnnkn%7 y y bqj_pekj_kluIa?]hh^]_gAnnknIaoo]ca$naoqhp(arajp=nco%w `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktAnnknIaoo]ca*?heajpE@!:#%*ejjanPatp9± naoqhp7 odksIaoo]ca$%7 y bqj_pekjodksA`epkn$]hhksDpih(l]najp%w odksIaoo]ca$%7 `k_qiajp*capAhaiajp>uE`$#8!9A`epPatp>kt*?heajpE@!:#%*`eo]^ha`9pnqa7 `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*`eo]^ha`9pnqa7 `k_qiajp*capAhaiajp>uE`$#8!9A`epPatp>kt*?heajpE@!:#%*± opuha*^]_gcnkqj`?khkn9oehran7 `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*± opuha*^]_gcnkqj`?khkn9oehran7 `k_qiajp*capAhaiajp>uE`$#AnnknIaoo]ca#%*opuha*`eolh]u9jkja7 l]najpK^f9l]najp7 ++ei]casepd]ppne^qpanabanaj_ejcpkk^fa_p`]p] r]nap^9`k_qiajp*capAhaiajp>uE`$#patp>kt?kjp]ejan#%7 ++PK@K6oqllknpikna]ppne^qpao r]n]ppn9l]najpK^f*cap=ppne^qpa$]ppne^qpao%7 r]n]9]ppn*olhep$(%7 bkn$e9,7e8]*hajcpd7e''%w Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

osep_d$]WeY%w _]oaPepha6 ^na]g7 _]oaPatp6 `k_qiajp*capAhaiajp>uE`$#8!9A`epPatp>kt*?heajpE@!:#%*± `eo]^ha`9b]hoa7 `k_qiajp*capAhaiajp>uE`$#8!9A`epPatp>kt*?heajpE@!:#%*± opuha*^]_gcnkqj`?khkn97 ap^*opuha*reoe^ehepu9#reoe^ha#7 ap^*opuha*`eolh]u9#ejheja#7 ^na]g7 _]oaPkkhPel6 `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*± `eo]^ha`9b]hoa7 `k_qiajp*capAhaiajp>uE`$#8!9Patp>ktPkkhpel*?heajpE@!:#%*± opuha*^]_gcnkqj`?khkn9sdepa7 ^na]g7 _]oaAnnknIaoo]ca6 `k_qiajp*capAhaiajp>uE`$#AnnknIaoo]ca#%*opuha*`eolh]u9^hk_g7 ^na]g7 y y hk]`Ia$%7 odksIa$%7 y bqj_pekjde`aA`epkn$%w r]nap^9`k_qiajp*capAhaiajp>uE`$#patp>kt?kjp]ejan#%7 ap^*opuha*reoe^ehepu9#de``aj#7 ap^*opuha*`eolh]u9#jkja#7 de`aIa$%7 y bqj_pekjejepA`epkn$%w ++ejep r]noah9`k_qiajp*capAhaiajp>uE`$#NaotH]jcq]caOaha_pkn#%7 eb$oah*klpekjo*hajcpd99,%w ejepH]jcq]cao$%7 y de`aA`epkn$%7 y 8+o_nelp: This longer JavaScript code block invokes the Web Services. The pattern is, according to !JAXCONVENTION ASYNCHRONOUS/NEMETHODCALLSTHE7EB3ERVICE DEFININGCALLBACKMETHODSAS parameters. Once the Web Service responds, the callback method is invoked. This could be either a success or error path, depending on the outcome. The result is written back into the elements of the editor window. Other methods transfer data from the editor window to the server. Due to the complexity, several methods are required:

s 3AVE88%ACH3AVEMETHODSAVESAPARTICULARCONTROLSCONTENT



s ,OAD88%ACH,OADMETHODLOADSTHECONTENTFROMTHESERVER



s #OPY884HECOPYMETHODCOPIESFROMONELANGUAGETOANOTHER



s 88#ALLBACK4HECALLBACKCONTAININGTHEDATA Download at WoweBook.Com

239

240

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

Some callback methods invoke the subsequent step. For the Load procedure, the Hk]`Ia func tion is the entry point. In the callback, the next control’s resource is retrieved from the server and read in its own callback method. This creates a chain of callbacks that are dependent on each other. This is similar for the Save procedure. After defining the access methods to the server, the editor WINDOWCANBECREATED ASSHOWNIN,ISTING  Listing 5-22. Part 3: The Editor Popup Window Definition 8`ere`9pdaH]uanopuha9^]_gcnkqj`)_khkn6oehran7lkoepekj6]^okhqpa7pkl60,lt7habp6 -31lt7se`pd630,lt7^kn`an6okhe`.ltcn]u7 l]``ejc61lt7bkjp)b]iehu6Ran`]j]7_khkn6>hqa7bkjp)oeva6-,lp7reoe^ehepu6reoe^ha7 v)ej`at6-,,,,: 8p]^ha^kn`an9,se`pd9-,,!^c_khkn9pn]jol]najp_ahhol]_ejc9,_ahhl]``ejc9,: 8pn: 8p`se`pd9-,,!: 8p]^ha^kn`an9,^c_khkn9^hqase`pd9-,,!_ahhol]_ejc9,_ahhl]``ejc9/ daecdp9/.: 8pn: 8p`e`9pepha>]nopuha9_qnokn6ikrase`pd951!: 8eh]uanse`pd9-,,!kjoaha_pop]np9napqnjb]hoa: 8h]uanse`pd9-,,!kjIkqoakran9eoDkp9pnqa7eb$eoJ0%``J0$pdaH]uan% kjIkqoakqp9eoDkp9b]hoa: 8ol]jopuha9bkjp)b]iehu6Ran`]j]7bkjp)oeva6-.lp7bkjp)saecdp6^kh`7 _khkn6Sda]p:KjhejaNaokqn_aA`epkn8+ol]j: 8+h]uan: 8+eh]uan: 8+p`: 8p`opuha9_qnokn6d]j`r]hecj9pkl]hecj9necdpse`pd91!: 8`erkj_he_g9de`aA`epkn$%7napqnjb]hoaopuha9l]``ejc6.lt7_khkn6bbbbbb7 ^]_gcnkqj`)_khkn6Na`7se`pd64lt7daecdp6-.lt7bkjp)oeva65lt7 bkjp)b]iehu6Ran`]j]7patp)`a_kn]pekj6jkja7patp)]hecj6_ajpan7 ranpe_]h)]hecj6pkl: t 8+`er: 8+p`: 8+pn: 8pn: 8p`se`pd9-,,!^c_khkn9BBBBBBopuha9l]``ejc60lt_khol]j9. `eo]^ha`9pnqae`9pda?kjpajp?kjp]ejan: 8p]^ha: 8pn: 8p`: H]jcq]caoaha_pekj6 8+p`: 8p`: 8oaha_pe`9NaotH]jcq]caOaha_pknkj_d]jca9hk]`Ia$%7: 8+oaha_p: 8+p`: 8+pn: 8pn: 8p`: ?klubnkih]jcq]ca6 8+p`: 8p`: 8oaha_pe`9Naot?kluOaha_pknkj_d]jca9_kluIa$%7: 8+oaha_p: 8+p`: Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

8+pn: 8+p]^ha: 8dnse`pd9-,,!oeva9._khkn9cn]u+: Naokqn_a68ol]jopuha9bkjp)saecdp6^kh`7 e`9H]^ah?kjpnkhE`:8+ol]j:"j^ol7kj"j^ol7 8ol]jopuha9bkjp)saecdp6^kh`7 e`9H]^ahL]caE`: 8+ol]j: 8^n+: 8dnse`pd9-,,!oeva9._khkn9cn]u+: Pkkhpel68^n+: 8]ol6Patp>ktnqj]p9oanranE@9Patp>ktPkkhpel PatpIk`a9OejchaHejaSe`pd93.,lt Reoe^ha9pnqa:8+]ol6Patp>kt: 8ol]jopuha9`eolh]u6jkjae`9AnnknIaoo]ca: AnnknIaoo]ca$Iaoo]caejcnkql(Patp9Iaoo]capatp% 8^n+: 8]ol6Patp>ktnqj]p9oanranE@9Patp>ktAnnknIaoo]ca PatpIk`a9OejchaHejaSe`pd93.,lt Reoe^ha9pnqa:8+]ol6Patp>kt: 8+ol]j: 8dnse`pd9-,,!oeva9._khkn9cn]u+: 8]ol6?da_g>ktnqj]p9oanranE@9?dg>ktReoe^ha Patp9I]gaahaiajpreoe^ha+: 8dnse`pd9-,,!oeva9._khkn9cn]u+: 8`ere`9patp>kt?kjp]ejanopuha9reoe^ehepu6de``aj: 8]ol6Patp>ktnqj]p9oanranE@9A`epPatp>kt PatpIk`a9IqhpeHeja Daecdp90,,ltSe`pd93.,lt Reoe^ha9pnqa:8+]ol6Patp>kt: 8+`er: 8^n+: 8p]^ha^kn`an9,se`pd9-,,!: 8pn: 8p`]hecj9habpse`pd94,!: 8h]^ah: 8ejlqpe`9o]raIa?hkoa?da_g^kt pula9_da_g^ktr]hqa9?hkoa+: ?hkoa]bpanO]ra 8+h]^ah: 8+p`: 8p`]hecj9necdpse`pd9.,!: 8ejlqppula9^qppkj kj_he_g9o]raIa$%7napqnjb]hoa7r]hqa9O]ra+:"j^ol7 8ejlqppula9^qppkj kj_he_g9de`aA`epkn$%7napqnjb]hoa7r]hqa9?hkoa+: 8+p`: 8+pn: 8+p]^ha: 8^n+: 8`ere`9Iaoo]caH]^ahopuha9_khkn6Cnaaj7 bkjp)saecdp6^kh`: 8+`er: 8^n+: 8ol]jopuha9_khkn6Na`:8opnkjc:Dejp68+opnkjc:± Nabnaodl]ca^u_dkkoejc]jkpdanh]jcq]ca8+ol]j: 8+p`: Download at WoweBook.Com

241

242

CH APT ER 5 N EX TENDING THE R ES OU R C E MO D E L

8+pn: 8+p]^ha: 8+p`: 8+pn: 8+p]^ha: 8+`er: 8o_nelph]jcq]ca9f]r]o_nelppula9patp+f]r]o_nelp: sde_d@kc9eoEA;`k_qiajp*]hh*pdaH]uan6`k_qiajp*capAhaiajp>uE`$pdaH]uan%7 oapPeiakqp$#ejepA`epkn$%#(-,,%7 eb$pulakb$Ouo%99qj`abeja`%Ouo*=llhe_]pekj*jkpebuO_nelpHk]`a`$%7 8+o_nelp: This is simply a fragment of HTML containing the controls and the supporting script that man AGESTHEPAGELOADINGCYCLE4HECONTROLHASAFEWTRIVIALLINESOFCODE BEHIND,ISTING  !S written, everything relies on JavaScript in the client. The Web Service on the server acts as an access layer to the underlying resource provider. Listing 5-23. The “code-behind” for the Control qoejcOuopai7 qoejcOuopai*Sa^*QE7 lq^he_l]npe]h_h]ooa`ep6Ouopai*Sa^*QE*Qoan?kjpnkh w lnkpa_pa`kranne`arke`KjEjep$Arajp=ncoa% w L]ca*Aj]^haArajpR]he`]pekj9b]hoa7 ^]oa*KjEjep$a%7 y lnkpa_pa`kranne`arke`KjHk]`$Arajp=ncoa% w ^]oa*KjHk]`$a%7 y lnkpa_pa`opnejcPdaia w cap w napqnjOaooekjWpdaiaY]oopnejc7 y y y The only public parameter we need is the currently selected theme. This value is included in the Web Service calls, where it is used to route the resource data into the right resource storage.

Download at WoweBook.Com

C H A P T E R 5 N E X T E N D I N G T H E R E S O U R C E M O D E L

Summary In this chapter, we looked closely at how to handle resource providers. A complete solution is capa BLEOFCHANGINGINTERNALBEHAVIORWITHOUTLOSINGANYDEFAULTFEATURES ANDINCLUDESADESIGN TIME CONTROL$ESIGN TIMESUPPORTISANIMPORTANTPARTOFANYCUSTOMSOLUTION ANDITWOULDBESHORT sighted to ignore the option of using designer tools (even if you do not intend to employ them YOURSELF !LLCODESHOWNINTHISCHAPTERHASFULLDESIGN TIMESUPPORT INCLUDINGTHESTEPSFOR enabling debugging. &URTHERMORE WEMADETHERESOURCEPROVIDERACCESSIBLEVIAA7EB3ERVICE7EBUILTA*AVA3CRIPT BASEDEDITORONTHECLIENTTOREADANDSAVERESOURCESATRUNTIME ENABLINGRESOURCE BASEDPAGESTOBE editable online. The examples demonstrate how to implement a highly customized solution, which fits well into the existing ASP.NET framework.

Download at WoweBook.Com

243

Download at WoweBook.Com

CHAPTER

6

Page and Session Management

T

he Hypertext Transfer Protocol (HTTP) is the reason for the success of the Internet. It is also the source of the drawbacks in the usability of applications. To overcome these limitations, ASP.NET provides several ways of maintaining the state of pages—and the controls between postbacks— throughout the whole session. Whatever the type of data existing within an application, there are two things to consider: the storage of application data on the server, and how to integrate the user’s session with the application data. In this chapter, I’ll explain how to customize in both of these areas for your real-life applications. In particular, you’ll find information about:

s 4HEPAGEPERSISTERTECHNIQUE



s 7RITINGACUSTOMPAGEPERSISTER



s 4HEINTERNALSOFTHESESSIONSTATEPROVIDER



s 7RITINGACUSTOMSESSIONSTATEPROVIDER

The approach presented here is based on the provider model as explained in Chapter 4. Please refer back for useful information about providers, their purpose, and how they fit into the ASP.NET framework.

The Page State Persister Handling active content and creating rich internet applications are difficult to integrate. Page persistence is the key to overcoming this challenge, and a good understanding of this feature is the basis of creating complex applications.

A Look Back The protocol spoken between server and browser is HTTP, and there are many books, articles, blogs, and newsgroup posts complaining about its limitations. However, HTTP has succeeded mainly BECAUSEOFITSSIMPLICITY4HEREARETHREEKEYPROPERTIESWHICHMAKE(440UNIQUE

s )TUSESTEXTTOTRANSPORTBOTHMESSAGESANDCONTENT



s )TRUNSONTOPOF4#0



s )TISASTATELESSPROTOCOL.

245 Download at WoweBook.Com

246

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

h3TATELESSvCANBETHOUGHTOFAShFIREANDFORGETv4HECLIENTINITIATESAREQUESTTOTHESERVERTHE SERVERPROCESSESTHEREQUESTANDRESPONDSWITHTHEANSWER!FTERTHAT THESERVERFORGETSALLABOUT the procedure. Once the conversation has ended, nothing is left for further processing—at least, this is the case for the protocol.

The Default Page State Persister The statelessness of HTTP means that there is no formal way of remembering, either on the client or the server, the state of any past actions involving the same user. However, every web development environment provides some means of recognizing session states and storing user data. ASP.NET is no exception, and as for many other parts of the .NET Framework, there are several ways of achieving this.

State Storage in ASP.NET Since all stateMANAGEMENTAPPROACHESREQUIRECUSTOMCODINGBYAPPLICATIONDEVELOPERS ITSWORTH looking into them in more detail. Understanding the pros and cons of each method makes it easier to decide which one to use, where to customize it, and how to get the most out of it. ASP.NET can store information about the page’s state in several collections:

s Cookies: You can create private cookies and store them on the client’s machine in order to obtain information from them. This is not the best method, but it’s the default method.



s View State: ASP.NET controls, as well as several other parts, use view state to store control-specific information about the previous state. We’ll discuss all facets of view state later in the section “Persisting Page State Information.”



s Session: This is a collection of key-value pairs related to the current user’s session. It’s a way of adding more information, on the server side, to a session state stored elsewhere (in a cookie, for instance).

The Application collection is another set of key-value pairs that retain application-level data SHAREDAMONGALLUSERS)NCONTRAST THE#ONTEXTCOLLECTIONISLIMITEDTOTHECURRENTREQUEST RESPONSE flow—data in the Context collection does not survive the page cycle. Cookies, View State and the Session collection give the developer the illusion of stateful page handling. Most commonly, they will use a single cookie, called the session cookie, to store an ID with the shortest lifetime possible in the browser’s cookie memory, just until the session ends. 7HENTHECLIENTMAKESANEWREQUEST THECOOKIEISRETURNEDINTHEREQUEST4HESERVERDECODESTHE )$TODETERMINEWHICHBROWSERINSTANCEANDHENCE WHICHUSER ISSENDINGTHEREQUEST As an experienced developer, you might already know how to use the Cookie, Session, and Application collections. Each of them has a different storage mechanism and must be used wisely. You may remember that there are many code snippets scattered throughout the page’s code which OBTAINACCESSTOTHEINFORMATIONWHENEVERITISREQUIRED(OWEVER THISISNOTIDEAL ASITDETRACTS from the declarative nature of ASP.NET pages. Not only does it make pages harder to read, but it could lead to bugs if overused.

Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

Persisting Page State Information 4HEFIRSTSTEPINMANAGINGSTATEDATAISTOMASTERTHETECHNIQUESFORRETAININGTHEPAGESTATETHROUGH each postback. The information on the “current” page is generally stored within several controls. Therefore, we’ll need a way of storing the controls’ state information. The state storageRELIESONTWOSIMILARTECHNIQUESTHEVIEWSTATEANDTHECONTROLSTATE4HE internal nature and pitfalls of the view state were described in Chapter 1. Here, I’ll show how to change the storage and retrieval mechanism.

View State Explained Recall the purpose of view state: to store data about the properties of controls that are set programmatically. View state is not responsible for the sticky form behavior that retains the controls’ current state according to the user’s selection. The control state holding this information is retrieved from the form’s data, which is posted back to the server during a normal postback. Additional information is stored in a special hidden field. Internally, view state uses an object of type Op]pa>]c. It retains data and includes code that serializes the data into text format and stores it in the hidden field. Consider using a H]^ah control, where you set the color to turn red if an error occurs. You’ll want to maintain this state until the error has been corrected, without checking and setting the property repeatedly. Once set programmatically, view state stores this value in the Op]pa>]c and persists it in the page via a hidden field. When the page is initialized after a postback, the value is RETRIEVEDANDASSIGNEDTOTHEPROPERTYˆNOCUSTOMCODEREQUIRED Clearly, view state plays a crucial role in page development, and can be used internally to store a control’s state.

Control State Explained View state and control state are related and therefore need to be discussed together. Whereas view STATECONTAINSPROGRAMMATICALLY SETPROPERTYVALUES CONTROLSTATECONTAINSTHEDATAREQUIREDFOR one control to make it appear after a postback in the same state that it was in beforehand. Frustratingly, the control state is stored as part of the view state data by default. This means that there are two different ways of saving control data during postbacks, but both use the same storage—the hidden view state field. However, control developers may decide to write the control state into private hidden fields to retain the state and decouple view state and control state storage, then.

NNote

Control state is only for small amounts of critical data that are essential for the control across postbacks. It is not seen as an alternative to view state.

Download at WoweBook.Com

247

248

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

In fact, there is no way to treat both states separately from each other from page-level code. Disabling the view state suppresses the serialization and storage mechanism entirely, so the control state gets lost. Complex controls, such as Cne`Reas, store information about paging and sorting, because there are no corresponding HTML fields able to store and send such data as part of a regular form. The Cne`Reas has several indices that retain the internal state. Changes to underlying data are tracked and used to fire appropriate events. These are properties such as A`epEj`at, L]caEj`at, and Oknp@ena_pekj. Several internal actions might lead to changes that need to be stored during postbacks, but this does not use the same path through the code as the view state would use for public properties. The view state data stored in the hidden field would expand, and developers using your control might by concerned by the growing page and form data. Control developers should be careful about using the control state because of its dependency on view state. A disabled view state could cause the control state to not function properly. However, as a control developer, you have several options for managing the way your control stores internal state values. First, the L]ca*NaceopanNamqenao?kjpnkhOp]pa method must be called to ensure that the control starts storing the control state. Apart from within view state, there is no Op]pa>]c that stores values directly. It’s up to you to implement the whole storage level. This is both GOODANDBAD ASALTHOUGHYOULLHAVEMORECONTROLOFWHATHAPPENSINTERNALLY ITREQUIRESMORE effort to store a few primitive values. Listing 6-1 shows a simple control that stores several values in the control state. Listing 6-1. A Custom Control Using the Control State lq^he__h]ooIu?kjpnkh6?kjpnkh w opnejcop]pa@]p]7 lnkpa_pa`kranne`arke`KjEjep$Arajp=ncoa% w L]ca*NaceopanNamqenao?kjpnkhOp]pa$pdeo%7 ^]oa*KjEjep$a%7 y lnkpa_pa`kranne`arke`Hk]`?kjpnkhOp]pa$k^fa_po]ra`Op]pa% w k^fa_pWY_pnhOp]pa9$k^fa_pWY%o]ra`Op]pa7 ^]oa*Hk]`?kjpnkhOp]pa$_pnhOp]paW,Y%7 op]pa@]p]9$opnejc%_pnhOp]paW-Y7 y lnkpa_pa`kranne`ak^fa_pO]ra?kjpnkhOp]pa$% w k^fa_pWY_pnhOp]pa9jask^fa_pW.Y7 _pnhOp]paW,Y9^]oa*O]ra?kjpnkhOp]pa$%7 _pnhOp]paW-Y9op]pa@]p]7 napqnj_pnhOp]pa7 y y

Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

If you plan to write a custom page state persister, you’ll have to handle the control state’s data ASWELLASTHEVIEWSTATESDATA4HEPERSISTERSPROVIDERMUSTSTOREBOTHOTHERWISEALMOSTALLCUStom controls will stop functioning properly. An alternative is to store the values your own way—using private hidden fields, perhaps—in order to remain independent of the provider. However, this is beyond the scope of this chapter. Besides, adding infrastructure logic to custom controls runs counter to the ASP.NET paradigm, in which the base framework contains and exposes a rich infrastructure. In conclusion, view state and control state are stored in the same place in order to completely and automatically restore a control’s properties. Since the storage and management of view state and control state are related, I’ll discuss them together in this chapter. When I use the term “view state” consider it as including control state as well.

The Default Providers ASP.NET uses a provider to manage storage of the view state. The preceding description assumes the usage of one of the two providers’ available out-of-the-box. Both providers derive from an abstract base class, L]caOp]paLanoeopan:

s De``ajBeah`L]caOp]paLanoeopan



s OaooekjL]caOp]paLanoeopan

By default, the De``ajBeah`L]caOp]paLanoeopan is used to store the view state in a hidden field. When you look into a page’s source code in the browser, you’ll find a field with the name __VIEWSTATE. This is the serialized, encoded, and optionally encrypted collection of properties stored in the Op]pa>]c (see Figure 6-1).

Figure 6-1. Typical view of the view state’s hidden field

Download at WoweBook.Com

249

250

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

This is what you’ll see if the De``ajBeah`L]caOp]paLanoeopan is used. There are several pros and cons to using this method. Many pages store information, and many users have individual data. The state is associated with the current page, and apart from session data that is independent of the current page, this data is specific to the page and the user. Storing the data on the client computer MOVESTHEMEMORYREQUIREDFROMTHESERVERTOTHECLIENT4HISCOSTSBANDWIDTH BUTSAVESSERVER resources. If you have 1KB of session data and 1,000 users accessing the server simultaneously, you’ll need to store 1MB of data. If this happens for 100 pages, you’ll need to store 100MB. This isn’t usually significant, but growing traffic will increase the resource consumption accordingly. For this reason, using the browser’s memory is a better option for scalability, and this is why the default provider uses the De``ajBeah`L]caOp]paLanoeopan option. However, sometimes it’s not the server’s resources that cause the bottleneck, but the bandWIDTH PARTICULARLYONMOBILEDEVICES6IEWSTATEISTRANSMITTEDTWICEFOREACHREQUEST!CCESSING a dozen pages with 1KB of session data each would force the device to transfer and process an additional 24KB of data, and this could be even higher for badly-developed pages. To investigate the contents of the view state, a tool such as Fritz Onion’s ViewStateDecoder is invaluable. Knowing what is stored in view state makes it’s easier to design a custom page state persister as shown in Figure 6-2. You can find the most recent version of ViewStateDecoder at: dppl6++sss*lhqn]hoecdp*_ki+_kiiqjepu+ia`e]+l+1-244*]olt.

Figure 6-2. Examine the contents of the view state. At this point, the particular contents of the view state aren’t important. Decoding the data is merely to understand the internal behavior.

Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

Changing the Default Provider The alternative provider, OaooekjL]caOp]paLanoeopan, moves the storage strategy from the client to the server. The data is stored in the session, along with other session variables. However, view state data is not session data—merely the state of controls. View state for each page is stored separately in this provider. To change from the default provider, you must override the L]caOp]paLanoeopan property of the L]ca class: lnkpa_pa`kranne`aL]caOp]paLanoeopanL]caOp]paLanoeopan w cap w napqnjjasOaooekjL]caOp]paLanoeopan$pdeo%7 y y It’s also possible to set this globally by assigning the following attribute to the l]cao tag in the web.config file. 8Ouopai*sa^: 8l]caol]ca>]oaPula9Lanoeopan>]oaL]ca: *** 8+Ouopai*sa^: This assigns a base page to all pages—PersisterBasePage, for example, which derives from the L]ca class and overrides the L]caOp]paLanoeopan property. However, this prevents you from using code-behind. You could set the base class individually for each page. This is more flexible, but more demanding. The page’s definition could look like the following: lq^he_l]npe]h_h]oo[@ab]qhp6Lanoeopan>]oaL]ca As easy as this seems, it always involves a compromise. The workload is either on the client or the server. Fortunately, the extensibility model of ASP.NET allows you to create custom providers to transparently replace the existing ones.

Developing a Custom Page State Provider As already mentioned, the entry point into a custom provider is the implementation of an abstract BASECLASS"EFOREYOUSTARTCODING YOULLNEEDTOANSWERTWOQUESTIONS

s 7HERESHALL)STOREDATADURINGPOSTBACKS



s (OWDO)IDENTIFYWHENDATAISNOLONGERCURRENT

The first answer is easy. Data is typically stored in a file system, a database, or in memory. The second answer is more complicated. Data is related to a particular page, and when a user leaves the page, the data becomes redundant. This event is difficult to recognize. The user can leave the page by navigating to another page within the same application, by jumping to a different Web site on another server, or even by simply closing the browser. Keeping the data in storage forever is not an option, as this would increase the storage space used and the effort of retrieving the right DATA7HILETHEDEFAULTPROVIDERISNOTTHEIDEALSOLUTIONEITHER ITDOESANSWERTHESECONDQUESTION if the user moves on to another page, the browser removes the data from the client’s memory. Thus, you don’t need to worry about obsolete data.

Download at WoweBook.Com

251

252

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

4HEREISNOSATISFACTORYANSWERTOTHISQUESTION)TSUSUALLYSUFFICIENTSIMPLYTOREMOVEOUTdated data that has not been refreshed for a specific period of time. This assumes that a user is no longer connected to the server. Selecting a value corresponding to the session timeout will be ADEQUATE for most applications.

Choosing the Data Storage In this example, I’ll make the storage as easy as possible to implement. The data is stored on the server in the file system. This could even be a shared drive, if you need to support a web farm. File systems are highly efficient for storing and retrieving data and avoid dependency on a database. However, this is simply an example of how to extend the page state persister. The storage solution you use depends entirely on the characteristics of your application. You’ll notice that the hidden field is still in charge, because it contains some information for IDENTIFYINGUNIQUEPAGES4HISISWHYTHEHIDDENFIELDISNOTEMPTYWHENUSINGTHEDEFAULTPROVIDER even if the view state is disabled. However, the identifier only needs a few bytes, and shouldn’t affect BANDWIDTHREQUIREMENTS

Analyzing a Provider Before implementing the provider from scratch, let’s examine the OaooekjL]caOp]paLanoeopan class for firsthand information about the internal structure of such a provider. This class stores data on the server, just as the custom provider is intended to do. If you investigate the view state value captured from the hidden field, you’ll see a simple hexadecimal number, such as 8cb5cd5d086eee0. 4HISISTHEHEXADECIMALREPRESENTATIONOFTHEPROCEDURE5SINGTHEFOLLOWINGCODESEQUENCE YOU can decode the value: jas@]paPeia$,t4_^1_`1`,42aaa,(@]paPeiaGej`*Hk_]h%*PkOpnejc$% This value decodes to 14 February 2009, 4:09pm and 57 seconds. The OaooekjL]caOp]paLanoeopan stores not one, but nine of these values internally, to keep the history of page accesses alive. When the user presses the browser’s back button, a previous page is pulled from the server. Using the timestamp as a key, the correct data is retrieved from the server’s storage. The name of the internal QUEUEIS??6)%734!4%15%5%#ONSTRAININGTHENUMBEROFPAGESINTHEHISTORYSOLVESTHESECOND QUESTIONRAISEDEARLIERANDLIMITSTHESTORAGESPACEUSED3INCETHEUSERSBEHAVIORDEPENDSON THEAPPLICATIONSNAVIGATIONSTRUCTURE YOUCANALTERTHEQUEUESIZEUSINGTHEFOLLOWINGENTRYINTHE web.config file: 8oaooekjL]caOp]padeopknuOeva9-.+: This value allows 12 pages in the history list. The value you choose is always a compromise BETWEENCONVENIENCEANDRESOURCEUSAGE)FTHEUSEREXCEEDSTHEQUEUESIZELIMIT THEVIEWSTATE becomes invalid and an exception is thrown. You can catch the exception, deliver an error page, and end the session, or simply redirect to a default page. However, as this is not an ideal solution, the following example shows an alternative way of dealing with “dead” data.

Implementing the Provider As we learned from the default implementation, the whole procedure of loading and saving the state consists of two methods, Hk]` and O]ra, respectively. Both use the fully implemented serialization and deserialization methods provided by the base class to convert between the Op]pa>]c object and a text string. The example stores the data in single files in the file system. Each page’s data becomes one file. To retrieve the values, two pieces of information must be held in the view state field: the name of the file and the timestamp. The timestamp is needed for private garbage collection to Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

remove expired data. The file name associates the page’s view state field with the file itself. After rendering to the browser, the hidden view state looks like the following: 8ejlqppula9de``ajj]ia9[[REASOP=PAE@e`9[[REASOP=PAE@± r]hqa94_^1_`1`,42aaa,).me,mlnvk`erdd11qskc/g01*ro+: The first part of the value, before the hyphen, is the timestamp. I have retained the coding schema. The second part is a randomly generated value, plus the extension, *ro. Listing 6-2 shows the code for the custom provider, as described thus far. Listing 6-2. Persisting the View State Using Local File System lq^he__h]ooBehaL]caLanoeopan6L]caOp]paLanoeopan w lner]pa_kjopopnejcReasOp]paBkniBeah`E@9[[REASOP=PAE@7 lner]pa_kjopopnejcOp]paBehaBkh`anL]pd9z+Op]pa@]p]+7

lq^he_BehaL]caLanoeopan$L]cal% 6^]oa$l% w y lq^he_kranne`arke`Hk]`$% w opnejcop]paE`ajpebeanR]hqa9± Dppl?kjpatp*?qnnajp*Namqaop*BkniWReasOp]paBkniBeah`E@Y7 eb$op]paE`ajpebeanR]hqa*Hajcpd:,% w opnejcbehaJ]ia9op]paE`ajpebeanR]hqa7 opnejcbehaL]pd9Dppl?kjpatp*?qnnajp*Oanran*I]lL]pd$± Op]paBehaBkh`anL]pd'behaJ]ia%7 opnejc_kjpajpo9Beha*Na]`=hhPatp$behaL]pd%7 L]enop]pa9^]oa*Op]paBkni]ppan*@aoane]heva$_kjpajpo%]oL]en7 eb$op]pa9jqhh% w ^]oa*ReasOp]pa9op]pa*Benop7 ^]oa*?kjpnkhOp]pa9op]pa*Oa_kj`7 y y y lq^he_kranne`arke`O]ra$% w eb$^]oa*L]ca*Bkni9jqhh± ""$^]oa*?kjpnkhOp]pa9jqhhxx^]oa*ReasOp]pa9jqhh%% w ++?na]pabehaj]iabkno]ra opnejcbehaJ]ia9Opnejc*Bkni]p$w,6t4y)w-y*ro(@]paPeia*Jks*Pe_go(± Dppl?kjpatp*?qnnajp*Oaooekj*OaooekjE@%7 opnejcbehaL]pd9Dppl?kjpatp*?qnnajp*Oanran*I]lL]pd$± Op]paBehaBkh`anL]pd'behaJ]ia%7 L]enl9jasL]en$^]oa*ReasOp]pa(^]oa*?kjpnkhOp]pa%7 Beha*Snepa=hhPatp$behaL]pd(^]oa*Op]paBkni]ppan*Oane]heva$l%%7 r]ndb9jasDe``ajBeah` Download at WoweBook.Com

253

254

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

w R]hqa9behaJ]ia( E@9ReasOp]paBkniBeah`E@ y ^]oa*L]ca*Bkni*?kjpnkho*=``=p$,(db%7 y y y The base class provides methods of serializing and deserializing the data. You can access these methods by calling ^]oa*Op]paBkni]ppan. The provider saves both the control state and the view state, and creates a L]en from them, to group the values together. The serialized L]en is written directly into the file using Beha*Snepa=hhPatp and retrieved using Beha*Na]`=hhPatp. We are not concerned about threading here, because each storage location is dedicated to one user session and one page. There’s a chance that a user could send the same page twice to the server at the same moment, but that’s unlikely—and out of our scope. The Hk]` method is the reverse of the O]ra method, using the same approach. The O]ra method creates a hidden field using the De``ajBeah` control and adds it to the beginning of the current control collection.

Extending the Provider Although, from this example, custom implementation seems very simple, this isn’t entirely true. Over time, the folder for state files accumulates more and more files. You might consider deleting session state files triggered by the session end event, but that’s not reliable. The event is fired only if the session ends by command. If the user closes the browser the session dies “silently,” and only the session timeout can be used to remove remaining objects. One option is to remove old files regularly, but using such a cleanup process for each page REQUESTWOULDINCREASETHENUMBEROFFILEACCESSESANDTHUSDECREASEPERFORMANCE!BETTER APPROACHISTOINCLUDEAREGULARFOLDERCHECKINDEPENDENTOFANYREQUESTS5SINGTHISTEST YOUCAN delete all files over a certain age. Implementing the tidy-up code in the provider is undesirable. Recall the goals and intended behavior of a provider: it’s not a good idea to have them running basic tasks. Rather, the health monitoring system provided by ASP.NET is ideal for managing the “health” of the provider’s storage.

Maintaining the Storage by Using the Health Monitor Since the cleaning-up procedure must be run regularly, the Sa^Da]np^a]pArajp is an ideal trigger. This event fires at regular intervals, invoking another provider. The health monitoring system itself is based on a provider model. Therefore, the second part of a custom view state storage solution consists of a “custom cleanup provider.” Before you implement this provider, take a look at the configuration step needed in the web. config file in the 8ouopai*sa^: section (see Listing 6-3). Listing 6-3. Activating the Health Monitor 8da]hpdIkjepknejcaj]^ha`9pnqada]np^a]pEjpanr]h91: 8lnkre`ano: 8]``j]ia9Beha?ha]jqlLnkre`an pula9=lnaoo*Atpajoe^ehepu*ArajpLnkre`an*Beha?ha]jqlLnkre`an(± =lnaoo*Atpajoe^ehepu*ArajpLnkre`an+: 8+lnkre`ano: 8arajpI]llejco: 8]``j]ia9Beha?ha]jqlArajppula9Ouopai*Sa^*I]j]caiajp*Sa^Da]np^a]pArajp op]npArajp?k`a9,aj`Arajp?k`a9.-0304/203:8+]``: Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

8+arajpI]llejco: 8nqhao: 8]``j]ia9?ha]jqlArajparajpJ]ia9Beha?ha]jqlArajp lnkre`an9Beha?ha]jqlLnkre`an+: 8+nqhao: 8+da]hpdIkjepknejc: The da]hpdIkjepknejcELEMENTREQUIRESTHREECHILDELEMENTS

s lnkre`an: The provider that issues the action



s arajpI]llejc: The event that invokes the action



s nqhao: A relation between a specific event and a provider

The event is based on the Sa^Da]np^a]pArajp class. Enable the monitor using the aj]^ha`9pnqa attribute. The da]np^a]pEjpanr]h91ATTRIBUTESETSTHEHEARTBEATTOFIVESECONDS this is just for testing and debugging purposes. In real-life scenarios, set a value that provides a compromise between memory consumption and cleanup effort in order to monitor the number of files stored in the data folder. A heartbeat interval of one hour is a good starting value. The example provider configured here is called the Beha?ha]jqlLnkre`an. Listing 6-4 demonstrates its implementation. Before beginning, you’ll need to know a few things about health monitoring providers. The monitoring system is implemented to observe an ASP.NET application. It must be active before the application starts and after it ends, and it must exist independently of CURRENTREQUESTS THECURRENTREQUESTSSTATEINTHEPIPELINE AND))34HEREFORE THECLASSMUSTBE implemented in an assembly that can be loaded separately. Adding the class to App_Code or any place in your current project will fail. Instead, create a simple class library project, reference it from the Web application you wish to monitor, and add the following class to that project. 4HECODEREQUIRESTHEOuopai*Sa^*I]j]caiajp namespace to be available. Listing 6-4. Simple Health Monitor Provider That Tidies Up a Folder lq^he__h]ooBeha?ha]jqlLnkre`an6Sa^ArajpLnkre`an w lner]pa_kjopopnejcOp]paBehaBkh`anL]pd9Op]pa@]p]+7 lq^he_Beha?ha]jqlLnkre`an$% 6^]oa$% w  y lq^he_kranne`arke`Bhqod$% w ++jkpnamqena` y lq^he_kranne`arke`Lnk_aooArajp$Sa^>]oaArajpn]eoa`Arajp% w @]paPeia`pN]eoa`9n]eoa`Arajp*ArajpPeia7 ++Naikrabehao opnejcbehaL]pd9L]pd*?ki^eja$DpplNqjpeia*=ll@ki]ej=llL]pd(± Op]paBehaBkh`anL]pd%7 bkna]_d$opnejcbehaej@ena_pknu*CapBehao$behaL]pd%% w eb$`pN]eoa`)Beha*Cap?na]pekjPeia$beha%:PeiaOl]j*BnkiDkqno$2%% Download at WoweBook.Com

255

256

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

w Beha*@ahapa$beha%7 y y y lq^he_kranne`arke`Odqp`ksj$% w ++?ha]jqlkjodqp`ksj opnejcbehaL]pd9L]pd*?ki^eja$DpplNqjpeia*=ll@ki]ej=llL]pd(± Op]paBehaBkh`anL]pd%7 bkna]_d$opnejcbehaej@ena_pknu*CapBehao$behaL]pd%% w Beha*@ahapa$beha%7 y y y Each heartbeat of the monitor invokes the Lnk_aooArajp method. A simple loop locates all the files exceeding the specified age—six hours in the example—and deletes them. The file expiry test can be extended to suit your needs. You could check if the corresponding session is still alive, or if the data in the file matches certain conditions. The current timestamp is passed to the method with the n]eoa`Arajp*ArajpPeia value. The path to the application can be retrieved using the DpplNqjpeia object. Remember that Dppl?kjpatp might not be available, because the first heartbeat arrives when the application has not yet begun. Other monitoring events could provide the Dppl?kjpatp object, but basic events such as the Sa^Da]np^a]pArajp don’t support this.

Conclusion In this section, we looked at replacing the default page state persister provider that is responsible for storing view state and embedded control state information. Using the health monitoring system with another custom provider allows us to maintain cleanup routines. Page states are not the only state persisted during a user’s session. Data is also stored in session variables, which are, by default, stored in memory. However, as in several other parts of ASP.NET, the session state is built on the provider model. The next section explains this in detail and shows how to extend the behavior using a custom provider.

Session State Providers As shown in Chapter 4, providers are responsible for allowing storage access to services. The session state module is one such service relying on several out-of-the-box storage options. For all available options, a dedicated provider exists. You can also add your own provider to implement a fully customized storage strategy.

The Session State Service The session state service is defined in the Ouopai*Sa^*OaooekjOp]pa*OaooekjOp]paIk`qha. Each instance creates a module that in turn creates a space to store data. The data is—as the name implies—associated with the user’s session. Ouopai*Sa^*OaooekjOp]pa*OaooekjOp]paOpkna@]p] is the class that defines the storage space. One instance is created for each user session. The OaooekjOp]paOpkna@]p] class is responsible for serializing and deserializing the session data. Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

The serialization uses a highly efficient binary format partly customized with hardcoded transformations for scalar values and the >ej]nuBkni]ppan type for all other values. This type is defined in the Ouopai*Nqjpeia*Oane]hev]pekj*Bkni]ppano*>ej]nu namespace. Since the session serializes all objects, the process includes two types of data: static and non-static. Non-static data are held in an Epaio collection. This collection is defined as an interface of type EOaooekjOp]paEpai?khha_pekj, which is a simple collection based on E?khha_pekj and EAjqian]^ha. It’s exposed by the Oaooekj object through an indexer and the Epaio property. The Op]pe_K^fa_po property relies on the DpplOp]pe_K^fa_po?khha_pekj type, which in turn is a collection that implements the same interfaces. However, the serialization is implemented slightly differently here. For both Epaio and Op]pe_K^fa_po, you can call the Oane]heva and @aoane]heva methods to translate the data to and from a storable format. Apart from the two types of data previously mentioned, the data store has its own Peiakqp PROPERTY4HISISNECESSARY ASTHESERVICEISIMPLEMENTEDASAN(440MODULEANDRELIESONREQUEST events. If the final event is not raised, the store would become an orphan if the timeout did not terminate it. Internally, the session state service class is defined as follows: lq^he_oa]ha`_h]ooOaooekjOp]paIk`qha6EDpplIk`qha The session state module is executed before the handlers in the =_mqenaNamqaopOp]pa pipeline state. This ensures that session data is already present when the page’s handler is loaded. The modULEATTEMPTSTORETRIEVETHESESSION)$FROMTHEREQUESTANDUSESTHISTOOBTAINDATAFROMTHESESSION store provider. If both function correctly, the session data is rebuilt as a dictionary and exposed to the DpplOaooekjOBJECT4HESESSIONDATAISSTOREDATTHEENDOFTHEREQUESTPROCESSING WITHINTHE Naha]oaNamqaopOaooekj stage of the pipeline. If no session ID is present, a new one is created. If the ID is there and some session data is changed, the provider is used to store these data. The service’s providers use the OaooekjOp]paOpknaLnkre`an>]oa provider base class, which defines a subset of methods all providers share. As shown in Listing 6-5, this is an embedded class used here as a basis for custom providers. Listing 6-5. The OaooekjOp]paOpknaLnkre`an>]oa Is the Base for All Session State Providers W=olJapDkopejcLanieooekj$Oa_qnepu=_pekj*Hejg@ai]j`(± Harah9=olJapDkopejcLanieooekjHarah*Iejei]h%( =olJapDkopejcLanieooekj$Oa_qnepu=_pekj*Ejdanep]j_a@ai]j`(± Harah9=olJapDkopejcLanieooekjHarah*Iejei]h%Y lq^he_]^opn]_p_h]ooOaooekjOp]paOpknaLnkre`an>]oa6Lnkre`an>]oa w lnkpa_pa`OaooekjOp]paOpknaLnkre`an>]oa$% w y lq^he_]^opn]_pOaooekjOp]paOpkna@]p]?na]paJasOpkna@]p]$Dppl?kjpatp_kjpatp(± ejppeiakqp%7 lq^he_]^opn]_prke`?na]paQjejepe]heva`Epai$Dppl?kjpatp_kjpatp(± opnejce`(± ejppeiakqp%7 lq^he_]^opn]_prke`@eolkoa$%7 lq^he_]^opn]_prke`Aj`Namqaop$Dppl?kjpatp_kjpatp%7 lq^he_]^opn]_pOaooekjOp]paOpkna@]p]CapEpai$Dppl?kjpatp_kjpatp(± opnejce`(± kqp^kkhhk_ga`(± kqpPeiaOl]jhk_g=ca(± kqpk^fa_phk_gE`(± kqpOaooekjOp]pa=_pekjo]_pekjo%7

Download at WoweBook.Com

257

258

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

lq^he_]^opn]_pOaooekjOp]paOpkna@]p]CapEpaiAt_hqoera$Dppl?kjpatp_kjpatp(± opnejce`(± kqp^kkhhk_ga`(± kqpPeiaOl]jhk_g=ca(± kqpk^fa_phk_gE`(± kqpOaooekjOp]pa=_pekjo]_pekjo%7 ejpanj]hrenpq]hrke`Ejepe]heva$opnejcj]ia(± J]iaR]hqa?khha_pekj_kjbec(± EL]npepekjNaokhranl]npepekjNaokhran% w y lq^he_]^opn]_prke`Ejepe]hevaNamqaop$Dppl?kjpatp_kjpatp%7 lq^he_]^opn]_prke`Naha]oaEpaiAt_hqoera$Dppl?kjpatp_kjpatp(± opnejce`(± k^fa_phk_gE`%7 lq^he_]^opn]_prke`NaikraEpai$Dppl?kjpatp_kjpatp(± opnejce`(± k^fa_phk_gE`(± OaooekjOp]paOpkna@]p]epai%7 lq^he_]^opn]_prke`NaoapEpaiPeiakqp$Dppl?kjpatp_kjpatp(opnejce`%7 lq^he_]^opn]_prke`Oap=j`Naha]oaEpaiAt_hqoera$Dppl?kjpatp_kjpatp(± opnejce`(± OaooekjOp]paOpkna@]p]epai(± k^fa_phk_gE`(± ^kkhjasEpai%7 lq^he_]^opn]_p^kkhOapEpaiAtlena?]hh^]_g$± OaooekjOp]paEpaiAtlena?]hh^]_gatlena?]hh^]_g%7 y Inspecting the CapEpai and NaikraEpai methods, you’ll notice that the provider is responsible for creating (via the kqp parameter for CapEpai) the session-specific OaooekjOp]pa@]p]Opkna. The vital parameter is Dppl?kjpatp ASITPASSESALLTHEINFORMATIONREQUIREDFORIDENTIFYINGTHESESSION However, the base class is abstract. In order to understand the code and learn how to implement a custom provider, we’ll need to examine certain implementations. The next sections will cover the nature of sessions and cookies that are tightly coupled with the session provider’s behavior.

Identifying the Session Despite storage management, the session state service needs to retrieve the session ID. The first attempt to overcome this stateless behavior led to the invention of cookies.

Cookies Make HTTP Taste Good . . . A cookie is a small piece of text-based information stored in the browser’s memory or disk space. It’s under the browser’s control, and it exists to send information about the state back to the server. 7HENTHEBROWSERREQUESTSANEWRESOURCE ITSEARCHESFORCOOKIESSTOREDBYTHISSPECIFICSERVERAND returns this information. The server recognizes the information, reading it back from the headers of THE(440REQUEST ANDUSESITTO obtain the client’s state.

. . . and Bad However, cookies have some serious drawbacks. If a server sends portions of a page only, this very portion would send the information back to this server and not the one serving the main page. An advertising banner is an example of such a section. At the end of the last century, the company Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

DoubleClick (eventually bought out by Google) invented a business concept based on cookies. Once a banner ad appears, the cookies related to it are placed in the browser’s memory. When the user moves to a page drawn from another server, but containing a banner pulled from the original ad server, the ad server’s code would receive the same cookie back. The original server knows that the user has been on different pages, and it also recognizes where these pages originated. The cookie makes it possible for the ad server to trace the user and track his or her behavior. By the third page, the banner ad has not been selected at random. Based on the user’s behavior, the ad server chooses the banner that best fits the user’s interests. This leads to a much higher click rate, which in turn results in more money made. This is the concept invented by DoubleClick—with which Google now generates a lot of revenue. It is as simple as it sounds. However, it has faced criticism in that it compromises the user’s privacy. The ad server knows much more of a user’s behavior than people would tell strangers voluntarily. Since cookies work silently, the user is never asked to accept or deny them. Even if modern browsers managed cookies well, it’s still a complicated task to deal with them, erasing them where appropriate and retaining them if harmless.

Beyond Cookies Avoiding the usage of cookies or even limiting them to just one—to store the session state—would give your users the opportunity to operate within a restrictive cookie usage policy. It is an advantage for a site avoiding cookies. However, it makes your life as a developer much more difficult because cookies simplify the session handling. Fortunately, ASP.NET provides a number of sophisticated TECHNIQUESTHATHELPYOUHANDLETHEDRAWBACKSOF(440SSTATELESSNESS)NTERMSOFTHESESSION state, you can decide whether to work with session cookies or without cookies at all. !30.%4MAINTAINSTHECOOKIELESSSESSIONSTATEBYAUTOMATICALLYINSERTINGAUNIQUESESSION)$ into the URL. This would look like this: dppl6++sss*]lnaoo*_ki+ $O$hep/fg.2p,1v20r-0rhi,0o,5%%+`ab]qhp*]olt. The following configuration in the web.configFILEISREQUIRED 8_kjbecqn]pekj: 8ouopai*sa^: 8oaooekjOp]pa_kkgeahaoo9pnqanacajan]paAtlena`OaooekjE`9pnqa+: 8+ouopai*sa^: 8+_kjbecqn]pekj: A session ID will eventually expire when the session ends, or has been timed out. In this case, THE)$ISRECYCLEDALATERSESSIONCOULDHAVETHESAME)$)FA52,ISSTOREDSOMEWHEREONTHE client—such as within the favorites folder, sent by email, or gathered by a search engine—this could cause a security hole, as the older session ID located in the URL could be the same as that of another current session. The nacajan]paAtlena`OaooekjE`9pnqa attribute reduces that risk by forcing it to create a new ID every time. If this behavior is not sufficient for your application, you can write your own session ID module. For complete control, consider implementing the EOaooekjE@I]j]can interface. To just control the creation of the ID, inherit from the OaooekjE@I]j]can base class. Both types are defined in the Ouopai*Sa^*OaooekjOp]pa namespace. The next example demonstrates how to replace the session ID with a custom value (see Listing 6-6). Listing 6-6. Simple Session ID Manager with Custom ID Creation j]iaol]_a=lnaoo*OaooekjOp]pa*?k`a w lq^he__h]ooOeilhaOaooekjE@I]j]can6OaooekjE@I]j]can w

Download at WoweBook.Com

259

260

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

lq^he_kranne`aopnejc?na]paOaooekjE@$Dppl?kjpatp_kjpatp% w napqnjCqe`*JasCqe`$%*PkOpnejc$%7 y lq^he_kranne`a^kkhR]he`]pa$opnejce`% w pnu w Cqe`paopCqe`9jasCqe`$e`%7 eb$e`*Amq]ho$paopCqe`*PkOpnejc$%%% w napqnjpnqa7 y y _]p_d w y napqnjb]hoa7 y y y The only methods to override are ?na]paOaooekjE@ and R]he`]pa. However, the basic form of the ID, such as $O$***%%, is still used. To obtain completely different behavior, you must implement the interFACE WHICHREQUIRESSEVERALADDITIONALMETHODSTOBEIMPLEMENTED4HISISACHIEVEDBEHINDTHESCENES by adding the ID to the URL first and then redirecting to the new URL. The changed URL is then passed to the browser. However you implement this, you must configure the new session ID manager in the web.config file: 8oaooekjOp]paik`a9EjLnk_ _kkgeahaoo9pnqa nacajan]paAtlena`OaooekjE`9b]hoa peiakqp9., oaooekjE@I]j]canPula9=lnaoo*OaooekjOp]pa*?k`a*IuOaooekjE@I]j]can(± =lnaoo*OaooekjOp]pa+: The oaooekjE@I]j]canPula attribute contains the class’s name and the namespace of the containing assembly. All other options depend on the entire configuration and are not directly associated with the session ID manager.

The Internal State Providers ASP.NET includes three internal state providers. You should investigate these before planning the development of a custom provider.

s EjLnk_OaooekjOp]paOpkna



s KqpKbLnk_OaooekjOp]paOpkna



s OmhOaooekjOp]paOpkna

Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

This section gives a brief overview of the internal state providers, which have several features in common. You can control their behavior with the Aj]^haOaooekjOp]pa attribute located in the
Figure 6-3. Principles of the session state providers

InProcSessionStateStore The EjLnk_OaooekjOp]paOpkna class defines the default session state provider if no other provider is specified. It stores session data within the current process, using the Dppl?]_da module to store data in memory. This provider is the most efficient. The overhead is limited to the extracting of the session ID and the serializing and deserializing of the data. Everything happens in memory using a cache lookup, which merely retrieves the data and refreshes the cache expiration timestamp. However, the EjLnk_OaooekjOp]paOpkna has some drawbacks. This provider does not survive an application restart, since the cache objects are rebuilt on restart—meaning all previous sessions WOULDBELOST)TALSODOESNOTFUNCTIONRELIABLYINWEBFARMSCENARIOS WHERETHENEXTREQUESTMIGHT reach a different server that doesn’t see the session data in the first server’s memory. The following web.config file snippet shows the configuration: 8oaooekjOp]pa ik`a9EjLnk_ _kkgeahaoo9b]hoa +: Download at WoweBook.Com

261

262

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

OutOfProcSessionStateStore This class enables out-of-process storage based on an unmanaged stream that is created when an INCOMINGREQUESTISHANDLEDBYTHESESSIONSTATESERVICE4HESTREAMISREADFROMANDWRITTENBACK to a state server service. This Windows service runs independently of IIS and allows the sharing of memory data through several servers that make up a web farm. The provider is not as efficient as the in-process version, as it takes time to pass data beyond process boundaries. Internally, the process communicates with a Windows service that passes the data from one server to another using HTTP. This is a very slim and fast implementation of a Web Server handling only a subset of Web Server functions. While the HTTP protocol adds overhead to REQUESTS THEKqpKbLnk_OaooekjOp]paOpkna will survive an application restart, as the storage is not part of the ASP.NET process. The following snippet from the web.config file shows the configuration: 8oaooekjOp]pa ik`a9Op]paOanran op]pa?kjja_pekjOpnejc9p_lel9-.3*,*,*-60.0.0 _kkgeahaoo9b]hoa +: The service runs on local machines and on port 42424 by default. The state service can be found here: !ouopainkkp!XIe_nkokbp*JAPXBn]iaskngX8ranoekj:X]oljap[op]pa*ata It must be installed and started as a service. By default, it’s installed, but set to start manually. To launch the service after the Web Server starts, set the ASP.NET state service’s start option to Automatic.

SqlSessionStateStore ASP.NET provides the OmhOaooekjOp]paOpkna in order to share state across multiple front-end servers. The provider consists of several pieces you must assemble:

s !DATATABLEFORTHESESSIONDATA



s 3TOREDPROCEDURESTOWRITEANDREADTHESESSIONDATAFROM31,3ERVER



s !CONNECTIONSTRINGDEFINEDINweb.config, which declares the database connection



s 4HEOmhOaooekjOp]paOpkna set in the web.config as the default provider

To create the data table and add the stored procedures, use the !SPNET?REQSQLEXE tool. You can find it at: ?6XSej`ksoXIe_nkokbp*JAPXBn]iaskngXr.*,*1,3.3 Details about all the command line options are at: dppl6++io`j*ie_nkokbp*_ki+aj)qo+he^n]nu+io..542.*]olt 4HETOOLALSOSUPPORTSSETTINGSREQUIREDBYOTHER31,3ERVERBASEDMODULES&ORTHESESSION state, the following options are important:

s )Ooanranj]ia: The name of the database server, such as locahost\sqlexpress



s )``]p]^]oaj]ia4HENAMEOFTHEDATABASEREQUIRES)oopula_



s )oo]``: Adds support

Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T



s )oonaikra: Removes support



s )oopulap: Installs the data table into the tempdb database



s )oopulal: Installs the data table into a persistent database, like aspnetdb



s )oopula_)NSTALLSTHEDATATABLEINTOACUSTOMDATABASEUSE)``]p]^]oaj]ia to choose one

NTip If you start the Aspnet_reqsql tool without any parameters, a wizard is launched that leads you through the required steps. This web.config file snippet shows an example of the configuration: 8oaooekjOp]pa ik`a9OMHOanran _kkgeahaoo9pnqa omh?kjja_pekjOpnejc9Ejpacn]pa`Oa_qnepu9OOLE7`]p]okqn_a9IuOmhOanran7 omh?kii]j`Peiakqp9-,+:

Improving the Session State The session state service adds a considerable overhead to the performance of your application. Since it’s a valuable tool, most developers choose to use session data. However, the serializing and DESERIALIZINGPROCEDURESREQUIREDFOREACHREQUESTTAKETIME)FTHEAPPLICATIONCOMESUNDERPRESsure, and if you decide to work with a web farm in order to balance the load, things might become WORSE4HESESSION RELATEDTRAFFICWOULDINCREASEONTHELOCALNETWORKBETWEENTHE31,3ERVEROR State server and the Web Servers. There are several ways of improving performance, and it’s important to think about these before you start creating your own session state providers. Some optimizations are implemented by default in order to avoid having a bottleneck for standard features. First, the ability to handle the session state can be disabled. You can set this using the
s Aj]^haOaooekjOp]pa9pnqa



s Aj]^haOaooekjOp]pa9b]hoa



s Aj]^haOaooekjOp]pa9Na]`Kjhu

%NABLINGANDDISABLINGTHESESSIONSTATEISTRIVIALWHENDISABLED NOSESSIONDATAISSTORED4HE Na]`Kjhu option is more subtle. Imagine that a user has several browser windows or tabs open and all of them are in the same session using the same session ID. If the user accesses the Web Server MULTIPLETIMESATONCE THEFIRSTREQUESTGAINSEXCLUSIVEACCESS LOCKINGACCESSFOROTHERREQUESTS4HE SECONDREQUESTMUSTWAITINORDERTOOBTAINITSEXCLUSIVEACCESSWHENTHEFIRSTREQUESTENDS4HIS could lead to an unsatisfactory user experience, as the user will probably open several windows to launch simultaneous tasks, such as downloading files. Instead of speeding things up, the windows would be blocked. To avoid this, the Na]`Kjhu option is used to allow concurrent read access to the SESSIONDATA4HELOCKISSTILLTHEREFORWRITEACCESSANDITBLOCKSOTHERREQUESTSWITHSAMESESSION)$ You will only benefit from this setting if you use the session variables carefully.

Download at WoweBook.Com

263

264

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

Implementing the Session State Store Provider You might wish to create a custom session-state store provider to:

s 3TORESESSION STATEINFORMATIONINADATASOURCEOTHERTHAN31,3ERVER SUCHASA-Y31, database or another third party database.



s -ANAGESESSION STATEINFORMATIONUSINGADATABASESCHEMATHATISDIFFERENTFROMTHEDEFAULT database schema.



s 5SEATOTALLYDIFFERENTSTORAGE strategy, such as the file system.

The Session State Module Session state is managed by the OaooekjOp]paIk`qha class, which calls the session-state STOREDPROVIDERTOREADANDWRITEDATATOTHEDATASTOREDURINGAREQUEST4HEMODULEUSESA OaooekjOp]paOpknaLnkre`an>]oa derived class as its data source. The actual implementation provides THEMEMBERSUSEDHERE3EE4ABLE FORALISTOFALLAVAILABLEMEMBERS!TTHESTARTOFAREQUEST the OaooekjOp]paIk`qha instance retrieves data from the data source by calling its CapEpaiAt_hqoera or CapEpai method4HEEXCLUSIVEACCESSISTHEDEFAULTTHECapEpai method also supports the Aj]^haOaooekjOp]pa9Na]`Kjhu attribute, allowing shared read access, as explained in the previous SECTION!TTHEENDOFAREQUEST IFTHESESSION STATEVALUESHAVEBEENCHANGED THEOaooekjOp]paIk`qha instance calls the Oap=j`Naha]oaEpaiAt_hqoera method to write the updated values to the data store. The OaooekjOp]paIk`qha class itself determines the session ID value, rather than relying on the session-state store provider. The session ID manager is responsible for the ID format, which is based on the implementation of the OaooekjE@I]j]can class. The OaooekjOp]paIk`qha class reverts to the ASP.NET process identity in order to access any secured resource, such as a database server. You can specify the OaooekjOp]paIk`qha instance to impersonate the process identity by setting the qoaDkopejcE`ajpepu attribute of the 8oaooekjOp]pa: configuration element to b]hoa. 8oaooekjOp]paqoaDkopejcE`ajpepu9b]hoa+: If the qoaDkopejcE`ajpepu attribute is pnqa, ASP.NET will impersonate either the process identity or the user credentials when connecting to the data source. Usually this is a cumbersome process, as you’ll have to manage all your users. Table 6-1. SessionStateStoreProvider Members

Member

Description

Ejepe]hevaNamqaop

Uses the Dppl?kjpatpOFTHECURRENTREQUESTANDPERFORMSANY INITIALIZATIONREQUIREDBYTHEPROVIDER

Aj`Namqaop

Uses the Dppl?kjpatpOFTHECURRENTREQUESTANDPERFORMSANY cleanup.

@eolkoa

Frees any resources no longer in use by the provider.

CapEpaiAt_hqoera

Retrieves session values and information from the session data store for a given Session ID and Dppl?kjpatp. Locks the SESSION ITEMDATAINTHESTOREFORTHEDURATIONOFTHEREQUEST3ETS several output-parameter values that inform OaooekjOp]paIk`qha about the state of the current item.



Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

Member

Description

CapEpai

Same as for the CapEpaiAt_hqoera method, except that it does not attempt to lock the session item in the data store. This method is used when you set the Aj]^haOaooekjOp]pa attribute of
Oap=j`Naha]oaEpaiAt_hqoera

Updates or releases the lock for the current session-state data. The jasEpai property forces the creation of a new item. Calls the NaoapEpaiPeiakqp method internally to extend the expiration period.

Naha]oaEpaiAt_hqoera

This method is called when the CapEpai or CapEpaiAt_hqoera method is called and the item is locked, but the lock duration has exceeded the Ata_qpekjPeiakqp value. Frees the item and releases the lock.

NaikraEpai

This method is called when the =^]j`kj method of the Oaooekj object is called. Deletes the session information from the data store.

?na]paQjejepe]heva`Epai

Adds an uninitialized item to the session data store with an ]_pekjBh]co value set to Ejepe]hevaEpai.

?na]paJasOpkna@]p]

Returns a new OaooekjOp]paOpkna@]p] object with empty data collections.

OapEpaiAtlena?]hh^]_g

Takes a delegate that references the Oaooekj[KjAj` event. If this event is supported, the method returns pnqaOTHERWISEITRETURNS b]hoa.

The CapEpaiAt_hqoera method is the most significant part of the provider. If no session item data is found in the data store, the method sets the hk_ga` output parameter to b]hoa and returns jqhh. This causes the OaooekjOp]paIk`qha to call the ?na]paJasOpkna@]p] method in order to create a new OaooekjOp]paOpkna@]p]OBJECTFORTHEREQUEST)FTHEITEMISLOCATEDBUTTHEDATAISLOCKED the CapEpaiAt_hqoera method sets the hk_ga` output parameter to pnqa, sets the hk_g=ca output parameter to the current age of the item (that is, current timestamp minus creation timestamp), sets the hk_gE` output parameter to the lock identifier retrieved from the data store, and returns jqhh. This causes the OaooekjOp]paIk`qha to call the CapEpaiAt_hqoera method again after a half-second interval in an attempt to retrieve the session-item information and obtain a lock on the data. If the hk_g=ca exceeds the Ata_qpekjPeiakqp value, OaooekjOp]paIk`qha calls the Naha]oaEpaiAt_hqoera method in order to clear the lock on the session-item data and calls the CapEpaiAt_hqoera method again. The ]_pekjBh]co parameter is used with sessions whose ?kkgeahaoo property is pnqa and whose nacajan]paAtlena`OaooekjE` attribute is set to pnqa. The ]_pekjBh]co value can be set to either Ejepe]hevaEpai or Jkja. Ejepe]hevaEpai indicates that the entry in the session data STOREISANEWSESSIONREQUIRINGINITIALIZATION5NINITIALIZEDENTRIESARECREATEDBYACALLTOTHE ?na]paQjejepe]heva`Epai method. If the item from the session data store is already initialized, the ]_pekjBh]co parameter is set to Jkja. If your provider supports cookieless sessions, set the ]_pekjBh]co output parameter to the value returned from the session data store for the current item. If the ]_pekjBh]co parameter value for the REQUESTEDSESSION STOREITEMEQUALSEjepe]hevaEpai, the CapEpaiAt_hqoera method should set the session data in the data store to zero after setting the ]_pekjBh]co out parameter.

Download at WoweBook.Com

265

266

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

The ?na]paQjejepe]heva`Epai method is used with cookieless sessions when the nacajan]paAtlena`OaooekjE` attribute is set to pnqa. This causes the OaooekjOp]paIk`qha to generate a new session ID value when an expired session is encountered. The process of generating ANEWSESSION)$VALUEREQUIRESTHEBROWSERTOBEREDIRECTEDTOA52,THATCONTAINSTHENEWLYGENERated ID. Refer to Listing 6-6 for an example of how to control the session ID generation process. The ?na]paQjejepe]heva`EpaiMETHODISCALLEDDURINGANINITIALREQUESTCONTAININGANEXPIRED session. After the OaooekjOp]paIk`qhaACQUIRESANEW)$TOREPLACETHEEXPIREDONE ITCALLSTHE ?na]paQjejepe]heva`Epai method. The browser is then redirected to the URL containing the newly generated ID. The existence of the uninitialized entry in the session data store ensures that the rediRECTEDREQUESTWITHTHENEWLYGENERATED)$ISNOTMISTAKENFORAREQUESTFORANEXPIREDSESSION ANDIS treated as a new session.

Preface Before developing a new session state persister, let’s briefly investigate what it can be used for. There are three major tasks:

s (ANDLINGSESSIONLOCKINGFORCONCURRENTREQUESTSTOTHESAMEDATA



s )DENTIFYINGANDOCCASIONALLYREMOVINGEXPIREDSESSIONDATA



s !LLOWINGMORETHANONEAPPLICATIONTOUSETHEPROVIDER

Locking Session-Store Data ASP.NET applicationsRESPONDTOMULTIPLECONCURRENTREQUESTS4HOSEREQUESTSMIGHTATTEMPT to access the same session information, as explained previously. When implementing your own provider, you’ll need to manage the locking behavior. A lock is set on session-store data at the BEGINNINGOFTHEREQUESTINTHECALLTOTHECapEpaiAt_hqoeraMETHOD7HENTHEREQUESTISCOMpleted, the lock is released during the call to the Oap=j`Naha]oaEpaiAt_hqoera method. If the OaooekjOp]paIk`qha instance encounters locked session data during the call to either the CapEpaiAt_hqoera or CapEpaiMETHOD ITWILLRE REQUESTTHESESSIONDATA4HISOCCURSATHALF SECOND intervals until either the lock is released or the amount of time specified in the Ata_qpekjPeiakqp property has elapsed. After a timeout occurs, the Naha]oaEpaiAt_hqoera method is called in order to free the session-store data. Additionally, a lock identifier is used to distinguish between concurRENTREQUESTSACCESSINGTHESAMESESSIONDATA4HISISNECESSARY ASTHESEREQUESTSRUNONSEPARATE threads. A call to the Naha]oaEpaiAt_hqoera appears before the Oap=j`Naha]oaEpaiAt_hqoera method is called for the current response.

Handling Expired Data Expiration occurs when a session times out or explicitly ends. A session ends with a user action, when the =^]j`kj method is called. The data for that session is deleted from the data store using the NaikraEpai method. The mechanism for deleting expired session data depends on the capabilities of your data source. If the session expires according to the session Peiakqp property, you can use the OapEpaiAtlena?]hh^]_g method to handle the Oaooekj[KjAj` event.

Set Application Name To maintain sessionSCOPE SESSION STATEPROVIDERSSTORESESSIONINFORMATIONUNIQUELYFOREACH application. This allows multiple ASP.NET applications to use the same data source without conFLICTING(OWYOUENSUREUNIQUENESSDEPENDSENTIRELYONTHESTORAGEMECHANISM&ORAFILE BASED provider, as in the following example, a subfolder named after the application will suffice. In a database scenario, an ApplicationName column in the data table would be necessary. Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

Implementation of a File-Based Session State Persister There are many steps to a complete implementation. None are difficult, but careful preparation ISREQUIRED4OIMPLEMENTASESSIONSTOREPROVIDER YOUMUSTCREATEACLASSTHATINHERITSTHE OaooekjOp]paOpknaLnkre`an>]oa abstract class. This class in turn inherits the Lnkre`an>]oa abstract CLASS SOYOUMUSTALSOIMPLEMENTTHEREQUIREDMEMBERSOFTHELnkre`an>]oa class. (Refer to Chapter 4 to read more about the structure of a provider.) The following tables list and describe the properties and methods you must implement from the abstract classes. The following example shows the basic implementation steps for a file-based store. This is not intended for real-life scenarios, but simply for learning and testing. Files are easy to monitor and you can see where the data goes (see Listing 6-7). Listing 6-7. A Simple File-Based Session State Persister qoejcOuopai7 qoejcOuopai*?khha_pekjo*Ola_e]heva`7 qoejcOuopai*EK7 qoejcOuopai*Sa^7 qoejcOuopai*Sa^*?kjbecqn]pekj7 qoejcOuopai*Sa^*OaooekjOp]pa7 j]iaol]_a=lnaoo*Atpajoe^ehepu*OaooekjOp]pa w lq^he_oa]ha`_h]ooBehaOaooekjOp]paOpkna6OaooekjOp]paOpknaLnkre`an>]oa w lner]paOaooekjOp]paOa_pekjoaoo_kjbec9jqhh7 lner]paopnejc^]oaL]pd7 lner]paopnejc]llhe_]pekjJ]ia7 lq^he_opnejc=llhe_]pekjJ]ia w cap w napqnj]llhe_]pekjJ]ia7 y y lq^he_kranne`arke`Ejepe]heva$opnejcj]ia(J]iaR]hqa?khha_pekj_kjbec% w eb$_kjbec99jqhh% w pdnksjas=ncqiajpJqhhAt_alpekj$_kjbec%7 y eb$Opnejc*EoJqhhKnAilpu$j]ia%% w j]ia9BehaOaooekjOp]paOpkna7 y eb$Opnejc*EoJqhhKnAilpu$_kjbecW`ao_nelpekjY%% w _kjbec*Naikra$`ao_nelpekj%7 _kjbec*=``$`ao_nelpekj(BehaOaooekjOp]paOpkna± lnkre`anat]ilha%7 y ^]oa*Ejepe]heva$j]ia(_kjbec%7 ]llhe_]pekjJ]ia9Ouopai*Sa^*Dkopejc*DkopejcAjrenkjiajp± *=llhe_]pekjRenpq]hL]pd7 Download at WoweBook.Com

267

268

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

^]oaL]pd9_kjbecW^]oaL]pdY7 Ouopai*?kjbecqn]pekj*?kjbecqn]pekj_bc9Sa^?kjbecqn]pekjI]j]can± *KlajSa^?kjbecqn]pekj$=llhe_]pekjJ]ia%7 oaoo_kjbec9$OaooekjOp]paOa_pekj%_bc± *CapOa_pekj$ouopai*sa^+oaooekjOp]pa%7 y lq^he_kranne`arke`@eolkoa$% w y lq^he_kranne`a^kkhOapEpaiAtlena?]hh^]_g$± OaooekjOp]paEpaiAtlena?]hh^]_gatlena?]hh^]_g% w napqnjb]hoa7 y lq^he_kranne`arke`Oap=j`Naha]oaEpaiAt_hqoera$Dppl?kjpatp_kjpatp(± opnejce`(± OaooekjOp]paOpkna@]p]epai(± K^fa_phk_gE`(± ^kkhjasEpai% w ++Oane]hevapdaOaooekjOp]paEpai?khha_pekj]o]opnejc* opnejcoaooEpaio9Oane]heva$$OaooekjOp]paEpai?khha_pekj%epai*Epaio%7 opnejcl]pd9L]pd*?ki^eja$^]oaL]pd(Opnejc*Bkni]p$w,y*oo`(e`%%7 BehaOpna]ibo9jqhh7 pnu w eb$jasEpai% w eb$Beha*Ateopo$l]pd%% w Beha*@ahapa$l]pd%7 y bo9jasBehaOpna]i$l]pd(BehaIk`a*?na]paJas(± Beha=__aoo*Snepa(BehaOd]na*Na]`%7 y ahoa w ++ql`]paepai bo9jasBehaOpna]i$l]pd(BehaIk`a*Klaj(± Beha=__aoo*Snepa(BehaOd]na*Na]`%7 y Opna]iSnepanos9jasOpna]iSnepan$bo%7 os*Snepa$oaooEpaio%7 os*?hkoa$%7 y _]p_d$EKAt_alpekjat_alpekj% w ++]``annknd]j`hejc y bej]hhu w eb$bo9jqhh% w bo*?hkoa$%7 Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

bo*@eolkoa$%7 y y y lq^he_kranne`aOaooekjOp]paOpkna@]p]CapEpai$Dppl?kjpatp_kjpatp(± opnejce`(± kqp^kkhhk_ga`(± kqpPeiaOl]jhk_g=ca( kqpk^fa_phk_gE`(± kqpOaooekjOp]pa=_pekjo]_pekjBh]co% w napqnjCapOaooekjOpknaEpai$b]hoa(_kjpatp(e`(kqphk_ga`(± kqphk_g=ca(kqphk_gE`(kqp]_pekjBh]co%7 y lq^he_kranne`aOaooekjOp]paOpkna@]p]CapEpaiAt_hqoera$Dppl?kjpatp_kjpatp(± opnejce`(± kqp^kkhhk_ga`(± kqpPeiaOl]jhk_g=ca( kqpk^fa_phk_gE`(± kqpOaooekjOp]pa=_pekjo]_pekjBh]co% w napqnjCapOaooekjOpknaEpai$pnqa(_kjpatp(e`(kqphk_ga`(± kqphk_g=ca(kqphk_gE`(kqp]_pekjBh]co%7 y lner]paOaooekjOp]paOpkna@]p]CapOaooekjOpknaEpai$^kkhhk_gNa_kn`( Dppl?kjpatp_kjpatp(± opnejce`(± kqp^kkhhk_ga`(± kqpPeiaOl]jhk_g=ca( kqpk^fa_phk_gE`(± kqpOaooekjOp]pa=_pekjo]_pekjBh]co% w ++Ejepe]hr]hqaobknNapqnjr]hqa]j`kqpl]n]iapano* OaooekjOp]paOpkna@]p]epai9jqhh7 hk_g=ca9PeiaOl]j*Vank7 hk_gE`9jqhh7 hk_ga`9b]hoa7 ]_pekjBh]co9OaooekjOp]pa=_pekjo*Jkja7 opnejcoane]heva`Epaio9Opnejc*Ailpu7 opnejcl]pd9L]pd*?ki^eja$^]oaL]pd(Opnejc*Bkni]p$w,y*oo`(e`%%7 BehaOpna]ibo9jqhh7 pnu w bo9jasBehaOpna]i$l]pd(BehaIk`a*Klaj(Beha=__aoo*Na]`(± BehaOd]na*Na]`%7 Opna]iNa]`anon9jasOpna]iNa]`an$bo%7 oane]heva`Epaio9on*Na]`PkAj`$%7 on*?hkoa$%7 y _]p_d$EKAt_alpekj% w ++]``annknd]j`hejcdana y bej]hhu Download at WoweBook.Com

269

270

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

w eb$bo9jqhh% w bo*?hkoa$%7 bo*@eolkoa$%7 y y epai9@aoane]heva$_kjpatp(oane]heva`Epaio(-,.0%7 napqnjepai7 y lner]paop]pe_opnejcOane]heva$OaooekjOp]paEpai?khha_pekjepaio% w IaiknuOpna]iio9jasIaiknuOpna]i$%7 >ej]nuSnepansnepan9jas>ej]nuSnepan$io%7 eb$epaio9jqhh% w epaio*Oane]heva$snepan%7 y snepan*?hkoa$%7 napqnj?kjranp*Pk>]oa20Opnejc$io*Pk=nn]u$%%7 y lner]paop]pe_OaooekjOp]paOpkna@]p]@aoane]heva$Dppl?kjpatp_kjpatp(± opnejcoane]heva`Epaio(± ejppeiakqp% w IaiknuOpna]iio9jasIaiknuOpna]i$± ?kjranp*Bnki>]oa20Opnejc$oane]heva`Epaio%%7 OaooekjOp]paEpai?khha_pekjoaooekjEpaio9± jasOaooekjOp]paEpai?khha_pekj$%7 eb$io*Hajcpd:,% w >ej]nuNa]`anna]`an9jas>ej]nuNa]`an$io%7 oaooekjEpaio9OaooekjOp]paEpai?khha_pekj*@aoane]heva$na]`an%7 y napqnjjasOaooekjOp]paOpkna@]p]$oaooekjEpaio(± OaooekjOp]paQpehepu*CapOaooekjOp]pe_K^fa_po$_kjpatp%(peiakqp%7 y lq^he_kranne`arke`Naha]oaEpaiAt_hqoera$Dppl?kjpatp_kjpatp(± opnejce`(k^fa_phk_gE`% w ++naha]oahk_g y

lq^he_kranne`arke`NaikraEpai$Dppl?kjpatp_kjpatp(opnejce`(± k^fa_phk_gE`(OaooekjOp]paOpkna@]p]epai% w opnejcl]pd9L]pd*?ki^eja$^]oaL]pd(Opnejc*Bkni]p$w,y*oo`(e`%%7 Beha*@ahapa$l]pd%7 y lq^he_kranne`arke`?na]paQjejepe]heva`Epai$Dppl?kjpatp_kjpatp(opnejce`( ejppeiakqp% w Download at WoweBook.Com

C H A P T E R 6 N P A G E A N D S E S S I O N M A N A G E M E N T

opnejcl]pd9L]pd*?ki^eja$^]oaL]pd(Opnejc*Bkni]p$w,y*oo`(e`%%7 BehaOpna]ibo9Beha*?na]pa$l]pd%7 bo*?hkoa$%7 y lq^he_kranne`aOaooekjOp]paOpkna@]p]?na]paJasOpkna@]p]$ Dppl?kjpatp_kjpatp(ejppeiakqp% w napqnjjasOaooekjOp]paOpkna@]p]$jasOaooekjOp]paEpai?khha_pekj$%(± OaooekjOp]paQpehepu*CapOaooekjOp]pe_K^fa_po$_kjpatp%(peiakqp%7 y lq^he_kranne`arke`NaoapEpaiPeiakqp$Dppl?kjpatp_kjpatp(opnejce`% w ++nabnaodepai y lq^he_kranne`arke`Ejepe]hevaNamqaop$Dppl?kjpatp_kjpatp% w y lq^he_kranne`arke`Aj`Namqaop$Dppl?kjpatp_kjpatp% w y y y The implementation lacks error handling and several advanced features. However, the basic parts of the session provider are implemented to demonstrate how you can implement actions appropriate to the provider. Essentially, the provider obtains session data, serializes it, and stores it in a file. The expiration handling is based on the file’s last access timestamp. Concurrent access is also handled on the file level.

Configuring the Provider Before you start working with the provider, you must configure the oaooekjOp]pa element in the web.config file, as shown in Listing 6-8. Listing 6-8. Configuring the Provider 8oaooekjOp]pa _kkgeahaoo9pnqa nacajan]paAtlena`OaooekjE`9b]hoa peiakqp9., ik`a9?qopki _qopkiLnkre`an9BehaOaooekjLnkre`an oaooekjE@I]j]canPula9=lnaoo*OaooekjOp]pa*?k`a*OeilhaOaooekjE@I]j]can( =lnaoo*OaooekjOp]pa: 8lnkre`ano: 8]``j]ia9BehaOaooekjLnkre`an pula9=lnaoo*Atpajoe^ehepu*OaooekjOp]pa*BehaOaooekjOp]paOpkna( =lnaoo*Atpajoe^ehepu*OaooekjOp]pa Download at WoweBook.Com

271

272

CH APT ER 6 N P A G E A ND S ES S ION MA NA G EM E N T

^]oaL]pd9_6Xpail+: 8+lnkre`ano: 8+oaooekjOp]pa: 4HEREAREATLEASTTHREEREQUIREDSETTINGS&IRSTLY THEik`a must be set to “Custom”. Secondly, the _qopkiLnkre`an attribute must be set to the name of the provider. Finally, the provider itself must be configured as a sub-element of the oaooekjOp]pa element. The additional ^]oaL]pd attribute is a private configuration setting used in the previous code. With these settings, all session data is written to and retrieved from the file system, using the path C:\temp for the default (root) application and c:\ temp\ for any other application.

Summary )NTHISCHAPTER WEEXAMINEDSEVERALPERSISTENCETECHNIQUES ANDDISCOVEREDTHATBOTHPAGEPERSISTers and session state persisters exist in order to overcome the limitations of HTTP’s statelessness. Page persisters store page or form related data using control state and view state. The default storage location is a hidden field within the form. An alternative method is to store the data in local memory. The provider model is used to customize this storage, and the sample implementation demonstrates how to store data in the file system. Session state persisters, which are also based on the provider model, store session-related data. The preceding example also shows how to replace the default storage with custom storage, and how to store the data in the file system. Extending persisters is a great way of improving performance, maintaining data within a web garden or farm, adding special features in order to handle specific environmental conditions, or better serving particular clients, such as mobile devices.

Download at WoweBook.Com

CHAPTER

7

Security and User Management

M

ost business applications include user management. Such applications must therefore handle security and user settings. In ASP.NET, you’ll find a comprehensive collection of features, services, classes, and controls to manage users, as well as their roles, settings, and access conditions. In this chapter, you’ll learn about

s 4HECOMPONENTSFORMINGSECURITYANDUSERMANAGEMENT



s %XTENDINGTHEUNDERLYINGPROVIDERS ESPECIALLYTHE-EMBERSHIPAND2OLEPROVIDERS



s #USTOMIZINGANDEXTENDINGTHE0ROFILEPROVIDER

!LLOFTHESECAPABILITIESAREBASEDONTHEPROVIDERMODELINTRODUCEDIN#HAPTER/FCOURSE THATISTHERESOURCEFORMOREABOUTTHEBASICDESIGNOFPROVIDERSANDHOWTOEXTENDANDCONFIGURE them.)

Built-In Capabilities #ONCEPTUALLY !30.%4EMPLOYSTHEPRINCIPLEOFhGATEKEEPERSv!GATEKEEPERISAMODULETHATSITS ONTOPOFTHEPIPELINEOBSERVINGEVERYINCOMINGREQUEST,IKEANYOTHERMODULE ITSIMPLEMENTATION is based on the EDpplIk`qha interface. There are usually several such modules in a row, each of them HANDLINGASPECIFICKINDOFACCESSSECURITYORAUTHORIZATION!SYOUVELEARNEDIN#HAPTERSTO THE PROVIDERANDMODULEMODELSAREHIGHLYEXTENSIBLE4HISGIVESYOUTHEOPPORTUNITYTOADDNEWMODules specific to the needs of your application and your desired security levels. /NEOFTHEBASICCONCEPTSOFWEBSECURITYISTHESTATELESSNESSOF(440"ECAUSETHEPROTOCOL ESSENTIALLYUSESAhFIREANDFORGETvAPPROACH THESECURITYASPECTSOFEVERYREQUESTMUSTBECHECKED 3INCESUBSEQUENTACTIONSMIGHTREQUIREAUTHORIZATIONORAUTHENTICATION THESECURITYMODULESARE POSITIONEDFIRSTINTHELINEINVOKEDBYPIPELINEEVENTS DEPENDINGONACTUALCONFIGURATIONASSEENIN Figure 7-1. The pipeline fires events in a specific order. First, the user is authenticated via the =qpdajpe_]paNamqaop event!FTERESTABLISHINGTHEUSERSIDENTITY AUTHORIZATIONOCCURS AND the =qpdknevaNamqaop event allows the user access to certain resources. The order in which these events are fired is crucial, as the session state becomes available only after both events are handled SEE&IGURE  4HISMEANSTHATNOSESSION RELATEDDATACANBESTOREDTOSUPPORTTHEAUTHENTICATIONANDAUTHORIZATIONMODULES

273 Download at WoweBook.Com

274

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Figure 7-1. The chain of authentication and authorization providers After successful user identification, their credentials are stored as an object containing their information. These credentials consist of a username/password pair and, optionally, additional data SUCHASROLESORLIFETIME$IFFERENTAUTHORIZATIONTECHNIQUES, such as Windows authentication or "ASICAUTHENTICATION CREATEDIFFERENTSETSOFCREDENTIALS)NFORMATIONTHATMUSTBEAVAILABLEDURING THEWHOLEPROCESSINGCYCLEISBOUNDTOTHECURRENTCONTEXT NAMELYTHEDppl?kjpatp object. The user credentials are stored in the Qoan property, and can be accessed in this manner: Ouopai*Sa^*Oa_qnepu*ELnej_el]hqoan9?kjpatp*Qoan7 ?kjpatp is provided by the L]ca class. If you’re not using the L]ca class, Dppl?kjpatp*?qnnajp* Qoan retrieves the same object. The ELnej_el]h interface is a simple definition for a credential store. It contains the user idenTITYACCESSIBLETHROUGHTHEE`ajpepu property provided via an object that implements EE`ajpepu) and the EoEjNkha method TOPROVIDEBASICAUTHORIZATIONSUPPORT(OWEVER THISISNTSUFFICIENT for typical applications. Several different implementations of these interfaces are available that fill in the gaps. EE`ajpepu provides additional support properties, while =qpdajpe_]pekjPula indiCATESWHICHMETHODWASUSEDTOAUTHENTICATEAUSERˆSUCHASh&ORMS vh.4,- vORh#USTOMv Eo=qpdajpe_]pa` reveals that one module of the chain of authentication modules has identified THEUSER%ACHMODULECANCHECKWHETHERTHEPREVIOUSMODULEHASIDENTIFIEDTHEUSERAND IFSO Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

CREATETHEAPPROPRIATEIDENTITYOBJECTANDSKIPTHEMODULESOWNAUTHENTICATIONPROCESS&INALLY the username is stored in the J]ia property of the EE`ajpepuOBJECTASAUNIQUEKEY4HEREARESEVeral built-in implementations of the EE`ajpepu interface:

s Ouopai*Sa^*Oa_qnepu*BknioE`ajpepu



s Ouopai*Oa_qnepu*Lnej_el]h*Sej`ksoE`ajpepu



s Ouopai*Oa_qnepu*Lnej_el]h*Cajane_E`ajpepu

The namespaces reveal that the identity model is not limited to Web applications. Instead, the IDENTITYMODELISEMBEDDEDWITHINTHEFRAMEWORKSSECURITYCOMPONENTS ANDASWITHMOSTTHINGS in .NET, itISEXTENSIBLE

Figure 7-2. Application events involved in the authentication and authorization cycle

Download at WoweBook.Com

275

276

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Authentication Modules Several authentication modulesAREAVAILABLEIN!30.%4"EFOREBUILDINGYOUROWNMODULE CONSIDERMODIFYINGANEXISTINGONE)DENTIFYINGAMODULECLOSETOYOURREQUIREMENTSANDCUSTOMIZINGIT is always a simpler solution than writing a new module from scratch. ASP.NET provides these core modules:

s &ORMS!UTHENTICATION-ODULE



s 7INDOWS!UTHENTICATION-ODULE

4HE&ORMS!UTHENTICATION-ODULE provides a simple form-based technique which is highly COMPATIBLEWITHMOSTEXISTINGCLIENTS BUTITISNOTTHEMOSTSECURE5NLESSTHECONNECTIONBETWEEN THECLIENTANDSERVERUSES33,SECURESOCKETLAYER THEUSERNAMEANDPASSWORDTRAVELUNENCRYPTED at least once through the Internet. For most applications, this isn’t acceptable. The WindowsAuTHENTICATION-ODULE, on the other hand, requires specific support from the client. Although most BROWSERSHANDLEITWELL KEEPINMINDTHATSOMEDEVICESSUCHASMOBILEGADGETS COULDFAIL4HE 0ASSPORT!UTHENTICATION-ODULEISNOTLISTEDBECAUSEITISNTAVIABLEALTERNATIVEANDMARKEDAS DEPRECATED-ICROSOFTS0ASSPORTCONCEPTWASDISCONTINUEDANDHASNOWBEENREPLACEDBY,IVE)$ which has not yet attracted wide-spread client support.

Set Up the Authentication Module 4OSETUPANAUTHENTICATIONMODULE YOULLNEEDTOMAKEANENTRYINTHEweb.config file. The element 8]qpdajpe_]pekj: is responsible for defining and configuring the appropriate module. As a module is responsible for handling all incoming requests, you can’t define the element in subfolders, and OVERRIDINGTHEROOTSETTINGSWOULDCREATEACONFLICTWITHINTHEPIPELINE(OWEVER THISWILLBEPOSSIBLEFORTHEAUTHORIZATIONMETHODDISCUSSEDINTHESECTIONh!UTHORIZATION-ODULESv The ik`a attribute has three commonly used values: 8]qpdajpe_]pekjik`a9Bknio+: 8]qpdajpe_]pekjik`a9Sej`kso+: 8]qpdajpe_]pekjik`a9Jkja+: !STHEREISNOh#USTOMvVALUE YOULLHAVETOUTILIZEONEOFTHEEXISTINGTECHNIQUESWHENYOU ADDYOUROWNMEMBERSHIPSYSTEM4HEh#USTOMvVALUEISNTPROVIDEDBECAUSEYOUDNEEDTO SUPPORTEXISTINGCLIENTS ANDWRITINGCUSTOMCLIENTSISNTFEASIBLE 7EBAPPLICATIONSTHATDEALWITH private data are usually protected by a form of transport layer security that allows the usage of forms authentication for publicly accessible sites and Windows authentication for intranet applications. For the configuration of forms authentication, the child element 8bkni: provides the appropriate settings.

NNote

IIS7 has several more capabilities to set up both authentication and authorization. Because it’s out of scope of this chapter, the security settings provided here are just to get the examples running. The description is in no way complete enough for security-driven applications.

Authorization Modules After authenticating the user, you need to determine what he or she is permitted to request. This is ALLABOUTACCESSINGRESOURCES!STHEREARETWOKINDSOFRESOURCESONA7EB3ERVER FILESAND52,S THEREARETWOBUILT INAUTHORIZATIONMODULES

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T



s &ILE!UTHORIZATION



s 5RL!UTHORIZATION

)FYOUHAVEALREADYSETUPTHEMEMBERSHIPSYSTEMANDNOTDEFINEDTHEAUTHORIZATIONEXPLICITLY YOUMIGHTWONDERHOWITWORKSASEXPECTED4HISISBECAUSE!30.%4USESTHEBeha=qpdknev]pekj module if Windows authentication is set. No additional configuration step is required. Thus, if 7INDOWAUTHENTICATIONISUSED THE.4&3FILEACCESSSECURITYISEMPLOYED BASEDON7INDOWS!#,S ACCESSCONTROLLISTS 

Using Impersonation )NTHECONTEXTOF Windows authentication, impersonation occurs when the identity of the logged-in user is changed and the new identity’s credentials are used to access resources. This is a common technique, but it’s dangerous. If the user base is large, and the roles and access policies grow, manAGEMENTBECOMESARDUOUS&URTHERMORE AUTHENTICATIONMISTAKESCREATESECURITYHOLES ASPARTSOF the application could run under an account other than that intended by the developer.

Set Up Authorization 4HE52,AUTHORIZATION controls access to directories and files. It can be configured by setting the appropriate child elements of the current 8]qpdknev]pekj:ELEMENT2ESTRICTIONSMAYBESETBASED ONBOTHUSERANDROLE&ILEAUTHORIZATIONDOESNOTREQUIREANYSETTINGSHERE 4OMANAGETHEAUTHORIZATION TWOELEMENTSARECRUCIAL8`aju: and 8]hhks:"OTHACCEPTAFEW attributes:

s 5SERS: A list of user accounts



s 2OLES: A list of roles



s 6ERBS!LISTOF(440TRANSMISSIONMETHODS

5SINGTHESESETTINGS YOUCANEXPLICITLYALLOWORDENYACCESSTOUSERS ROLES ORREGARDINGA(440 METHODLIKE'%4OR0/344HEqoano attribute accepts two special characters. You can specify all USERSWITHANASTERISKh vANDALLANONYMOUSUSERSWITHAQUESTIONMARKhv,ISTSOFBOTHROLESAND users are comma-separated.

The User Management Interfaces Included with ASP.NET are a number of tools to support user management, the details of which are BEYONDTHESCOPEOFTHISBOOK(OWEVER )LLGIVEAGENERALOVERVIEWOFTHEEXTENSIBILITYINTERFACES There are three parts responsible for handling user management:

s -EMBERSHIPSERVICE



s 2OLESERVICE



s 0ROFILESERVICE

Membership is about user identification and management. With the appropriate classes and controls, you can create, edit, and delete user accounts. This includes login and logout facilities BASEDONCONTROLS ASWELLASSEVERALFEATURESTHATENHANCEUSEREXPERIENCESUCHASPASSWORD recovery or ability to view the current name and login status). ASP.NET includes several built-in management tools to assist administrators with handling users, based on a SQL Server database store.

Download at WoweBook.Com

277

278

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

RolePERFORMSAUTHORIZATIONTASKS2OLESPROVIDEACCESSTORESOURCESANDCANBEASSIGNEDTO many users. If the user becomes a member of a role, he or she gains access to the resources the role is permitted to retrieve. The built-in management tools support the role model. Profile complements the user management by adding a user-specific data store. This allows you to maintain per-user settings between visits. Profiles are not intended to support session-related PROCESSES)NSTEAD THEYALLOWAUSERTOCUSTOMIZEASITESPECIFICALLYFORTHEIROWNPREFERENCESˆTHINK OFAh-Y3ITEvTYPEOFFUNCTIONALITY!30.%4INCLUDESMANYFEATURES SERVICES ANDOBJECTTYPES to support profiles.

Extensibility Issues 4HEEXTENSIBILITYMODEL is based on providers. The three services previously mentioned use proVIDERSTOSAVEANDRETRIEVETHEIRDATA"YDEFAULT DATAISSTOREDINA31,3ERVERDATABASE)TSOFTEN NECESSARYTOUSEALTERNATIVEOREXISTINGSTORAGE !CTIVE$IRECTORY ,$!0 ORACUSTOMSOLUTION 3EVERALBUILT INPROVIDERSAREINCLUDEDWITHEACHSERVICEINORDERTOSUPPORTDIFFERENTSTORESSEE &IGURE  

Figure 7-3. The class hierarchy for built-in Membership and Role providers The default providers use a SQL Server database. These are the OmhIai^anodelLnkre`an and the OmhNkhaLnkre`an!30.%4ALSOSUPPORTS!CTIVE$IRECTORY!$ OUTOFTHEBOX VIATHE =_pera@ena_pknuIai^anodelLnkre`an. 4ABLE SHOWSALLTHEBASICMEMBERSOFTHE-EMBERSHIPPROVIDERCLASSES

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Table 7-1. Members of the MembershipProvider Classes*

Name

Description

Methods ?d]jcaL]ooskn`

#HANGESTHEPASSWORD

?d]jcaL]ooskn`Mqaopekj=j`=josan

#HANGESTHEPASSWORDQUESTIONANDANSWER

?na]paQoan

#REATESANEWUSER

@a_nulpL]ooskn`

Decrypts the password.

@ahapaQoan

Deletes a user.

Aj_nulpL]ooskn`

Encrypts the password.

Bej`Qoano>uAi]eh

Finds a user using his or her email address.

Bej`Qoano>uJ]ia

Finds a user using his or her name.

Cap=hhQoano

2ETRIEVESALISTOFALLUSERS

CapJqi^anKbQoanoKjheja

2ETRIEVESALISTOFALLCURRENTLYLOGGED INUSERS4HEBEhavior depends on the provider and does not necessarILYREPORTTHEEXACTVALUE

CapL]ooskn`

2ETRIEVESTHEPASSWORDFORAGIVENNAME

CapQoan

2ETRIEVESAOuopai*Sa^*Oa_qnepu*Iai^anodelQoan object based on the name.

CapQoanJ]ia>uAi]eh

2ETRIEVESTHENAMEUSINGANEMAILADDRESS

Ejepe]heva

)NITIALIZESTHEPROVIDER)NHERITEDFROMLnkre`an>]oa.

NaoapL]ooskn`

2ESETSTHECURRENTPASSWORDWITHANAUTOMATICALLY generated one.

Qjhk_gQoan

5NLOCKSALOCKEDUSER

Ql`]paQoan

5PDATESTHEUSERSINFORMATIONINTHEDATASTORE

R]he`]paQoan

#HECKSWHETHERTHEUSERWITHTHEPROVIDEDPASSWORDIS a legitimate user.

Events R]he`]pejcL]ooskn`

An event fired while the provider validates the password.

Properties =llhe_]pekjJ]ia

4HENAMEOFTHEAPPLICATION!-EMBERSHIPPROVIDER can support several applications and supports different data storage for each application. Inherited from Lnkre`an>]oa.

Aj]^haL]ooskn`Naoap

Defines whether or not the user can reset their password.

Aj]^haL]ooskn`Napnear]h

Defines whether or not the user can retrieve their password.

I]tEjr]he`L]ooskn`=ppailpo

$ETERMINESTHEMAXIMUMNUMBEROFFALSEPASSWORD ATTEMPTSALLOWEDBEFORETHEACCOUNTISLOCKED

IejNamqena`Jkj=hld]jqiane_?d]n]_pano

-INIMUMNUMBEROFNON ALPHANUMERICCHARACTERS a password must have.

IejNamqena`L]ooskn`Hajcpd

-INIMUMPASSWORDLENGTH

J]ia

Name of the provider. Inherited from Lnkre`an>]oa. Continued

Download at WoweBook.Com

279

280

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Table 7-1. Continued

Name

Description

L]ooskn`=ppailpSej`ks

0REVENTShBRUTEFORCEvATTEMPTSTOGUESSAPASSWORD If the I]tEjr]he`L]ooskn`=ppailpo occur within L]ooskn`=ppailpSej`ksINMINUTES THATUSERS ACCOUNTISLOCKED

L]ooskn`Bkni]p

Format in which the password is saved in the storage. This is a value from the enumeration Iai^anodelL]ooskn`Bkni]p, which provides the values ?ha]n, D]oda`, or Aj_nulpa`(ASHESAREUNIDIRECTIONAL ENCRYPTIONMETHODS4HEDEFAULTHASHFORMATIS3(!

L]ooskn`OpnajcpdNacqh]nAtlnaooekj

!REGULAREXPRESSIONTHATISUSEDTOCHECKWHETHER or not the password meets the minimum password strength required by your application.

NamqenaoMqaopekj=j`=josan

Determines whether the provider supports the password retrieval using the question and answer technique.

NamqenaoQjemqaAi]eh

Determines whether or not the email address must be unique in the database.

*Covers both SqlMembershipProvider and ActiveDirectoryMembershipProvider

&ORTHE2OLEPROVIDER THINGSLOOKALITTLEDIFFERENT4HE=qpdknev]pekjOpknaNkhaLnkre`an class SUPPORTSTHREEKINDSOFROLEDATASTORAGETHE!CTIVE$IRECTORYITSELF AN!CTIVE$IRECTORY!PPLICATION -ODESERVER!$!- ORAN8-,FILE&ORTHESETHREEMODES ACONNECTIONSTRINGDEFINESTHEDATA source. The connection string begins with iotih6++FORAN8-,FILE ORWITHioh`]l6++ for Active $IRECTORYOR!$!- ASSHOWNINTHEFOLLOWINGCODE 8_kjja_pekjOpnejco: 8]``j]ia9=qpdknev]pekjOanre_ao± _kjja_pekjOpnejc9iotih6++zX=ll[@]p]XIu=`]iOpkna*tih+: 8+_kjja_pekjOpnejco: The Sej`ksoPkgajNkhaLnkre`an uses the local Windows user database to retrieve the role information. Don’t confuse this with Windows groups. Direct access to Windows group information is not supported by this provider. While you can obtain membership information about a group, you cannot write, delete, or change these memberships even if management tools support this. From the perspective of ASP.NET, the Sej`ksoPkgajNkhaLnkre`an provides read-only access. None of these classes are sealed. This means that you can inherit from each class and override methods and properties to change behavior as desired. 4ABLE SHOWSALLBASICMEMBERSOFTHE2OLEPROVIDERCLASSES Table 7-2. Members of the RoleProvider Classes

Name

Description

Not Supported In*

=``QoanoPkNkhao

Add users to roles. Defined in NkhaLnkre`an.

W

?na]paNkha

#REATEANEWROLE$EFINEDINNkhaLnkre`an.

W

@ahapaNkha

Delete a role. Defined in NkhaLnkre`an.

W

Bej`QoanoEjNkha

Find all users within a role. Defined in NkhaLnkre`an.

W, A

Cap=hhNkhao

'ETALISTOFALLROLES$EFINEDINNkhaLnkre`an.

W

Methods

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Name

Description

CapNkhaoBknQoan

'ETALLROLESFORAUSER$EFINEDINNkhaLnkre`an.

CapQoanoEjNkha

'ETALLUSERSINAROLE$EFINEDINNkhaLnkre`an.

EoQoanEjNkha

Indicates whether or not a user is in a role. Defined in NkhaLnkre`an.

NaikraQoanoBnkiNkhao

2EMOVEUSERSFROMROLES$EFINEDIN NkhaLnkre`an.

NkhaAteopo

)NDICATESWHETHERTHEROLEEXISTS$EFINEDIN NkhaLnkre`an.

Not Supported In* W

W

Properties =llhe_]pekjJ]ia

.AMEOFTHEAPPLICATION!2OLEPROVIDERCAN support several applications and different data storage for each application. Defined in Lnkre`an>]oa.

@ao_nelpekj

Description used in Lnkre`an>]oa.

O_klaJ]ia

3COPEFORTHEAUTHORIZATIONSTORE

W, S

?]_daNabnaodEjpanr]h

4IMEINMINUTES THEPROVIDERCACHESROLE information.

W, S

*W = WindowsTokenRoleProvider, S = SqlRoleProvider, A = AuthorizationStoreRoleProvider

With this overview of the capabilities of different providers, you can now investigate how to EXTENDTHEM

Extending Membership and Role Providers The functionality ofTHEBUILT INPROVIDERSSUITSMOSTCOMMONTYPESOFAPPLICATIONS"EFORECONSTRUCTINGYOUROWNPROVIDER LETSTAKEALOOKATWHENANDWHYITSMOREPRACTICALTOCREATEOREXTEND a built-in one.

Why Create a Membership Provider? 4HEPURPOSEOFAPROVIDERISTOMANAGEACCESSTODATASTORAGE%XTENDINGTHEPROVIDERMODELIS necessary if you want to use a different storage for your user database. The OmhIai^anodelLnkre`an supports a SQL Server database, while the =_pera@ena_pknuIai^anodelLnkre`an supports the Active $IRECTORY#REATINGASERVICEINFRASTRUCTUREFOLLOWINGTHEPRINCIPLESOFSERVICE ORIENTEDARCHITECTURES 3/! REQUIRESANOTHERMETHODˆ7EB3ERVICES/NEREASONFORCREATINGACUSTOM-EMBERSHIP provider is the ability to use Web Services. As shown in Table 7-1, the Iai^anodelLnkre`an base class supports an incredible number of features. Whether you require some or all of these depends on the needs of your application. )NTHEFOLLOWINGEXAMPLE )LLDEMONSTRATETHEBASICPRINCIPLESOFACUSTOM-EMBERSHIPPROvider in the particular case of authenticating users against a Web Service. The service provides a transparent tier against a data store. This means that the service can run anywhere in your organiZATIONASACENTRALPOINTOFSERVICE ANDTHEUSERSOFTHESERVICEˆTHEPROVIDERˆKNOWSNOTHINGABOUT the data storage behind the service. Security is enhanced by hiding all data storage implementation details behind the publicly visible Web Service methods. For simplicity and demonstration purposes ONLY THEEXAMPLESERVICESTORESUSERINFORMATIONINASIMPLE8-,FILE4HISALLOWSYOUTOOBSERVE THEFILEANDLEARNEXACTLYHOWTHEPROVIDERBEHAVES )NTHEFOLLOWINGSECTIONS )LLSHOWTHESAMPLECODEANDEXPLAINTHEIMPLEMENTATIONDETAILS Download at WoweBook.Com

281

282

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Solution Details $EVELOPINGACUSTOMPROVIDERFIRSTREQUIRESADATASOURCE)NTHISEXAMPLE )LLUSEAN8-,FILEAS STORAGEANDA7#&7INDOWS#OMMUNICATION&OUNDATION) service to access the file remotely. This demonstrates that it’s possible to transparently access a remote data store using standard frameWORKTECHNIQUES The solution consists of the following:

s !7#&SERVICEPROJECTWITHTWOSERVICES ONEFORMEMBERSHIPANDTHEOTHERFORROLES



s !7EBPROJECTCONFIGUREDTOUSETHECUSTOMPROVIDERTHATHAS s !NIMPLEMENTATIONOFACUSTOM-EMBERSHIPPROVIDER s !NIMPLEMENTATIONOFACUSTOM2OLEPROVIDER s !SERVICEREFERENCETOUSETHE7#&SERVICE

Developing Membership and Role Providers "OTH-EMBERSHIPAND2OLEPROVIDERSSUPPORT several features. Whether or not you implement all FEATURES EXTENDADDITIONALONES ORSIMPLYCREATEARUDIMENTARYSERVICEDEPENDSONYOURAPPLICATIONANDREQUIREMENTS)NTHISEXAMPLE )LLIMPLEMENTALLTHEBASICFEATURESVIAASIMPLIFIED approach for theSAKEOFBREVITY

Create Web Service–Driven Membership Provider The Web Service–driven-EMBERSHIPPROVIDERCONSISTSOFTHEFOLLOWINGTHREEPARTS 1. 4HEUSERDATASTOREˆAN8-,FILE 2. The service tier—a Web Service with several useful methods 3. 4HE-EMBERSHIP provider implementation

Create Web Service–Driven Role Provider The Web service–driven2OLEPROVIDERALSO consists of the following three parts: 1. 4HESAME8-,FILEASUSEDINTHEUSERDATASTORE EXTENDEDWITHROLEPROPERTIES 2. The service tier—a Web Service with several useful methods 3. 4HE2OLEPROVIDERIMPLEMENTATION &ORBOTHPROVIDERS WELLNEEDASIMPLETESTENVIRONMENT#ONSIDERCREATINGSOMEPAGESUSING various Login controls, such as the ?na]paQoanSev]n`. This functions well but requires additional WORK4OBEGINWITH )RECOMMENDUSINGTHEBUILT IN!30.%4CONFIGURATIONAPPLICATION,AUNCHIT LOCALLYIN6ISUAL3TUDIOFROMTHEProject and ASP.NET configurationMENUITEMS5SINGTHEEMBEDDED7EB3ERVER 6ISUAL3TUDIOSTARTSA7EBAPPLICATIONTHATALLOWSYOUTOMANAGEUSERSANDROLES WITHTHECURRENTPROVIDER"EFOREDOINGSO YOULLNEEDTOCONFIGURETHEPROVIDERS(OWEVER WELL begin by developing the entire application.

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Developing the Service Tier The service tier uses7#&TOCREATETWO7EB3ERVICES ONEFORMEMBERSHIPMANAGEMENTANDONEFOR role management. To create the service: 1. 7ITHIN6ISUAL3TUDIO CREATEANEWPROJECTVIAFile ° New ° Project ° Web ° WCF Service Library. 2. .AMETHEPROJECTh-EMBERSHIPv 3. Add two services to the project using AddFROMTHECONTEXTMENU3ELECTNew Item, and in the following dialog choose WCF ServiceSEE&IGURE  

Figure 7-4. Adding a new WCF service to the service library 4HEWIZARDCREATESASERVICEINTERFACETHECONTRACTFORTHESERVICE THECLASSWITHTHEIMPLEmentation, and the required entries in web.config or App.config file to define the service endpoint. The configuration file depends on type of project. The endpoint is a definition used later in the Web application where you can access the service. The contract is usually an interface decorated with the WOanre_a?kjpn]_pY attribute%ACHMETHODTHATISEXPOSEDASASERVICECALLISDECORATEDWITHTHE WKlan]pekj?kjpn]_pY attribute"OTHATTRIBUTESSUPPORTSEVERALSETTINGSFORMODIFYINGBEHAVIORAND APPEARANCE(OWEVER THISISBEYONDTHESCOPEOFTHISBOOK ANDDEFAULTSETTINGSCANBEUSEDFOR this EXAMPLEASWELL

NTip If you want to learn more about professional WCF development, refer to the book Pro WCF: Practical Microsoft SOA Implementation by Amit Bahree, Shawn Cicoria, Dennis Mulder, Nishith Pathak, and Chris Peiris (Apress, 2007).

Download at WoweBook.Com

283

284

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Creating the Membership Service 4HE-EMBERSHIPSERVICE consists of the following interfaces and classes:

s )-EMBERSHIP3ERVICEINTERFACE



s -EMBERSHIP3ERVICESERVICE



s -EMBERSHIP3ERVICECLASS



s 5SER$ATACLASS



s 5SERCLASS



s &ILE-ANAGERCLASS !LLTHECODETOBUILDTHESERVICEISSHOWNANDEXPLAINEDINTHEFOLLOWING

NNote

For sake of brevity and space, Listing 7-1 lacks error handling, “using” statements, and namespace definitions. Additionally, to get the example running, a reference to System.web.dll is required. Please refer to the sample code provided with the book for the full implementation.

Listing 7-1. The IMembershipService Interface Defines the Contract WOanre_a?kjpn]_pY lq^he_ejpanb]_aEIai^anodelOanre_a w WKlan]pekj?kjpn]_pY ^kkh?d]jcaL]ooskn`$opnejcqoanj]ia(opnejckh`L]ooskn`(opnejcjasL]ooskn`%7 WKlan]pekj?kjpn]_pY ^kkh?d]jcaL]ooskn`Mqaopekj=j`=josan$opnejcqoanj]ia(opnejcl]ooskn`(± opnejcjasL]ooskn`Mqaopekj(± opnejcjasL]ooskn`=josan%7 WKlan]pekj?kjpn]_pY Qoan?na]paQoan$opnejcqoanj]ia(opnejcl]ooskn`(opnejcai]eh(± opnejcl]ooskn`Mqaopekj(opnejcl]ooskn`=josan(± ^kkheo=llnkra`(k^fa_plnkre`anQoanGau(± kqpIai^anodel?na]paOp]pqoop]pqo%7 WKlan]pekj?kjpn]_pY ^kkh@ahapaQoan$opnejcqoanj]ia(^kkh`ahapa=hhNah]pa`@]p]%7 WKlan]pekj?kjpn]_pY Heop8Qoan:Bej`Qoano>uAi]eh$opnejcai]ehPkI]p_d(ejpl]caEj`at(± ejpl]caOeva(kqpejppkp]hNa_kn`o%7 WKlan]pekj?kjpn]_pY Heop8Qoan:Bej`Qoano>uJ]ia$opnejcqoanj]iaPkI]p_d(ejpl]caEj`at(± ejpl]caOeva(kqpejppkp]hNa_kn`o%7 WKlan]pekj?kjpn]_pY Heop8Qoan:Cap=hhQoano$ejpl]caEj`at(ejpl]caOeva(kqpejppkp]hNa_kn`o%7

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

WKlan]pekj?kjpn]_pY ejpCapJqi^anKbQoanoKjheja$%7 WKlan]pekj?kjpn]_pY opnejcCapL]ooskn`$opnejcqoanj]ia(opnejc]josan%7 WKlan]pekj?kjpn]_p$J]ia9CapQoan^uJ]ia%Y QoanCapQoan$opnejcqoanj]ia(^kkhqoanEoKjheja%7 WKlan]pekj?kjpn]_pY opnejcCapQoanJ]ia>uAi]eh$opnejcai]eh%7 WKlan]pekj?kjpn]_pY opnejcNaoapL]ooskn`$opnejcqoanj]ia(opnejc]josan%7 WKlan]pekj?kjpn]_pY ^kkhQjhk_gQoan$opnejcqoanJ]ia%7 WKlan]pekj?kjpn]_pY rke`Ql`]paQoan$Qoanqoan%7 WKlan]pekj?kjpn]_pY ^kkhR]he`]paQoan$opnejcqoanj]ia(opnejcl]ooskn`%7 y The interface is not unusual. Each method decorated with the Klan]pekj?kjpn]_p attribute is EXPOSEDBYTHESERVICE!SSHOWNINTHELISTINGFORTHECapQoan method, the method’s name can be MODIFIED4HISISNECESSARYIFYOUWISHTOUSEOVERLOADEDMETHODSMETHODSTHATHAVETHESAME NAME BUTADIFFERENTPARAMETERLISTSIGNATURE 4HESERVICELACKSTHISCAPABILITYANDREQUIRESUNIQUE names. The Klan]pekj?kjpn]_p attribute’s J]iaPROPERTYSEPARATESINTERNALLOGICFROMTHEEXTERNAL service façade. /NCETHEINTERFACEISCOMPLETED ITMUSTBEIMPLEMENTED"EGINWITHASERVICEFILETHATLINKSTO ACODE BEHINDFILESEE,ISTINGS   Listing 7-2. The MembershipService.svc File Is Required in Order to Publish the Service 8!<Oanre_aDkopH]jcq]ca9?@a^qc9pnqa± Oanre_a9=lnaoo*Atpajoe^ehepu*Iai^anodel*Iai^anodelOanre_a± ?k`a>adej`9Iai^anodelOanre_a*or_*_o!: 4HELOGICOFTHESERVICEISCODEDINTHECODE BEHINDFILE SHOWNIN,ISTING  Listing 7-3. The MembershipService Class Is the Implementation WBehaEKLanieooekj$Oa_qnepu=_pekj*Hejg@ai]j`%Y lq^he__h]ooIai^anodelOanre_a6EIai^anodelOanre_a w lq^he_^kkh?d]jcaL]ooskn`$opnejcqoanj]ia(opnejckh`L]ooskn`(± opnejcjasL]ooskn`% w pdnksjasJkpEilhaiajpa`At_alpekj$%7 y lq^he_^kkh?d]jcaL]ooskn`Mqaopekj=j`=josan$opnejcqoanj]ia(opnejcl]ooskn`(± opnejcjasL]ooskn`Mqaopekj(± Download at WoweBook.Com

285

286

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

opnejcjasL]ooskn`=josan% w pdnksjasJkpEilhaiajpa`At_alpekj$%7 y lq^he_Qoan?na]paQoan$opnejcqoanj]ia(opnejcl]ooskn`(opnejcai]eh(± opnejcl]ooskn`Mqaopekj(opnejcl]ooskn`=josan(± ^kkheo=llnkra`(k^fa_plnkre`anQoanGau(± kqpOuopai*Sa^*Oa_qnepu*Iai^anodel?na]paOp]pqoop]pqo% w Qoanqoan9jqhh7 Qoan@]p]q`9BehaI]j]can*Hk]`$%7 ++_da_gqoano(_kjoe`an]``ejcikna`]p]dana r]nd]oQoan9bnkiqejq`*Qoanosdanaq*QoanJ]ia*Amq]ho$qoanj]ia%oaha_pq7 eb$d]oQoan*?kqjp$%:,% w op]pqo9Iai^anodel?na]paOp]pqo*@qlhe_]paQoanJ]ia7 napqnjjqhh7 y r]nd]oAi]eh9bnkiqejq`*Qoanosdanaq*Ai]eh*Amq]ho$ai]eh%oaha_pq7 eb$d]oAi]eh*?kqjp$%:,% w op]pqo9Iai^anodel?na]paOp]pqo*@qlhe_]paAi]eh7 napqnjjqhh7 y pnu w qoan9jasQoan$ qoanj]ia( ai]eh( l]ooskn`Mqaopekj( ( eo=llnkra`( b]hoa( @]paPeia*Jks( @]paPeia*IejR]hqa( @]paPeia*IejR]hqa( @]paPeia*Jks( @]paPeia*IejR]hqa%7 ++OpknaD]odKjhu qoan*L]ooskn`9BehaI]j]can*?]h_qh]paOD=-$l]ooskn`%7 q`*Qoano*=``$qoan%7 BehaI]j]can*O]ra$q`%7 op]pqo9Iai^anodel?na]paOp]pqo*Oq__aoo7 y _]p_d w op]pqo9Iai^anodel?na]paOp]pqo*Lnkre`anAnnkn7 y napqnjqoan7 y lq^he_^kkh@ahapaQoan$opnejcqoanj]ia(^kkh`ahapa=hhNah]pa`@]p]% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoan9$bnkiqejq`*Qoano sdanaq*QoanJ]ia*Amq]ho$qoanj]ia% Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

oaha_pq%*BenopKn@ab]qhp8Qoan:$%7 eb$qoan9jqhh% w q`*Qoano*Naikra$qoan%7 BehaI]j]can*O]ra$q`%7 napqnjpnqa7 y napqnjb]hoa7 y lq^he_Heop8Qoan:Bej`Qoano>uAi]eh$opnejcai]ehPkI]p_d(ejpl]caEj`at(± ejpl]caOeva(kqpejppkp]hNa_kn`o% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoano9$bnkiqejq`*Qoano sdanaq*Ai]eh*Amq]ho$ai]ehPkI]p_d% oaha_pq%*PkHeop8Qoan:$%7 pkp]hNa_kn`o9qoano*?kqjp$%7 napqnjCapL]ca`$qoano(l]caEj`at(l]caOeva%7 y lq^he_Heop8Qoan:Bej`Qoano>uJ]ia$opnejcqoanj]iaPkI]p_d(ejpl]caEj`at(± ejpl]caOeva(kqpejppkp]hNa_kn`o% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoano9$bnkiqejq`*Qoano sdanaq*QoanJ]ia*Amq]ho$qoanj]iaPkI]p_d% oaha_pq%*PkHeop8Qoan:$%7 pkp]hNa_kn`o9qoano*?kqjp$%7 napqnjCapL]ca`$qoano(l]caEj`at(l]caOeva%7 y lq^he_Heop8Qoan:Cap=hhQoano$ejpl]caEj`at(ejpl]caOeva(kqpejppkp]hNa_kn`o% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 pkp]hNa_kn`o9q`*Qoano*?kqjp7 napqnjCapL]ca`$q`*Qoano(l]caEj`at(l]caOeva%7 y lner]paHeop8Qoan:CapL]ca`$Heop8Qoan:q`(ejpl]caEj`at(ejpl]caOeva% w l]caOeva9I]pd*Iej$q`*?kqjp(l]caOeva%7 napqnjq`*CapN]jca$l]caEj`at&l]caOeva(l]caOeva%7 y lq^he_ejpCapJqi^anKbQoanoKjheja$% w ++Qoanosdkhkcca`ejsepdejpdah]op-1iejo Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoano9$bnkiqejq`*Qoano sdanaq*H]op=_perepu@]pa*=``Iejqpao$-1%:@]paPeia*Jks oaha_pq%7 napqnjqoano*?kqjp$%7 y lq^he_opnejcCapL]ooskn`$opnejcqoanj]ia(opnejc]josan% w Download at WoweBook.Com

287

288

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoan9$bnkiqejq`*Qoano sdanaq*QoanJ]ia*Amq]ho$qoanj]ia%""± q*L]ooskn`=josan*Amq]ho$]josan% oaha_pq%*Benop8Qoan:$%7 eb$qoan9jqhh% w napqnjqoan*L]ooskn`7 y napqnjjqhh7 y lq^he_QoanCapQoan$opnejcqoanj]ia(^kkhqoanEoKjheja% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoan9$bnkiqejq`*Qoano sdanaq*QoanJ]ia*Amq]ho$qoanj]ia%"" $qoanEoKjheja%; q*H]op=_perepu@]pa*=``Iejqpao$-1%:@]paPeia*Jks6 pnqa++]hhqoano oaha_pq%*BenopKn@ab]qhp8Qoan:$%7 napqnjqoan7 y lq^he_opnejcCapQoanJ]ia>uAi]eh$opnejcai]eh% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoan9$bnkiqejq`*Qoano sdanaq*Ai]eh*Amq]ho$ai]eh% oaha_pq%*BenopKn@ab]qhp8Qoan:$%7 eb$qoan9jqhh% w napqnjqoan*QoanJ]ia7 y napqnjjqhh7 y lq^he_opnejcNaoapL]ooskn`$opnejcqoanj]ia(opnejc]josan% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoan9$bnkiqejq`*Qoano sdanaq*QoanJ]ia*Amq]ho$qoanj]ia%""± q*L]ooskn`=josan*Amq]ho$]josan% oaha_pq%*BenopKn@ab]qhp8Qoan:$%7 eb$qoan9jqhh% w napqnjqoan*L]ooskn`7 y napqnjjqhh7 y lq^he_^kkhQjhk_gQoan$opnejcqoanJ]ia% w pdnksjasJkpEilhaiajpa`At_alpekj$%7 y lq^he_rke`Ql`]paQoan$Qoanqoan% Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoanPkQl`]pa9$bnkiqejq`*Qoano sdanaq*QoanJ]ia*Amq]ho$qoan*QoanJ]ia% oaha_pq%*BenopKn@ab]qhp8Qoan:$%7 bkna]_d$LnklanpuEjbkleejqoan*CapPula$%*CapLnklanpeao$± >ej`ejcBh]co*Lq^he_x>ej`ejcBh]co*Ejop]j_a%% w LnklanpuEjbkleP]ncap9pulakb$Qoan%*CapLnklanpu$le*J]ia%7 eb$leP]ncap9jqhh% w leP]ncap*OapR]hqa$qoanPkQl`]pa(le*CapR]hqa$qoan(jqhh%(jqhh%7 y y BehaI]j]can*O]ra$q`%7 y lq^he_^kkhR]he`]paQoan$opnejcqoanj]ia(opnejcl]ooskn`% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 opnejcd]od9BehaI]j]can*?]h_qh]paOD=-$l]ooskn`%7 r]nqoan9$bnkiqejq`*Qoano sdanaq*QoanJ]ia*Amq]ho$qoanj]ia%"" q*L]ooskn`*Amq]ho$d]od% oaha_pq%*BenopKn@ab]qhp8Qoan:$%7 qoan*H]op=_perepu@]pa9@]paPeia*Jks7 BehaI]j]can*O]ra$q`%7 napqnj$qoan9jqhh%7 y y -OSTOFTHESEMETHODSFOLLOWTHESAMECODEPATTERN4HECURRENTCONTENTOFTHEMEMBERSHIPDATASTOREˆAN8-,FILEˆISLOADEDBYCALLINGBehaI]j]can*Hk]`SEE,ISTING  LATERINTHIS chapter). This ensures that changes made by parallel calls are handled properly. Each method uses a LINQ query to obtain the required data. If the method needs to persist changes, the updated Qoan@]p]OBJECTISSAVEDBACKTOTHESTORAGEFILE

NTip If you want to learn more about LINQ, I recommend LINQ for Visual C# 2008 by Fabio Claudio Ferracchiati (Apress, 2008). Passwords require special treatment. They aren’t usually stored in an unencrypted format, so you’ll need to choose to either encrypt the password or store a hash of the password. (ASHESAREAONE WAYENCRYPTIONTECHNIQUE4OVALIDATEAUSERLOGGINGIN YOUSIMPLYHASH their supplied password and compare the result with the stored hash value. Storing a hash is good PRACTICE BECAUSETHEHASHALGORITHMWASDESIGNEDTOMAKEITALMOSTIMPOSSIBLETODERIVETHE ORIGINALTEXTFROMTHEHASHVALUE/NTHEOTHERHAND THEHASHDOESNTSUPPORTPASSWORDRETRIEVAL Instead, the user receives a new password when he or she requests a lost one. This requires more effort, as the provider must create generic passwords, and the application must support password CHANGEFORMS ANDSOFORTH)NTHEEXAMPLE THEPASSWORDISSTOREDASAHASH DESPITETHEREBEINGNO PASSWORDGENERATOR4HEPASSWORDISHASHEDUSINGTHE3(!HASHALGORITHM4HISISSAFEANDEASY TOUSE,ISTING SHOWSTHEBehaI]j]can*?]h_qh]paOD=- method. If you plan to implement the provider in an application, consider using an encrypted password that you can decrypt on request.

Download at WoweBook.Com

289

290

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

4HECODEALSOHASAHARD CODEDSETTINGFORTHECALCULATIONOFTHENUMBEROFUSERSONLINETHE CapJqi^anKbQoanoKjheja method "ASEDONTHETIMEOFLASTACTIVITY ALLUSERSTHATHAVELOGGEDIN within the last 15 minutes are counted as being online. The H]op=_perepu@]pa property is set in the R]he`]paQoanMETHOD4HISISANEXTREMELYSIMPLIFIEDALGORITHM BUTITDEMONSTRATESONEPOSSIBLE approach. /NESIGNIFICANTMETHODIS?na]paQoan)TCHECKSSEVERALCONDITIONSINORDERTOAVOID DUPLICATEUSERNAMES EMAILADDRESSES OROTHERUNWANTEDDATA4HEEXAMPLECHECKSJUSTTWO of a wide range of possible conditions. First, it tests for duplicate user names. If this occurs, the method sets the property status to Iai^anodel?na]paOp]pqo*@qlhe_]paQoanJ]ia3ECOND ITCHECKS for duplicate email addresses and sets the status to Iai^anodel?na]paOp]pqo*@qlhe_]paAi]eh, if required. You can refer to the Iai^anodel?na]paOp]pqo enumeration to find more return values and CONDITIONSTOTEST)FEVERYTHINGCHECKSOUT THEIai^anodel?na]paOp]pqo*Oq__aoo value is set. The Iai^anodel?na]paOp]pqo*Lnkre`anAnnknCONDITIONISUSEDIFUNEXPECTEDERRORSARECAUGHTBYTHE pny)_]p_d statement. The class uses the Qoan@]p] classHEAVILY4HISCLASSISSTRAIGHTFORWARD CONTAININGASERIALIZABLE collection of Qoan and NkhaOBJECTS ASSHOWNIN,ISTING  Listing 7-4. The UserData Class Is the Container for Serializing Users and Roles lq^he__h]ooQoan@]p] w lq^he_Qoan@]p]$% w y WTihAhaiajpY lq^he_Heop8Qoan:Qoano w cap7 oap7 y WTihAhaiajpY lq^he_Heop8opnejc:Nkhao w cap7 oap7 y y "ECAUSETHESERIALIZATIONUSESTHETihOane]hevan ALLELEMENTSREQUIRINGSERIALIZATIONARETAGGED with the TihAhaiajp attribute. The Qoan object contains all data pertaining to a specific account. This CLASSISSHOWNNEXTIN,ISTING  Listing 7-5. The User Class Serializes a Single User WOane]hev]^haY W@]p]?kjpn]_pY lq^he__h]ooQoan w lq^he_Qoan$% w y

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

lq^he_Qoan$opnejcj]ia(opnejcai]eh(opnejcl]ooskn`Mqaopekj(± opnejc_kiiajp(^kkheo=llnkra`(^kkheoHk_ga`Kqp(± @]paPeia_na]pekj@]pa(@]paPeiah]opHkcej@]pa(± @]paPeiah]op=_perepu@]pa(@]paPeiah]opL]ooskn`?d]jca`@]pa(± @]paPeiah]opHk_gkqp@]pa% w pdeo*QoanJ]ia9j]ia7 pdeo*Ai]eh9ai]eh7 pdeo*?kiiajp9_kiiajp7 pdeo*Eo=llnkra`9eo=llnkra`7 pdeo*EoHk_ga`Kqp9eoHk_ga`Kqp7 pdeo*?na]pekj@]pa9_na]pekj@]pa7 pdeo*H]opHkcej@]pa9h]opHkcej@]pa7 pdeo*L]ooskn`Mqaopekj9l]ooskn`Mqaopekj7 pdeo*H]op=_perepu@]pa9h]op=_perepu@]pa7 pdeo*H]opL]ooskn`?d]jca`@]pa9h]opL]ooskn`?d]jca`@]pa7 pdeo*H]opHk_gkqp@]pa9h]opHk_gkqp@]pa7 y W@]p]Iai^anY WTihAhaiajpY lq^he_opnejc?kiiajpwcap7oap7y W@]p]Iai^anY WTihAhaiajpY lq^he_@]paPeia?na]pekj@]pawcap7oap7y W@]p]Iai^anY WTihAhaiajpY lq^he_opnejcAi]ehwcap7oap7y W@]p]Iai^anY WTih=ppne^qpaY lq^he_^kkhEo=llnkra`wcap7oap7y W@]p]Iai^anY WTih=ppne^qpaY lq^he_^kkhEoHk_ga`Kqpwcap7oap7y W@]p]Iai^anY WTihAhaiajpY lq^he_@]paPeiaH]op=_perepu@]pawcap7oap7y W@]p]Iai^anY WTihAhaiajpY lq^he_@]paPeiaH]opHk_gkqp@]pawcap7oap7y W@]p]Iai^anY WTihAhaiajpY lq^he_@]paPeiaH]opHkcej@]pawcap7oap7y W@]p]Iai^anY WTihAhaiajpY lq^he_@]paPeiaH]opL]ooskn`?d]jca`@]pawcap7oap7y W@]p]Iai^anY WTihAhaiajpY lq^he_opnejcL]ooskn`Mqaopekjwcap7oap7y W@]p]Iai^anY WTihAhaiajpY lq^he_opnejcL]ooskn`=josanwcap7oap7y W@]p]Iai^anY WTihAhaiajpY lq^he_opnejcQoanJ]iawcap7oap7y W@]p]Iai^anY WTihAhaiajpY Download at WoweBook.Com

291

292

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

lq^he_opnejcL]ooskn`wcap7oap7y W@]p]Iai^anY WTih=nn]u$AhaiajpJ]ia9Nkhao%(Tih=nn]uEpai$AhaiajpJ]ia9Nkha%Y lq^he_Heop8opnejc:Nkhao w cap7 oap7 y lq^he_^kkh?d]jcaL]ooskn`$opnejckh`L]ooskn`(opnejcjasL]ooskn`% w eb$L]ooskn`*Amq]ho$kh`L]ooskn`%% w L]ooskn`9jasL]ooskn`7 napqnjpnqa7 y napqnjb]hoa7 y lq^he_^kkh?d]jcaL]ooskn`Mqaopekj=j`=josan$opnejcl]ooskn`(± opnejcjasL]ooskn`Mqaopekj(opnejcjasL]ooskn`=josan% w eb$L]ooskn`*Amq]ho$l]ooskn`%% w L]ooskn`Mqaopekj9jasL]ooskn`Mqaopekj7 L]ooskn`=josan9jasL]ooskn`=josan7 napqnjpnqa7 y napqnjb]hoa7 y lq^he_opnejcCapL]ooskn`$opnejcl]ooskn`=josan% w napqnjL]ooskn`7 y lq^he_opnejcNaoapL]ooskn`$% w napqnjL]ooskn`7 y lq^he_opnejcNaoapL]ooskn`$opnejcl]ooskn`=josan% w napqnjL]ooskn`7 y lq^he_^kkhQjhk_gQoan$% w napqnjEoHk_ga`Kqp9b]hoa7 y y This class supports two features. It must be transferred via the service and it is part of the data CONTRACT!DATACONTRACTIN7#&DEFINESTHESTRUCTUREOFCOMPLEXDATA!PPLYINGTHE@]p]?kjpn]_p attributeTOACLASSMAKESTHATCLASSINTOADATACONTRACT%ACHSERIALIZABLEMEMBERINTHEDATACONtract class is tagged with the @]p]Iai^an=ppne^qpa)NTHEEXAMPLE THESAMECLASSISUSEDINTERNALLY TOSERIALIZETHEUSEROBJECTSTOTHE8-,FILE4HETihAhaiajpATTRIBUTESMARKTHEELEMENTSTOBESERIALIZED

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Each user can be the member of none, one, or many roles. The roles are simple strings stored in another collection. To reference the roles in the user object, a copy of the role’s name is stored. A Heop8opnejc:OBJECTISUSEDINTERNALLY(OWEVER IN8-, THEFORMATSHOULDBEMOREREADABLE The Tih=nn]u and Tih=nn]uEpai attributesENSURETHATTHEELEMENTNAMESARECORRECT2EFERTO ,ISTING  LATERINTHISCHAPTER TOVIEWTHECREATED8-, )N,ISTING  THEHELPERCLASSISSHOWNTOCOMPLETETHECODENEEDEDTOBUILDTHESERVICE Listing 7-6. A Helper Class That Is Used to Access the Data File ejpanj]hop]pe__h]ooBehaI]j]can w lner]pa_kjopopnejc@=P=L=PD9=ll[@]p]XXQoan@]p]*tih7 lner]paop]pe_na]`kjhuopnejc`]p]L]pd7 lner]paop]pe_k^fa_phk_gan9jask^fa_p$%7 op]pe_BehaI]j]can$% w Qne_k`aQne9jasQne$pulakb$Qoan@]p]%*=ooai^hu*?k`a>]oa%7 `]p]L]pd9L]pd*?ki^eja$@ena_pknu*CapL]najp$± L]pd*Cap@ena_pknuJ]ia$_k`aQne*Hk_]hL]pd%%*BqhhJ]ia(@=P=L=PD%7 ++_da_gbehalanieooekjo BehaEKLanieooekjlanieooekj9jasBehaEKLanieooekj$± BehaEKLanieooekj=__aoo*=hh=__aoo(`]p]L]pd%7 lanieooekj*@ai]j`$%7 y ejpanj]hop]pe_Qoan@]p]Hk]`$% w hk_g$hk_gan% w TihOane]hevanto9jasTihOane]hevan$pulakb$Qoan@]p]%%7 Qoan@]p]q`9jqhh7 pnu w qoejc$BehaOpna]ibo9jasBehaOpna]i$`]p]L]pd(BehaIk`a*Klaj%% w q`9to*@aoane]heva$bo%]oQoan@]p]7 y y _]p_d w ++o]ranq`eiajp]nubkni]p q`9jasQoan@]p]$%7 O]ra$q`%7 y napqnjq`7 y y ejpanj]hop]pe_rke`O]ra$Qoan@]p]q`% w hk_g$hk_gan% w TihOane]hevanto9jasTihOane]hevan$pulakb$Qoan@]p]%%7 qoejc$BehaOpna]ibo9jasBehaOpna]i$`]p]L]pd(BehaIk`a*?na]pa%% w Download at WoweBook.Com

293

294

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

to*Oane]heva$bo(q`%7 y y y ejpanj]hop]pe_opnejc?]h_qh]paOD=-$opnejcpatp% w ^upaWY^qbban9Aj_k`ejc*=O?EE*Cap>upao$patp%7 OD=-?nulpkOanre_aLnkre`an_nulpkPn]jobkniOD=-9± jasOD=-?nulpkOanre_aLnkre`an$%7 opnejcd]od9>ep?kjranpan*PkOpnejc$± _nulpkPn]jobkniOD=-*?kilqpaD]od$^qbban%%7 napqnjd]od7 y y The class is static and provides three methods. With Hk]`, the caller can retrieve the current contents of the stored data. In O]ra THEDATAISWRITTENBACKTODISK"OTHMETHODSBLOCKCONCURRENT threads because this is a multi-threaded environment. The thread handling is in neither way optiMIZEDBUTGIVESYOUTHEIDEAWHATYOUSHOULDBEAWAREOF The ?]h_qh]paOD=- methodCREATESTHE3(!HASHOFAGIVENSTRING)TSUSEDINTERNALLYTOHASH the password. )FEVERYTHINGWORKSASINTENDED THESERVICECREATESA8-,FILESIMILARTOTHEONESHOWNIN Listing 7-7. Listing 7-7. The Data File Filled with Some Users and Roles 8;tihranoekj9-*,;: 8Qoan@]p]tihjo6toe9dppl6++sss*s/*knc+.,,-+TIHO_dai])ejop]j_atihjo6to`9dppl6++sss* s/*knc+.,,-+TIHO_dai]: 8QoanoEo=llnkra`9b]hoaEoHk_ga`Kqp9b]hoa: 8?kiiajp:Paop8+?kiiajp: 8?na]pekj@]pa:.,,5),0)/,P-/6-.6./*2,,4451',.6,,8+?na]pekj@]pa: 8Ai]eh:gn]qoa<_kivalp*`a8+Ai]eh: 8H]op=_perepu@]pa:,,,-),-),-P,-6,,6,,',-6,,8+H]op=_perepu@]pa: 8H]opHk_gkqp@]pa:,,,-),-),-P,-6,,6,,',-6,,8+H]opHk_gkqp@]pa: 8H]opHkcej@]pa:,,,-),-),-P,-6,,6,,',-6,,8+H]opHkcej@]pa: 8H]opL]ooskn`?d]jca`@]pa:,,,-),-),-P,-6,,6,,',-6,,8+H]opL]ooskn`?d]jca`@]pa: 8QoanJ]ia:FkancGn]qoa8+QoanJ]ia: 8Nkhao+: 8+Qoano: 8QoanoEo=llnkra`9pnqaEoHk_ga`Kqp9b]hoa: 8?kiiajp+: 8?na]pekj@]pa:.,,5),0)/,P-56,260.*/5.4451',.6,,8+?na]pekj@]pa: 8Ai]eh:jeoo]j<_kivalp*`a8+Ai]eh: 8H]op=_perepu@]pa:,,,-),-),-P,,6,,6,,8+H]op=_perepu@]pa: 8H]opHk_gkqp@]pa:,,,-),-),-P,,6,,6,,8+H]opHk_gkqp@]pa: 8H]opHkcej@]pa:,,,-),-),-P,,6,,6,,8+H]opHkcej@]pa: 8H]opL]ooskn`?d]jca`@]pa:,,,-),-),-P,,6,,6,,8+H]opL]ooskn`?d]jca`@]pa: 8QoanJ]ia:>anj`=h^na_dp8+QoanJ]ia: 8L]ooskn`:12)1A)A5),B)=5)2,).?),?)-2)05)-=)3=),B)/B)2?)3,)@5)-3)=/).>8+L]ooskn`: 8Nkhao: 8Nkha:Qoan8+Nkha: 8Nkha:?kjpne^qpkn8+Nkha: 8+Nkhao: 8+Qoano:

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

8QoanoEo=llnkra`9pnqaEoHk_ga`Kqp9b]hoa: 8?kiiajp+: 8?na]pekj@]pa:.,,5),0)/,P-56/5600*-1.4451',.6,,8+?na]pekj@]pa: 8Ai]eh:fkanc4)?1)@A)0?)32)2,)4,)?1)5-)?2)50)@1)03)1@)>4)A/)1/)>,)B/8+L]ooskn`: 8Nkhao: 8Nkha:A`epkn8+Nkha: 8+Nkhao: 8+Qoano: 8Nkhao:=`iej8+Nkhao: 8Nkhao:Qoan8+Nkhao: 8Nkhao:?kjpne^qpkn8+Nkhao: 8Nkhao:A`epkn8+Nkhao: 8+Qoan@]p]: The collection of Nkhao elements at the end contains the list of roles used in the provider. In the Qoano element, the Nkhao element contains the assigned roles for that user. The other elements contain the properties. Eo=llnkra` and EoHk_ga`Kqp are stored as attributes because they only contain scalar values. The L]ooskn`ELEMENTDISPLAYSTHEHASHINPLAINTEXTFORMAT )NTHISSECTION WEVELOOKEDATTHEBASICOPERATIONSOFTHEMEMBERSHIPSERVICEANDITSSTORAGE classes. The roles are already in this schema, and the Qoan object accepts setting the assigned roles. All available roles are stored in separate Nkhao items at the end of the file—see the bold elements IN,ISTING &ROMWHEREDOTHEROLESORIGINATE)NTHENEXTSECTION WELLLOOKATA2OLESERVICE)T requires less code, as it reuses portions ofTHE-EMBERSHIPSERVICE

Creating the Role Service The role service isMUCHSIMPLERTHANTHE-EMBERSHIPSERVICE)NSTEADOFDEALINGWITHAh2OLEv object, we’ll simply store roles as strings. The functions of the role service are to assign users to EXISTINGROLES CREATEORREMOVEROLES ANDSEARCHFORUSERSTHATAREMEMBERSOFSPECIFICROLES4HE DATASTORAGEISTHESAMEASFORTHEMEMBERSHIPSERVICE2EFERTOTHE-EMBERSHIPCLASSESTOSEEHOW both parts operate together. 4HE2OLESERVICEREQUIRESTHREECOMPONENTS

s )2OLE3ERVICEINTERFACE



s 2OLE3ERVICESERVICE



s 2OLE3ERVICECLASS

As before, the interface defines the service contract, while the class implements the service. The SERVICEFILEISTHESERVICEEXPOSEDBY7#&ASTHEENDPOINT ANDITREFERSTOTHECLASSSIMPLEMENTATION INACODE BEHINDFILESEE,ISTING  

Download at WoweBook.Com

295

296

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Listing 7-8. The Contract Defined by an Interface WOanre_a?kjpn]_pY lq^he_ejpanb]_aENkhaOanre_a w WKlan]pekj?kjpn]_pY rke`=``QoanoPkNkhao$opnejcWYqoanj]iao(opnejcWYnkhaJ]iao%7 WKlan]pekj?kjpn]_pY rke`?na]paNkha$opnejcnkhaJ]ia%7 WKlan]pekj?kjpn]_pY ^kkh@ahapaNkha$opnejcnkhaJ]ia(^kkhpdnksKjLklqh]pa`Nkha%7 WKlan]pekj?kjpn]_pY opnejcWYBej`QoanoEjNkha$opnejcnkhaJ]ia(opnejcqoanj]iaPkI]p_d%7 WKlan]pekj?kjpn]_pY opnejcWYCap=hhNkhao$%7 WKlan]pekj?kjpn]_pY opnejcWYCapNkhaoBknQoan$opnejcqoanj]ia%7 WKlan]pekj?kjpn]_pY opnejcWYCapQoanoEjNkha$opnejcnkhaJ]ia%7 WKlan]pekj?kjpn]_pY ^kkhEoQoanEjNkha$opnejcqoanj]ia(opnejcnkhaJ]ia%7 WKlan]pekj?kjpn]_pY rke`NaikraQoanoBnkiNkhao$opnejcWYqoanj]iao(opnejcWYnkhaJ]iao%7 WKlan]pekj?kjpn]_pY ^kkhNkhaAteopo$opnejcnkhaJ]ia%7 y The service defines a direct mirror of the NkhaLnkre`anCLASS4HISMAKESITEASIERTOCALLTHE service’s methods from the provider shown later. So far, this is very straightforward, as shown in Listing 7-9. Listing 7-9. The Service Class 8!<Oanre_aDkopH]jcq]ca9?@a^qc9pnqa± Oanre_a9=lnaoo*Atpajoe^ehepu*Iai^anodel*NkhaOanre_a± ?k`a>adej`9NkhaOanre_a*or_*_o!: 4HESERVICECLASS*or_FILE POINTSTOTHECODE BEHINDFILECONTAININGTHEIMPLEMENTATIONSEE Listing 7-10). Listing 7-10. The Implementation of the Service lq^he__h]ooNkhaOanre_a6ENkhaOanre_a w lq^he_rke`=``QoanoPkNkhao$opnejcWYqoanj]iao(opnejcWYnkhaJ]iao% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoano9$bnkiqejq`*Qoano

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

sdanaqoanj]iao*?kjp]ejo$q*QoanJ]ia% oaha_pq%7 bkna]_d$Qoanqoanejqoano% w qoan*Nkhao*Naikra=hh$nkha9:nkhaJ]iao*?kjp]ejo$nkha%%7 qoan*Nkhao*=``N]jca$nkhaJ]iao%7 y BehaI]j]can*O]ra$q`%7 y lq^he_rke`?na]paNkha$opnejcnkhaJ]ia% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 eb$q`*Nkhao*?kjp]ejo$nkhaJ]ia%% w q`*Nkhao*=``$nkhaJ]ia%7 BehaI]j]can*O]ra$q`%7 y y lq^he_^kkh@ahapaNkha$opnejcnkhaJ]ia(^kkhpdnksKjLklqh]pa`Nkha% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoanEjNkha9bnkiqejq`*Qoano sdanaq*Nkhao*?kjp]ejo$nkhaJ]ia% oaha_pq7 eb$qoanEjNkha*?kqjp$%:,""pdnksKjLklqh]pa`Nkha% w napqnjb]hoa7 y q`*Nkhao*Naikra$nkhaJ]ia%7 BehaI]j]can*O]ra$q`%7 napqnjpnqa7 y lq^he_opnejcWYBej`QoanoEjNkha$opnejcnkhaJ]ia(opnejcqoanj]iaPkI]p_d% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nqoanEjNkha9bnkiqejq`*Qoano sdanaq*QoanJ]ia*?kjp]ejo$qoanj]iaPkI]p_d%""± q*Nkhao*?kjp]ejo$nkhaJ]ia% oaha_pq*QoanJ]ia7 napqnjqoanEjNkha*Pk=nn]u8opnejc:$%7 y lq^he_opnejcWYCap=hhNkhao$% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nnkhao9bnkinejq`*Nkhaooaha_pn7 napqnjnkhao*Pk=nn]u8opnejc:$%7 y lq^he_opnejcWYCapNkhaoBknQoan$opnejcqoanj]ia% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nnkhao9$bnkiqejq`*Qoano sdanaq*QoanJ]ia*Amq]ho$qoanj]ia% oaha_pq*Nkhao%*Benop$%7 Download at WoweBook.Com

297

298

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

napqnjnkhao*Pk=nn]u$%7 y lq^he_opnejcWYCapQoanoEjNkha$opnejcnkhaJ]ia% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nnkhao9$bnkiqejq`*Qoano sdanaq*Nkhao*?kjp]ejo$nkhaJ]ia% oaha_pq*QoanJ]ia%7 napqnjnkhao*Pk=nn]u$%7 y lq^he_^kkhEoQoanEjNkha$opnejcqoanj]ia(opnejcnkhaJ]ia% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nnkhao9$bnkiqejq`*Qoano sdanaq*QoanJ]ia*Amq]ho$qoanj]ia%""q*Nkhao*?kjp]ejo$nkhaJ]ia% oaha_pq*QoanJ]ia%7 napqnjnkhao*?kqjp$%:,7 y lq^he_rke`NaikraQoanoBnkiNkhao$opnejcWYqoanj]iao(opnejcWYnkhaJ]iao% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nnkhao9$bnkiqejq`*Qoano sdanaqoanj]iao*?kjp]ejo$q*QoanJ]ia%""± nkhaJ]iao*Ejpanoa_p$q*Nkhao%*?kqjp$%:, oaha_pq*QoanJ]ia%7 BehaI]j]can*O]ra$q`%7 y lq^he_^kkhNkhaAteopo$opnejcnkhaJ]ia% w Qoan@]p]q`9BehaI]j]can*Hk]`$%7 r]nnkhao9$bnkinejq`*Nkhao sdanan*Amq]ho$nkhaJ]ia% oaha_pn%7 napqnjnkhao*?kqjp$%:,7 y y Again, LINQ is used to access the data store. As the Qoan@]p] class already covers the roles by providing the Nkhao element, the whole NkhaOanre_a class doesn’t require its own data access. The BehaI]j]can*O]ra method is called for methods that create roles data.

Configuring the Services /NCETHESERVICESHAVEBEENDEFINED THEYMUSTBECONFIGURED7#&HASITSOWNDEFINITIONLANGUAGE WHICHEXTENDSTHEweb.config file. The definition has three parts, but some settings can be omitted IFTHEDEFAULTVALUESARESUITABLE7#&ISBASEDONTHE!"#MNEMONIC, which stands for Address, "INDING AND#ONTRACT#ONTRACTISDEFINEDBYADDINGSPECIFICATTRIBUTESTOACLASSORINTERFACEDEFInition, as shown earlier. The binding and address are defined in the configuration. The address defines where a client can reach the service. The binding defines the protocol used between client and service. A complete description consisting of address and binding is also called an endpoint. !SAMPLE8-,CONFIGURATIONISSHOWNIN,ISTING 

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Listing 7-11. The Configuration of the Service 8ouopai*oanre_aIk`ah: 8oanre_ao: 8oanre_a^ad]rekn?kjbecqn]pekj9Iai^anodelOanre_a>ad]rekn± j]ia9=lnaoo*Atpajoe^ehepu*Iai^anodel*Iai^anodelOanre_a: 8aj`lkejp]``naoo9^ej`ejc9soDppl>ej`ejc± _kjpn]_p9=lnaoo*Atpajoe^ehepu*Iai^anodel*EIai^anodelOanre_a: 8e`ajpepu: 8`jor]hqa9hk_]hdkop+: 8+e`ajpepu: 8+aj`lkejp: 8aj`lkejp]``naoo9iat^ej`ejc9iatDppl>ej`ejc± _kjpn]_p9EIap]`]p]At_d]jca+: 8dkop: 8^]oa=``naooao: 8]``^]oa=``naoo9dppl6++hk_]hdkop+oanre_a+: 8+^]oa=``naooao: 8+dkop: 8+oanre_a: 8oanre_a^ad]rekn?kjbecqn]pekj9NkhaOanre_a>ad]rekn± j]ia9=lnaoo*Atpajoe^ehepu*Iai^anodel*NkhaOanre_a: 8aj`lkejp]``naoo9^ej`ejc9soDppl>ej`ejc± _kjpn]_p9=lnaoo*Atpajoe^ehepu*Iai^anodel*ENkhaOanre_a: 8e`ajpepu: 8`jor]hqa9hk_]hdkop+: 8+e`ajpepu: 8+aj`lkejp: 8aj`lkejp]``naoo9iat^ej`ejc9iatDppl>ej`ejc± _kjpn]_p9EIap]`]p]At_d]jca+: 8+oanre_a: 8+oanre_ao: 8^ad]rekno: 8oanre_a>ad]rekno: 8^ad]reknj]ia9Iai^anodelOanre_a>ad]rekn: 8oanre_aIap]`]p]dpplCapAj]^ha`9pnqa+: 8oanre_a@a^qcej_hq`aAt_alpekj@ap]ehEjB]qhpo9pnqa+: 8+^ad]rekn: 8^ad]reknj]ia9NkhaOanre_a>ad]rekn: 8oanre_aIap]`]p]dpplCapAj]^ha`9pnqa+: 8oanre_a@a^qcej_hq`aAt_alpekj@ap]ehEjB]qhpo9b]hoa+: 8+^ad]rekn: 8+oanre_a>ad]rekno: 8+^ad]rekno: 8+ouopai*oanre_aIk`ah: The ouopai*oanre_aIk`ah sectionCONTAINSALLTHESETTINGSREQUIREDBYTHE7#&SERVICES)TS DEFINITIONCONSISTSOFTWOSERVICESANDTWOCORRESPONDINGBEHAVIORS"ECAUSEAREGULAR7EB3ERVICE is required, the soDppl>ej`ejcISUSED!NADDITIONALENDPOINTISDEFINEDFORMETADATAEXCHANGE using the iatDppl>ej`ejc4HISALLOWSTHECLIENTTOCREATEAPROXYTHATTALKSTOTHESERVICE4HECLIENT ISTECHNICALLYCREATEDWHENYOUREFERENCETHESERVICEIN6ISUAL3TUDIO 7HENTHISOCCURS THEMETA data endpoint is called to retrieve the service’s description. This includes all methods, signatures, and data objects used by the service, as well as the endpoint configuration. )FYOUUSEANDDEBUGTHEWHOLESOLUTION YOUMIGHTENCOUNTERANEXCEPTION&ORSECURITYREASONS THEDETAILSOFANEXCEPTIONARENOTTRANSFERREDTOTHECLIENT ASINTRUDERSCOULDTRYTOPROVOKE ANERRORBYATTACKINGTHESERVICE)FTHEINTERNALLYTHROWNEXCEPTIONEXPOSESDETAILS THEHACKERSWILL

Download at WoweBook.Com

299

300

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

RECEIVEINFORMATIONWITHWHICHTHEYCANREFINETHEIRATTACK$URINGTHEDEVELOPMENTCYCLE however, you’ll need as much information as possible in order to troubleshoot errors. Set the ej_hq`aAt_alpekj@ap]ehEjB]qhpo attributeTOhTRUEvWHILEDEBUGGINGANDCHANGEITTOhFALSEv before publishing the service. .OWTHESERVICEISUPANDRUNNING9OUCANCHECKTHISBYLAUNCHINGTHE*or_ endpoints in the BROWSER*USTRIGHT CLICKTHESERVICEANDCHOOSEView in browser. You should see a service description similar to that shown in Figure 7-5.

Figure 7-5. The service is up and running. 5SETHESAMEPROCEDURETOCHECKTHE2OLE3ERVICE

Implementing the Provider The provider requires a few more steps: 1. 2EFERENCINGTHESERVICES 2. )MPLEMENTINGTHE-EMBERSHIPPROVIDER 3. )MPLEMENTINGTHE2OLEPROVIDER 4. #ONFIGURINGTHE7EBPROJECTSOTHATITACCEPTSTHEPROVIDERS The reference is easy. Simply choose Add service referenceFROMTHECONTEXTMENUOFYOURPROJECT4HENCLICKONDiscover and Services in Solution SEE&IGURE  

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Figure 7-6. Adding the service references /PENTHESERVICEINTHETREEVIEWTOTHELEFTANDCHOOSETHECONTRACT'IVETHESERVICEASUITABLE NAME)NTHEEXAMPLE )VEUSEDIai^anodelOanre_a and NkhaOanre_a RESPECTIVELY2EPEATTHESTEPS for the other service. You now have two service references in your project.

Provider-Specific Configuration 4HEPROVIDERCANBECOMBINEDWITHITSOWNCONFIGURATIONTOSUPPORTSPECIFICSETTINGS2EFERTO #HAPTERFORMOREINFORMATIONABOUTTHEBASICSTEPSOFPROVIDERIMPLEMENTATION&ORTHESAKEOF BREVITY )HAVEREMOVEDFROMTHEEXAMPLEANYCODENOTREQUIREDFORBASICTASKS

Create the Membership Provider 4HE-EMBERSHIPPROVIDERIMPLEMENTSTHEIai^anodelLnkre`an base class. To avoid confusion I named the class SOIai^anodelLnkre`an WHERETHE73PREFIXREMINDSUSTHATITSBASEDONA7EB 3ERVICESEE,ISTING   Listing 7-12. The WSMembershipProvider lq^he__h]ooSOIai^anodelLnkre`an6Iai^anodelLnkre`an w lner]paIai^anodelOanre_a?heajp_heajp7 lner]pa^kkh[aj]^haL]ooskn`Naoap7 lq^he_kranne`arke`Ejepe]heva$opnejcj]ia(± Ouopai*?khha_pekjo*Ola_e]heva`*J]iaR]hqa?khha_pekj_kjbec% w eb$_kjbec99jqhh% Download at WoweBook.Com

301

302

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

pdnksjas=ncqiajpJqhhAt_alpekj$_kjbec%7 eb$Opnejc*EoJqhhKnAilpu$j]ia%% w j]ia9pdeo*CapPula$%*J]ia7 y eb$Opnejc*EoJqhhKnAilpu$_kjbecW`ao_nelpekjY%% w _kjbec*Naikra$`ao_nelpekj%7 _kjbec*=``$`ao_nelpekj(SO>]oa`Iai^anodelLnkre`an%7 y ^]oa*Ejepe]heva$j]ia(_kjbec%7 _heajp9jasIai^anodelOanre_a?heajp$%7 ++klpekj]hl]n]iapano eb$Opnejc*EoJqhhKnAilpu$_kjbecWAj]^haL]ooskn`NaoapY%% w [aj]^haL]ooskn`Naoap9>kkha]j*L]noa$_kjbecWAj]^haL]ooskn`NaoapY%7 _kjbec*Naikra$Aj]^haL]ooskn`Naoap%7 y ++i]j`]pknul]n]iapano =llhe_]pekjJ]ia9_kjbecW=llhe_]pekjJ]iaY7 y lq^he_kranne`aopnejc=llhe_]pekjJ]ia w cap7 oap7 y lq^he_kranne`a^kkh?d]jcaL]ooskn`$opnejcqoanj]ia(opnejckh`L]ooskn`(± opnejcjasL]ooskn`% w napqnj_heajp*?d]jcaL]ooskn`$qoanj]ia(kh`L]ooskn`(jasL]ooskn`%7 y lq^he_kranne`a^kkh?d]jcaL]ooskn`Mqaopekj=j`=josan$opnejcqoanj]ia(± opnejcl]ooskn`(± opnejcjasL]ooskn`Mqaopekj( opnejcjasL]ooskn`=josan% w napqnj_heajp*?d]jcaL]ooskn`Mqaopekj=j`=josan$qoanj]ia(l]ooskn`(± jasL]ooskn`Mqaopekj(± jasL]ooskn`=josan%7 y lq^he_kranne`aIai^anodelQoan?na]paQoan$opnejcqoanj]ia(± opnejcl]ooskn`(± opnejcai]eh(± opnejcl]ooskn`Mqaopekj(± opnejcl]ooskn`=josan(± ^kkheo=llnkra`(± k^fa_plnkre`anQoanGau(± kqpIai^anodel?na]paOp]pqoop]pqo% w Qoanqoan9_heajp*?na]paQoan$kqpop]pqo(qoanj]ia(l]ooskn`(ai]eh(± l]ooskn`Mqaopekj(l]ooskn`=josan(± Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

eo=llnkra`(lnkre`anQoanGau%7 eb$qoan99jqhh%napqnjjqhh7 Iai^anodelQoaniq9jasIai^anodelQoan$pdeo*CapPula$%*J]ia( qoan*QoanJ]ia( lnkre`anQoanGau( qoan*Ai]eh( qoan*L]ooskn`Mqaopekj( ( qoan*Eo=llnkra`( qoan*EoHk_ga`Kqp( qoan*?na]pekj@]pa( qoan*H]opHkcej@]pa( qoan*H]op=_perepu@]pa( qoan*H]opL]ooskn`?d]jca`@]pa( qoan*H]opHk_gkqp@]pa %7 napqnjiq7 y lq^he_kranne`a^kkh@ahapaQoan$opnejcqoanj]ia(^kkh`ahapa=hhNah]pa`@]p]% w napqnj_heajp*@ahapaQoan$qoanj]ia(`ahapa=hhNah]pa`@]p]%7 y lq^he_kranne`a^kkhAj]^haL]ooskn`Naoap w capwnapqnj[aj]^haL]ooskn`Naoap7y y lq^he_kranne`a^kkhAj]^haL]ooskn`Napnear]h w capwpdnksjasJkpEilhaiajpa`At_alpekj$%7y y lq^he_kranne`aIai^anodelQoan?khha_pekjBej`Qoano>uAi]eh$opnejcai]ehPkI]p_d(± ejpl]caEj`at(ejpl]caOeva(kqpejppkp]hNa_kn`o% w napqnj?kluPkIai^anodel?khha_pekj$_heajp*Bej`Qoano>uAi]eh$kqppkp]hNa_kn`o(± ai]ehPkI]p_d(l]caEj`at(l]caOeva%%7 y lq^he_kranne`aIai^anodelQoan?khha_pekjBej`Qoano>uJ]ia$opnejcqoanj]iaPkI]p_d( ejpl]caEj`at(ejpl]caOeva(kqpejppkp]hNa_kn`o% w napqnj?kluPkIai^anodel?khha_pekj$_heajp*Bej`Qoano>uJ]ia$kqppkp]hNa_kn`o( qoanj]iaPkI]p_d(l]caEj`at(l]caOeva%%7 y lq^he_kranne`aIai^anodelQoan?khha_pekjCap=hhQoano$ejpl]caEj`at(± ejpl]caOeva(kqpejppkp]hNa_kn`o% w napqnj?kluPkIai^anodel?khha_pekj$_heajp*Cap=hhQoano$kqppkp]hNa_kn`o(± l]caEj`at(l]caOeva%%7 y lner]paIai^anodelQoan?khha_pekj?kluPkIai^anodel?khha_pekj$QoanWYqoano% w Download at WoweBook.Com

303

304

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Iai^anodelQoan?khha_pekjiq_9jasIai^anodelQoan?khha_pekj$%7 bkna]_d$Qoanqoanejqoano% w iq_*=``$?kluPkIai^anodelQoan$qoan%%7 y napqnjiq_7 y lner]paIai^anodelQoan?kluPkIai^anodelQoan$Qoanqoan% w Iai^anodelQoaniq9jasIai^anodelQoan$pdeo*CapPula$%*J]ia( qoan*QoanJ]ia( ( qoan*Ai]eh( qoan*L]ooskn`Mqaopekj( qoan*?kiiajp( qoan*Eo=llnkra`( qoan*EoHk_ga`Kqp( qoan*?na]pekj@]pa( qoan*H]opHkcej@]pa( qoan*H]op=_perepu@]pa( qoan*H]opL]ooskn`?d]jca`@]pa( qoan*H]opHk_gkqp@]pa%7 napqnjiq7 y lq^he_kranne`aejpCapJqi^anKbQoanoKjheja$% w napqnj_heajp*CapJqi^anKbQoanoKjheja$%7 y lq^he_kranne`aopnejcCapL]ooskn`$opnejcqoanj]ia(opnejc]josan% w napqnj_heajp*CapL]ooskn`$qoanj]ia(]josan%7 y lq^he_kranne`aIai^anodelQoanCapQoan$opnejcqoanj]ia(^kkhqoanEoKjheja% w napqnj?kluPkIai^anodelQoan$_heajp*CapQoan^uJ]ia$qoanj]ia(qoanEoKjheja%%7 y lq^he_kranne`aIai^anodelQoanCapQoan$k^fa_plnkre`anQoanGau(± ^kkhqoanEoKjheja% w pdnksjasJkpEilhaiajpa`At_alpekj$%7 y lq^he_kranne`aopnejcCapQoanJ]ia>uAi]eh$opnejcai]eh% w napqnj_heajp*CapQoanJ]ia>uAi]eh$ai]eh%7 y lq^he_kranne`aejpI]tEjr]he`L]ooskn`=ppailpo w capwnapqnj17y y

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

lq^he_kranne`aejpIejNamqena`Jkj=hld]jqiane_?d]n]_pano w capwnapqnj-7y y lq^he_kranne`aejpIejNamqena`L]ooskn`Hajcpd w capwnapqnj27y y lq^he_kranne`aejpL]ooskn`=ppailpSej`ks w capwnapqnj-,7y y lq^he_kranne`aIai^anodelL]ooskn`Bkni]pL]ooskn`Bkni]p w capwnapqnjIai^anodelL]ooskn`Bkni]p*?ha]n7y y lq^he_kranne`aopnejcL]ooskn`OpnajcpdNacqh]nAtlnaooekj w capwnapqnj7y y lq^he_kranne`a^kkhNamqenaoMqaopekj=j`=josan w capwnapqnjb]hoa7y y lq^he_kranne`a^kkhNamqenaoQjemqaAi]eh w capwnapqnjb]hoa7y y lq^he_kranne`aopnejcNaoapL]ooskn`$opnejcqoanj]ia(opnejc]josan% w napqnj_heajp*NaoapL]ooskn`$qoanj]ia(]josan%7 y lq^he_kranne`a^kkhQjhk_gQoan$opnejcqoanJ]ia% w pdnksjasJkpEilhaiajpa`At_alpekj$%7 y lq^he_kranne`arke`Ql`]paQoan$Iai^anodelQoanqoan% w Qoanq9jasQoan$%7 bkna]_d$LnklanpuEjbkleejq*CapPula$%*CapLnklanpeao$%% w LnklanpuEjbkleP]ncap9qoan*CapPula$%*CapLnklanpu$le*J]ia%7 eb$leP]ncap9jqhh% w le*OapR]hqa$q(leP]ncap*CapR]hqa$qoan(jqhh%(jqhh%7 y y

Download at WoweBook.Com

305

306

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

_heajp*Ql`]paQoan$q%7 y lq^he_kranne`a^kkhR]he`]paQoan$opnejcqoanj]ia(opnejcl]ooskn`% w napqnj_heajp*R]he`]paQoan$qoanj]ia(l]ooskn`%7 y y The client is instantiated in the Ejepe]heva method. The provider’s methods subsequently use THECLIENTTOCALLTHEAPPROPRIATEFUNCTIONSREMOTELY4HEONLYISSUEREQUIRINGMOREWORKISTHEFACT that the Iai^anodelQoan class cannot be used directly by the service. The internally employed Qoan CLASSHASASIMILARSTRUCTUREBUTNODEPENDENCIESONTHEUNDERLYINGPROVIDER,ATER IN,ISTING  I use reflection to iterate over the properties and, where a property is both public and available in the target class, copy the value from the Iai^anodelQoan class to the Qoan class. This is in the Ql`]paQoan method. The provider also has several hard-coded settings. In a full-fledged application, these would be obtained from web.config!DDITIONALLY INAREAL WORLDEXAMPLE )WOULDSUGGEST separating the data layer into another assembly to get a multi-tier architecture.

Create the Role Provider 4HE2OLEPROVIDERIMPLEMENTSTHENkhaLnkre`an base class. Again, to avoid confusion, our new class is named SONkhaLnkre`an, where the WS reminds us that it’s based on a Web Service. See ,ISTING  Listing 7-13. The WSRoleProvider lq^he__h]ooSONkhaLnkre`an6NkhaLnkre`an w lner]paNkhaOanre_a?heajp_heajp7 lq^he_kranne`arke`Ejepe]heva$opnejcj]ia(± Ouopai*?khha_pekjo*Ola_e]heva`*J]iaR]hqa?khha_pekj_kjbec% w eb$_kjbec99jqhh% pdnksjas=ncqiajpJqhhAt_alpekj$_kjbec%7 eb$Opnejc*EoJqhhKnAilpu$j]ia%% w j]ia9pdeo*CapPula$%*J]ia7 y eb$Opnejc*EoJqhhKnAilpu$_kjbecW`ao_nelpekjY%% w _kjbec*Naikra$`ao_nelpekj%7 _kjbec*=``$`ao_nelpekj(SO>]oa`Iai^anodelLnkre`an%7 y ^]oa*Ejepe]heva$j]ia(_kjbec%7 _heajp9jasNkhaOanre_a?heajp$%7 ++i]j`]pknul]n]iapano =llhe_]pekjJ]ia9_kjbecW=llhe_]pekjJ]iaY7 y lq^he_kranne`arke`=``QoanoPkNkhao$opnejcWYqoanj]iao(opnejcWYnkhaJ]iao% w _heajp*=``QoanoPkNkhao$qoanj]iao(nkhaJ]iao%7 y Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

lq^he_kranne`aopnejc=llhe_]pekjJ]ia w cap7 oap7 y lq^he_kranne`arke`?na]paNkha$opnejcnkhaJ]ia% w _heajp*?na]paNkha$nkhaJ]ia%7 y lq^he_kranne`a^kkh@ahapaNkha$opnejcnkhaJ]ia(^kkhpdnksKjLklqh]pa`Nkha% w napqnj_heajp*@ahapaNkha$nkhaJ]ia(pdnksKjLklqh]pa`Nkha%7 y lq^he_kranne`aopnejcWYBej`QoanoEjNkha$opnejcnkhaJ]ia(± opnejcqoanj]iaPkI]p_d% w napqnj_heajp*Bej`QoanoEjNkha$nkhaJ]ia(qoanj]iaPkI]p_d%7 y lq^he_kranne`aopnejcWYCap=hhNkhao$% w napqnj_heajp*Cap=hhNkhao$%7 y lq^he_kranne`aopnejcWYCapNkhaoBknQoan$opnejcqoanj]ia% w napqnj_heajp*CapNkhaoBknQoan$qoanj]ia%7 y lq^he_kranne`aopnejcWYCapQoanoEjNkha$opnejcnkhaJ]ia% w napqnj_heajp*CapQoanoEjNkha$nkhaJ]ia%7 y lq^he_kranne`a^kkhEoQoanEjNkha$opnejcqoanj]ia(opnejcnkhaJ]ia% w napqnj_heajp*EoQoanEjNkha$qoanj]ia(nkhaJ]ia%7 y lq^he_kranne`arke`NaikraQoanoBnkiNkhao$opnejcWYqoanj]iao(± opnejcWYnkhaJ]iao% w _heajp*NaikraQoanoBnkiNkhao$qoanj]iao(nkhaJ]iao%7 y lq^he_kranne`a^kkhNkhaAteopo$opnejcnkhaJ]ia% w napqnj_heajp*NkhaAteopo$nkhaJ]ia%7 y y

Download at WoweBook.Com

307

308

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Configuring the Provider After the provider is implemented, it must be configured. As for any other provider, this is achieved within the web.configFILE!SYOUCANSEEIN,ISTING  THESONkhaLnkre`an class is simpler than the provider shown before. The methods predominantly call the corresponding service methods and do not add additional logic. Again, the Ejepe]heva method contains the instantiation of the NkhaOanre_a?heajp class. Listing 7-14. Configuring the Providers 8ouopai*sa^: 8iai^anodel`ab]qhpLnkre`an9SOIai^anodelLnkre`an: 8lnkre`ano: 8]``j]ia9SOIai^anodelLnkre`an pula9=lnaoo*Atpajoe^ehepu*Iai^anodel*SOIai^anodelLnkre`an( =lnaoo*Atpajoe^ehepu*Iai^anodel Aj]^haL]ooskn`Naoap9Pnqa +: 8+lnkre`ano: 8+iai^anodel: 8nkhaI]j]can`ab]qhpLnkre`an9SONkhaLnkre`anaj]^ha`9pnqa: 8lnkre`ano: 8_ha]n+: 8]``j]ia9SONkhaLnkre`an pula9=lnaoo*Atpajoe^ehepu*Iai^anodel*SONkhaLnkre`an( =lnaoo*Atpajoe^ehepu*Iai^anodel+: 8+lnkre`ano: 8+nkhaI]j]can: The provider’s ]`` element requires the j]ia, the pula and optionally the parameters defined in the configuration. The pula is the full class name, including the assembly name. In this case, I’ve USEDAREGULAR6ISUAL3TUDIOPROJECT WHICHCOMPILESINTOA$,,4HENAMEANDNAMESPACEOF the DLL are specified here.

Testing the Providers You can nowUSETHEPROVIDERS(OWEVER YOULLNEEDSEVERALADDITIONALPAGESINORDERTOADDUSERS ORROLES RETRIEVEDATA CHECKUSERS ASSIGNROLES ETC&ORTUNATELY 6ISUAL3TUDIOCONTAINSANEMBEDded tool that allows you to manage users and roles. This tool is available from the Project menu and is called ASP.NET configuration. You can add and change users, add and assign roles, and test all common settings of the new providers without WRITINGASINGLELINEOFCODE/NTHESTARTPAGE CHOOSETHE3ECURITYTABTOVIEWTHECURRENTSTATEOF the providers. If you have already defined some users and roles, their quantities are displayed, as shown in Figure 7-7.

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Figure 7-7. The security tab uses the custom provider if properly configured. You can use the tool to create or modify users and add or assign roles. If the tool does not WORKASEXPECTED CHECKWHETHERORNOTTHECUSTOMPROVIDERSAREPROPERLYREGISTERED/PENTHE0ROVIDERTABANDCLICKONSelect a different provider for each feature (advanced). Your custom providers 73-EMBERSHIP0ROVIDERAND732OLE0ROVIDER SHOULD be selected, as shown in&IGURE 

Figure 7-8. The provider tab shows the custom provider if properly configured.

Download at WoweBook.Com

309

310

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Extending Profile Providers The Profile service is an integrated module for storing and retrieving user settings. Settings are not limited to ASP.NET, but are widely used in distributed multi-user environments; even for Win &ORMSAPPLICATION ASIMILARCONCEPTEXISTS4HE0ROFILESERVICEEMPLOYSA0ROFILEPROVIDERTOREAD DATAFROM ANDSAVEDATATO ASTORAGEDEVICE"YDEFAULT THEDATASTOREISA31,3ERVEROR31,3ERVER %XPRESSINSTANCE ANDTHEPROVIDERCLASSISOuopai*Sa^*Lnkbeha*OmhLnkbehaLnkre`an. This provider is ALSORESPONSIBLEFORALLOWINGUSERSTOUPDATETHEIRSETTINGS#OMMONMANAGEMENTFUNCTIONS SUCH as deleting a Profile after a period of inactivity, are located here as well.

NNote

Profile providers are part of the provider model. It is described in detail in Chapter 4.

The Profile Service The purpose of the Profile service is to store and retrieve user settings. With these settings, users can PERSONALIZETHEIRWEBPAGES4YPICALINFORMATIONSTOREDHEREINCLUDESTHEFOLLOWING

s 5SERINFORMATION SUCHASCITYANDPHONENUMBER



s 0REFERENCESFORACCESSIBILITY COLORS ANDFONTSIZE



s $ATARELATEDTOTHECURRENTSESSION SUCHASTHECONTENTSOFASHOPPINGBASKET



s )NDIVIDUALSELECTIONSOFSERVICES SUCHASNEWSFEEDSORNEWSLETTERTOPIC

4HEPERSONALIZATIONPOSSIBILITIESARELIMITLESS)NSTEADOFBUILDINGCUSTOMDATABASEMODULES FROMSCRATCHTOSTORETHEUSERSSETTINGS THISISWHERETHE0ROFILESERVICEEXCELS The services’ definition consists of two parts—Profile properties and related user. The Profile service retrieves properties for the current user from the underlying provider. In order to use Profiles, you must first activate this feature by defining the Provider in the web.configFILE"YDEFAULT the OmhLnkbehaLnkre`an stores properties in the local SQL Server database. The properties are defined in the web.configFILE TOO5NLIKEAPPLICATIONSETTINGS WHEREKEYVALUEPAIRSARESTOREDIN web.config, the Profile property definition consists of the property definition only. Actual values are stored in the Profile provider’s data store.

Understanding the Profile Provider "EFOREYOUCONSIDEREXTENDINGTHE0ROFILEPROVIDER LETSLOOKATTHEFEATURESTHATTHEPROVIDER supports. The LnkbehaLnkre`an class implements the Lnkre`an>]oa base class and the Ouopai* ?kjbecqn]pekj*OappejcoLnkre`an. As the namespace implies, the concepts are not limited to ASP. .%44HE0ROFILEPROVIDEREXTENDSTHESETTINGSCONCEPTWITHSOMEFEATURESTHATALLOWFORTHEMANAGEMENTOFUSER0ROFILES SUCHASDELETINGOF0ROFILESANDACTIVITYMONITORINGSEE4ABLE   When implementing a custom Profile provider, it must support as a minimum the preceding methods in order to be used transparently in applications. The Profile data always has a specific scope, which is usually the current user’s username. (OWEVER THE0ROFILEPROVIDERALSOSUPPORTSANONYMOUSUSERS4HISMEANSTHATAUSERNOTCURRENTLY logged in gets a Profile as a non-authenticated user. #ONSIDERAVISITORWHOSELECTSSEVERALITEMSTOPURCHASEATA7EBSITE BUTTHEYHAVENOTYET LOGGEDIN4HEIR0ROFILECONTAINSSEVERALITEMSINTHEIRSHOPPINGBASKET)TISTHEREFOREIMPORTANTTO KEEPTHEIR0ROFILECONTAININGTHEIRSELECTIONS SEPARATEFROMTHE0ROFILESOFOTHERNON AUTHENTICATED users. To accomplish this, the Profile provider assigns each anonymous user an ID that is used as AKEYINTHEABSENCEOFAUSERNAME Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Table 7-3. Methods and Properties Defined by the ProfileProvider Class

Method

Description

Ejepe]heva

Derived from Lnkre`an>]oa#ONTAINSTHECODEFORSETTINGUP the provider and reading the settings.

=llhe_]pekjJ]ia

Derived from OappejcoLnkre`an. Name of the current application. The data store can use this to handle multiple applications that use the same database.

CapLnklanpuR]hqao

Derived from OappejcoLnkre`an2ETRIEVESALISTOFPROPERTIES using a Oappejco?kjpatp object containing information about the user. You could use this to retrieve Profile information FORAUSER4HECONTEXTPROVIDESINFORMATIONABOUTAUTHENTIcated or anonymous users. The method returns an object of type OappejcoLnklanpu?khha_pekj, which is a collection of OappejcoLnklanpu objects, each containing the name and type of a property, as well as additional information such as default SETTINGSANDREAD ONLYSTATE5SINGTHISMETHODUPDATESTHE H]op=_perepu@]paVALUETHATISUSEDTOTRACKACTIVITYANDTHUS monitor logged-on or inactive users).

OapLnklanpuR]hqao

Derived from OappejcoLnkre`an5SESAOappejco?kjpatp object and a OappejcoLnklanpuR]hqa?khha_pekj object to write PROPERTYVALUESBACKTOTHEDATASTORE5SINGTHISMETHODALSO updates the H]op=_perepu@]pa.

@ahapaLnkbehao

5SINGANARRAYOFUSERNAMES THISMETHODDELETESTHERELATED Profiles. An overloaded version of the same method accepts LnkbehaEjbk objects.

@ahapaEj]_peraLnkbehao

Accepts a Lnkbeha=qpdajpe_]pekjKlpekj value and a @]paPeia object in order to delete inactive Profiles. The Profiles should be deleted if the supplied date and time value is equal to or less than the Profile’s H]op=_perepu@]pa.

Cap=hhLnkbehao

2ETRIEVESALLAVAILABLE0ROFILEOBJECTSUSINGA Lnkbeha=qpdajpe_]pekjKlpekj value and an integer VALUEFORTHEPAGEANDTHEMAXIMUMNUMBEROF0ROFILES 4HEPAGEINDEXALLOWSAPAGEDRETRIEVAL4HEMETHODRETURNS a LnkbehaEjbk?khha_pekj with LnkbehaEjbk objects.

Cap=hhEj]_peraLnkbehao

5SINGTHESAMECONDITIONSASCap=hhLnkbehao, this method returns only Profiles that have not been used for a given time.

Bej`Lnkbehao>uQoanJ]ia

2ETRIEVES0ROFILESVIATHEIRUSERNAMES)NDERIVEDCLASSES THIS METHODMIGHTACCEPTWILDCARDS REGULAREXPRESSIONS ORANY OTHERKINDOFSEARCHPATTERNINORDERTORETRIEVEMULTIPLEVALues matching the search string. This method behaves similarly to Cap=hhLnkbehao.

Bej`Ej]_peraLnkbehao>uQoanJ]ia

2ETRIEVESINACTIVE0ROFILESVIATHEIRUSERNAMES)NDERIVED CLASSES THISMETHODMIGHTACCEPTWILDCARDS REGULAREXPRESSIONS ORANYOTHERKINDOFSEARCHPATTERNINORDERTORETRIEVE multiple values matching the search string. This method behaves similarly to Cap=hhLnkbehao.

CapJqi^anKbEj]_peraLnkbehao

2ETRIEVESTHENUMBEROFINACTIVE0ROFILES

Download at WoweBook.Com

311

312

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

When the user leaves the session, the Profile becomes obsolete. This is why the last activity date ISIMPORTANT)FYOUSPECIFYAMINIMUMINACTIVITYTIMEPERIOD THEPROVIDERISABLETODELETEEXPIRED Profiles. The Lnkbeha=qpdajpe_]pekjKlpekj parameter determines which of the anonymous or authenticated Profiles are to be deleted. You can use a different time span for each type. The data store itself is data agnostic—any properties can be stored there. The definition of acceptable values is set in the web.config file for all users.

Serializing and Deserializing 6ALUESFORCUSTOMSETTINGSCANSUPPORTSEVERALDATATYPES-OSTSTORAGESYSTEMSREQUIRESERIALIZED VALUESINSTEADOF.%4OBJECTS&ORTUNATELY THEBASECLASSPROVIDESTHECODEFORSERIALIZINGANDDESERIALIZINGOBJECTS(OWEVER WHENRETRIEVINGVALUES THISCODEISNOTCALLEDAUTOMATICALLY#ONSIDER THECASEWHEREYOUHAVESEVERALSETTINGS ANDDESERIALIZINGTHEMTAKESSOMETIME)FTHECALLINGPARTY REQUIRESONLYONEORTWOOFTHESEVALUES DESERIALIZINGALLOFTHEMWILLWASTERESOURCES4OIMPROVE PERFORMANCE YOUCANCALLTHEBASEMETHODSTODESERIALIZETHEDESIREDPROPERTIESANDIGNOREALLTHE others. This method isKNOWNAShLAZYDESERIALIZATIONvSEE,ISTING   Listing 7-15. Typical Strategy for Retrieving and Deserializing Values OappejcoLnklanpuR]hqa?khha_pekjoappejco9jasOappejcoLnklanpuR]hqa?khha_pekj$%7 bkna]_d$OappejcoLnklanpulnklanpuejlnklanpeao% w OappejcoLnklanpuR]hqall9jasOappejcoLnklanpuR]hqa$lnklanpu%7 k^fa_pr]h9CapLnklanpuR]hqaBnki@]p]Okqn_a$lnklanpu*J]ia%7 eb$r]h99jqhh% w ll*LnklanpuR]hqa9jqhh7 ll*@aoane]heva`9pnqa7 ll*Eo@enpu9b]hoa7 y ahoa w ll*LnklanpuR]hqa9@aoane]heva$r]h%7 ll*@aoane]heva`9pnqa7 ll*Eo@enpu9b]hoa7 y oappejco*=``$ll%7 y napqnjoappejco7

Defining Profile Settings A typical settingDEFINITIONLOOKSLIKETHECODEIN,ISTING  Listing 7-16. Define Available Properties 8lnkbeha: 8lnklanpeao: 8]``j]ia9Cnaapejcpula9Opnejc+: 8]``j]ia9?kqjppula9Ejp/.`ab]qhpR]hqa9,+: 8+lnklanpeao: 8+lnkbeha:

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

The name of the property and the type are required. A default value can also be specified, which the provider will use if the data store does not retrieve one. 4HESERIALIZATIONCANBEREFINEDBYADDINGTHEoane]heva=o attribute to the Profile property defiNITIONSHOWNINTHENEXTSECTION4HISATTRIBUTEALLOWSTHEPRE SELECTIONOFAPREDEFINEDSERIALIZER

s 3TRING



s "INARY



s 8ML



s 0ROVIDER3PECIFIC

The provider can also be selected on a per-property basis. This allows for different data stores for different types of data. Each property can be limited to authenticated users only by setting the attribute ]hhks=jkjuikqo to b]hoa. &ORMORECOMPLEXSCENARIOS YOUCANGROUPSETTINGSWITHTHE8cnkql: tag. If you plan on supporting hundreds of settings, groups can help you to manage your settings.

Using the Profile Data There are twoWAYSOFREACHING0ROFILEDATAFROMWITHINYOURCODE)NA7EBAPPLICATIONPROJECTAS opposed to a Web site project), the Lnkbeha class is not auto-generated from the current configuration. You will need to use the following two techniques to manage your Profile settings. To retrieve values, use the following pattern: opnejciuR]hqa9$opnejc%?kjpatp*Lnkbeha*CapLnklanpuR]hqa$IuR]hqa%7 Setting values is similarly straightforward: eb$?kjpatp*Lnkbeha*QoanJ]ia9jqhh%w ?kjpatp*Lnkbeha*OapLnklanpuR]hqa$IuR]hqa(okiapdejc%7 ?kjpatp*Lnkbeha*O]ra$%7 y )NA7EBSITEPROJECT 6ISUAL3TUDIOGENERATESALnkbeha class from the configuration settings, WHICHEXPOSESTHE0ROFILEPROPERTIESASTYPEDPROPERTIES opnejciuR]hqa9Lnkbeha*IuR]hqa7 Several free tools are available for overcoming the limitation of Web application projects that DOESNTSUPPORT0ROFILECREATION4HE7EB0ROFILE"UILDERFOUNDATdppl6++_k`a*io`j*ie_nkokbp* _ki+Sa^Lnkbeha>qeh`anISAGOODSTARTINGPOINT(OWEVER DIGGINGDEEPERINTOTHEBUILDTECHNIQUES USEDIN6ISUAL Studio is beyondTHESCOPEOFTHISBOOK

NNote

To overcome the limitations of Web application projects, in this chapter I use the Web site project template. This is the opposite of what I recommend in other parts of the book. As long as you’re not using Profiles, you should stay with Web application projects. If you do use Profiles, it depends on whether strongly typed access is important.

Download at WoweBook.Com

313

314

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Configuring Custom Profile Providers The Profile settings use the embedded provider if no other is specified. The settings follow the SCHEMAFORPROVIDERSEXPLAINEDIN#HAPTER,ISTING SHOWSHOWTODEFINESETTINGSANDHOWTO configure the provider typically. Listing 7-17. Define Available Properties 8lnkbeha`ab]qhpLnkre`an9IuLnkbehaLnkre`an: 8lnklanpeao: 8]``j]ia9BenopJ]iapula9Ouopai*Opnejc+: 8]``j]ia9H]opJ]iapula9Ouopai*Opnejc+: 8]``j]ia9Ai]eh=``naoopula9Ouopai*Opnejc+: 8]``j]ia9I]gaJ]iaLq^he_pula9Ouopai*>kkha]j+: 8]``j]ia9JasoBaa`pula9Ouopai*Opnejc+: 8+lnklanpeao: 8lnkre`ano: 8]``j]ia9IuLnkbehaLnkre`an pula9=lnaoo*Atpajoe^ehepu*TihLnkbehaLnkre`an+: 8+lnkre`ano: 8+lnkbeha: To implement the custom Profile provider, select the preferred data access method.

Implementing a Custom Profile Provider The custom Profile provider shown inTHEFOLLOWINGEXAMPLEUSESAN8-,FILETOSTOREALLUSERSDATA )TDOESNOTIMPLEMENTUSAGEFUNCTIONSSUCHASCHECKINGINACTIVITYORDELETING0ROFILES(OWEVER IT DOESIMPLEMENTTHESAVEANDLOADFUNCTIONSASWELLASTHEUNDERLYINGSERIALIZATIONANDDESERIALIZAtion methods. A Profile provider requires several steps to run properly. Even if only one provider class is necessary for retrieving the code, you need several users and authentication capabilities in order to CHECK the provider.

Preparation Steps To test a custom provider, which requires the ability to log in and log out of different user accounts, I set up Forms Authentication in web.config. Furthermore, I defined the users’ credentials directly in web.config and force the Iai^anodel provider to use data from that file instead of from the default SQL Server. This is accomplished by handling the authentication event manually. The web.config sectionDEFININGTHEUSERSLOOKSLIKETHECODEIN,ISTING  Listing 7-18. Define Several Users to Test the Application 8]qpdknev]pekj: 8`ajuqoano9;+: 8+]qpdknev]pekj: 8]qpdajpe_]pekjik`a9Bknio: 8bknio: 8_na`ajpe]hol]ooskn`Bkni]p9?ha]n: 8qoanj]ia9Qoan-l]ooskn`9Qoan-+: 8qoanj]ia9Qoan.l]ooskn`9Qoan.+: 8qoanj]ia9Qoan/l]ooskn`9Qoan/+: 8+_na`ajpe]ho: 8+bknio: 8+]qpdajpe_]pekj: Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

NCaution Storing user credentials in clear text format in web.config is not intended to run in a production environment. It is here only in order to rapidly set up a test environment. .EXT THEAPPLICATIONREQUIRESATLEASTONEPAGEFORCHANGINGANDUSING0ROFILESETTINGS PLUS a login page. The login page consists of a single Hkcej control and an event handler, as shown in ,ISTINGS AND  Listing 7-19. The “Core” Component of the Login Page 8^k`u: 8bknie`9bkni-nqj]p9oanran: 8`er: 8]ol6HkcejE@9Hkcej-nqj]p9oanrankj]qpdajpe_]pa9Hkcej-[=qpdajpe_]pa: 8+]ol6Hkcej: 8^n+: Jkpuapnaceopana`;?na]pajas]__kqjp8]ol6DulanHejgE@9DulanHejg- nqj]p9oanranJ]rec]paQnh9z+?na]paQoan*]olt:dana8+]ol6DulanHejg:* 8+`er: 8+bkni: 8+^k`u:

Listing 7-20. An Event Handler Forces the Login Control to Use the Configured User Names lq^he_l]npe]h_h]ooHkcej6Ouopai*Sa^*QE*L]ca w lnkpa_pa`rke`L]ca[Hk]`$k^fa_poaj`an(Arajp=ncoa% w y lnkpa_pa`rke`Hkcej-[=qpdajpe_]pa$k^fa_poaj`an(=qpdajpe_]paArajp=ncoa% w a*=qpdajpe_]pa`9Bknio=qpdajpe_]pekj*=qpdajpe_]pa$Hkcej-*QoanJ]ia(± Hkcej-*L]ooskn`%7 y y 4HENEXTPAGEISALSOFORTESTINGPURPOSES)TCONTAINSASIMPLEFORMTOSAVENEW0ROFILESETTINGS DISPLAYCURRENTSETTINGS ANDCHANGEACCOUNTSSEE,ISTING   Listing 7-21. ASPX Page Used to Test the Profile Provider 8^k`u: 8bknie`9bkni-nqj]p9oanran: 8^n+:OapukqnLnkbeha`]p]( 8]ol6HkcejJ]iaE@9HkcejJ]ia-nqj]p9oanran+: 68^n+: 8^n+:A)i]eh6 8]ol6Patp>ktnqj]p9oanranE@9ptpAi]eh:8+]ol6Patp>kt: 8^n+:Bkna?khkn6 8]ol6@nkl@ksjHeopE@9`nlBkna?khknnqj]p9oanran: 8]ol6HeopEpai:Na`8+]ol6HeopEpai: 8]ol6HeopEpai:Cnaaj8+]ol6HeopEpai: 8]ol6HeopEpai:>hqa8+]ol6HeopEpai: 8]ol6HeopEpai:8+]ol6HeopEpai: Download at WoweBook.Com

315

316

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

8+]ol6@nkl@ksjHeop: 8^n+:>]_g?khkn68]ol6@nkl@ksjHeopE@9`nl>]_g?khknnqj]p9oanran: 8]ol6HeopEpai:Sdepa8+]ol6HeopEpai: 8]ol6HeopEpai:>aeca8+]ol6HeopEpai: 8]ol6HeopEpai:Uahhks8+]ol6HeopEpai: 8+]ol6@nkl@ksjHeop: 8^n+: 8^n+: 8]ol6>qppkjE@9^pjOaj`nqj]p9oanrankj_he_g9^pjOaj`[?he_g Patp9OapLnkbeha@]p]+: 8^n+: 8^n+: Hkckqppkqoa]jkjuikqoik`a(hkcej]o`ebbanajpqoanpkpaop`ebbanajp oappejco6 8]ol6HkcejOp]pqoE@9HkcejOp]pqo-nqj]p9oanran+: "j^ol7$Lna`abeja`68e:Qoan-8+e:(8e:Qoan.8+e:(8e:Qoan/8+e:(eja]_d_]oaqoapda j]ia]ol]ooskn`(pkk%8^n+: 8^n+:Naoqhpkbukqn_qnnajpoappejco68^n+: 8`er: 8]ol6L]jahE@9L]jahOappejconqj]p9oanran: Pdeol]jah"/57o`aoecjeona]`bnki_qnnajpqoan"/57oLnkbeha* 8+]ol6L]jah: 8+`er: 8+bkni: 8+^k`u: The page allows you to set an email address and a color. The color type is used here to demonSTRATESERIALIZATIONOFNON SCALARVALUESSEE&IGURE  

Figure 7-9. A simple form to set and retrieve Profile data 4HEPAGESHOWSTHECURRENTLYLOGGED INUSERANDTHESETTINGSTHATFORMATA0ANELCONTROLSEE ,ISTING  4HECODE BEHINDSECTIONSHOWSHOWTHE0ROFILEPROVIDERISINVOKED Listing 7-22. Direct Calls to the Profile Provider and Typed Access lq^he_l]npe]h_h]oo[@ab]qhp6Ouopai*Sa^*QE*L]ca w lnkpa_pa`rke`L]ca[Hk]`$k^fa_poaj`an(Arajp=ncoa% w OapLnkbeha@]p]$%7 y Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

lnkpa_pa`rke`^pjOaj`[?he_g$k^fa_poaj`an(Arajp=ncoa% w Lnkbeha*Bkna?khkn9?khkn*BnkiJ]ia$`nlBkna?khkn*Oaha_pa`R]hqa%7 Lnkbeha*>]_g?khkn9?khkn*BnkiJ]ia$`nl>]_g?khkn*Oaha_pa`R]hqa%7 Lnkbeha*Qoan*Ai]eh9ptpAi]eh*Patp7 OapLnkbeha@]p]$%7 y lner]parke`OapLnkbeha@]p]$% w L]jahOappejco*>]_g?khkn9Lnkbeha*>]_g?khkn7 L]jahOappejco*Bkna?khkn9Lnkbeha*Bkna?khkn7 H]^ahh9jasH]^ah$%7 h*Patp9Lnkbeha*Qoan*Ai]eh7 L]jahOappejco*?kjpnkho*=``$h%7 y y The Lnkbeha classSHOWNIN,ISTING ISAUTO GENERATEDANDDERIVESFROMTHELnkbeha>]oa. It provides typed access to properties. The Profile provider returns settings of type k^fa_p and the access layer casts these types to the final values. Listing 7-23. An Auto-Generated Profile Class ++)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))) ++8]qpk)cajan]pa`: ++Pdeo_k`as]ocajan]pa`^u]pkkh* ++NqjpeiaRanoekj6.*,*1,3.3*/,30 ++ ++?d]jcaopkpdeobehai]u_]qoaej_knna_p^ad]rekn]j`sehh^ahkopeb ++pda_k`aeonacajan]pa`* ++8+]qpk)cajan]pa`: ++)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))) qoejcOuopai7 qoejcOuopai*Sa^7 qoejcOuopai*Sa^*Lnkbeha7 lq^he__h]ooLnkbehaCnkqlQoan6Ouopai*Sa^*Lnkbeha*LnkbehaCnkql>]oaw lq^he_renpq]hopnejcJ]iaw capw napqnj$$opnejc%$pdeo*CapLnklanpuR]hqa$J]ia%%%7 y oapw pdeo*OapLnklanpuR]hqa$J]ia(r]hqa%7 y y lq^he_renpq]hopnejcAi]ehw capw napqnj$$opnejc%$pdeo*CapLnklanpuR]hqa$Ai]eh%%%7 y oapw pdeo*OapLnklanpuR]hqa$Ai]eh(r]hqa%7 y y Download at WoweBook.Com

317

318

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

y lq^he__h]ooLnkbeha?kiikj6Ouopai*Sa^*Lnkbeha*Lnkbeha>]oaw lq^he_renpq]hejpOevaw capw napqnj$$ejp%$pdeo*CapLnklanpuR]hqa$Oeva%%%7 y oapw pdeo*OapLnklanpuR]hqa$Oeva(r]hqa%7 y y lq^he_renpq]hOuopai*@n]sejc*?khknBkna?khknw capw napqnj$$Ouopai*@n]sejc*?khkn%$pdeo*CapLnklanpuR]hqa$Bkna?khkn%%%7 y oapw pdeo*OapLnklanpuR]hqa$Bkna?khkn(r]hqa%7 y y lq^he_renpq]hOuopai*@n]sejc*?khkn>]_g?khknw capw napqnj$$Ouopai*@n]sejc*?khkn%$pdeo*CapLnklanpuR]hqa$>]_g?khkn%%%7 y oapw pdeo*OapLnklanpuR]hqa$>]_g?khkn(r]hqa%7 y y lq^he_renpq]hLnkbehaCnkqlQoanQoanw capw napqnj$$LnkbehaCnkqlQoan%$pdeo*CapLnkbehaCnkql$Qoan%%%7 y y lq^he_renpq]hLnkbeha?kiikjCapLnkbeha$opnejcqoanj]ia%w napqnj$$Lnkbeha?kiikj%$Lnkbeha>]oa*?na]pa$qoanj]ia%%%7 y y 4OUNDERSTANDTHESESETTINGS TAKEALOOKATTHEweb.config file where the properties are defined, ASSHOWNIN,ISTING  Listing 7-24. Definition of Profile Properties 8lnkbeha]qpki]pe_O]raAj]^ha`9pnqa`ab]qhpLnkre`an9TihLnkbehaLnkre`an: 8lnklanpeao: 8cnkqlj]ia9Qoan: 8]``j]ia9J]iapula9Ouopai*Opnejc+: 8]``j]ia9Ai]ehpula9Ouopai*Opnejc+: 8+cnkql: 8]``j]ia9Oevapula9Ouopai*Ejp/.+: 8]``j]ia9Bkna?khknpula9Ouopai*@n]sejc*?khkn+: 8]``j]ia9>]_g?khknpula9Ouopai*@n]sejc*?khkn+: 8+lnklanpeao: Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

8lnkre`ano: 8_ha]n+: 8]``j]ia9TihLnkbehaLnkre`an pula9=lnaoo*Atpajoe^ehepu*LnkbehaLnkre`an*TihLnkbehaLnkre`an+: 8+lnkre`ano: 8+lnkbeha: 4HESETTINGSFORUSERNAMEANDEMAILAREGROUPEDBYTHEh5SERvGROUPELEMENT4HISISMERELY FORORGANIZATIONALPURPOSES ANDHASNODIRECTINFLUENCEONTHEBEHAVIOROFTHEPROVIDER4HE 8lnkre`ano: section contains the definition of the provider’s type. The name is used to set this provider as the default one.

Implementing the Provider You now have the requisite components. The last step is to construct the custom Profile provider ITSELF ASSHOWNIN,ISTING !NEXPLANATIONFOLLOWSTHECODE Listing 7-25. A Custom Profile Provider That Can Save and Retrieve Settings qoejcOuopai7 qoejcOuopai*?khha_pekjo*Cajane_7 qoejcOuopai*?kilkjajpIk`ah7 qoejcOuopai*?kjbecqn]pekj7 qoejcOuopai*?kjbecqn]pekj*Lnkre`an7 qoejcOuopai*EK7 qoejcOuopai*Hejm7 qoejcOuopai*Oa_qnepu*Lanieooekjo7 qoejcOuopai*Patp7 qoejcOuopai*Sa^7 qoejcOuopai*Sa^*Lnkbeha7 qoejcOuopai*Tih*Hejm7 j]iaol]_a=lnaoo*Atpajoe^ehepu*LnkbehaLnkre`an w WOa_qnepuLanieooekj$Oa_qnepu=_pekj*=ooanp( Bh]co9Oa_qnepuLanieooekjBh]c*Oane]hev]pekjBkni]ppan%Y lq^he__h]ooTihLnkbehaLnkre`an6Ouopai*Sa^*Lnkbeha*LnkbehaLnkre`an w lner]pa_kjopopnejc@=P=L=PD9z+=ll[@]p]+Lnkbeha[@]p]7 lq^he_kranne`aopnejc=llhe_]pekjJ]ia w capwpdnksjasJkpOqllknpa`At_alpekj$%7y oapwpdnksjasJkpOqllknpa`At_alpekj$%7y y lq^he_kranne`arke`Ejepe]heva$opnejcj]ia(± Ouopai*?khha_pekjo*Ola_e]heva`*J]iaR]hqa?khha_pekj_kjbec% w ^]oa*Ejepe]heva$j]ia(_kjbec%7 eb$_kjbec*?kqjp:,% pdnksjasLnkre`anAt_alpekj$Qjna_kcjeva`]ppne^qpa6'± _kjbec*CapGau$,%%7 y Download at WoweBook.Com

319

320

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

lq^he_kranne`aOuopai*?kjbecqn]pekj*OappejcoLnklanpuR]hqa?khha_pekj± CapLnklanpuR]hqao$Ouopai*?kjbecqn]pekj*Oappejco?kjpatp_kjpatp(± Ouopai*?kjbecqn]pekj*OappejcoLnklanpu?khha_pekj_khha_pekj% w OappejcoLnklanpuR]hqa?khha_pekjoappejco9± jasOappejcoLnklanpuR]hqa?khha_pekj$%7 ++I]gaoqnaukqd]ra]jajpnubknpdeoqoanj]iaejpdaTIH`]p] opnejcqoanj]ia9_kjpatpWQoanJ]iaY]oopnejc7 eb$opnejc*EoJqhhKnAilpu$qoanj]ia%% w ++Cappdalnkbehar]hqaobknpdaqoan @e_pekj]nu8opnejc(k^fa_p:qoanoLnklanpeao9CapQoanLnkbeha$qoanj]ia%7 bkna]_d$OappejcoLnklanpulnklanpuej_khha_pekj% w eb$lnklanpu*LnklanpuPula*EoLneieperaxx± lnklanpu*LnklanpuPula99pulakb$Opnejc%% lnklanpu*Oane]heva=o9OappejcoOane]heva=o*Opnejc7 ahoa lnklanpu*Oane]heva=o9OappejcoOane]heva=o*Tih7 OappejcoLnklanpuR]hqaoappejc9jasOappejcoLnklanpuR]hqa$lnklanpu%7 eb$qoanoLnklanpeao9jqhh% w oappejc*Eo@enpu9b]hoa7 eb$qoanoLnklanpeao*?kjp]ejoGau$lnklanpu*J]ia%% w oappejc*Oane]heva`R]hqa9qoanoLnklanpeaoWlnklanpu*J]iaY7 oappejc*@aoane]heva`9b]hoa7 y y oappejco*=``$oappejc%7++=``pdaoappejcor]hqapkpda_khha_pekj y y napqnjoappejco7++Napqnjpdaoappejco_khha_pekj y lnkpa_pa`renpq]h@e_pekj]nu8opnejc(k^fa_p:CapQoanLnkbeha$opnejcqoanj]ia% w @e_pekj]nu8opnejc(k^fa_p:lnklanpuR]hqao9jas@e_pekj]nu8opnejc(k^fa_p:$%7 T@k_qiajptLnkbehao9T@k_qiajp*Hk]`$LnkbehaBehaL]pd%7 r]ntLnkb9$bnkilejtLnkbehao*Nkkp*Ahaiajpo$%± sdanal*=ppne^qpa$QoanJ]ia%*R]hqa*Amq]ho$qoanj]ia%± oaha_pl%7 bkna]_d$TAhaiajptihLnklanpuejtLnkb*Ahaiajpo$%% w OappejcoOane]heva=ooo9$OappejcoOane]heva=o%± Ajqi*L]noa$pulakb$OappejcoOane]heva=o%(± tihLnklanpu*=ppne^qpa$oane]heva`=o%*R]hqa%7 osep_d$oo% Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

w _]oaOappejcoOane]heva=o*>ej]nu6 lnklanpuR]hqao*=``$ tihLnklanpu*J]ia*Hk_]hJ]ia( Aj_k`ejc*=O?EE*CapOpnejc$± ?kjranp*Bnki>]oa20Opnejc$$$$T?@]p]%tihLnklanpu*BenopJk`a%*R]hqa%%%%7 ^na]g7 _]oaOappejcoOane]heva=o*Opnejc6 lnklanpuR]hqao*=``$ tihLnklanpu*J]ia*Hk_]hJ]ia( tihLnklanpu*R]hqa%7 ^na]g7 _]oaOappejcoOane]heva=o*Tih6 eb$tihLnklanpu*=ppne^qpa$pula?kjranpan%9jqhh% w Pula?kjranpan_kjranpan9$Pula?kjranpan%± =_per]pkn*?na]paEjop]j_a$± Pula*CapPula$tihLnklanpu*=ppne^qpa$pula?kjranpan%*R]hqa%%7 lnklanpuR]hqao*=``$± tihLnklanpu*J]ia*Hk_]hJ]ia(± _kjranpan*?kjranpBnkiOpnejc$tihLnklanpu*R]hqa%%7 y ^na]g7 _]oaOappejcoOane]heva=o*Lnkre`anOla_ebe_6 pdnksjasJkpOqllknpa`At_alpekj$%7 y y napqnjlnklanpuR]hqao7 y

lq^he_kranne`arke`OapLnklanpuR]hqao$± Ouopai*?kjbecqn]pekj*Oappejco?kjpatp_kjpatp(± Ouopai*?kjbecqn]pekj*OappejcoLnklanpuR]hqa?khha_pekj_khha_pekj% w opnejcqoanj]ia9_kjpatpWQoanJ]iaY]oopnejc7 ^kkhqoanEo=qpdajpe_]pa`9$^kkh%_kjpatpWEo=qpdajpe_]pa`Y7 ++Ebjkqoanj]iaeoola_ebea`(knebjklnklanpeao]napk^ao]ra`(atep eb$opnejc*EoJqhhKnAilpu$qoanj]ia%xx_khha_pekj*?kqjp99,% napqnj7 eb$Ateopo@enpuLnklanpu$_khha_pekj%% napqnj7 T@k_qiajptLnkbehao9T@k_qiajp*Hk]`$LnkbehaBehaL]pd%7 ++_da_gahaiajpo r]ntLnkb9$bnkilejtLnkbehao*Nkkp*Ahaiajpo$%± sdanal*=ppne^qpa$QoanJ]ia%*R]hqa*Amq]ho$qoanj]ia%± oaha_pl%*BenopKn@ab]qhp$%7 eb$tLnkb99jqhh% w ++=``]`ab]qhpailpulnkbeha tLnkb9jasTAhaiajp$Lnkbeha(jasT=ppne^qpa$QoanJ]ia(qoanj]ia%%7 tLnkbehao*Nkkp*=``$tLnkb%7 tLnkbehao*O]ra$LnkbehaBehaL]pd%7 y Download at WoweBook.Com

321

322

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

++]ooqnaailpuahaiajp]osnepaaranupdejc^]_g tLnkb*NaikraJk`ao$%7 bkna]_d$OappejcoLnklanpuR]hqaoappejcej_khha_pekj% w ++Ebpdaqoaneojkp]qpdajpe_]pa`]j`pdalnklanpu`kao ++jkp]hhks]jkjuikqo]__aoo(ogeloane]hevejcep eb$qoanEo=qpdajpe_]pa`""± $^kkh%oappejc*Lnklanpu*=ppne^qpaoW=hhks=jkjuikqoY% _kjpejqa7 ++Ogelpda_qnnajplnklanpuebep#ojkp`enpu]j`eo_qnnajphu ++]ooecja`epo`ab]qhpr]hqa eb$oappejc*Eo@enpu""oappejc*Qoejc@ab]qhpR]hqa% _kjpejqa7 ++Oane]heva`]p]^]oa`kjlnklanpu#oOane]heva=opula osep_d$oappejc*Lnklanpu*Oane]heva=o% w _]oaOappejcoOane]heva=o*Opnejc6 tLnkb*=``$jasTAhaiajp$± oappejc*J]ia(± ?kjranp*PkOpnejc$oappejc*Oane]heva`R]hqa%(± jasT=ppne^qpa$oane]heva`=o(oappejc*Lnklanpu*Oane]heva=o%%%7 ^na]g7 _]oaOappejcoOane]heva=o*Tih6 ++ejopa]`kbTIHsa]ogpda`ab]qhp_kjranpan Pula?kjranpan_kjranpan9Pula@ao_nelpkn*Cap?kjranpan$± oappejc*Lnklanpu*LnklanpuPula%7 opnejc`]p]9_kjranpan*?kjranpPkOpnejc$oappejc*LnklanpuR]hqa%7 tLnkb*=``$jasTAhaiajp$± oappejc*J]ia(± `]p](± jasT=ppne^qpa$oane]heva`=o(oappejc*Lnklanpu*Oane]heva=o%(± jasT=ppne^qpa$pula?kjranpan((± _kjranpan*CapPula$%*=ooai^huMq]hebea`J]ia%%%7 ^na]g7 _]oaOappejcoOane]heva=o*>ej]nu6 ++aj_k`apda^ej]nu`]p]qoejc^]oa20aj_k`ejc opnejcaj_k`a`>ej]nu@]p]9?kjranp*Pk>]oa20Opnejc$(± oappejc*Oane]heva`R]hqa]o^upaWY%7 tLnkb*=``$jasTAhaiajp$± oappejc*J]ia(± jasT?@]p]$aj_k`a`>ej]nu@]p]%(± jasT=ppne^qpa$oane]heva`=o(oappejc*Lnklanpu*Oane]heva=o%%%7 ^na]g7 `ab]qhp6 ++qjgjksjoane]hevapula pdnksjasLnkre`anAt_alpekj$opnejc*Bkni]p$(± Ejr]he`r]hqabknOane]heva=o7atla_pa`Opnejc(Tih(kn>ej]nu((± na_aera`w,y((± Ouopai*Ajqi*CapJ]ia$oappejc*Lnklanpu*Oane]heva=o*CapPula$%((± oappejc*Lnklanpu*Oane]heva=o%%%7 y y tLnkbehao*O]ra$LnkbehaBehaL]pd%7 y

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

lnkpa_pa`renpq]hopnejcLnkbehaBehaL]pd w cap w napqnjL]pd*?ki^eja$Dppl?kjpatp*?qnnajp*Oanran*I]lL]pd$@=P=L=PD%(± Lnkbehao*tih%7 y y lnkpa_pa`renpq]h^kkhAteopo@enpuLnklanpu$± Ouopai*?kjbecqn]pekj*OappejcoLnklanpuR]hqa?khha_pekj_khha_pekj% w bkna]_d$OappejcoLnklanpuR]hqaoappejcej_khha_pekj% eb$oappejc*Eo@enpu% napqnjpnqa7 ++Ebsana]_ddana(jkja]na`enpu napqnjb]hoa7 y lq^he_kranne`aejp@ahapaEj]_peraLnkbehao$± Lnkbeha=qpdajpe_]pekjKlpekj]qpdajpe_]pekjKlpekj(± @]paPeiaqoanEj]_peraOej_a@]pa% w pdnksjasAt_alpekj$Pdaiapdk`knklan]pekjeojkpeilhaiajpa`*%7 y lq^he_kranne`aejp@ahapaLnkbehao$opnejcWYqoanj]iao% w pdnksjasAt_alpekj$Pdaiapdk`knklan]pekjeojkpeilhaiajpa`*%7 y lq^he_kranne`aejp@ahapaLnkbehao$LnkbehaEjbk?khha_pekjlnkbehao% w pdnksjasAt_alpekj$Pdaiapdk`knklan]pekjeojkpeilhaiajpa`*%7 y lq^he_kranne`aLnkbehaEjbk?khha_pekjBej`Ej]_peraLnkbehao>uQoanJ]ia$± Lnkbeha=qpdajpe_]pekjKlpekj]qpdajpe_]pekjKlpekj(± opnejcqoanj]iaPkI]p_d(± @]paPeiaqoanEj]_peraOej_a@]pa(± ejpl]caEj`at(ejpl]caOeva(kqpejppkp]hNa_kn`o% w pdnksjasAt_alpekj$Pdaiapdk`knklan]pekjeojkpeilhaiajpa`*%7 y lq^he_kranne`aLnkbehaEjbk?khha_pekjBej`Lnkbehao>uQoanJ]ia$± Lnkbeha=qpdajpe_]pekjKlpekj]qpdajpe_]pekjKlpekj(± opnejcqoanj]iaPkI]p_d(ejpl]caEj`at(ejpl]caOeva(kqpejppkp]hNa_kn`o% w pdnksjasAt_alpekj$Pdaiapdk`knklan]pekjeojkpeilhaiajpa`*%7 y lq^he_kranne`aLnkbehaEjbk?khha_pekjCap=hhEj]_peraLnkbehao$± Lnkbeha=qpdajpe_]pekjKlpekj]qpdajpe_]pekjKlpekj(± @]paPeiaqoanEj]_peraOej_a@]pa(ejpl]caEj`at(± ejpl]caOeva(kqpejppkp]hNa_kn`o% Download at WoweBook.Com

323

324

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

w pdnksjasAt_alpekj$Pdaiapdk`knklan]pekjeojkpeilhaiajpa`*%7 y lq^he_kranne`aLnkbehaEjbk?khha_pekjCap=hhLnkbehao$± Lnkbeha=qpdajpe_]pekjKlpekj]qpdajpe_]pekjKlpekj(± ejpl]caEj`at(ejpl]caOeva(kqpejppkp]hNa_kn`o% w pdnksjasAt_alpekj$Pdaiapdk`knklan]pekjeojkpeilhaiajpa`*%7 y lq^he_kranne`aejpCapJqi^anKbEj]_peraLnkbehao$± Lnkbeha=qpdajpe_]pekjKlpekj]qpdajpe_]pekjKlpekj(± @]paPeiaqoanEj]_peraOej_a@]pa% w pdnksjasAt_alpekj$Pdaiapdk`knklan]pekjeojkpeilhaiajpa`*%7 y y y The class has two principal methods, CapLnklanpuR]hqao and OapLnklanpuR]hqao, for retrieving and saving Profile settings. The CapLnklanpuR]hqao method is called to obtain data from the Profile class. It then calls CapQoanLnkbehaTOREADTHESPECIFIC0ROFILEFROMTHE8-,FILE7ITHINTHE CapQoanLnkbehaMETHOD A,).1QUERYRETRIEVESTHE0ROFILE!LOOPREADSEACHVALUEANDDESERIALIZES ITDEPENDINGONITSSETTINGS"INARYDATAISSAVEDIN"ASEENCODEDFORMATANDPROTECTEDWITHINTHE 8?@=P=: section. The content node is cast to T_`]p]ANDSTRINGVALUESAREREADDIRECTLY-ORECOMPLEXTYPESARETREATEDASLnkre`anOla_ebe_, which means that the provider is responsible for finding THERIGHTSERIALIZATION4OSUPPORTTYPICAL.%4TYPESLIKEOuopai*@n]sejc*?khkn, without writing type specific code, the internal use type converter is used. This type converter usually supports the DESIGN TIMEEXPERIENCE&ORINSTANCE TOSHOWCOLORSWITHINTHELnklanpuCne` control, a type conVERTERISUSED)NTHISEXAMPLE THETYPECONVERTERSTYPEISSAVEDINTOTHEDOCUMENTANDRETRIEVED from the pula?kjranpan attribute)NTHE8-,FILE THEFULLYQUALIFIEDNAMEISSTOREDANDUSEDTO create an instance of the converter. The converter provides a ?kjranpBnkiOpnejc method, which converts from string format to the specified object. The OapLnklanpuR]hqao method reverses the whole process. First, the same LINQ statement ISUSEDTORETRIEVETHESPECIFICUSERSSECTION)FITDOESNTEXIST ANEMPTYSECTIONISADDED4HECOLlection of settings defined in the web.config file is used to assemble the current user’s Profile. Each SETTINGShTYPEvASDEFINEDINTHEweb.config) is used to obtain the associated Pula?kjranpan object, whose ?kjranpPkOpnejc methodSERIALIZESTHESETTINGSVALUE)FEVERYTHINGGOESCORRECTLY THE8-, FRAGMENTISSAVEDINTHE8-,FILE

NNote

This is a simplified scenario lacking error handling and multiuser support. It is only intended to show the construction of a custom provider and how to change the way the data is persisted.

4HE8-,WRITTENUSINGTHISCODELOOKSVERYSIMPLE ASSHOWNIN,ISTING  Listing 7-26. XML That Stores User Profile Settings 8;tihranoekj9-*,aj_k`ejc9qpb)4;: 8Lnkbehao: 8LnkbehaQoanJ]ia9Qoan-: 8>]_g?khknoane]heva`=o9Lnkre`anOla_ebe_ Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

pula?kjranpan9Ouopai*@n]sejc*?khkn?kjranpan(Ouopai*@n]sejc( Ranoekj9.*,*,*,(?qhpqna9jaqpn]h( Lq^he_GauPkgaj9^,/b1b3b--`1,]/]:Na`+>]_g?khkn: 8Qoan*Ai]ehoane]heva`=o9Opnejc:fkanc]_g?khknoane]heva`=o9Lnkre`anOla_ebe_ pula?kjranpan9Ouopai*@n]sejc*?khkn?kjranpan(Ouopai*@n]sejc( Ranoekj9.*,*,*,(?qhpqna9jaqpn]h( Lq^he_GauPkgaj9^,/b1b3b--`1,]/]:>hqa8+>]_g?khkn: 8Qoan*Ai]ehoane]heva`=o9Opnejc:Qoan/
A Client Side–Driven Profile Provider 7ITH!*!8!SYNCHRONOUS*AVA3CRIPTAND8-,), youCANALSOWORKWITHTHECUSTOM0ROFILETECHnology directly from your client-side script. This section is slightly different, as most of the code IS*AVA3CRIPT INSTEADOF#4HECODEEXTENDSTHEPROFILEUSAGETOTHECLIENTANDEMPOWERSSCRIPT developers predominantly.

Exposing Profile Settings to AJAX Using Web.config There’s a minor addition required to the web.configFILETOENABLE!*!8TOMANAGE0ROFILES ,ISTING  9OUNEEDTOSPECIFYWHICHPROPERTIESINTHE0ROFILECANBEREADFROMANDWHICHONES can be changed. The Profiles settings you saw in Listing 7-10 are unchanged. The required settings ARESHOWNIN,ISTING  Listing 7-27. Web.config Settings to Configure AJAX Access to User Profile Properties 8ouopai*sa^*atpajoekjo: 8o_nelpejc: 8sa^Oanre_ao: 8lnkbehaOanre_aaj]^ha`9pnqa na]`=__aooLnklanpeao9Qoan*J]ia(Qoan*Ai]eh(Oeva(Bkna?khkn(>]_g?khkn snepa=__aooLnklanpeao9Qoan*Ai]eh(Bkna?khkn(>]_g?khkn+: 8+sa^Oanre_ao: 8+o_nelpejc: 8+ouopai*sa^*atpajoekjo: All you need to do now is write the appropriate client code.

Download at WoweBook.Com

325

326

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Creating the User Interface "ECAUSEWELLUSEPURE!*!8TOCOMMUNICATEWITHTHESERVER YOUDONTNEEDSERVER SIDECONTROLS 4HEFOLLOWINGFORMUSESBASIC(4-,TOBUILDTHE5)4HEREAREAFEW(4-,INPUTCONTROLS WITHAN )$ATTRIBUTEASSIGNEDTOEACHONESEE,ISTING   Listing 7-28. Client Side Part of the Solution—the HTML Form 8bkninqj]p9oanran: 8]ol6O_nelpI]j]canE@9O_nelpI]j]cannqj]p9oanran+: 8beah`oape`9?kjp]_pBeah`oap: 8h]^ah: A)i]eh 8ejlqppula9patpe`9aI]eh+:8+h]^ah:8^n+: 8h]^ah: QoanJ]ia 8ejlqppula9patpe`9qoanJ]ia`eo]^ha`9`eo]^ha`+:8+h]^ah: 8h]^ah: 8^n+: Bkna?khkn6 8^n+: Na` 8ejlqppula9n]`ekj]ia9Bkna?khkne`9b_-r]hqa9Na`+: >hqa 8ejlqppula9n]`ekj]ia9Bkna?khkne`9b_.r]hqa9>hqa+: Cnaaj 8ejlqppula9n]`ekj]ia9Bkna?khkne`9b_/r]hqa9Cnaaj+: 8+h]^ah: 8^n+: 8h]^ah: >]_g?khkn6 8^n+: Sdepa 8ejlqppula9n]`ekj]ia9>]_g?khkne`9^_-r]hqa9Sdepa+: >aeca 8ejlqppula9n]`ekj]ia9>]_g?khkne`9^_.r]hqa9>aeca+: Uahhks 8ejlqppula9n]`ekj]ia9>]_g?khkne`9^_/r]hqa9Uahhks+: 8+h]^ah: 8^n+: 8^qppkjkj_he_g9O]raLnklanpeao$%7: O]ra8+^qppkj: 8+beah`oap: 8dn+: 8le`9Op]pqo: 8+l: 8+bkni: Figure 7-10 shows the form that appears.

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Figure 7-10. The form with simple HTML form controls

The JavaScript to Tie It Together The final step is to add the JavaScript code which will communicate between the client and the server. First, we’ll bring up the Profile for the current user and populate the form when the page LOADS4HENWELLEXPOSEAh3AVEvBUTTONSOTHATTHEUSERCANUPDATETHEIR0ROFILE4HEFINALSTEPIS to inform the user that their Profile has been saved. We’ll accomplish this with a status label that will hide itself after 5 seconds. "REAKINGTHISDOWNINTOSTEPS WELLFIRSTLOADTHE0ROFILEFORTHEAUTHENTICATEDUSERBYCALLING the Hk]` method of the Ouo*Oanre_ao*LnkbehaOanre_a object. If this call is successful, we’ll populate THEFORM)FTHEREWASANERROR WELLALERTTHEUSER4HECALLBACKMETHODSAREUSEDTOCHECKSUCCESS and error conditions. If successful, the values are read directly from the generic JavaScript class, USINGTHESAMESYNTAXFORPROPERTIESASTHESERVER3EE,ISTING  Listing 7-29. JavaScript That Stores User Profile Settings sej`ks*kjhk]`9bqj_pekj$%w Ouo*Oanre_ao*LnkbehaOanre_a*hk]`$jqhh(kjHk]`Oq__aoo(kjAnnkn%7 y bqj_pekjkjHk]`Oq__aoo$k^f%w  cap$aI]eh%*r]hqa9Ouo*Oanre_ao*LnkbehaOanre_a*lnklanpeao*Qoan*Ai]eh7  cap$qoanJ]ia%*r]hqa9Ouo*Oanre_ao*LnkbehaOanre_a*lnklanpeao*Qoan*J]ia7 r]nb_9Ouo*Oanre_ao*LnkbehaOanre_a*lnklanpeao*Bkna?khkn*J]ia7  cap$b_-%*_da_ga`9$b_99#Na`#%7  cap$b_.%*_da_ga`9$b_99#>hqa#%7  cap$b_/%*_da_ga`9$b_99#Cnaaj#%7 r]n^_9Ouo*Oanre_ao*LnkbehaOanre_a*lnklanpeao*>]_g?khkn*J]ia7  cap$^_-%*_da_ga`9$^_99#Sdepa#%7  cap$^_.%*_da_ga`9$^_99#>aeca#%7  cap$__/%*_da_ga`9$^_99#Uahhks#%7 y bqj_pekjkjAnnkn$annkn%w  cap$Op]pqo%*ejjanDPIH9annkn*cap[iaoo]ca$%7 y The preceding code will attempt to load the Profile for the current user when the page loads. If this is successful, the kjHk]`Oq__aoo function will fire and you can populate the form. If there was an error, the kjAnnkn function will fire and an error message will be displayed to the user. 4HEFINALSTEPISTOBUILDTHEh3AVE0ROFILEvFUNCTION4HISISSIMILARTOTHEHk]` method that was previously called. Assign the new values to the Profile object in JavaScript and then call O]ra on the Ouo*Oanre_ao*LnkbehaOanre_a object!GAIN THECALLBACKMETHODSAREUSEDTOCHECKFORSUCCESS ANDERRORS ASSHOWNIN,ISTING 

Download at WoweBook.Com

327

328

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Listing 7-30. Script Code That Stores User Profile Settings bqj_pekjO]raLnklanpeao$%w Ouo*Oanre_ao*LnkbehaOanre_a*lnklanpeao*Qoan*Ai]eh9 cap$aI]eh%*r]hqa7 Ouo*Oanre_ao*LnkbehaOanre_a*lnklanpeao*Qoan*J]ia9 cap$qoanj]ia%*r]hqa7 r]nb_9##7 b_'9$ cap$b_-%*_da_ga`%;#Na`#6##7 b_'9$ cap$b_.%*_da_ga`%;#>hqa#6##7 b_'9$ cap$b_/%*_da_ga`%;#Cnaaj#6##7 Ouo*Oanre_ao*LnkbehaOanre_a*lnklanpeao*Bkna?khkn9b_7 r]n^_9##7 ^_'9$ cap$b_-%*_da_ga`%;#Sdepa#6##7 ^_'9$ cap$b_.%*_da_ga`%;#>aeca#6##7 ^_'9$ cap$b_/%*_da_ga`%;#Uahhks#6##7 Ouo*Oanre_ao*LnkbehaOanre_a*lnklanpeao*>]_g?khkn9^_7 Ouo*Oanre_ao*LnkbehaOanre_a*o]ra$jqhh(kjO]raOq__aoo(kjAnnkn%7 y bqj_pekjkjO]raOq__aoo$%w _ha]nPeiakqp$%7 ++@eolh]updaoq__aooiaoo]capkpdaqoan*  cap$Op]pqo%*ejjanDPIH9Ukqnlnkbehad]o^aajo]ra`*7 ++Naoappda`eolh]u]bpan1oa_kj`od]ral]ooa`* oapPeiakqp$bqj_pekj$%w cap$Op]pqo%*ejjanDPIH97y(1,,,%7 y )FALLGOESWELL WHENYOUCLICKTHE3AVEBUTTONYOUSHOULDSEEAMESSAGELIKETHEONEIN Figure 7-11.

Figure 7-11. The form response when the Profile access was successful 4HISISAVERYSIMPLEEXAMPLEWHICHDEMONSTRATESHOWTOACCESSTHE0ROFILEUSINGTHE!*!8 library. Its power comes from the library and its close relation to basic ASP.NET features. If you’re NOTCONFIDENTUSINGTHE!30.%4!*!8LIBRARIESBECAUSEOFTHEIRSIZEORPERFORMANCE KEEPINMIND THATTHEYSUPPORTLARGERPARTSOF!30.%4OUTOFTHEBOX4HISISVERYUSEFULFORSMALLERPROJECTS AS WELLASFORCONSTRUCTINGCOMPLEXFEATURESQUICKLY(OWEVER INLARGEPROJECTSWITHHEAVYACCESSYOU MIGHTCONSIDERDIFFERENTWAYS LIKEOTHERTHIRD PARTYLIBRARIESTHAT support the specific parts required for Profiles only.

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Extending Web Parts Personalization Providers Web Parts areSPECIALIZEDUSERCONTROLSTHATHAVEEXTENSIVECLIENTSUPPORT7EB0ARTSMAKEUPPORTIONSOFAWEBPAGE ANDALLOWUSERSTOCHANGETHEPAGEDESIGN&OREXAMPLE USERSCANMOVE7EB Parts around, hide or close them, and change their behavior. Web Parts are typically used to create PORTALPAGESTHATUSERSCANPERSONALIZE!30.%4COMESWITHALLTHEPIECESNEEDEDTOCONSTRUCT ACOMPLETELYPERSONALIZABLEPAGE4HEFRAMEWORKINCLUDESCOMPONENTSWHICHPERFORMTHEFOLLOWINGTASKS

s $EFINEANDHANDLECUSTOMIZABLESECTIONSTHROUGHZONES



s 0ULL7EB0ARTSFROMACATALOGUE



s %XPORTANDIMPORT7EB0ARTSSOTHATUSERSCANSHARETHEMLIKEGADGETS



s 3AVETHEUSERSPREFERENCESTOAPERMANENTDATASTORE

"YNOW ITSHOULDBECLEARTHATAPROVIDERPLAYSAROLEINTHIS7EB0ARTSSETTINGS LOCATIONS AND properties must be stored and retrieved when the user revisits the site. This implies that the user MUSTBEAUTHENTICATED4HEREISANINDIRECTRELATIONSHIPBETWEENTHE-EMBERSHIPAND2OLEPROVIDERS ANDTHE7EB0ARTPERSONALIZATIONPROVIDER4HEREISNODEPENDENCYONTHE0ROFILEPROVIDER AS EXPLAINEDINTHEPREVIOUSSECTION

Understanding the Web Parts Personalization Provider "EFOREYOUSTARTWORKINGWITHTHEPERSONALIZATIONPROVIDERANDPLANNINGACUSTOMIMPLEMENTATION you should understand the default provider and how it behaves. The default provider is Ouopai* Sa^*QE*Sa^?kjpnkho*Sa^L]npo*OmhLanokj]hev]pekjLnkre`an, and it accesses the same SQL Server database used to support membership, roles, and profiles internally. The prime job of the personALIZATIONPROVIDERISTOSTORETHESTATEOF7EB0ARTS WHICHCONSISTSOF7EB0ARTSCONTENTANDTHE layout of Web Parts pages. The state is held in a container of type Ouopai*Sa^*QE*Sa^?kjpnkho* Sa^L]npo*Lanokj]hev]pekjOp]pa4HEPERSONALIZATIONSERVICEUSINGTHEPROVIDERSERIALIZESTHEDATA ANDSENDSITTOTHEPROVIDERASASTREAMOFBYTESTOSTORE#ONVERSELY ITRETRIEVESANDDESERIALIZES data to restore the state of Web Parts. "ECAUSETHEOmhLanokj]hev]pekjLnkre`anISAFINALIMPLEMENTATION THEREEXISTSANABSTRACT BASECLASSFORSUCHPERSONALIZATIONPROVIDERSˆTHELanokj]hev]pekjLnkre`an class. lq^he_]^opn]_p_h]ooLanokj]hev]pekjLnkre`an6Lnkre`an>]oa w lnkpa_pa`Lanokj]hev]pekjLnkre`an$%7 lq^he_]^opn]_popnejc=llhe_]pekjJ]iawcap7oap7y lnkpa_pa`renpq]hEHeop?na]paOqllknpa`Qoan?]l]^ehepeao$%7 lq^he_renpq]hLanokj]hev]pekjO_kla@apaniejaEjepe]hO_kla$± Sa^L]npI]j]cansa^L]npI]j]can(Lanokj]hev]pekjOp]pahk]`a`Op]pa%7 lq^he_renpq]hE@e_pekj]nu@apaniejaQoan?]l]^ehepeao$± Sa^L]npI]j]cansa^L]npI]j]can%7 lq^he_]^opn]_pLanokj]hev]pekjOp]paEjbk?khha_pekjBej`Op]pa$± Lanokj]hev]pekjO_klao_kla(Lanokj]hev]pekjOp]paMqanumqanu(± ejpl]caEj`at(ejpl]caOeva(kqpejppkp]hNa_kn`o%7 lq^he_]^opn]_pejpCap?kqjpKbOp]pa$Lanokj]hev]pekjO_klao_kla(± Lanokj]hev]pekjOp]paMqanumqanu%7 lnkpa_pa`]^opn]_prke`Hk]`Lanokj]hev]pekj>hk^o$Sa^L]npI]j]cansa^L]npI]j]can(± opnejcl]pd(opnejcqoanJ]ia(± nab^upaWYod]na`@]p]>hk^(nab^upaWYqoan@]p]>hk^%7 lq^he_renpq]hLanokj]hev]pekjOp]paHk]`Lanokj]hev]pekjOp]pa$± Sa^L]npI]j]cansa^L]npI]j]can(^kkhecjkna?qnnajpQoan%7 Download at WoweBook.Com

329

330

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

lnkpa_pa`]^opn]_prke`NaoapLanokj]hev]pekj>hk^$± Sa^L]npI]j]cansa^L]npI]j]can(opnejcl]pd(opnejcqoanJ]ia%7 lq^he_renpq]hrke`NaoapLanokj]hev]pekjOp]pa$Sa^L]npI]j]cansa^L]npI]j]can%7 lq^he_]^opn]_pejpNaoapOp]pa$Lanokj]hev]pekjO_klao_kla(± opnejcWYl]pdo(± opnejcWYqoanj]iao%7 lq^he_]^opn]_pejpNaoapQoanOp]pa$opnejcl]pd(@]paPeiaqoanEj]_peraOej_a@]pa%7 lnkpa_pa`]^opn]_prke`O]raLanokj]hev]pekj>hk^$Sa^L]npI]j]cansa^L]npI]j]can(± opnejcl]pd(opnejcqoanJ]ia(^upaWY`]p]>hk^%7 lq^he_renpq]hrke`O]raLanokj]hev]pekjOp]pa$Lanokj]hev]pekjOp]paop]pa%7 y 4HEFOLLOWINGTABLEEXPLAINSTHEMETHODSANDPROPERTIES4HEVARIOUS]^opn]_p and renpq]h KEYWORDSINDICATETHATONLYAFEWMETHODSNEEDTOBEIMPLEMENTEDˆTHEOTHERMETHODSARE optional. As a result, this base class is a better starting point for a custom implementation than the Lnkre`an>]oaBASECLASSSEE4ABLE   Table 7-4. Members of the PersonalizationProvider Base Class

Member

Description

=llhe_]pekjJ]ia

'ETSORSETSTHENAMEOFTHEAPPLICATION

J]ia

Name of the provider.

@ao_nelpekj

Friendly name or description.

?na]paOqllknpa`Qoan?]l]^ehepeao

2ETURNSALISTOFOuopai*Sa^*QE*Sa^?kjpnkho*Sa^L]npo* Sa^L]npQoan?]l]^ehepu objects that represent the set of KNOWNCAPABILITIES

@apaniejaEjepe]hO_kla

$ETERMINESWHETHERTHEINITIALPERSONALIZATIONSCOPESHOULD BE3HAREDOR5SERFROMLanokj]hev]pekjO_klaENUM 4AKES a Sa^L]npI]j]canOBJECTTHATMANAGESTHEPERSONALIZATION INFORMATIONANDTHEPERSONALIZATIONSTATEINFORMATION4HE method returns a Lanokj]hev]pekjO_kla enum value.

@apaniejaQoan?]l]^ehepeao

2ETURNSADICTIONARYCONTAININGSa^L]npQoan?]l]^ehepu INSTANCESTHATREPRESENTTHEPERSONALIZATION RELATEDCAPABILITIESOFTHECURRENTLYEXECUTINGUSERACCOUNT

Bej`Op]pa

2ETURNSACOLLECTIONCONTAININGZEROORMORE Lanokj]hev]pekjOp]paEjbk objects based on scope and specific query parameters. Depends on scope, query, and paging information.

Cap?kqjpKbOp]pa

2ETURNSTHENUMBEROFROWSINTHEUNDERLYINGDATASTORETHAT EXISTWITHINTHESPECIFIEDSCOPE$EPENDSONQUERYANDSCOPE

Hk]`Lanokj]hev]pekj>hk^o

,OADSRAWPERSONALIZATIONDATAFROMTHEUNDERLYINGDATA STORE4AKESAREFERENCETOTHESa^L]npI]j]can object managINGTHEPERSONALIZATIONDATA APATHASKEY THEUSERSNAME and the blob data for shared and user part.

Hk]`Lanokj]hev]pekjOp]pa

Loads the raw data from the underlying data store and converts it into a Lanokj]hev]pekjOp]pa object.

NaoapLanokj]hev]pekj>hk^

$ELETESRAWPERSONALIZATIONDATAFROMTHEUNDERLYINGDATA store.

NaoapLanokj]hev]pekjOp]pa

2ESETSPERSONALIZATIONDATATOTHEUNDERLYINGDATASTORE

NaoapOp]pa

$ELETESPERSONALIZATIONSTATEFROMTHEUNDERLYINGDATASTORE BASEDONTHESPECIFIEDPARAMETERS2ETURNSTHENUMBEROF rows deleted.

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Member

Description

NaoapQoanOp]pa

$ELETES7EB0ARTSPERSONALIZATIONDATAFROMTHEUNDERLYING data store based on the specified parameters.

O]raLanokj]hev]pekj>hk^

3AVESRAWPERSONALIZATIONDATATOTHEUNDERLYINGDATASTORE

O]raLanokj]hev]pekjOp]pa

3AVESPERSONALIZATIONDATATOADATASTORE

Implementing this is not difficult. The Hk]`, O]ra, and Naoap methods are the core parts of this class. /NECRUCIALASPECTISTHESCOPEOFTHEPERSONALIZATIONDATA7EB0ARTSPERSONALIZATIONHASTWO SCOPESBYUSERANDBYPATH4HISALLOWSYOUTOPERSONALIZETHEBEHAVIOREITHERFOREACHINDIVIDUAL USERORBYEACHPAGESPATH3COPINGBYREQUESTPATHISCALLEDhSHAREDvINTHEMETHODNAMESUSED by the provider. In these cases, the user name is set to jqhh and all settings apply to all users. The PROVIDERMUSTTAKECAREOFSUCHDATAANDSTOREITSEPARATELYFROMTHEUSERSSTORAGE The provider support is optional for multiple applications based on the =llhe_]pekjJ]ia property BUTRECOMMENDED)FYOUUSEALOCALSTORE SUCHASAN8-,FILEASSHOWNINTHEFOLLOWING EXAMPLE THEAPPLICATIONNAME can be ignored.

Implementing a Custom Personalization Provider !CUSTOMPERSONALIZATION provider has several prerequisites:

s !PORTALPAGEMUSTEXISTTHATHANDLESSEVERAL7EB0ARTS



s 4HESITEMUSTSUPPORT!UTHENTICATIONANDUSERMEMBERSHIP



s 4HECUSTOM7EB0ARTPERSONALIZATIONPROVIDERANDITSSTOREMUSTEXIST



s 4HEweb.configFILEMUSTBEPROPERLYCONFIGUREDTOSUPPORT7EB0ARTPERSONALIZATION 4HENEXTSECTIONSEXPLAINTHEREQUIRED steps one-by-one.

Creating a Portal Page /UR0ORTALPAGETOTESTTHESOLUTIONISASIMPLE7EB0ARTPAGE ASSHOWNIN,ISTING  Listing 7-31. The “Portal” Page to Test the Solution 8bknie`9bkni-nqj]p9oanran: 8`er: 8]ol6Sa^L]npI]j]canE@9Sa^L]npI]j]can-nqj]p9oanran: 8Lanokj]hev]pekjAj]^ha`9pnqaLnkre`anJ]ia9TihLanokj]hev]pekjLnkre`an+: 8+]ol6Sa^L]npI]j]can: 8p]^haopuha9se`pd6-,,!: 8pnr]hecj9ie``haopuha9^]_gcnkqj`6``````: 8p`_khol]j9.: 8d.: Sah_kiapkkqnLknp]h( 8]ol6HkcejJ]iaE@9HkcejJ]ia-nqj]p9oanran+: 8+d.: 8+p`: 8p`: 8]ol6IajqE@9Iajq-nqj]p9oanran± KjIajqEpai?he_g9Iajq-[IajqEpai?he_g: 8+]ol6Iajq: Download at WoweBook.Com

331

332

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

8+p`: 8+pn: 8pnr]hecj9pkl: 8p`opuha9se`pd6.,!: 8]ol6?]p]hkcVkjaE@9?]p]hkcVkja-nqj]p9oanran: 8VkjaPailh]pa: 8]ol6L]ca?]p]hkcL]npE@9L]ca?]p]hkcL]np-nqj]p9oanran+: 8+VkjaPailh]pa: 8+]ol6?]p]hkcVkja: 8]ol6A`epknVkjaE@9A`epknVkja-nqj]p9oanran: 8+]ol6A`epknVkja: 8+p`: 8p`opuha9se`pd62,!: 8]ol6Sa^L]npVkjaE@9Sa^L]npVkja-nqj]p9oanran: 8+]ol6Sa^L]npVkja: 8+p`: 8p`opuha9se`pd6.,!: 8]ol6Sa^L]npVkjaE@9Sa^L]npVkja.nqj]p9oanran: 8Pepha>]nRan^Opuha>]_g?khkn9=_pera>kn`an+: 8VkjaPailh]pa: 8]ol6?]haj`]nE@9?]haj`]n-nqj]p9oanran:8+]ol6?]haj`]n: 8]ol6BehaQlhk]`E@9BehaQlhk]`-nqj]p9oanran+: 8+VkjaPailh]pa: 8+]ol6Sa^L]npVkja: 8+p`: 8+pn: 8pn: 8p`_khol]j9/: 8]ol6HkcejOp]pqoE@9HkcejOp]pqo-nqj]p9oanran+: 8+p`: 8+pn: 8+p]^ha: 8+`er: 8+bkni: The only dependency on other code parts is the selection of the current provider: 8Lanokj]hev]pekjAj]^ha`9pnqaLnkre`anJ]ia9TihLanokj]hev]pekjLnkre`an+: !SSHOWN THEPERSONALIZATIONMUSTBETURNEDONINORDERTOACTIVATETHEPROVIDERUSINGTHE Aj]^ha` attribute. The name of the provider is defined in web.config3EETHESECTIONh#ONFIGURE the Provider” for more details.) 4OFORCETHEPAGETOCHANGETHESETTINGSANDINVOKETHEPROVIDER THEUSERMUSTENTERTHE%DIT mode of the Web Part page. To do this easily, the following code-behind code is used: lq^he_l]npe]h_h]oo[@ab]qhp6Ouopai*Sa^*QE*L]ca w lnkpa_pa`rke`L]ca[Hk]`$k^fa_poaj`an(Arajp=ncoa% w eb$EoLkop>]_g% w ++?na]pa]iajqkbsa^l]npik`ao IajqEpainkkpEpai9jasIajqEpai$Oaha_pSa^L]npIk`a%7 bkna]_d$Sa^L]np@eolh]uIk`aik`aejSa^L]npI]j]can-*@eolh]uIk`ao% w nkkpEpai*?deh`Epaio*=``$jasIajqEpai$ik`a*J]ia%%7 y Iajq-*Epaio*=``$nkkpEpai%7 Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

y y lnkpa_pa`rke`Iajq-[IajqEpai?he_g$k^fa_poaj`an(IajqArajp=ncoa% w Sa^L]npI]j]can-*@eolh]uIk`a9Sa^L]npI]j]can-*@eolh]uIk`aoWa*Epai*PatpY7 y y The menu is filled with items from the collection of acceptable modes. In the IajqEpai?he_g event handler, the same value is used to set theCURRENTMODESEE&IGURE  

Figure 7-12. The Web Part page

Prepare Authentication For a simple scenario to login and logout users, I set up Forms authentication in web.config. Furthermore, I store the users’ credentials directly in web.config and configure the Iai^anodel provider TOUSETHATDATAINSTEADOFDATAFROMTHEDEFAULTPROVIDER31,3ERVER 4HISCANBEACCOMPLISHEDBY handling the authentication event manually. The web.configSECTIONTHATDEFINESTHEUSERSLOOKSLIKE ,ISTING  Listing 7-32. Define Some Users Quickly to Test the Application 8]qpdknev]pekj: 8`ajuqoano9;+: 8+]qpdknev]pekj: 8]qpdajpe_]pekjik`a9Bknio: 8bknio: 8_na`ajpe]hol]ooskn`Bkni]p9?ha]n: 8qoanj]ia9Qoan-l]ooskn`9Qoan-+: 8qoanj]ia9Qoan.l]ooskn`9Qoan.+: 8qoanj]ia9Qoan/l]ooskn`9Qoan/+: 8+_na`ajpe]ho: 8+bknio: 8+]qpdajpe_]pekj: The application then requires at least one page in order to change and use the profile settings, as well as a login page. The login page consists of a single HkcejCONTROLANDANEVENTHANDLERSEE ,ISTINGS AND   Download at WoweBook.Com

333

334

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Listing 7-33. The Login Page in Its Simplest Form 8^k`u: 8bknie`9bkni-nqj]p9oanran: 8`er: 8]ol6HkcejE@9Hkcej-nqj]p9oanrankj]qpdajpe_]pa9Hkcej-[=qpdajpe_]pa: 8+]ol6Hkcej: 8^n+: 8+`er: 8+bkni: 8+^k`u: 8+dpih:

Listing 7-34. An Event Handler Forces the Login Control to Use the Configured User Names lq^he_l]npe]h_h]ooHkcej6Ouopai*Sa^*QE*L]ca w lnkpa_pa`rke`L]ca[Hk]`$k^fa_poaj`an(Arajp=ncoa% w y lnkpa_pa`rke`Hkcej-[=qpdajpe_]pa$k^fa_poaj`an(=qpdajpe_]paArajp=ncoa% w a*=qpdajpe_]pa`9Bknio=qpdajpe_]pekj*=qpdajpe_]pa$Hkcej-*QoanJ]ia(± Hkcej-*L]ooskn`%7 y y 4HENEXTPAGEISALSOFORTESTINGPURPOSES)TCONTAINSASIMPLEFORMTOSAVENEWPROFILESETTINGS show current settings, and change accounts.

Create the Provider The following implementationUSES8-,TOSTOREDATA)TRENDERSTHEAPPLICATIONINDEPENDENTOF a SQL Server database. The implementation is as simple as possible—only the basic methods for LOADINGANDSAVINGDATAAREFULLYIMPLEMENTEDSEE,ISTING   Listing 7-35. A Web Part Personalization Provider Using XML qoejcOuopai7 qoejcOuopai*?khha_pekjo*Cajane_7 qoejcOuopai*Hejm7 qoejcOuopai*Sa^7 qoejcOuopai*Sa^*QE*Sa^?kjpnkho*Sa^L]npo7 qoejcOuopai*EK7 qoejcOuopai*Sa^*Dkopejc7 qoejcOuopai*@]p]7 qoejcOuopai*Tih*Hejm7 qoejcOuopai*Tih*TL]pd7 j]iaol]_a=lnaoo*Atpajoe^ehepu*Sa^L]npLnkre`an w lq^he__h]ooTihLanokj]hev]pekjLnkre`an6Lanokj]hev]pekjLnkre`an w lner]pa_kjopopnejcOAPPEJCOJ=IA9SLOappejco*tih7 lner]pa_kjopopnejcOAPPEJCOP=C9SLOappejco7 lner]paopnejc_kjbecBeha7 Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

lq^he_kranne`arke`Ejepe]heva$opnejcj]ia((± Ouopai*?khha_pekjo*Ola_e]heva`*J]iaR]hqa?khha_pekj_kjbec% w ^]oa*Ejepe]heva$j]ia(_kjbec%7 _kjbecBeha9Dppl?kjpatp*?qnnajp*Namqaop*I]lL]pd$(± L]pd*?ki^eja$z+=ll[@]p]+(OAPPEJCOJ=IA%%7 ++TIH eb$Beha*Ateopo$_kjbecBeha%% w T@k_qiajp_bc@k_9jasT@k_qiajp$ jasTAhaiajp$Sa^L]np@]p](jasT=ppne^qpa$?na]pa`((± @]paPeia*Jks*PkOdknp@]paOpnejc$%%( jasTAhaiajp$QoanO_kla%( jasTAhaiajp$Od]na`O_kla%%%7 _bc@k_*@a_h]n]pekj9jasT@a_h]n]pekj$-*,(qpb)4(pnqa%7 _bc@k_*O]ra$_kjbecBeha%7 y y ++JKPA6kjhuOd]na`)o_klalanokj]hev]pekjeohk]`a` lnkpa_pa`kranne`arke`Hk]`Lanokj]hev]pekj>hk^o$ Sa^L]npI]j]cansa^L]npI]j]can( opnejcl]pd( opnejcqoanJ]ia( nab^upaWYod]na`@]p]>hk^( nab^upaWYqoan@]p]>hk^% w T@k_qiajp_bc@k_9T@k_qiajp*Hk]`$_kjbecBeha%7 r]nnkkp9_bc@k_*Ahaiajp$Sa^L]np@]p]%7 eb$qoanJ]ia99jqhh% w k^fa_p_]_da`L]caOappejco9Dppl?kjpatp*?qnnajp*?]_daW± OAPPEJCOP=C'6'l]pdY7 eb$_]_da`L]caOappejco9jqhh% w od]na`@]p]>hk^9$^upaWY%_]_da`L]caOappejco7 y ahoa w r]nod]na`9nkkp*Ahaiajp$Od]na`O_kla% *Ahaiajpo$L]ca% *Oejcha$j9:± j*=ppne^qpa$j]ia%*R]hqa*Amq]ho$qoanJ]ia%%7 eb$od]na`99jqhh% w od]na`@]p]>hk^9jqhh7 y ahoa w od]na`@]p]>hk^9?kjranp*Bnki>]oa20Opnejc$od]na`*R]hqa%7 ++_]_daod]na`oappejco sa^L]npI]j]can*L]ca*?]_da*Ejoanp$OAPPEJCOP=C'6'l]pd(± od]na`@]p]>hk^(± jasOuopai*Sa^*?]_dejc*?]_da@alaj`aj_u$_kjbecBeha%%7 y y Download at WoweBook.Com

335

336

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

y ahoa w r]nl]caAhaiajp9nkkp*TL]pdOaha_pAhaiajp$ Opnejc*Bkni]p$++QoanO_kla+QoanW<j]ia9#w,y#Y+L]caW<j]ia9#w-y#Y( qoanJ]ia( l]pd%%7 eb$l]caAhaiajp9jqhh% w qoan@]p]>hk^9?kjranp*Bnki>]oa20Opnejc$l]caAhaiajp*R]hqa%7 y y y lnkpa_pa`kranne`arke`NaoapLanokj]hev]pekj>hk^$ Sa^L]npI]j]cansa^L]npI]j]can( opnejcl]pd( opnejcqoanJ]ia% w y lnkpa_pa`kranne`arke`O]raLanokj]hev]pekj>hk^$ Sa^L]npI]j]cansa^L]npI]j]can( opnejcl]pd( opnejcqoanJ]ia( ^upaWY`]p]>hk^% w opnejco>hk^9?kjranp*Pk>]oa20Opnejc$`]p]>hk^%7 hk_g$pdeo% w T@k_qiajp_bc@k_9T@k_qiajp*Hk]`$_kjbecBeha%7 r]nnkkp9_bc@k_*Ahaiajp$Sa^L]np@]p]%7 eb$Opnejc*EoJqhhKnAilpu$qoanJ]ia%% w ++O_kla6qoan r]nqoanAhaiajp9nkkp*TL]pdOaha_pAhaiajp$ Opnejc*Bkni]p$++QoanO_kla+QoanW<j]ia9#w,y#Y( qoanJ]ia%%7 eb$qoanAhaiajp99jqhh% w qoanAhaiajp9nkkp*Ahaiajp$QoanO_kla%7 ++jkqoan(]``_kilhapapnaa qoanAhaiajp*=``$ jasTAhaiajp$Qoan(jasT=ppne^qpa$j]ia(qoanJ]ia%( jasTAhaiajp$L]ca(jasT=ppne^qpa$j]ia(l]pd%( o>hk^%%%7 y ahoa w ++sepdqoan(_da_gl]ca r]nl]caAhaiajp9qoanAhaiajp*Ahaiajpo$L]ca% *Oejcha$j9:± j*=ppne^qpa$j]ia%*R]hqa*Amq]ho$l]pd%%7 eb$l]caAhaiajp99jqhh% w ++jkl]ca qoanAhaiajp*=``$jasTAhaiajp$L]ca( Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

jasT=ppne^qpa$j]ia(l]pd%( o>hk^%%7 y ahoa w ++jas`]p]bknl]ca l]caAhaiajp*R]hqa9o>hk^7 y y y ahoa w ++O_kla6Od]na` r]nod]na`Ahaiajp9nkkp*Ahaiajpo$Od]na`O_kla% *Ahaiajpo$L]ca% *Oejcha$l9:± l*=ppne^qpa$J]ia%*R]hqa*Amq]ho$l]pd%%7 eb$od]na`Ahaiajp99jqhh% w od]na`Ahaiajp*=``$jasTAhaiajp$L]ca( jasT=ppne^qpa$j]ia(l]pd%( o>hk^%%7 y ahoa w od]na`Ahaiajp*R]hqa9o>hk^7 y y _bc@k_*O]ra$_kjbecBeha%7 y y lq^he_kranne`aopnejc=llhe_]pekjJ]ia w cap7 oap7 y lq^he_kranne`aejpCap?kqjpKbOp]pa$ Lanokj]hev]pekjO_klao_kla( Lanokj]hev]pekjOp]paMqanumqanu% w napqnj,7 y lq^he_kranne`aLanokj]hev]pekjOp]paEjbk?khha_pekjBej`Op]pa$ Lanokj]hev]pekjO_klao_kla( Lanokj]hev]pekjOp]paMqanumqanu( ejpl]caEj`at( ejpl]caOeva( kqpejppkp]hNa_kn`o% w pkp]hNa_kn`o9,7 napqnjjqhh7 y lq^he_kranne`aejpNaoapOp]pa$ Download at WoweBook.Com

337

338

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Lanokj]hev]pekjO_klao_kla( opnejcWYl]pdo( opnejcWYqoanj]iao% w napqnj,7 y lq^he_kranne`aejpNaoapQoanOp]pa$ opnejcl]pd( @]paPeiaqoanEj]_peraOej_a@]pa% w napqnj,7 y y y During the call to Ejepe]heva ADATASTOREINTHEFORMOFAN8-,FILEWILLBECREATED IFTHERE isn’t one already. When the user changes properties of Web Parts, the O]raLanokj]hev]pekj>hk^ method is called. The approach used is to search for the qoanJ]ia, and if it is jqhh, meaning the user ISNOTAUTHENTICATED ASSUMETHATITSASHAREDSCOPESETTING/THERWISE ITSAPERSONALSETTING AND THEUSERELEMENTISRETRIEVED)ALSOASSUMETHATDATAFORTHISUSERDOESNOTALREADYEXIST4HISISWHY 80ATHEXPRESSIONSAREUSEDINSTEADOF8,INQEXPRESSIONCHAINS )FTHE8Qoan:ELEMENTDOESNOTEXIST it’s created using the current data. The data is passed to the provider as a byte array, and stored as A"ASEENCODEDSTRINGINTHE8-,ELEMENT)FTHE8Qoan:ELEMENTEXISTS THE8L]ca: element is RETRIEVED%ACHPERSONALIZEDPAGEHASITSOWN8-,ELEMENT)FTHISELEMENTDOESNOTEXIST ITSCREATEDANDTHEENCODEDSTRINGISUSEDASITSVALUE)FITDOESEXIST THECURRENTCONTENTSAREREPLACED with the R]hqa property. A similar technique is used to retrieve the data. Every time the page refreshes, the provider is called to return the data as a byte array. If there is no data, you can safely return jqhh. While THESHAREDDATAISSTOREDINACACHE THEDATAFOREACHUSERISRETRIEVEDDIRECTLYFROMTHE8-,FILE There is plenty of scope for improving the file handling and caching, but that’s beyond the scope OFTHISCHAPTER4OLOCATETHEDATAAGAIN AN80ATHEXPRESSIONISUSED)FAVALUEISPRESENT THE Bnki>]oa20Opnejc method converts the string into a byte array. 4HISCODEPRODUCESAN8-,FILEINTHE=ll[@]p] folder in this manner: 8;tihranoekj9-*,aj_k`ejc9qpb)4;: 8Sa^L]np@]p]?na]pa`91+-2+.,,5: 8QoanO_kla: 8Qoanj]ia9Qoan-: 8L]caj]ia9z+@ab]qhp*]olt:+sAQGs=G=cE?=NgmIRJ1_/Nh^O1TVSEqRQgqR.ReM.5q`DFr^DIqR) .ReQCBu`DIqR.ReQCBu`A-d^iBjVTEB>R5b`/>pVcE>Dd>TVSFMUTF,Q/Nd`CRR_.RuB?o=?=QIV/`sM.BoVS1gUT) Et>MtTVSFMUTF,Si5qVPFi]=QKV/`sNihoVRRs^C5dV@AB@B`hUh>d_jN]^.1hISVk]Cc98+L]ca: 8+Qoan: 8Qoanj]ia9Qoan.: 8L]caj]ia9z+@ab]qhp*]olt:+sAQGs=G=cE?=NgmIRJ1_/Nh^O1TVSEqRQgqR.ReM.5q`DFr^DIqR) .ReQCBu`DIqR.ReQCBu`A-d^iBjVTEB>R5b`/>pVcE>Dd>TVSFMUTF,Q/Nd`CRR_.RuB?o=?=QIV/`sM.BoVS1gUT) Et>MtTVSFMUTF,Si5qVPBi]=QKV/`sNihoVRRs^C5dV@AB@B`hUh>d_jN]^.1hIiVk]Cc98+L]ca: 8+Qoan: 8+QoanO_kla: 8Od]na`O_kla+: 8+Sa^L]np@]p]:

Download at WoweBook.Com

C H A P T E R 7 N S E C U R I T Y A N D U S E R M A N A G E M E N T

Although its format is not impressive, this has everything you need in order to store data for any NUMBEROFUSERSANDANYNUMBEROFPERSONALIZEDPAGES4HENUMBEROFPAGESISUSUALLYLOWˆFOR ACUSTOMIZABLEPORTALPAGEITSONEˆANDTHENUMBEROFACTIVEUSERSDEPENDSONYOURAPPLICATION &ORANINTRANETWITHUPTOSEVERALHUNDREDUSERS THE8-,FILESTORAGESOLUTIONISEASYTOIMPLEMENT and sufficiently fast.

Configure the Provider (AVINGBUILTTHEPROVIDER ITNEEDSTOBECONFIGUREDFORUSE)USE&ORMS!UTHENTICATIONINTHEEXAMple and store the users’ data in web.config, as shown in the following. This is not meant to be used as production code, but it simplifies developmentBYMAKING user management very easy. 8ouopai*sa^: 8sa^L]npo: 8lanokj]hev]pekj`ab]qhpLnkre`an9TihLanokj]hev]pekjLnkre`an: 8lnkre`ano: 8]``j]ia9TihLanokj]hev]pekjLnkre`an pula9=lnaoo*Atpajoe^ehepu*Sa^L]npLnkre`an*TihLanokj]hev]pekjLnkre`an+: 8+lnkre`ano: 8+lanokj]hev]pekj: 8+sa^L]npo: 8]qpdajpe_]pekjik`a9Bknio: 8bknio: 8_na`ajpe]hol]ooskn`Bkni]p9?ha]n: 8qoanj]ia9Qoan-l]ooskn`9qoan-+: 8qoanj]ia9Qoan.l]ooskn`9qoan.+: 8qoanj]ia9Qoan/l]ooskn`9qoan/+: 8+_na`ajpe]ho: 8+bknio: 8+]qpdajpe_]pekj: 8]qpdknev]pekj: 8`ajuqoano9;+: 8+]qpdknev]pekj:

Testing the Custom Web Part Personalization Provider You can use the three prepared user accounts to test the provider. Simply launch the application ANDLOGONUSINGONEOFTHEPREVIOUSCREDENTIALS3WITCHTOh%DITvMODEWITHTHEMENU-OVETHE 7EB0ARTSAROUNDANDREARRANGETHEPAGE4HEDATAISSAVEDIMMEDIATELY,OGOUTANDLOGBACKIN ASADIFFERENTUSER#REATEANOTHERPAGELAYOUT,OGOUTAGAINANDLOGINWITHTHEACCOUNTYOUUSED FIRST4HEPAGELAYOUTFORTHEFIRSTUSERSHOULDREAPPEAR/THERTHANTHEPROVIDER THEREISNOOTHER CUSTOMCODEENABLINGTHISFEATURE4HE7EB0ART0ERSONALIZATIONINFRASTRUCTUREISALREADYAVAILABLE in ASP.NET, and Web Parts used here are oblivious to the custom provider.

NCaution The sample provider lacks error handling and testing, and does not fully implement all the features of Web Parts providers. Before using it as production code, more development is required.

Download at WoweBook.Com

339

340

CH APT ER 7 N S EC U R ITY A ND U S ER MA NA G EM E N T

Summary )NTHISCHAPTER YOULOOKEDATSECURITYAND0ROFILEFEATURES4HEUSER DRIVENSECURITYMODELISCOVEREDBYTHE-EMBERSHIPAND2OLESERVICES BOTHOFWHICHUSEPROVIDERSTOACCESSADATASTORE #REATINGCUSTOMIZEDPROVIDERSSIGNIFICANTLYEXTENDSTHEBUILT INROLEANDMEMBERSHIPMODELS /NCEAUSERISAUTHENTICATED YOUCANASSOCIATEDATAWITHHISORHER0ROFILE4HE0ROFILESERVICE USESAPROVIDERTHATCANBEEXTENDEDˆORREWRITTENUSINGACOMPLETELYCUSTOMIZEDVERSION!0ROFILE PROVIDERCANALSOBEREACHEDBYACLIENTUSINGPURE!*!8 ENABLINGYOUTOSAVEVALUESTOANDRETRIEVE VALUESFROMTHESERVERWITHOUTINVOKINGSERVER SIDECODE "OTHEXTENSIONMODELSPROVIDEATRANSPARENTANDSIMPLEWAYOFEXTENDINGANDCUSTOMIZING BEHAVIOR WHILEALLOWINGTHEEXISTINGCONTROLSTOFUNCTIONASTHEYWOULDWITHDEFAULTPROVIDERS 4HE7EB0ART0ERSONALIZATION0ROVIDERISANINTEGRATEDTECHNIQUEWHICHSTORESSETTINGSOF7EB0ART pages for an authenticated user in a custom data store. In this chapter, you learned which base class to implement in order to change the default behavior and storage medium.

Download at WoweBook.Com

CHAPTER

8

Site Management

I

n this chapter, I’ll look at site-specific extensibility features such as the Site Map provider, which is based on the extensible provider model that we’ve already learned about. A site map defines the navigation structure of a Web site. By default, the data store is the web.sitemap XML file. Although it’s easy to change the default setting, you’ll need a custom site map provider in order to store data anywhere other than in an XML file. The navigation depends usually on the web pages on disc. If you wish to hide the internal physical structure of your site or to serve pages that do not originate from disk files, the Renpq]hL]pdLnkre`an can accomplish this. Using this you can create a virtual site structure. In this chapter, you’ll learn how to implement and modify the behavior of the OepaI]lLnkre`an and Renpq]hL]pdLnkre`an.

Site Map Providers ASP.NET features a data-driven navigation system that uses hierarchical data sources and associated controls. It’s much easier to create a site navigational system and track the current position of the user if you use the Iajq control, PnaaReas control, or OepaI]lL]pd control. As is common in ASP.NET, these controls use a provider to obtain data from a specific data source.

Internal Site Map Provider Before you start writing your own provider, let’s look at how the internal one is implemented and how it works. The TihOepaI]lLnkre`an provider reads an XML file containing the site structure as a hierarchy of OepaI]lJk`a elements. The file itself looks like this: 8oepaI]l: 8oepaI]lJk`apepha9Dkia`ao_nelpekj9Dkiaqnh9z+`ab]qhp*]olt: 8oepaI]lJk`apepha9Oanre_ao`ao_nelpekj9Oanre_aosakbban± qnh9z+Oanre_ao*]olt: 8oepaI]lJk`apepha9Pn]ejejc`ao_nelpekj9Pn]ejejc_h]ooao± qnh9z+Pn]ejejc*]olt+: 8oepaI]lJk`apepha9?kjoqhpejc`ao_nelpekj9?kjoqhpejcoanre_ao± qnh9z+?kjoqhpejc*]olt+: 8+oepaI]lJk`a: 8+oepaI]lJk`a: 8+oepaI]l: The file is named web.sitemap by default. However, you can configure the provider to accept any filename. The best way is to use the OepaI]l@]p]Okqn_a control. A page using these controls could look like this: 341 Download at WoweBook.Com

342

CH APT ER 8 N S ITE MA NA G EMENT

8^k`u: 8bknie`9bkni-nqj]p9oanran: 8`er: 8d.:QoejcOepaI]lL]pd8+d.: 8]ol6OepaI]lL]pdE@9OepaI]lL]pd-Nqj]p9oanran:8+]ol6OepaI]lL]pd: 8]ol6OepaI]l@]p]Okqn_aE@9OepaI]l@]p]Okqn_a-Nqj]p9oanran+: 8d.:QoejcPnaaReas8+d.: 8]ol6PnaaReasE@9PnaaReas-Nqj]p9Oanran@]p]Okqn_aE@9OepaI]l@]p]Okqn_a-: 8+]ol6PnaaReas: 8d.:QoejcIajq8+d.: 8]ol6IajqE@9Iajq.Nqj]p9oanran@]p]Okqn_aE@9OepaI]l@]p]Okqn_a-: 8+]ol6Iajq: 8d.:Qoejc]Dknevkjp]hIajq8+d.: 8]ol6IajqE@9Iajq-Nqj]p9oanran@]p]Okqn_aE@9OepaI]l@]p]Okqn_a- Kneajp]pekj9Dknevkjp]h Op]pe_@eolh]uHaraho9.: 8+]ol6Iajq: 8+`er: 8+bkni: 8+^k`u: This web page already has a complete navigation structure. The OepaI]lL]pd control indicates your current position in the site structure via a “breadcrumb” style display. The PnaaReas and Iajq controls create a tree of all pages. The Iajq control provides additionally a JavaScript-driven drop-down menu. Both include plenty of features and assistance for creating sophisticated menus. As shown in the example, the controls can appear several times to create top level, side level, or other kinds of menu. You can even use several OepaI]l@]p]Okqn_a controls to define different entry points in the site structure or prepare submenus and partial menus.

NTip If you have not yet used these controls intensively, the following web address is one entry point into the documentation: dppl6++io`j*ie_nkokbp*_ki+aj)qo+he^n]nu+io..3114*]olt. This model has several advantages—as well as disadvantages. On the positive side, it’s easy and fast to use, and the structure of the content relates directly to the navigation. Navigation is usually structured hierarchically, and XML represents this perfectly. There are also some negatives. First, the URL is used internally as a key, which means that you cannot use the same URL twice to point to a page from different locations in the hierarchy. It’s possible to work around this—you could add a dummy querystring parameter, or use the UrlMappings defined in the web.config, but this isn’t ideal. Furthermore, the default provider reads the definition file once the application starts, and holds the whole content in memory. Large structures operating on several levels for submenus consume a lot of memory. The internal provider is defined in the web.config file like any other: 8ouopai*sa^: 8oepaI]l`ab]qhpLnkre`an9TihOepaI]lLnkre`anaj]^ha`9pnqa: 8lnkre`ano: 8]``j]ia9TihOepaI]lLnkre`an `ao_nelpekj9@ab]qhpOepaI]llnkre`an* pula9Ouopai*Sa^*TihOepaI]lLnkre`an Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

oepaI]lBeha9Sa^*oepai]l+: 8+lnkre`ano: 8+oepaI]l: 8+ouopai*sa^: The configuration, the Site Map file, and the appropriate controls are everything you need for complete site navigation.

Localization The embedded Site Map provider supports full localization. The resource provider (demonstrated in Chapter 4) is aware of the encoded resource keys and can obtain the content from a resource file. When providing different resource files for languages or cultures, you only need one Site Map definition for each different language. It is, however, not possible to have different site structures for each culture.

Security Issues The Site Map provider model does support a security concept. If you define the roles for each node, the provider will display only those nodes the user is permitted to view. Security trimming can be switched on and off. Microsoft states that using more than 150 nodes will have a serious performance impact. When using the Site Map programmatically, the provider will return jqhh if the current user has no access rights, and an exception will occur if the user is not permitted to read the root node.

Reasons to Write a Custom Site Map Provider There are several reasons why you might consider creating a custom provider:

s 9OUSUPPORTLOCALIZATIONANDNEEDADIFFERENTSITESTRUCTUREFOREACHCULTUREWITHOUTUSING several files.



s 9OUHAVEHUNDREDSOFNODESANDNEEDSECURITYTRIMMING



s 9OUHAVELIMITEDMEMORYBUTALARGESTRUCTURE



s 9OUWANTTOSUPPORTTHESAMENODESSEVERALTIMESINTHEHIERARCHY



s 9OUWANTTOALLOWUSERSTOADDREMOVENODES



s 9OUWANTTOPERSISTTHESTRUCTUREINANALTERNATIVEDATASTORE

There are two ways of customizing the provider’s behavior: either extending the default provider, or writing your own. Extending the default provider lets you keep the XML file, but allows different behavior when retrieving nodes or adding security features. Using your own provider gives you the ability to use a different data source.

NTip You can use Tih@k_qiajp or T@k_qiajp classes to retrieve and change nodes directly in the web.sitemap file in order to edit the site structure on the fly. This does not require a new provider, but extends the behavior of the site navigation universe. Consider this before writing a lot of code just to get read-write access.

Download at WoweBook.Com

343

344

CH APT ER 8 N S ITE MA NA G EMENT

Writing a Custom Site Map Provider The purpose of the provider shown here is to access another data source. For web farm or web garden scenarios, or flexible access to the site structure definition, a SQL Server database is the best choice. The amount of data is relatively small, and SQL Server retains it in memory, resulting in fast access.

Prerequisites A custom provider inherits from a base class (as we’ve seen many times). For the Site Map provider, you have a choice between the Ouopai*Sa^*Op]pe_OepaI]lLnkre`an class and its abstract base class, Ouopai*Sa^*OepaI]lLnkre`an. These greatly simplify things, because they come with several basic methods already implemented. You can use the Op]pe_OepaI]lLnkre`an if

s 9OUREADNODESEITHERONCEORRARELY



s !LLINFORMATIONISCACHEDTHROUGHTHELIFETIMEOFTHEPROVIDER

The lifetime of the provider is usually the lifetime of the application. Changing the Site Map requires a restart. If any one of the following conditions is met, the OepaI]lLnkre`an type is a better choice:

s 4HEDATAISSTOREDINADATABASE



s 4HEDATACHANGESFREQUENTLYTHROUGHOUTTHEAPPLICATIONSLIFETIME



s 4HEUSERCANCHANGETHE structure and personalize the menu.

Learning About the Base Classes Before you start implementing, you’ll need to know which methods you’ll be dealing with. First, take a look at the OepaI]lLnkre`an class: lq^he_]^opn]_p_h]ooOepaI]lLnkre`an6Lnkre`an>]oa w lnkpa_pa`OepaI]lLnkre`an$%7 lq^he_renpq]hOepaI]lJk`a?qnnajpJk`awcap7y lq^he_^kkhAj]^haHk_]hev]pekjwcap7oap7y lq^he_renpq]hOepaI]lLnkre`anL]najpLnkre`anwcap7oap7y lq^he_opnejcNaokqn_aGauwcap7oap7y lq^he_renpq]hOepaI]lJk`aNkkpJk`awcap7y lq^he_renpq]hOepaI]lLnkre`anNkkpLnkre`anwcap7y lq^he_^kkhOa_qnepuPneiiejcAj]^ha`wcap7y lq^he_arajpOepaI]lNaokhraArajpD]j`hanOepaI]lNaokhra7 lnkpa_pa`renpq]hrke`=``Jk`a$OepaI]lJk`ajk`a%7 lnkpa_pa`ejpanj]hrenpq]hrke`=``Jk`a$OepaI]lJk`ajk`a(± OepaI]lJk`al]najpJk`a%7 lq^he_renpq]hOepaI]lJk`aBej`OepaI]lJk`a$Dppl?kjpatp_kjpatp%7 lq^he_]^opn]_pOepaI]lJk`aBej`OepaI]lJk`a$opnejcn]sQnh%7 lq^he_renpq]hOepaI]lJk`aBej`OepaI]lJk`aBnkiGau$opnejcgau%7 lq^he_]^opn]_pOepaI]lJk`a?khha_pekjCap?deh`Jk`ao$OepaI]lJk`ajk`a%7 lq^he_renpq]hOepaI]lJk`aCap?qnnajpJk`a=j`Dejp=j_aopknJk`ao$ejpqlHarah%7

Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

lq^he_renpq]hOepaI]lJk`aCap?qnnajpJk`a=j`DejpJaecd^kndkk`Jk`ao$ejpqlHarah(± ejp`ksjHarah%7 lq^he_]^opn]_pOepaI]lJk`aCapL]najpJk`a$OepaI]lJk`ajk`a%7 lq^he_renpq]hOepaI]lJk`a± CapL]najpJk`aNah]peraPk?qnnajpJk`a=j`Dejp@ksjBnkiL]najp$± ejps]hgqlHaraho(± ejpnah]pera@alpdBnkiS]hgql%7 lq^he_renpq]hOepaI]lJk`aCapL]najpJk`aNah]peraPkJk`a=j`Dejp@ksjBnkiL]najp$± OepaI]lJk`ajk`a(ejps]hgqlHaraho(ejpnah]pera@alpdBnkiS]hgql%7 lnkpa_pa`ejpanj]h]^opn]_pOepaI]lJk`aCapNkkpJk`a?kna$%7 lnkpa_pa`op]pe_OepaI]lJk`aCapNkkpJk`a?knaBnkiLnkre`an$± OepaI]lLnkre`anlnkre`an%7 lq^he_renpq]hrke`Dejp=j_aopknJk`ao$OepaI]lJk`ajk`a(ejpqlHarah%7 lq^he_renpq]hrke`DejpJaecd^kndkk`Jk`ao$OepaI]lJk`ajk`a(ejpqlHarah(± ejp`ksjHarah%7 lq^he_kranne`arke`Ejepe]heva$opnejcj]ia(J]iaR]hqa?khha_pekj]ppne^qpao%7 lq^he_renpq]h^kkhEo=__aooe^haPkQoan$Dppl?kjpatp_kjpatp(OepaI]lJk`ajk`a%7 lnkpa_pa`ejpanj]hrenpq]hrke`NaikraJk`a$OepaI]lJk`ajk`a%7 lnkpa_pa`OepaI]lJk`aNaokhraOepaI]lJk`a$Dppl?kjpatp_kjpatp%7 y Tables 8-1, 8-2, and 8-3 explain the methods, events, and properties, as we need to know what to implement and the intended behavior. The only unusual thing is the length of some method names, but these names clarify the methods usage. Because the provider is transparent, controls such as Iajq or PnaaReas using the abstract base class to get their data work with a custom implementation, too. First, the properties defined by the provider are shown in Table 8-1. Table 8-1. Properties Defined in SiteMapProvider

Property

Description

J]ia

The name of the provider as configured in web.config (inherited from Lnkre`an>]oa).

@ao_nelpekj

A friendly description (inherited from Lnkre`an>]oa).

?qnnajpJk`a

Reference to the current node (and therefore the related page).

Aj]^haHk_]hev]pekj

Indicates whether the provider supports localization using resources.

L]najpLnkre`an

The parent provider, if the provider supports a hierarchy of providers.

Naokqn_aGau

The root name of the resources used to localize content.

NkkpJk`a

The root node.

NkkpLnkre`an

The root provider, if a hierarchy of providers is used.

Oa_qnepuPneiiejcAj]^ha`

Indicates whether or not the provider supports security settings. If supported, the provider doesn’t return nodes that don’t match the security level.

Second, an event that the provider should support is shown in Table 8-2.

Download at WoweBook.Com

345

346

CH APT ER 8 N S ITE MA NA G EMENT

Table 8-2. Events Defined in SiteMapProvider

Event

Description

OepaI]lNaokhra

Event raised when data requested from data sources is ready. In the original implementation, this is the case when the ?qnnajpJk`a property is called.

Third, the methods that build most features are shown in Table 8-3. Table 8-3. Methods Defined in SiteMapProvider

Method

Description

=``Jk`a

Adds either the root node or another node

Bej`OepaI]lJk`a

Finds a node

Bej`OepaI]lJk`aBnkiGau

Finds a node using a key

Cap?deh`Jk`ao

Gets all child nodes of the specified node

Cap?qnnajpJk`a=j`Dejp=j_aopknJk`ao

Gets the current node and pre-loads the ancestors

Cap?qnnajpJk`a=j`DejpJaecd^kndkk`Jk`ao

Gets the current node and pre-loads the neighbors

CapL]najpJk`a

Gets the parent node

CapL]najpJk`aNah]peraPk?qnnajpJk`a=j`Dejp@ksjBnki) Gets the current node’s parent node and L]najp pre-loads all ancestors for the provided number of levels CapL]najpJk`aNah]peraPkJk`a=j`Dejp@ksjBnkiL]najp

Gets the given node’s parent and pre-loads all ancestors for the provided number of levels

CapNkkpJk`a?kna

Gets the parent regardless of the provider if a hierarchy of providers is used

CapNkkpJk`a?knaBnkiLnkre`an

Gets the parent of the specified provider if a hierarchy of providers is used

DejpJaecd^kndkk`Jk`ao

Pre-loads a number of levels down or up the hierarchy from the given node

Dejp=j_aopknJk`ao

Returns ancestor nodes for the given number of levels above the current node

Eo=__aooe^haPkQoan

Checks whether the given node is accessible to the user

Ejepe]heva

Initializes the provider (inherited from base class)

NaikraJk`a

Removes a node

NaokhraOepaI]lJk`a

Fires the OepaI]lNaokhra` event

Several methods include “Hint” in their name. Use these methods to handle data in huge hierarchies, as they allow you to deal with large amounts of data and they avoid holding the whole tree in memory. Consider implementations such as SharePoint, which could create deep hierarchies of site collections, sites, pages, and subpages that might have their own navigation systems. Using the “Hint” methods, you can define the depth that is populated from the tree. This limits the data handled by the provider to an amount that makes sense for the specific action taken by the user. It also assumes that nobody wants to see the whole hierarchy at once. Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

Sitemap Nodes in Code The provider transforms the data from the data source into a hierarchy of OepaI]lJk`a objects. The base class implements three interfaces, E?hkja]^ha, EDean]n_du@]p], and EJ]rec]paQE@]p]. This indicates the true nature of the object hierarchy, as well as how to deal with the nodes (see Table 8-4). Table 8-4. Members Defined in SiteMapNode

Member

Description

Cap=hhJk`ao

Gets a read-only list of all nodes beginning from the current node.

Cap@]p]Okqn_aReas

Gets the OepaI]l@]p]Okqn_aReas object that represents the underlying data source.

CapDean]n_de_]h@]p]Okqn_aReas

Gets the OepaI]lDean]n_de_]h@]p]Okqn_aReas object that represents the underlying hierarchical data source.

Eo=__aooe^haPkQoan

Determines whether the node is accessible according to current security context.

Eo@ao_aj`]jpKb

Determines whether the current node is a descendant of the given node.

CapAtlhe_epNaokqn_aOpnejc

Gets the localized string to retrieve the explicit resource definition. Accessible in derived classes only.

CapEilhe_epNaokqn_aOpnejc

Gets the localized string to retrieve the implicit resource definition.

?deh`Jk`ao

Gets all child nodes.

L]najpJk`a

Gets the parent node.

D]o?deh`Jk`ao

Indicates whether a node has children.

Epai

Gets the current node.

L]pd

Gets the path that describes the node.

Pula

Gets the node’s type.

@ao_nelpekj

Gets the node’s description.

J]ia

Gets the node’s name.

J]rec]paQnh

Gets the node’s URL.

R]hqa

Gets the node’s title.

=ppne^qpao

Additional attributes of the node as J]iaR]hqa?khha_pekj.

Gau

Key the node uses internally to get identified.

JatpOe^hejc

The next sibling node.

LnarekqoOe^hejc

The previous sibling node.

Na]`Kjhu

Indicates whether the node is read only.

Naokqn_aGau

The resource key used to localize the parameters.

Nkhao

The assigned roles that indicate who can access the nodes.

NkkpJk`a

The root node.

Pepha

The title of the node.

Qnh

The URL the node leads to.

Download at WoweBook.Com

347

348

CH APT ER 8 N S ITE MA NA G EMENT

Implementing Security The Oa_qnepuPneiiejcAj]^ha` property indicates if the nodes are limited for the current user. It can be set in web.config as shown next. The authorization settings added show role definitions that correspond to the roles attribute of the associated web.sitemap file. 8oepaI]l`ab]qhpLnkre`an9TihOepaI]lLnkre`anaj]^ha`9pnqa: 8lnkre`ano: 8]``j]ia9TihOepaI]lLnkre`an `ao_nelpekj9@ab]qhpOepaI]llnkre`an* pula9Ouopai*Sa^*TihOepaI]lLnkre`an oepaI]lBeha9Sa^*oepai]l oa_qnepuPneiiejcAj]^ha`9pnqa+: 8+lnkre`ano: 8+oepaI]l: 8hk_]pekjl]pd9z+]`iej*]olt: 8ouopai*sa^: 8]qpdknev]pekj: 8]hhksnkhao9=`iej+: 8`ajuqoano9&+: 8+]qpdknev]pekj: 8+ouopai*sa^: 8+hk_]pekj: The default implementation used in TihOepaI]lLnkre`an resolves the nkhao attributes defined in the oepaI]lJk`a elements in the web.sitemap file. If the current user is in the role, and the NkhaLnkre`an is activated, the TihOepaI]lLnkre`an limits visibility to the correct nodes. If used programmatically, the Eo=__aooe^haPkQoan property possessed by each OepaI]lJk`a instance indicates the same thing. The list of available roles is also available in the Nkhao property. A query can use either the EHeop type directly or “*” for all. The programmatic access uses a simple fallback strategy:

s )FTHEROLEWASFOUNDORTHEQUERYCONSISTSOFh v RETURNTHENODE



s )FTHEROLEWASNOTFOUND ATTEMPTTOAUTHENTICATETHE52,DEFINEDBYTHENODE



s )F7INDOWSAUTHENTICATIONISUSED ATTEMPTTOAUTHENTICATEAGAINUSINGTHECREDENTIALSOF the current user and the ACL (access control list) of the target file for the URL.

If everything fails, the provider does not return the node and assumes that the user does not have sufficient authority. Note that this is not an inheritance strategy. If a user has the right to read a specific node, it does not follow that he or she has the right to read any subsequent node. This allows different security settings for each level. However, if the right to access a specific node is denied, the strategy stops and all child nodes are blocked. This ensures that there are no isolated child nodes accessible from any places other than the sitemap hierarchy.

Implementing a SQL Server–Based Navigation SQL Server 2008 includes a new data type, Dean]n_duE`. This can be used to implement a custom database-driven Site Map provider.

Preparing the Database First, a database is required. In this example, I use the common aspnetdb.mdf database created for the role and membership provider, if default providers are used. Listing 8-1 defines an additional table named aspnet_Navigation.

Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

Listing 8-1. The Table Definition Using the HierarchyId Data Type ?NA=PAP=>HA]oljap[J]rec]pekj $ OepaI]lJk`a dean]n_due` Pephar]n_d]n$-,,% @ao_nelpekj r]n_d]n$.,,% Qnhr]n_d]n$.,,% Nkhaor]n_d]n$.,,% %

JKPJQHH( JKPJQHH( JQHH( JQHH( JQHH

Let’s proceed by filling in some data, as shown in Figure 8-1.

Figure 8-1. Table with some test values in Visual Studio Professional The Dean]n_duE` column contains the node definition as a path beginning with a slash. The internal format is binary and must be transformed using the PkOpnejc method SQL provides for this type. This is what Visual Studio does when presenting the table data in edit mode.

Creating the Provider Now that we have everything, we can create the custom provider. Listing 8-2 shows the final result. You can create it in the current Web project or in a separate project. Using it in a Web project will change the configuration slightly. The big advantage of building a custom Site Map provider in its own project is to be able to reuse it with other web applications. Listing 8-2. The SqlSiteMapProvider Using the HierarchyId Data Type qoejcOuopai7 qoejcOuopai*?khha_pekjo*Cajane_7 qoejcOuopai*?khha_pekjo*Ola_e]heva`7 qoejcOuopai*?kjbecqn]pekj*Lnkre`an7 qoejcOuopai*@]p]7 qoejcOuopai*@]p]*?kiikj7 qoejcOuopai*@]p]*Omh?heajp7 qoejcOuopai*Hejm7 qoejcOuopai*Oa_qnepu*Lanieooekjo7 qoejcOuopai*Sa^7 qoejcOuopai*Sa^*?kjbecqn]pekj7 j]iaol]_a=lnaoo*Atpajoe^ehepu*OmhOepaI]l w WOmh?heajpLanieooekj$Oa_qnepu=_pekj*@ai]j`(Qjnaopne_pa`9pnqa%Y lq^he__h]ooOmhOepaI]lLnkre`an6Op]pe_OepaI]lLnkre`an w lner]paopnejc[_kjja_p7 lner]paejp[ej`atJk`a7 lner]paejp[ej`atPepha7 Download at WoweBook.Com

349

350

CH APT ER 8 N S ITE MA NA G EMENT

lner]paejp[ej`atQnh7 lner]paejp[ej`at@ao_7 lner]paejp[ej`atNkhao7 lner]paejp[ej`atL]najp7 lner]paejp[ej`atNkkp7 lner]paOepaI]lJk`a[nkkp7 lner]pa@e_pekj]nu8opnejc(OepaI]lJk`a:[jk`ao9± jas@e_pekj]nu8opnejc(OepaI]lJk`a:$-2%7 lq^he_kranne`arke`Ejepe]heva$opnejcj]ia(J]iaR]hqa?khha_pekj_kjbec% w eb$_kjbec99jqhh% pdnksjas=ncqiajpJqhhAt_alpekj$_kjbec%7 eb$Opnejc*EoJqhhKnAilpu$j]ia%% j]ia9OmhOepaI]lLnkre`an7 ^]oa*Ejepe]heva$j]ia(_kjbec%7 opnejc_kjja_p9oepaI]l7 eb$Sa^?kjbecqn]pekjI]j]can*?kjja_pekjOpnejcoW_kjja_pY99jqhh% pdnksjasLnkre`anAt_alpekj$Jk_kjja_pekj%7 [_kjja_p9Sa^?kjbecqn]pekjI]j]can*?kjja_pekjOpnejcoW_kjja_pY*± ?kjja_pekjOpnejc7 eb$Opnejc*EoJqhhKnAilpu$[_kjja_p%% pdnksjasLnkre`anAt_alpekj$jk_kjja_pekjopnejc%7 y lq^he_kranne`aOepaI]lJk`a>qeh`OepaI]l$% w hk_g$pdeo% w eb$[nkkp9jqhh% napqnj[nkkp7 Omh?kjja_pekj_kjja_pekj9jasOmh?kjja_pekj$[_kjja_p%7 pnu w _kjja_pekj*Klaj$%7 Omh?kii]j`_kii]j`7 _kii]j`9jasOmh?kii]j`$ <OAHA?P&(OepaI]lJk`a*PkOpnejc$%=OOepaI]lJk`aOpnejc( OepaI]lJk`a*Cap=j_aopkn$-%*PkOpnejc$%=OL]najp( dean]n_due`66CapNkkp$%*PkOpnejc$%=ONkkp BNKI]oljap[J]rec]pekj(_kjja_pekj%7 _kii]j`*?kii]j`Pula9?kii]j`Pula*Patp7 Omh@]p]Na]`anna]`an9_kii]j`*Ata_qpaNa]`an$%7 [ej`atJk`a9na]`an*CapKn`ej]h$OepaI]lJk`aOpnejc%7 [ej`atQnh9na]`an*CapKn`ej]h$Qnh%7 [ej`atPepha9na]`an*CapKn`ej]h$Pepha%7 [ej`at@ao_9na]`an*CapKn`ej]h$@ao_nelpekj%7 [ej`atNkhao9na]`an*CapKn`ej]h$Nkhao%7 [ej`atL]najp9na]`an*CapKn`ej]h$L]najp%7 [ej`atNkkp9na]`an*CapKn`ej]h$Nkkp%7 opnejcl]najpGau7 eb$na]`an*Na]`$%% w [nkkp9?na]paOepaI]lJk`a$na]`an(pnqa(kqpl]najpGau%7 =``Jk`a$[nkkp(jqhh%7 sdeha$na]`an*Na]`$%% Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

w OepaI]lJk`ajk`a9?na]paOepaI]lJk`a$na]`an(b]hoa(± kqpl]najpGau%7 OepaI]lJk`al]najp9CapL]najpOepaI]lJk`a$l]najpGau%7 =``Jk`a$jk`a(l]najp%7 y y y bej]hhu w _kjja_pekj*?hkoa$%7 y napqnj[nkkp7 y y lnkpa_pa`kranne`aOepaI]lJk`aCapNkkpJk`a?kna$% w >qeh`OepaI]l$%7 napqnj[nkkp7 y lner]paOepaI]lJk`a?na]paOepaI]lJk`a$@^@]p]Na]`anna]`an(^kkhbknNkkp(± kqpopnejcl]najpGau% w opnejcjk`aOpnejc9na]`an*CapOpnejc$bknNkkp;[ej`atNkkp6[ej`atJk`a%7 opnejcpepha9na]`an*Eo@>Jqhh$[ej`atPepha%;jqhh6± na]`an*CapOpnejc$[ej`atPepha%*Pnei$%7 opnejcqnh9na]`an*Eo@>Jqhh$[ej`atQnh%;jqhh6± na]`an*CapOpnejc$[ej`atQnh%*Pnei$%7 opnejc`ao_nelpekj9na]`an*Eo@>Jqhh$[ej`at@ao_%;jqhh6± na]`an*CapOpnejc$[ej`at@ao_%*Pnei$%7 opnejcnkhao9na]`an*Eo@>Jqhh$[ej`atNkhao%;jqhh6± na]`an*CapOpnejc$[ej`atNkhao%*Pnei$%7 opnejcWYnkhaheop9jqhh7 eb$Opnejc*EoJqhhKnAilpu$nkhao%% nkhaheop9nkhao*Olhep$jas_d]nWYw#(#(#7#y(1-.%7 OepaI]lJk`ajk`a9jasOepaI]lJk`a$pdeo(jk`aOpnejc( qnh( pepha( `ao_nelpekj( nkhaheop(jqhh(jqhh(jqhh%7 l]najpGau9na]`an*Eo@>Jqhh$[ej`atL]najp%;jqhh6± na]`an*CapOpnejc$[ej`atL]najp%7 [jk`ao*=``$jk`aOpnejc(jk`a%7 napqnjjk`a7 y lner]paOepaI]lJk`aCapL]najpOepaI]lJk`a$opnejcl]najpGau% w r]nl]najp9bnkijej[jk`ao± sdanaj*Gau*Amq]ho$l]najpGau%± oaha_pj*R]hqa7 napqnjl]najp*BenopKn@ab]qhp8OepaI]lJk`a:$%7 y y y Download at WoweBook.Com

351

352

CH APT ER 8 N S ITE MA NA G EMENT

The implementation is intentionally brief. The Dean]n_duE` datatype makes it much easier to fetch a hierarchy. The heart is this SQL query, which retrieves all the needed data in one query: OAHA?P&(OepaI]lJk`a*PkOpnejc$%=OOepaI]lJk`aOpnejc( OepaI]lJk`a*Cap=j_aopkn$-%*PkOpnejc$%=OL]najp( dean]n_due`66CapNkkp$%*PkOpnejc$%=ONkkp BNKI]oljap[J]rec]pekj A great attribute of SQL Server is the ability to provide additional methods for data types. Here I use the Cap=j_aopkn and CapNkkp methods. Cap=j_aopkn$-% fetches the parent element, while CapNkkp$% obtains the hierarchy’s root. Bear in mind that some methods of these T-SQL functions are members, such as Cap=j_aopkn, while other methods are static, like CapNkkp. The double colon, “::” indicates access to static methods in SQL Server syntax. A @]p]Na]`an object provides fast forward-only access to the SQL query results, from which we assemble OepaI]lJk`a objects. The node type is provided so that the same method can be reused. The value is retrieved using na]`an*CapOpnejc$8ej`at:%. The index is the number of the column returned by the SQL query. The member fields’ [ej`atNkkp, [ej`atJk`a, or [ej`atL]najp contain the ordinal number for the column. In the SQL statement, the result is cast using PkOpnejc. This requires the CapOpnejc method when returning results. The =``Jk`a method from the Op]pe_OepaI]lLnkre`an base class is responsible for building the hierarchy. To obtain the necessary information, provide a parent for each node. In the example, I assume that the parent is already defined as a node. This requires the table data to be ordered so that parents appear before their children. The CapL]najpOepaI]lJk`a method is used to retrieve the parent from the private [jk`ao collection when building the map. This collection exists for that purpose and is no longer used when the nodes are retrieved from the sitemap controls. The l]najpGau used here is simply the value returned from SQL with the Cap=j_aopkn method, as mentioned before.

Configuring the Custom Provider The configuration consists of two parts. The first step is to define the connection string in order to access the data source. 8_kjja_pekjOpnejco: 8]``_kjja_pekjOpnejc9@]p]Okqn_a9*XOMHATLNAOO7Ejepe]h± ?]p]hkc9]oljap`^7Ejpacn]pa`Oa_qnepu9Pnqa± j]ia9oepaI]l+: 8+_kjja_pekjOpnejco: The provider itself needs the basic format, as shown before: 8ouopai*sa^: 8oepaI]laj]^ha`9pnqa`ab]qhpLnkre`an9IuOmhOepaI]lLnkre`an: 8lnkre`ano: 8]``j]ia9IuOmhOepaI]lLnkre`an pula9=lnaoo*Atpajoe^ehepu*OmhOepaI]l*OmhOepaI]lLnkre`an `ao_nelpekj9IuOmhOepaI]lLnkre`an oa_qnepuPneiiejcAj]^ha`9b]hoa _kjja_pekjOpnejcJ]ia9oepaI]l +: 8+lnkre`ano: 8+oepaI]l: 8+ouopai*sa^:

Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

Finally, the data source used on the web pages needs to point to the provider. If you have several providers, each data source can use its own provider. 8]ol6OepaI]l@]p]Okqn_aE@9OepaI]l@]p]Okqn_a-nqj]p9oanran± OepaI]lLnkre`an9IuOmhOepaI]lLnkre`an+: Although there are no changes to the various controls using this data source, some features, such as security trimming, are not yet implemented. However, you’ve learned how to extend the default provider model regarding site maps, and how to benefit from the new features SQL Server 2008 provides.

Testing the Provider To test the provider, write a simple page that contains at least a Iajq and a OepaI]lL]pd control bound to the modified OepaI]l@]p]Okqn_a control. A page such as this one will suffice: 8bknie`9bkni-nqj]p9oanran: 8`er: 8]ol6OepaI]lL]pdE@9OepaI]lL]pd-nqj]p9oanran OepaI]lLnkre`an9IuOmhOepaI]lLnkre`an: 8+]ol6OepaI]lL]pd: 8^n+: 8^n+: Iajq68^n+: 8]ol6IajqE@9Iajq-nqj]p9oanran± Op]pe_@eolh]uHaraho9-@]p]Okqn_aE@9OepaI]l@]p]Okqn_a-: 8+]ol6Iajq: 8^n+: 8^n+: 8+`er: 8]ol6OepaI]l@]p]Okqn_aE@9OepaI]l@]p]Okqn_a-nqj]p9oanran OepaI]lLnkre`an9IuOmhOepaI]lLnkre`an+: 8+bkni: The data source is only required for the Iajq control. Breadcrumbs are displayed using a OepaI]lL]pd control, which can connect directly to the custom provider using its name. Figure 8-2 shows the output.

Figure 8-2. Menu and SiteMapPath controls with data from SQL Server Remember that you need to add the page names to the table data. Otherwise, you’ll encounter page load errors when you choose the menu items.

Download at WoweBook.Com

353

354

CH APT ER 8 N S ITE MA NA G EMENT

Suggestions for Extending the Example The example is as simple as possible, containing nothing more than the code required to get it working. It lacks error checking and proper exception handling. Consider making the following changes before using the code in a production environment:

s !LLOWDUPLICATENODES



s $ISPOSEOFTHEDICTIONARYTHATSTORESTHEPARENTS



s /RDERTHE31,QUERYTOACCEPTUNORDEREDNODEDEFINITIONS



s !DDAPRIMARYKEYTOTHETABLEINORDERTOIMPROVESPEEDFORLARGENODESETS There are further ways of extending the behavior.

Extending the VirtualPathProvider Complex sites with hundreds of pages are difficult to maintain. For some sections, a file structure with static data seems to be more productive, whereas other sections are composed dynamically from databases. This difference should be indiscernible to regular users and search engines alike. Search engines follow each link on a page and find the navigation paths through a site, indexing the content of each page on the way. Users bookmark pages and return directly to them later. However, neither of these behaviors are what developers are looking for in creating pages. The Renpq]hL]pdLnkre`an is designed to separate the internal and external structures. Like any other provider, it works transparently, using a pluggable approach. The difference is that the virtual path provider does not access a database and internally is different from all providers described so far. However, to implement a virtual path provider, you’ll have to inherit and implement an abstract base class—Renpq]hL]pdLnkre`an.

Using the VirtualPathProvider In Chapters 4 to 7, I started with a brief overview of the default provider before looking at a custom implementation. Here it’s a bit different. There is no default provider, which means that each page is handled at its physical location and dynamically-generated content appears as is, within the one and only page possessing that functionality. Implementing a virtual path provider is all about changing the default behavior of the path resolution for any regular Web site. Some examples of what it can accomplish might help you decide if it’s worth the effort:

s 3TORINGALLCONTENTINADATABASE



s )NTERCEPTINGTHEPARSINGOFPAGESINSCENARIOSWHEREPAGESCOMEFROMDIFFERENTSOURCES



s #USTOMIZINGTHEPATHRESOLUTIONFORTHEROOTOFTHEAPPLICATIONUSINGh^v



s -ODIFYINGTHECOMPILATIONPROCESS

The parsing aspect especially is not one that you’ll be using on a daily basis. You might have heard about large ASP.NET-based projects such as SharePoint. SharePoint is an application providing a content management system, among several other features. Users can create content and add active parts—called webparts—to these pages. The content is stored in a database and pages are built dynamically. ASP.NET does not support this out-of-the-box, as the compiler would not be able to locate any pages to compile. A powerful virtual path provider is used to resolve pages found in the database, mix them with those still stored as files, and create a final structure.

Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

While SharePoint is a technically admirable example of a virtual path provider, in our example we’ll consider a more modest scenario. Given a Web site with a “MySite” section, let’s expose it with a structure like this: Oepa IuOepaFkanc ?kjpnkho IuOepaFkdj ?kjpnkho IuOepaG]pdnuj ?kjpnkho Users will think that they have a private site. They can upload and modify pages there, and you could even allow them to store files. However, if users follow convention and use paths such as ~/controls/mycontrol.ascx to link their web pages to user controls, it will fail. Consider this example: 8!<NaceopanOn_9z+?kjpnkho+iu*]o_tP]cJ]ia9iuP]cLnabet9fkdj!: User John is allowed to upload active content to his private space under the path MySiteJohn. He assumes—wrongly—that this is the root for his private space. John expects it to resolve to /MySiteJohn/Controls/my.ascx. It actually resolves to /Site/Controls/my.ascx. Of course, this causes a compilation exception.

Register the VirtualPathProvider In the previous description, I noted that the virtual path provider is unlike other providers. In fact, “provider” is probably not the best word to describe it, as it’s different from other providers in the way it works, the way it accesses the data, and the way it’s configured. To correctly resolve paths, even during compilation, the provider must be initialized earlier in the ASP.NET framework. Thus, the web.config file is not the correct place for defining it. Instead, it has to be defined using a special static method, =llEjepe]heva, or in the global.asax file.

THE NATURE OF APPINITIALIZE You can use any class in either the code path of your Web site or in the App_Code folder of your web application project to define a public, static method called =llEjepe]heva: lq^he__h]ooOkiaEjep?h]oo w lq^he_op]pe_rke`=llEjepe]heva$% w ++=_pekjnamqena`pkejepe]hevapda]llhe_]pekj y y The method is called during the initialization cycle of the application. This is exactly the same as if you’d put the code in the Application_Start event handler defined in global.asax. There is little information available about why two ways exist to achieve the same thing. Perhaps it’s because some applications lack a global.asax file, and creating and maintaining one for a single event would be overkill or—if a non-HTTP environment is used—not an option at all. In this case, the =llEjepe]heva method is a better option, as it moves the code portion to one location. You can use any class to define this method—even the one we created here to define a Renpq]hL]pdLnkre`an. This puts the two parts—configuration and definition—tightly together.

Download at WoweBook.Com

355

356

CH APT ER 8 N S ITE MA NA G EMENT

With either method of registering the provider, the following code is required: j]iaol]_a=lnaoo*Atpajoe^ehepu*L]pdLnkre`an w lq^he_op]pe__h]oo=llOp]np w lq^he_op]pe_rke`=llEjepe]heva$% w PdaiaoL]pdLnkre`an_qopkiLnkre`an9jasPdaiaoL]pdLnkre`an$%7 DkopejcAjrenkjiajp*NaceopanRenpq]hL]pdLnkre`an$_qopkiLnkre`an%7 y y y This code assumes that the custom provider is named PdaiaoL]pdLnkre`an, as shown in the following example. The code also uses other types, and those that are useful regarding virtual path providers are explained.

Prerequisites for a VirtualPathProvider A custom Renpq]hL]pdLnkre`an requires specific permissions, according to MSDN. If you look into the code using Reflector, you’ll find the following: W=olJapDkopejcLanieooekj$Oa_qnepu=_pekj*@ai]j`(± Harah9=olJapDkopejcLanieooekjHarah*Decd%Y lq^he_op]pe_rke`NaceopanRenpq]hL]pdLnkre`an$± Renpq]hL]pdLnkre`anrenpq]hL]pdLnkre`an% w eb$[pdaDkopejcAjrenkjiajp99jqhh% w pdnksjasEjr]he`Klan]pekjAt_alpekj$%7 y eb$>qeh`I]j]can*EoLna_kileha`=ll% w NaceopanRenpq]hL]pdLnkre`anEjpanj]h$renpq]hL]pdLnkre`an%7 y y The =olJapDkopejcLanieooekj attribute means that you’ll need to run in full trust in order to register a provider. If you don’t have permission, a Oa_qnepuAt_alpekj is thrown. This is the same reason for the check regarding pre-compilation. Both tests ensure that a Renpq]hL]pdLnkre`an cannot be used without permissions or within a running environment. The third check searches for an existing hosting environment. Without this, a path provider cannot function. While the missing hosting environment throws an exception, the pre-compilation check allows the method to fail silently. To understand why, let’s examine the Ejepe]heva method in NaceopanRenpq]hL]pdLnkre`anEjpanj]h. It’s not the public method, but the internal one that looks like this: ejpanj]hrenpq]hrke`Ejepe]heva$Renpq]hL]pdLnkre`anlnarekqo% w pdeo*[lnarekqo9lnarekqo7 pdeo*Ejepe]heva$%7 y If a Renpq]hL]pdLnkre`an supports a fallback scenario, this setting ensures that the “fallback provider” is available. The overridden Ejepe]heva method that you may have changed is called after this.

Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

Helpful Classes for Path and File Operations DkopejcAjrenkjiajp is a class defined in Ouopai*Sa^*Dkopejc that defines the very basic types used to support the ASP.NET hosting environment. The same namespace contains the Renpq]hL]pdLnkre`an base class. The DkopejcAjrenkjiajp class contains several static methods. Some are useful when dealing with paths and path resolving issues.

The HostingEnvironment Class Let’s take a look at the path handling capabilities provided by ASP.NET before we start writing a path provider. Table 8-5 shows a selection of methods in the class, which explicitly support path operations. Table 8-5. Members of the HostingEnvironment Class Pertaining to Path Operations

Method or Property

Description

I]lL]pd

Maps a virtual path to its physical counterpart on the server

NaceopanRenpq]hL]pdLnkre`an

Registers a virtual path provider

=llhe_]pekjLduoe_]hL]pd

Gets the physical path of the application

=llhe_]pekjRenpq]hL]pd

Gets the virtual path of the application

Renpq]hL]pdLnkre`an

Gets the currently registered path provider

OepaJ]ia

The name of the site

All properties and methods mentioned here are static and don’t require an instance of the class. The other methods and properties concern application domains, object registering, caching, and impersonation. However, that’s beyond the scope of this chapter. If you’d like to learn more, take a look at the following MSDN page: dppl6++io`j*ie_nkokbp*_ki+aj)qo+he^n]nu+ouopai*sa^*dkopejc*dkopejcajrenkjiajp*]olt

VirtualFile and VirtualDirectory Renpq]hBeha allows direct access to virtual files and reads the file contents as a stream: lq^he_]^opn]_p_h]ooRenpq]hBeha6Renpq]hBeha>]oa w lnkpa_pa`Renpq]hBeha$opnejcrenpq]hL]pd%7 lq^he_kranne`a^kkhEo@ena_pknuwcap7y lq^he_]^opn]_pOpna]iKlaj$%7 y Eo@ena_pknu always returns b]hoa. The Klaj method must be overridden and return a read-only stream to the virtual resource. The Renpq]h@ena_pknu class is similar and manages a directory: lq^he_]^opn]_p_h]ooRenpq]h@ena_pknu6Renpq]hBeha>]oa w lnkpa_pa`Renpq]h@ena_pknu$opnejcrenpq]hL]pd%7 lq^he_]^opn]_pEAjqian]^ha?deh`najwcap7y lq^he_]^opn]_pEAjqian]^ha@ena_pkneaowcap7y lq^he_]^opn]_pEAjqian]^haBehaowcap7y lq^he_kranne`a^kkhEo@ena_pknuwcap7y y Download at WoweBook.Com

357

358

CH APT ER 8 N S ITE MA NA G EMENT

@ena_pkneao lists the subdirectories in this virtual directory. Behao returns the files only. ?deh`naj returns both the files and the folders. Eo@ena_pknu always returns pnqa.

VirtualPathUtility This class is defined in the Ouopai*Sa^ namespace and provides further useful methods (see Table 8-6). Table 8-6. Members of the VirtualPathUtility Class

Method or Property

Description

=llaj`Pn]ehejcOh]od

Adds a slash at the end of the path if there isn’t one

?ki^eja

Concatenates a base path and a relative path

Cap@ena_pknu

Gets the directory path of a virtual path

CapAtpajoekj

Gets the extension of a file with a virtual path

CapBehaJ]ia

Gets the file name of a file with a virtual path

Eo=^okhqpa

Indicates whether a path is absolute

Eo=llNah]pera

Indicates whether a virtual path is relative against the application

I]gaNah]pera

4RANSFORMSANAPPLICATIONRELATIVEPATHWITHSTEMOPERATORh^vINTO a relative virtual path

NaikraPn]ehejcOh]od

Removes a trailing slash from the end; does nothing if there is no slash present

Pk=^okhqpa

Converts a virtual path into an absolute one

Pk=llNah]pera

Converts an absolute path into a relative one

All of these methods are static, and thus don’t require an instance of the class to be created.

Creating a Virtual Path Provider to Get Themes from Database Now that we have all the prerequisites, let’s write a provider. In this example, I want to change the behavior of the =ll[Pdaiao folder. A theme is usually a static conglomeration of skins, style sheet files, and images. You can specify a theme either in web.config or within each web page. Let’s define individual themes in another folder and relate them to pages. This is possible using a custom Renpq]hL]pdLnkre`an. Its path is defined in web.config, and you can either set it dynamically or manipulate it. The provider shown in this section gives you the basic framework for handling file access and file resolving.

Prepare the Project The themes are still in a folder in your project. The database only defines a reference to the theme’s name. To avoid confusing Visual Studio with a regular theme, all themes are kept in a different folder named Path_Themes. You can use any valid name except for =ll[Pdaiao, which is reserved.

Create the VirtualPathProvider The path provider should function as a transparent layer for ASP.NET. Implementing it completely requires more steps than other providers. For the sake of brevity, I’ve created a simplified but functional path provider that consists of three classes:

Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T



s Renpq]hPdaiaBeha



s Renpq]hPdaia@ena_pknu



s PdaiaL]pdLnkre`an

This provider lacks caching, which causes it to work slowly, but it’s fully functional. However, the cache implementation is not particularly difficult and can be added easily. I’ve excluded it, as it’s out of this section’s scope. The Renpq]hPdaiaBeha class holds a reference to a specific file from the Path_Themes folder. This is usually a skin file, a style sheet, or a resource (such as an image) used with a theme. The file’s complete location is stored in the =^okhqpaL]pd property and used in the Klaj method. (The Klaj method is called to read the file’s contents.) The L]najp property points to the containing directory (see Listing 8-3). Listing 8-3. Handling Virtual Files lq^he__h]ooRenpq]hPdaiaBeha6Ouopai*Sa^*Dkopejc*Renpq]hBeha w lner]paopnejc[pdaia=^okhqpaL]pd9Opnejc*Ailpu7 lner]paopnejc[chk^]h=^okhqpaL]pd9Opnejc*Ailpu7 lner]paRenpq]hPdaia@ena_pknu[l]najp9jqhh7 lq^he_Renpq]hPdaiaBeha$Opnejcrenpq]hL]pd( opnejcpdaia=^okhqpaL]pd( opnejcchk^]h=^okhqpaL]pd( Renpq]hPdaia@ena_pknul]najp% 6^]oa$renpq]hL]pd% w [pdaia=^okhqpaL]pd9pdaia=^okhqpaL]pd7 [chk^]h=^okhqpaL]pd9chk^]h=^okhqpaL]pd7 [l]najp9l]najp7 y lq^he_kranne`aOpna]iKlaj$% w napqnjBeha*Klaj$=^okhqpaL]pd(BehaIk`a*Klaj%7 y lq^he_Renpq]hPdaia@ena_pknuL]najp w cap w napqnj[l]najp7 y y lner]paOpnejc=^okhqpaL]pd w cap w ++Cappda_qnnajpoapr]hqa Opnejc_qnnajpOap9PdaiaL]pdLnkre`an*?qnnajp*?qnnajpOap7 eb$$Opnejc*EoJqhhKnAilpu$[pdaia=^okhqpaL]pd%% ""$L]najp*BehaEoEj_hq`a`$J]ia(_qnnajpOap(pnqa%%% napqnj[pdaia=^okhqpaL]pd7 Download at WoweBook.Com

359

360

CH APT ER 8 N S ITE MA NA G EMENT

ahoaeb$$Opnejc*EoJqhhKnAilpu$[chk^]h=^okhqpaL]pd%% ""$L]najp*BehaEoEj_hq`a`$J]ia(_qnnajpOap(b]hoa%%% napqnj[chk^]h=^okhqpaL]pd7 napqnjOpnejc*Ailpu7 y y ejpanj]h>kkha]jAteopoEjPdaia@ena_pknu w cap w napqnj$Opnejc*EoJqhhKnAilpu$[pdaia=^okhqpaL]pd%%7 y y ejpanj]h>kkha]jAteopoEjChk^]h@ena_pknu w cap w napqnj$Opnejc*EoJqhhKnAilpu$[chk^]h=^okhqpaL]pd%%7 y y y The main focus of the implementation is the directory handling. Hence, the Renpq]hPdaia@ena_pknu class contains much more code (see Listing 8-4). Listing 8-4. Handling Virtual Directories lq^he__h]ooRenpq]hPdaia@ena_pknu6Renpq]h@ena_pknu w opnq_pEpaiOa]n_dEjbk w lq^he_OpnejcJ]ia7 lq^he_OpnejcRenpq]hL]pd7 lq^he_OpnejcPdaia=^okhqpaL]pd7 lq^he_OpnejcChk^]h=^okhqpaL]pd7 y lner]paRenpq]hPdaia@ena_pknu[l]najp9jqhh7 lner]paOpnejc[pdaia=^okhqpaL]pd9Opnejc*Ailpu7 lner]paOpnejc[chk^]h=^okhqpaL]pd9Opnejc*Ailpu7 lner]pa@e_pekj]nu8Opnejc(Renpq]hPdaia@ena_pknu:[`ena_pkneao9jqhh7 lner]pa@e_pekj]nu8Opnejc(Renpq]hPdaiaBeha:[behao9jqhh7 lner]pa@e_pekj]nu8Opnejc(Renpq]hBeha>]oa:[_deh`naj9jqhh7 lq^he_Renpq]hPdaia@ena_pknu$Opnejcrenpq]hL]pd% 6pdeo$renpq]hL]pd(Opnejc*Ailpu(Opnejc*Ailpu(jqhh% w y lq^he_Renpq]hPdaia@ena_pknu$Opnejcrenpq]hL]pd( Opnejcpdaia=^okhqpaL]pd( Opnejcchk^]h=^okhqpaL]pd% 6pdeo$renpq]hL]pd(pdaia=^okhqpaL]pd(chk^]h=^okhqpaL]pd(jqhh% w Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

y lq^he_Renpq]hPdaia@ena_pknu$Opnejcrenpq]hL]pd( Opnejcpdaia=^okhqpaL]pd( Opnejcchk^]h=^okhqpaL]pd( Renpq]hPdaia@ena_pknul]najp% 6^]oa$renpq]hL]pd% w eb$Opnejc*EoJqhhKnAilpu$pdaia=^okhqpaL]pd%% w OpnejcoPdaiaNah]peraL]pd9± PdaiaL]pdLnkre`an*?qnnajp*?kjranpPkPdaiaNah]peraL]pd$renpq]hL]pd%7 pdaia=^okhqpaL]pd9± Dppl?kjpatp*?qnnajp*Oanran*I]lL]pd$oPdaiaNah]peraL]pd%7 y eb$@ena_pknu*Ateopo$pdaia=^okhqpaL]pd%% w pdaia=^okhqpaL]pd9Opnejc*Ailpu7 y eb$Opnejc*EoJqhhKnAilpu$chk^]h=^okhqpaL]pd%% w OpnejcoChk^]hNah]peraL]pd9± PdaiaL]pdLnkre`an*?qnnajp*?kjranpPkChk^]hNah]peraL]pd$Renpq]hL]pd%7 chk^]h=^okhqpaL]pd9± Dppl?kjpatp*?qnnajp*Oanran*I]lL]pd$oChk^]hNah]peraL]pd%7 y eb$@ena_pknu*Ateopo$chk^]h=^okhqpaL]pd%% chk^]h=^okhqpaL]pd9Opnejc*Ailpu7 [pdaia=^okhqpaL]pd9pdaia=^okhqpaL]pd7 [chk^]h=^okhqpaL]pd9chk^]h=^okhqpaL]pd7 [l]najp9l]najp7 ++?na]papda_khha_pekjopkdkh`pdarenpq]hepaio [behao9jas@e_pekj]nu8opnejc(Renpq]hPdaiaBeha:$%7 [`ena_pkneao9jas@e_pekj]nu8opnejc(Renpq]hPdaia@ena_pknu:$%7 [_deh`naj9jas@e_pekj]nu8opnejc(Renpq]hBeha>]oa:$%7 Bej`Behao$%7 Bej`Oq^@ena_pkneao$%7 Bej`?deh`naj$%7 y lner]parke`Bej`Behao$% w @e_pekj]nu8Opnejc(EpaiOa]n_dEjbk:behaHeop9± jas@e_pekj]nu8opnejc(EpaiOa]n_dEjbk:$%7 eb$@ena_pknu*Ateopo$Pdaia=^okhqpaL]pd%% w r]nbehao9bnkibej@ena_pknu*CapBehao$Pdaia=^okhqpaL]pd% oaha_pjasEpaiOa]n_dEjbk w J]ia9L]pd*CapBehaJ]ia$b%( Renpq]hL]pd9Renpq]hL]pdQpehepu*?ki^eja$Renpq]hL]pd(± Download at WoweBook.Com

361

362

CH APT ER 8 N S ITE MA NA G EMENT

L]pd*CapBehaJ]ia$b%%( Pdaia=^okhqpaL]pd9b y7 bkna]_d$EpaiOa]n_dEjbkbehaEjbkejbehao% w behaHeop*=``$behaEjbk*J]ia(behaEjbk%7 y y eb$@ena_pknu*Ateopo$Chk^]h=^okhqpaL]pd%% w r]nbehao9bnkibej@ena_pknu*CapBehao$Chk^]h=^okhqpaL]pd% oaha_pjasEpaiOa]n_dEjbk w J]ia9L]pd*CapBehaJ]ia$b%( Renpq]hL]pd9Renpq]hL]pdQpehepu*?ki^eja$Renpq]hL]pd(± L]pd*CapBehaJ]ia$b%%( Chk^]h=^okhqpaL]pd9b y7 bkna]_d$EpaiOa]n_dEjbkbehaEjbkejbehao% w eb$behaHeop*?kjp]ejoGau$behaEjbk*J]ia%% w EpaiOa]n_dEjbkpdaiaBehaEjbk9behaHeopWbehaEjbk*J]iaY7 behaHeop*Naikra$pdaiaBehaEjbk*J]ia%7 behaHeop*=``$pdaiaBehaEjbk*J]ia(pdaiaBehaEjbk%7 y ahoa w behaHeop*=``$behaEjbk*J]ia(behaEjbk%7 y y y ++Hkklpdnkqcda]_dbehabkqj` bkna]_d$EpaiOa]n_dEjbkbehaEjbkejbehaHeop*R]hqao% w ++=``a]_dbehapkpdabehao`e_pekj]nuqoejcpda ++ejbkni]pekjopkna`bknpdabeha [behao*=``$behaEjbk*J]ia(jasRenpq]hPdaiaBeha$behaEjbk*Renpq]hL]pd(± behaEjbk*Pdaia=^okhqpaL]pd(± behaEjbk*Chk^]h=^okhqpaL]pd(± pdeo%%7 y y lner]parke`Bej`Oq^@ena_pkneao$% w @e_pekj]nu8Opnejc(EpaiOa]n_dEjbk:`ena_pknuHeop9± jas@e_pekj]nu8opnejc(EpaiOa]n_dEjbk:$%7 Bqj_8opnejc(opnejc(opnejc:I]gaL]pd9`ahac]pa$opnejc^(opnejcr% w napqnjRenpq]hL]pdQpehepu*=llaj`Pn]ehejcOh]od$± Renpq]hL]pdQpehepu*?ki^eja$^(r%%7 y7 eb$@ena_pknu*Ateopo$Pdaia=^okhqpaL]pd%% Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

w r]npdaia@ena_pkneao9± bnkipej@ena_pknu*Cap@ena_pkneao$Pdaia=^okhqpaL]pd% oaha_pjasEpaiOa]n_dEjbk w J]ia9L]pd*CapBehaJ]ia$p%( Renpq]hL]pd9I]gaL]pd$Renpq]hL]pd(± L]pd*CapBehaJ]ia$p%%( Pdaia=^okhqpaL]pd9p y7 bkna]_d$EpaiOa]n_dEjbk`ena_pknuEjbkejpdaia@ena_pkneao% w `ena_pknuHeop*=``$`ena_pknuEjbk*J]ia(`ena_pknuEjbk%7 y y eb$@ena_pknu*Ateopo$Chk^]h=^okhqpaL]pd%% w r]npdaia@ena_pkneao9± bnkipej@ena_pknu*Cap@ena_pkneao$Chk^]h=^okhqpaL]pd% oaha_pjasEpaiOa]n_dEjbk w J]ia9L]pd*CapBehaJ]ia$p%( Renpq]hL]pd9I]gaL]pd$Renpq]hL]pd(± L]pd*CapBehaJ]ia$p%%( Chk^]h=^okhqpaL]pd9p y7 bkna]_d$EpaiOa]n_dEjbk`ena_pknuEjbkejpdaia@ena_pkneao% w eb$`ena_pknuHeop*?kjp]ejoGau$`ena_pknuEjbk*J]ia%% w EpaiOa]n_dEjbkpdaia@ena_pknuEjbk9± `ena_pknuHeopW`ena_pknuEjbk*J]iaY7 `ena_pknuHeop*Naikra$pdaia@ena_pknuEjbk*J]ia%7 `ena_pknuHeop*=``$pdaia@ena_pknuEjbk*J]ia(pdaia@ena_pknuEjbk%7 y ahoa w `ena_pknuHeop*=``$`ena_pknuEjbk*J]ia(`ena_pknuEjbk%7 y y y bkna]_d$EpaiOa]n_dEjbk`ena_pknuEjbkej`ena_pknuHeop*R]hqao% w Renpq]hPdaia@ena_pknu`ena_pknu9jasRenpq]hPdaia@ena_pknu$± `ena_pknuEjbk*Renpq]hL]pd(± `ena_pknuEjbk*Pdaia=^okhqpaL]pd(± `ena_pknuEjbk*Chk^]h=^okhqpaL]pd(± pdeo%7 [`ena_pkneao*=``$`ena_pknu*J]ia(`ena_pknu%7 y y lner]parke`Bej`?deh`naj$% w bkna]_d$Renpq]hPdaia@ena_pknu`ena_pknuej@ena_pkneao% Download at WoweBook.Com

363

364

CH APT ER 8 N S ITE MA NA G EMENT

w [_deh`naj*=``$`ena_pknu*J]ia(`ena_pknu%7 y bkna]_d$Renpq]hPdaiaBehabehaejBehao% w [_deh`naj*=``$beha*J]ia(beha%7 y y lq^he_>kkha]jCapBehaEoEj_hq`a`$OpnejcbehaJ]ia% w Opnejc_qnnajpOap9PdaiaL]pdLnkre`an*?qnnajp*?qnnajpOap7 eb$BehaEoEj_hq`a`$behaJ]ia(_qnnajpOap(pnqa%% w napqnjpnqa7 y ahoa w napqnjBehaEoEj_hq`a`$behaJ]ia(_qnnajpOap(b]hoa%7 y y lq^he_>kkha]jCap@ena_pknuEoEj_hq`a`$Opnejc`ena_pknuJ]ia% w Opnejc_qnnajpOap9PdaiaL]pdLnkre`an*?qnnajp*?qnnajpOap7 eb$@ena_pknuEoEj_hq`a`$`ena_pknuJ]ia(_qnnajpOap(pnqa%% w napqnjpnqa7 y ahoa w napqnj@ena_pknuEoEj_hq`a`$`ena_pknuJ]ia(_qnnajpOap(b]hoa%7 y y ejpanj]h>kkha]jBehaEoEj_hq`a`$opnejcbehaJ]ia(opnejc_qnnajpOap(± ^kkh_da_g=c]ejopPdaia% w eb$[behao*?kjp]ejoGau$behaJ]ia%% napqnjb]hoa7 Renpq]hPdaiaBehabeha9[behaoWbehaJ]iaY7 eb$$_da_g=c]ejopPdaia% ""$beha*AteopoEjPdaia@ena_pknu% w napqnjb]hoa7 y ahoaeb$$_da_g=c]ejopPdaia% ""$beha*AteopoEjChk^]h@ena_pknu%% w napqnjb]hoa7 y eb$Opnejc*EoJqhhKnAilpu$_qnnajpOap%% napqnjpnqa7 OpnejcbehaAtpajoekj9L]pd*CapAtpajoekj$behaJ]ia%7 eb$behaAtpajoekj*PkQllan$%99*OGEJ xx behaAtpajoekj*PkQllan$%99*?OO Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

xx behaAtpajoekj*PkQllan$%99*FLC% w napqnjpnqa7 y napqnjb]hoa7 y ejpanj]h>kkha]j@ena_pknuEoEj_hq`a`$opnejc`ena_pknuJ]ia(± opnejc_qnnajpOap(± ^kkh_da_g=c]ejopPdaia% w eb$[`ena_pkneao*?kjp]ejoGau$`ena_pknuJ]ia%% napqnjb]hoa7 Renpq]hPdaia@ena_pknu`ena_pknu9[`ena_pkneaoW`ena_pknuJ]iaY7 eb$_da_g=c]ejopPdaia ""`ena_pknu*AteopoEjPdaia@ena_pknu% w napqnjb]hoa7 y ahoaeb$_da_g=c]ejopPdaia ""`ena_pknu*AteopoEjChk^]h@ena_pknu% w napqnjb]hoa7 y napqnjpnqa7 y ejpanj]hRenpq]hPdaiaBehaCapBeha$OpnejcbehaJ]ia% w napqnj[behaoWbehaJ]iaY7 y ejpanj]hRenpq]hPdaia@ena_pknuCap@ena_pknu$Opnejcrenpq]h@en% w eb$[`ena_pkneao*?kqjp99,% napqnjjqhh7 eb$renpq]h@en*Op]npoSepd$Renpq]hL]pd(± Opnejc?kil]neokj*Ejr]ne]jp?qhpqnaEcjkna?]oa%% napqnjjqhh7 Opnejcnah]peraRenpq]hL]pd9renpq]h@en*Oq^opnejc$Renpq]hL]pd*Hajcpd%7 Opnejc`ena_pknuJ]ia9nah]peraRenpq]hL]pd*Oq^opnejc$,(± nah]peraRenpq]hL]pd*Ej`atKb$+%%7 Renpq]hPdaia@ena_pknu_deh`@ena_pknu9[`ena_pkneaoW`ena_pknuJ]iaY7 eb$_deh`@ena_pknu*Renpq]hL]pd99renpq]h@en% napqnj_deh`@ena_pknu7 ahoa napqnj_deh`@ena_pknu*Cap@ena_pknu$renpq]h@en%7 y lq^he_Renpq]hPdaia@ena_pknuL]najp w cap w napqnj[l]najp7 y y Download at WoweBook.Com

365

366

CH APT ER 8 N S ITE MA NA G EMENT

lq^he_>kkha]jAteopo w cap w napqnj$$@ena_pknu*Ateopo$[pdaia=^okhqpaL]pd%% xx$@ena_pknu*Ateopo$[chk^]h=^okhqpaL]pd%%%7 y y lner]pa>kkha]jAteopoEjPdaia@ena_pknu w cap w napqnj$Opnejc*EoJqhhKnAilpu$[pdaia=^okhqpaL]pd%%7 y y lner]pa>kkha]jAteopoEjChk^]h@ena_pknu w cap w napqnj$Opnejc*EoJqhhKnAilpu$[chk^]h=^okhqpaL]pd%%7 y y lq^he_kranne`aEAjqian]^ha@ena_pkneao w cap w napqnj[`ena_pkneao*R]hqao7 y y lq^he_kranne`aEAjqian]^haBehao w cap w napqnj[behao*R]hqao7 y y lq^he_kranne`aEAjqian]^ha?deh`naj w cap w napqnj[_deh`naj*R]hqao7 y y lner]paOpnejcPdaia=^okhqpaL]pd w cap w napqnj[pdaia=^okhqpaL]pd7 y y Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

lner]paOpnejcChk^]h=^okhqpaL]pd w cap w napqnj[chk^]h=^okhqpaL]pd7 y y y The main purpose of this class is to build a copy of the directory and file structure found in the physical theme folder (Path_Themes) and to store references to the files. When the provider retrieves the files, it accesses this virtual structure. Three internal methods are called in the constructor: Bej`Behao, Bej`Oq^@ena_pkneao, and Bej`?deh`naj. The Bej`behao method reads files in the current base folder. Bej`Oq^@ena_pkneao loads directories recursively. In each directory located, the Bej`Behao method is called to load the files for that folder. The Bej`?deh`naj method creates a single combined list of both directories and files. The provider calls the Cap@ena_pknu method to retrieve a specific directory. A simple filter, BehaEoEj_hq`a`, limits the allowed file types. This is exclusive to the handling of themes; other Renpq]hL]pdLnkre`an implementations might require different types. The example ignores all files except for &*ogej, &*_oo, and &*flc, but you can extend the list to support any file type used in your themes. The CapBeha method allows access to a file once it has been located in a directory. The resolving of files and their paths occurs in the compiler module. A simple file list handles all files in all directories. The key contains the full path, so files with the same filename but located in different folders still have a unique full name (see Listing 8-5). Listing 8-5. Implementation of a Custom VirtualPathProvider lq^he_oa]ha`_h]ooPdaiaL]pdLnkre`an6Renpq]hL]pdLnkre`an w lner]paop]pe_PdaiaL]pdLnkre`an[_qnnajpLnkre`an9jqhh7 lner]pa_kjopopnejc=OLJapPdaia>]oaL]pd9+=ll[Pdaiao+7 lner]paopnejc[pdaiaNah]peraL]pd9Opnejc*Ailpu7 lner]paopnejc[_qnnajpPdaiaOap9Opnejc*Ailpu7 lner]paopnejc[chk^]hPdaiaJ]ia9Opnejc*Ailpu7 lner]paPdaiaL]pdLnkre`an$% w [pdaiaNah]peraL]pd9± Sa^?kjbecqn]pekjI]j]can*=llOappejcoW?qopkiPdaia>]oaL]pdY7 y lq^he_kranne`aOuopai*Sa^*?]_dejc*?]_da@alaj`aj_uCap?]_da@alaj`aj_u$± opnejcrenpq]hL]pd(± Ouopai*?khha_pekjo*EAjqian]^harenpq]hL]pd@alaj`aj_eao(± @]paPeiaqp_Op]np% w napqnjjqhh7 y lq^he_kranne`a^kkh@ena_pknuAteopo$opnejcrenpq]h@en% w eb$renpq]h@en*Ej`atKb$=OLJapPdaia>]oaL]pd%99)-% napqnj^]oa*@ena_pknuAteopo$renpq]h@en%7 Download at WoweBook.Com

367

368

CH APT ER 8 N S ITE MA NA G EMENT

Renpq]hPdaia@ena_pknu`ena_pknu9Cap@ena_pknu$renpq]h@en%]o± Renpq]hPdaia@ena_pknu7 napqnj`ena_pknu*Ateopo7 y lq^he_kranne`a^kkhBehaAteopo$opnejcrenpq]hL]pd% w eb$renpq]hL]pd*Ej`atKb$=OLJapPdaia>]oaL]pd%99)-% napqnj^]oa*BehaAteopo$renpq]hL]pd%7 opnejcbehaJ]ia9Ouopai*Sa^*Renpq]hL]pdQpehepu*CapBehaJ]ia$renpq]hL]pd%7 opnejcrenpq]h@ena_pknuL]pd9± Ouopai*Sa^*Renpq]hL]pdQpehepu*Cap@ena_pknu$renpq]hL]pd%7 Renpq]hPdaia@ena_pknu`ena_pknu9± Cap@ena_pknu$renpq]h@ena_pknuL]pd%]oRenpq]hPdaia@ena_pknu7 napqnj`ena_pknu*CapBehaEoEj_hq`a`$behaJ]ia%7 y lq^he_kranne`aRenpq]h@ena_pknuCap@ena_pknu$opnejcrenpq]h@en% w eb$renpq]h@en*Ej`atKb$=OLJapPdaia>]oaL]pd%99)-% napqnj^]oa*Cap@ena_pknu$renpq]h@en%7 eb$EoPdaia@ena_pknuRenpq]hL]pd$renpq]h@en%% w napqnjjasRenpq]hPdaia@ena_pknu$renpq]h@en%7 y ahoa w OpnejcpdaiaRenpq]hL]pd9CapPdaia@ena_pknuRenpq]hL]pd$renpq]h@en%7 Renpq]hPdaia@ena_pknu`ena_pknu9jasRenpq]hPdaia@ena_pknu$renpq]h@en%7 napqnj`ena_pknu*Cap@ena_pknu$renpq]h@en%7 y y lq^he_kranne`aRenpq]hBehaCapBeha$opnejcrenpq]hL]pd% w eb$renpq]hL]pd*Ej`atKb$=OLJapPdaia>]oaL]pd%99)-% napqnj^]oa*CapBeha$renpq]hL]pd%7 Opnejcrenpq]h@ena_pknuL]pd9± Ouopai*Sa^*Renpq]hL]pdQpehepu*Cap@ena_pknu$renpq]hL]pd%7 Renpq]hPdaia@ena_pknu`ena_pknu9± Cap@ena_pknu$renpq]h@ena_pknuL]pd%]oRenpq]hPdaia@ena_pknu7 OpnejcbehaJ]ia9Ouopai*Sa^*Renpq]hL]pdQpehepu*CapBehaJ]ia$renpq]hL]pd%7 napqnj`ena_pknu*CapBeha$behaJ]ia%7 y lner]paOpnejc?khha_pekjCap@alaj`ajp@ena_pkneao$ Opnejcl]najp@ena_pknuL]pd( Opnejc?khha_pekj`alaj`ajpL]pdo% w OpnejcWY`ena_pkneao9@ena_pknu*Cap@ena_pkneao$l]najp@ena_pknuL]pd%7 bkn$ejphkklEj`at9,7hkklEj`at8`ena_pkneao*Hajcpd7hkklEj`at''% w `alaj`ajpL]pdo*=``$`ena_pkneaoWhkklEj`atY%7 Cap@alaj`ajp@ena_pkneao$`ena_pkneaoWhkklEj`atY(`alaj`ajpL]pdo%7 y napqnj`alaj`ajpL]pdo7 y Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

lner]pa>kkha]jEoPdaia@ena_pknuRenpq]hL]pd$Opnejcrenpq]hL]pd% w Opnejcl]najpRenpq]hL]pd9± Ouopai*Sa^*Renpq]hL]pdQpehepu*Cap@ena_pknu$renpq]hL]pd%7 napqnjl]najpRenpq]hL]pd*Aj`oSepd$=OLJapPdaia>]oaL]pd(± Opnejc?kil]neokj*Ejr]ne]jp?qhpqnaEcjkna?]oa%7 y lner]paOpnejcCapPdaia@ena_pknuRenpq]hL]pd$Opnejcrenpq]hL]pd% w Opnejcl]najpRenpq]hL]pd9± Renpq]hL]pdQpehepu*Cap@ena_pknu$renpq]hL]pd%7 sdeha$EoPdaia@ena_pknuRenpq]hL]pd$l]najpRenpq]hL]pd%% w l]najpRenpq]hL]pd9± Ouopai*Sa^*Renpq]hL]pdQpehepu*Cap@ena_pknu$l]najpRenpq]hL]pd%7 y napqnjl]najpRenpq]hL]pd7 y ejpanj]hOpnejc?kjranpPkPdaiaNah]peraL]pd$Opnejcnah]peraL]pd% w napqnj?kjranpPkPdaiaJ]iaNah]peraL]pd$nah]peraL]pd(b]hoa%7 y ejpanj]hOpnejc?kjranpPkChk^]hNah]peraL]pd$Opnejcnah]peraL]pd% w napqnj?kjranpPkPdaiaJ]iaNah]peraL]pd$nah]peraL]pd(pnqa%7 y lner]paOpnejc?kjranpPkPdaiaJ]iaNah]peraL]pd$Opnejcnah]peraL]pd(± >kkha]jnalh]_aPdaiaJ]iaSepdChk^]h% w OpnejcpdaiaJ]iaNah]peraL]pd9Opnejc*Ailpu7 eb$$nah]peraL]pd*Op]npoSepd$=OLJapPdaia>]oaL]pd%% ""$[pdaiaNah]peraL]pd*Op]npoSepd$+%%% w pdaiaJ]iaNah]peraL]pd9nah]peraL]pd*Oq^opnejc$,(± nah]peraL]pd*Ej`atKb$=OLJapPdaia>]oaL]pd%%7 y eb$$pdaiaJ]iaNah]peraL]pd*Aj`oSepd$+%% ""$[pdaiaNah]peraL]pd*Op]npoSepd$+%%% w pdaiaJ]iaNah]peraL]pd9± Ouopai*Sa^*Renpq]hL]pdQpehepu*± =llaj`Pn]ehejcOh]od$pdaiaJ]iaNah]peraL]pd%7 y pdaiaJ]iaNah]peraL]pd'9[pdaiaNah]peraL]pd7 Opnejcnai]ej`anL]pd9nah]peraL]pd*Oq^opnejc$± nah]peraL]pd*Ej`atKb$=OLJapPdaia>]oaL]pd%'± =OLJapPdaia>]oaL]pd*Hajcpd%7 eb$nalh]_aPdaiaJ]iaSepdChk^]h% Download at WoweBook.Com

369

370

CH APT ER 8 N S ITE MA NA G EMENT

w nai]ej`anL]pd9nai]ej`anL]pd*Oq^opnejc$nai]ej`anL]pd*Ej`atKb$+%%7 y pdaiaJ]iaNah]peraL]pd'9nai]ej`anL]pd7 napqnjpdaiaJ]iaNah]peraL]pd7 y lq^he_op]pe_PdaiaL]pdLnkre`an?qnnajp w cap w eb$[_qnnajpLnkre`an9jqhh% napqnj[_qnnajpLnkre`an7 [_qnnajpLnkre`an9jasPdaiaL]pdLnkre`an$%7 napqnj[_qnnajpLnkre`an7 y y lq^he_Opnejc?qnnajpOap w cap w napqnj[_qnnajpPdaiaOap7 y oap w [_qnnajpPdaiaOap9r]hqa7 y y y The Cap?]_da@alaj`aj_u returns jqhh in order to suppress any internal caching. You must either return jqhh or fully implement the caching. Otherwise, the compiler will try to resolve the default path (App_Themes) from the cache and this will fail. Two methods are called when the compiler tries to resolve an internal path: Cap@ena_pknu and CapBeha. If a file is referenced in a page that points to a theme, the compiler asks the provider to retrieve the same. Using the CapBeha method, we first check whether the theme’s folder is being used. This is the folder for which the provider in the example is responsible. From the file’s name, the containing directory is built. The directory is used to obtain the Renpq]hPdaia@ena_pknu implementation, which in turn returns the file held there. At the core of this implementation is a path manipulation algorithm. It could be far more sophisticated than the simple code in the example. Before a folder or file is retrieved, the @ena_pknuAteopo and BehaAteopo methods are called. This allows the provider to programmatically “hide” parts of the structure or to check for the physical presence of the requested resource. The basic approach is always the same. The calling instance “asks” the provider for a physical file. The provider returns a Renpq]hBeha instance, which allows direct access to the file’s contents via a Opna]i object. The remarkable thing is that the file might not necessarily exist anywhere on the file system. If, for example, the stream is obtained from a database call, the Renpq]hL]pdLnkre`an is simulating a physical file system. The “Exists” methods could always return pnqa in order to simulate a system where the page developers can use any value, and the system returns a set of globally predefined resources.

Download at WoweBook.Com

C H A P T E R 8 N S I T E M A N A G E M E N T

Configuring the Path Provider The provider requires two final configuration steps. First, it must have a setting in web.config to show that it’s configurable. Second, the provider must be registered, which follows the pattern previously explained. To demonstrate, I’ve used the =llhe_]pekj[Op]np event handler defined in the global.asax file, as shown in Listing 8-6. Listing 8-6. Configuration Settings in web.config 8]llOappejco: 8]``gau9?qopkiPdaia>]oaL]pdr]hqa9+L]pd[Pdaiao++: 8+]llOappejco: In Listing 8-7, the key is used to configure the physical path. Listing 8-7. Registering the Path Provider Using the Application_Start event lnkpa_pa`rke`=llhe_]pekj[Op]np$k^fa_poaj`an(Arajp=ncoa% w DkopejcAjrenkjiajp*NaceopanRenpq]hL]pdLnkre`an$PdaiaL]pdLnkre`an*?qnnajp%7 y The registration uses a singleton instance of the provider instead of the constructor. This results in slightly shorter code. A singleton instance works well because the provider works globally and exists only once in the application.

Limitations of the VirtualPathProvider Approach The Renpq]hL]pdLnkre`an is deeply integrated in the ASP.NET engine. Although it’s very powerful, certain tasks can be problematic. In this section, I explain two typical issues found when working with custom path providers.

Working with LoadControl The Renpq]hL]pdLnkre`an allows you to override the way in which tilde-based paths are resolved in page directives: 8!<NaceopanP]cLnabet9PaopP]cJ]ia9Iu?kjpnkhOn_9z+qoan_pnh*]o_t!: However, the Renpq]hL]pdLnkre`an cannot affect the way in which tilde-based paths are resolved for dynamically loaded user controls: IuLh]_aDkh`an*?kjpnkho*=``$Hk]`?kjpnkh$z+qoan_pnh*]o_t%%7 For the Hk]`?kjpnkh method to resolve tilde-based paths in the same way as Naceopan directives, the page code-behind needs to override this method: lq^he_jas?kjpnkhHk]`?kjpnkh$opnejcnah]peraL]pd% w opnejcjasL]pd9nah]peraL]pd7 opnejcoepa9pdeo*Namqaop*MqanuOpnejcWoepaY7 eb$Opnejc*EoJqhhKnAilpu$oepa%% w jasL]pd9Renpq]hL]pdQpehepu*Pk=llNah]pera$jasL]pd%7 jasL]pd9jasL]pd*Oq^opnejc$-%7 jasL]pd9z+IuOepao+'oepa'jasL]pd7 y napqnj^]oa*Hk]`?kjpnkh$jasL]pd%7 y Download at WoweBook.Com

371

372

CH APT ER 8 N S ITE MA NA G EMENT

This workaround will function as long as Hk]`?kjpnkh is called directly on your derived class, since it’s not renpq]h. A similar override in a Qoan?kjpnkh base class might be also required, since Hk]`?kjpnkh lives on Pailh]pa?kjpnkh.

Working with Precompiled Sites Unfortunately, Renpq]hL]pdLnkre`an is not supported in precompiled Web sites at the moment. As shown in the section “Prerequisites for a VirtualPathProvider,” the precompiled state is explicitly detected. Consequently, MSDN notes that, “if a Web site is precompiled for deployment, content provided by a Renpq]hL]pdLnkre`an instance is not compiled, and no Renpq]hL]pdLnkre`an instances are used by the precompiled site.” One way to avoid deploying source code is to use the Web Application Project model, in which all classes and code-behind files are compiled. Although pre-compilation will give our site a performance boost, the difference in speed will only be noticeable during the first request to each folder. A more significant benefit is the new deployment option made available by pre-compilation—the option to deploy a site without copying any of the original source code to the server. This includes the code and markup in aspx, ascx, and master files.

HACK MODE There is also a hack available to force the path provider to work with pre-compiled pages. This is not intended for production code, but if you’re under pressure to solve a similar issue, this tip might help. The solution is @uj]ie_Iapdk`. Just call a Microsoft internal method to register Renpq]hL]pdLnkre`an directly. This method is internal and therefore only reflection can obtain it. The definition in DkopejcAjrenkjiajp looks like this: ejpanj]hop]pe_rke`NaceopanRenpq]hL]pdLnkre`anEjpanj]h$± Renpq]hL]pdLnkre`anrenpq]hL]pdLnkre`an% w Renpq]hL]pdLnkre`anlnarekqo9[pdaDkopejcAjrenkjiajp*[renpq]hL]pdLnkre`an7 [pdaDkopejcAjrenkjiajp*[renpq]hL]pdLnkre`an9renpq]hL]pdLnkre`an7 renpq]hL]pdLnkre`an*Ejepe]heva$lnarekqo%7 y This is, again, a simple hack that may fail in future versions due to changes to the internal code by Microsoft.

Summary In this chapter, we looked at site management. Providing an existing structure to the navigation is the primary task of the OepaI]lLnkre`an. This provider allows the management of larger sites based on any data store you decide to implement. It’s transparent to the controls used to create navigational elements. The Renpq]hL]pdLnkre`an gives you more control over internal (physical) and external (virtual) paths for directories and files. Replacing the provider allows you to “fake” the paths and set them to virtual ones, which makes it easy to manage complex file structures. The Renpq]hL]pdLnkre`an is not as straightforward as the other ones, but it makes sense to use it if your embedded features, such as themes that can be extended or customized, are based on special folders.

Download at WoweBook.Com

CHAPTER

9

Control Extensibility

W

eb Server controls are the essence of ASP.NET, as most ASPX pages contain both static HTML and dynamic Web Server controls. Although ASP.NET includes a comprehensive collection of controls, third-party developers have also built up an impressive array of controls, both free and commercial, for almost any task you can imagine. Furthermore, you can create your own controls by implementing both design-time and runtime behavior. Purchasing controls may not be the best solution if embedded ones will fit your needs with minor modification. A third-party control is usually a sophisticated component designed for a specific purpose. For basic functionality in a lightweight package, it’s probably not optimal. Another option is to extend a standard ASP.NET control and modify the way it renders. ASP. NET’s extensibility concepts are not limited to providers; controls are extensible and customizable if you use adapters. In this chapter, I’ll cover adapter techniques and explain:

s (OWTOIMPLEMENTANDACTIVATEACONTROLADAPTER



s (OWTOMAKETHEADAPTERWORKDEPENDINGONTHECURRENTBROWSER



s (OWTOCREATEADAPTERSATAPAGELEVEL

After reading this chapter, you’ll be able to “adapt” an existing control so that it renders according to your needs. This could include different ways of creating HTML, adding JavaScript, or using cascading style sheets to format the output.

Adaptive Control Behavior Adaptive control behavior is architecture that changes the way controls render in order to suit the needs of specific clients. Adapters intercept states of the life cycle to alter rendering behavior. By default, each control has a designated adapter in a one-to-one relationship. It’s possible to change this relationship under certain circumstances—when, for example, you encounter a browser that requires a different kind of markup. To control the adaptive behavior, choose from the following techniques:

s #ONFIGURETHEAPPLICATIONTOSUPPORTDIFFERENTMARKUPS



s #HOOSETHETdpihPatpSnepan or ?dpihPatpSnepan class to create specific markup.



s #REATEAPatpSnepan class that writes the markup to the output stream.



s 5SEAFILTERTORECOGNIZEACLIENTDEVICEANDDECIDEWHATKINDOFMARKUPYOUNEED



s #REATEANADAPTERANDASSIGNTHEADAPTERTOACONTROL

373 Download at WoweBook.Com

374

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

The markup is not the only aspect you may want to change. Depending on the capabilities of the target device, you may need to think about:

s (OWTOWORKWITHPOSTBACKDATA



s -ANAGINGTHEVIEWSTATE



s 0REVENTINGCHANGES to the control

The Default Behavior The render process of a page uses the DpihPatpSnepan class by default. The Naj`an?kjpnkh method is called recursively with an instance of the DpihPatpSnepan. Each control adds its markup to the writer. By the end of the process, the writer holds the complete markup of the page and writes it to the output stream. ASP.NET includes several writer types compatible with specific output devices. For HTML 3.2, the Dpih/.PatpSnepan is used. Which writer to use depends on the P]cSnepan of the Ouopai* Sa^*DpplNamqaop*>nksoan. If a browser supports HTML 4.0, the page framework should compose 8(4-,5SINGweb.config, you can configure this behavior and replace the Dpih/.PatpSnepan with an TDpihPatpSnepan. The >nksoan property of the DpplNamqaop class returns an Dppl>nksoan?]l]^ehepeao object. The underlying code is relatively straightforward. If a custom PatpSnepan is defined, the ?na]paDpihPatpSnepanBnkiPula is used. If not, the default Dpih/.PatpSnepan is used. The following code snippets are decompiled from the Ouopai*Sa^*DpplNamqaop class and the Ouopai*Sa^*QE*L]ca class, respectively. ejpanj]hDpihPatpSnepan?na]paDpihPatpSnepanEjpanj]h$PatpSnepanps% w Pulap]cSnepan9pdeo*P]cSnepan7 eb$p]cSnepan9jqhh% w napqnjL]ca*?na]paDpihPatpSnepanBnkiPula$ps(p]cSnepan%7 y napqnjjasDpih/.PatpSnepan$ps%7 y lq^he_PulaP]cSnepan w cap w pnu w eb$pdeo*[d]rap]csnepan% w opnejcopn9pdeoWp]csnepanY7 eb$opnejc*EoJqhhKnAilpu$opn%% w pdeo*[p]csnepan9jqhh7 y ahoaeb$opnejc*?kil]na$opn(pulakb$DpihPatpSnepan%*BqhhJ]ia(± Opnejc?kil]neokj*Kn`ej]h%99,% w

Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

pdeo*[p]csnepan9pulakb$DpihPatpSnepan%7 y ahoa w pdeo*[p]csnepan9>qeh`I]j]can*CapPula$opn(pnqa%7 y pdeo*[d]rap]csnepan9pnqa7 y y _]p_d$At_alpekjat_alpekj% w pdnkspdeo*>qeh`L]noaAnnkn$at_alpekj(p]csnepan%7 y napqnjpdeo*[p]csnepan7 y y lq^he_op]pe_DpihPatpSnepan?na]paDpihPatpSnepanBnkiPula$PatpSnepanps(± PulasnepanPula% w DpihPatpSnepansnepan7 eb$snepanPula99pulakb$DpihPatpSnepan%% w napqnjjasDpihPatpSnepan$ps%7 y eb$snepanPula99pulakb$Dpih/.PatpSnepan%% w napqnjjasDpih/.PatpSnepan$ps%7 y pnu w Qpeh*?da_g=ooecj]^haPula$pulakb$DpihPatpSnepan%(snepanPula%7 snepan9$DpihPatpSnepan%DpplNqjpeia*?na]paJkjLq^he_Ejop]j_a$± snepanPula(jask^fa_pWYwpsy%7 y _]p_d w pdnksjasDpplAt_alpekj$ON*CapOpnejc$Ejr]he`[DpihPatpSnepan(± jask^fa_pWYwsnepanPula*BqhhJ]iay%%7 y napqnjsnepan7 y As you can see, the instance of the abstract PatpSnepan class is responsible for the rendering process. Because ASP.NET produces HTML, the DpihPatpSnepan class is the optimum point for beginning to implement a custom writer class. The TdpihPatpSnepan and ?dpihPatpSnepan types mentioned earlier derive from the DpihPatpSnepan and Dpih/.PatpSnepan respectively. They are concrete implementations for specific rendering behavior. See Figure 9-1.

Download at WoweBook.Com

375

376

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

Figure 9-1. The control adapter architecture

Using Control Adapters To modify the behavior described earlier, you’ll need an implementation of the Ouopai*Sa^* QE*=`]lpano*?kjpnkh=`]lpan base class. In each phase of the life cycle, the control checks whether or not an adapter is available. If there is one present, the adapter provides an alternative method that replaces the default method that would otherwise be called in that step in the life cycle. If the adapter only modifies portions of the behavior, it can call the control’s default method instead. Adapters that modify the state persistence behavior differ in that they don’t modify, but completely replace, the default behavior. When the adapter intercepts the life cycle, the following actions (at a minimum) must occur:

s /VERRIDETHEKjEjep method of the control adapter to modify the initializing phase.



s /VERRIDETHENaj`an or Naj`an?deh`naj method to add custom markup. The abstract base class has the following structure:

lq^he_]^opn]_p_h]oo?kjpnkh=`]lpan w lnkpa_pa`?kjpnkh=`]lpan$%7 lnkpa_pa`Dppl>nksoan?]l]^ehepeao>nksoanwcap7y lnkpa_pa`?kjpnkh?kjpnkhwcap7y lnkpa_pa`L]caL]cawcap7y lnkpa_pa`L]ca=`]lpanL]ca=`]lpanwcap7y lnkpa_pa`ejpanj]hrenpq]hrke`>acejNaj`an$DpihPatpSnepansnepan%7 lnkpa_pa`ejpanj]hrenpq]hrke`Aj`Naj`an$DpihPatpSnepansnepan%7 lnkpa_pa`ejpanj]hrenpq]hrke`Hk]`=`]lpan?kjpnkhOp]pa$k^fa_pop]pa%7 lnkpa_pa`ejpanj]hrenpq]hrke`Hk]`=`]lpanReasOp]pa$k^fa_pop]pa%7 lnkpa_pa`ejpanj]hrenpq]hrke`KjEjep$Arajp=ncoa%7 lnkpa_pa`ejpanj]hrenpq]hrke`KjHk]`$Arajp=ncoa%7 lnkpa_pa`ejpanj]hrenpq]hrke`KjLnaNaj`an$Arajp=ncoa%7 lnkpa_pa`ejpanj]hrenpq]hrke`KjQjhk]`$Arajp=ncoa%7 lnkpa_pa`ejpanj]hrenpq]hrke`Naj`an$DpihPatpSnepansnepan%7 lnkpa_pa`renpq]hrke`Naj`an?deh`naj$DpihPatpSnepansnepan%7 lnkpa_pa`ejpanj]hrenpq]hk^fa_pO]ra=`]lpan?kjpnkhOp]pa$%7 Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

lnkpa_pa`ejpanj]hrenpq]hk^fa_pO]ra=`]lpanReasOp]pa$%7 y Before you start implementing adapters to change a control’s behavior, you’ll need to learn the purpose for each property and method (see Table 9-1). Table 9-1. The ControlAdapter Base Class

Class Member

Description

>nksoan

The browser capabilities (Dppl>nksoan?]l]^ehepeao) of the client making the current HTTP request.

?kjpnkh

The control to which this control adapter is attached.

L]ca

The page containing the control associated with this adapter.

L]ca=`]lpan

The page adapter (Ouopai*Sa^*QE*=`]lpano*L]ca=`]lpan) for the page defined by L]ca.

>acejNaj`an

#ALLEDPRIORTOTHERENDERINGOFACONTROL4HEMETHODGENERATES opening tags required by a specific target. It takes a Ouopai*Sa^* QE*DpihPatpSnepan object to render the target-specific output.

Aj`Naj`an

#ALLEDAFTERTHERENDERINGOFACONTROL4HEMETHODGENERATES closing tags that are required by a specific target. It takes a Ouopai* Sa^*QE*DpihPatpSnepan object to render the target-specific output.

?na]pa?deh`?kjpnkho

#REATESTHETARGET SPECIFICCHILDCONTROLSFORACOMPOSITECONTROL

Hk]`=`]lpan?kjpnkhOp]pa

Loads adapter control state information saved by the Ouopai*Sa^* QE*=`]lpano*?kjpnkh=`]lpan*O]ra=`]lpan?kjpnkhOp]pa method during a previous request to the L]ca. Receives the state as a Op]pa>]c object.

Hk]`=`]lpanReasOp]pa

Loads adapter view state information saved by the Ouopai*Sa^*QE* =`]lpano*?kjpnkh=`]lpan*O]ra=`]lpanReasOp]pa method during a previous request to the L]ca. Receives the state as a Op]pa>]c object.

KjEjep

/VERRIDESTHEOuopai*Sa^*QE*?kjpnkh*KjEjep method for the associated control in order to hook into the initializing phase.

KjHk]`

/VERRIDESTHEOuopai*Sa^*QE*?kjpnkh*KjHk]` method for the associated control in order to hook into the load phase.

KjLnaNaj`an

/VERRIDESTHEOuopai*Sa^*QE*?kjpnkh*KjLnaNaj`an method for the associated control.

KjQjhk]`

/VERRIDESTHEOuopai*Sa^*QE*?kjpnkh*KjQjhk]` method for the associated control.

Naj`an

Generates target-specific markup for the control to which the adapter is attached. Takes a Ouopai*Sa^*QE*DpihPatpSnepan object to render the target-specific output.

Naj`an?deh`naj

Generates the target-specific markup for the child controls in a composite control to which the adapter is attached. Takes a Ouopai*Sa^* QE*DpihPatpSnepan object to render the target-specific output.

O]ra=`]lpan?kjpnkhOp]pa

Saves control state information for the control adapter into a Op]pa>]c object.

O]ra=`]lpanReasOp]pa

Saves view state information for the control adapter into a Op]pa>]c object.

You now have all the information you need in order to implement a custom control adapter. (OWEVER BEFORETHEADAPTERCANBEUSED ITMUSTBECONFIGURED#ONFIGURATIONDEPENDSONADEVICE filter.

Download at WoweBook.Com

377

378

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

The Ouopai*Sa^*QE*Sa^?kjpnkho*=`]lpano*Sa^?kjpnkh=`]lpan base class is the preferred way to change the behavior of built-in web controls. This class adds virtual methods Naj`an>acejP]c, Naj`anAj`P]c, and Naj`an?kjpajpo, to more closely mirror the render behavior of web controls. lq^he__h]ooSa^?kjpnkh=`]lpan6?kjpnkh=`]lpan w lnkpa_pa`Sa^?kjpnkh?kjpnkhwcap7y lnkpa_pa`^kkhEoAj]^ha`wcap7y lnkpa_pa`renpq]hrke`Naj`an>acejP]c$DpihPatpSnepansnepan%7 lnkpa_pa`renpq]hrke`Naj`an?kjpajpo$DpihPatpSnepansnepan%7 lnkpa_pa`renpq]hrke`Naj`anAj`P]c$DpihPatpSnepansnepan%7 y Table 9-2 explains its properties and methods. Table 9-2. WebControlAdapter

Member

Description

?kjpnkh

The web control to which this adapter is attached

EoAj]^ha`

Indicates whether the web control and all its parent controls are enabled

Naj`an

Generates the target-specific markup for the control to which the adapter is attached

Naj`an>acejP]c

#REATESTHEBEGINNINGTAGINTHEMARKUPFORTHEWEBCONTROL

Naj`an?kjpajpo

Generates the target-specific inner markup for the web control to which the adapter is attached

Naj`anAj`P]c

#REATESTHECLOSINGTAGINTHEMARKUPFORTHEWEBCONTROL

Note that the Sa^?kjpnkh=`]lpan is not an abstract class, but the basic class in the hierarchy of adapters responsible for regular web controls. It’s in the Ouopai*Sa^*QE*Sa^?kjpnkho*=`]lpano namespace. The Sa^?kjpnkh=`]lpan class is the base class for the following implementations:

s Dean]n_de_]h@]p]>kqj`?kjpnkh=`]lpan



s @]p]>kqj`?kjpnkh=`]lpan



s De`a@eo]^ha`?kjpnkh=`]lpan



s Iajq=`]lpan

The Iajq=`]lpan is a concrete implementation used to render Iajq controls. The Dean]n_de_]h@]p]>kqj`?kjpnkh=`]lpan provides a virtual method, Lanbkni@]p]>ej`ejc, which calls ?kjpnkh*Lanbkni@]p]>ej`ejc/VERRIDINGTHISMETHODINADERIVEDCLASSALLOWSYOU to change the binding behavior. (This is also the case for the @]p]>kqj`?kjpnkh=`]lpan class.) The De`a@eo]^ha`?kjpnkh=`]lpanCANBEAPPLIEDTOANYCONTROL5SINGTHISADAPTERREMOVESTHECONTROL from pages in which the control is disabled. It overrides the adapter’s Naj`an method and, if its Aj]^ha` property is false, the control’s Naj`an method is not called, as shown in Figure 9-2.

Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

Figure 9-2. The class diagram for control adapter classes The base classes can be used to perform basic tasks without you having to implement your own adapter. With them you can also vary a single behavior, such as data binding, while benefiting from all the other default adapter functionality. In the class diagram, you’ll also find a L]ca=`]lpan class that derives from ?kjpnkh=`]lpan. Thus, pages can have adapters, too.

Using Page Adapters As a L]ca is essentially a specialized ?kjpnkh, the control adapter also supports pages. The L]ca=`]lpan base class exists to make writing a custom page adapter easy. This base class inherits from the ?kjpnkh=`]lpan described earlier and extends the adapter with page-specific features. lq^he_]^opn]_p_h]ooL]ca=`]lpan6?kjpnkh=`]lpan w lq^he_renpq]hOpnejc?khha_pekj?]_daR]nu>uDa]`anowcap7y lq^he_renpq]hOpnejc?khha_pekj?]_daR]nu>uL]n]iowcap7y lnkpa_pa`opnejc?heajpOp]pawcap7y lq^he_renpq]hJ]iaR]hqa?khha_pekj@apaniejaLkop>]_gIk`a$%7 lnkpa_pa`ejpanj]hrenpq]hopnejcCapLkop>]_gBkniNabanaj_a$opnejcbkniE`%7 lq^he_renpq]hE?khha_pekjCapN]`ek>qppkjo>uCnkql$opnejccnkqlJ]ia%7 lq^he_renpq]hL]caOp]paLanoeopanCapOp]paLanoeopan$%7 Download at WoweBook.Com

379

380

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

lq^he_renpq]hrke`NaceopanN]`ek>qppkj$N]`ek>qppkjn]`ek>qppkj%7 lq^he_renpq]hrke`Naj`an>acejDulanhejg$DpihPatpSnepansnepan(± opnejcp]ncapQnh(± ^kkhaj_k`aQnh(± opnejcokbpgauH]^ah%7 lq^he_renpq]hrke`Naj`an>acejDulanhejg$DpihPatpSnepansnepan(± opnejcp]ncapQnh(± ^kkhaj_k`aQnh(± opnejcokbpgauH]^ah(± opnejc]__aooGau%7 lq^he_renpq]hrke`Naj`anAj`Dulanhejg$DpihPatpSnepansnepan%7 lq^he_renpq]hrke`Naj`anLkop>]_gArajp$DpihPatpSnepansnepan(± opnejcp]ncap(± opnejc]ncqiajp(± opnejcokbpgauH]^ah(± opnejcpatp%7 lq^he_renpq]hrke`Naj`anLkop>]_gArajp$DpihPatpSnepansnepan(± opnejcp]ncap(± opnejc]ncqiajp(± opnejcokbpgauH]^ah(± opnejcpatp(± opnejclkopQnh(± opnejc]__aooGau%7 lnkpa_pa`rke`Naj`anLkop>]_gArajp$DpihPatpSnepansnepan(± opnejcp]ncap(± opnejc]ncqiajp(± opnejcokbpgauH]^ah(± opnejcpatp(± opnejclkopQnh(± opnejc]__aooGau(± ^kkhaj_k`a%7 lq^he_renpq]hopnejcPn]jobkniPatp$opnejcpatp%7 y Table 9-3 explains the properties and methods provided by the L]ca=`]lpan. (The L]ca=`]lpan attaches to a web page. This is the “page” referred to in the table descriptions.) The L]ca=`]lpan supports the persistence layer and the render behavior of controls that group multiple tags. N]`ek>qppkjo need special treatment when handling groups. You can define a group of radio buttons in HTML by giving them the same name. However, ASP.NET requires different IDs for each radio button, and by default the name and ID are the same. The L]ca=`]lpan will thus render each radio button group appropriately to keep the groups separate. The CapOp]paLanoeopan property can be overloaded in order to change the view state persister GLOBALLY5SINGTHEABSTRACTBASECLASS YOUCANWRITEACUSTOMPAGEADAPTERTOCHANGETHEBEHAVIOR of all pages. Why does the rendering of a page depend on the client device? Remember that the view state has a strong influence on the client. The view state could grow and consume a significant portion OFTHEPAGESRENDEREDCONTENT2EFERTO#HAPTERFORAREFRESHERABOUTVIEWSTATE 4HEUSEREXPErience on mobile devices and smart phones generally deteriorates with large pages. To mitigate THIS YOUCOULDWRITEAPAGEADAPTERTHATCREATESAREGULARVIEWSTATEFOR0# BASEDBROWSERSAND server-side view state for mobile devices. The implication is that, as for ?kjpnkh=`]lpan implementations, the L]ca=`]lpan must be configured and associated with a set of clients.

Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

Table 9-3. Properties and Methods in the PageAdapter, Additional to Those Provided by the ControlAdapter

Member

Description

?]_daR]nu>uDa]`ano

A list (of type EHeop) of additional HTTP headers by which caching is varied for the web page.

?]_daR]nu>uL]n]io

A list (of type EHeop) of additional parameters from HTTP GET and 0/34REQUESTSBYWHICHCACHINGISVARIEDFORTHEWEBPAGE

?heajpOp]pa

An encoded string containing the view and control state data of the web page.

@apaniejaLkop>]_gIk`a

Evaluates whether the web page is in postback mode and returns a name/value collection of type Ouopai*?khha_pekjo*Ola_e]heva`* J]iaR]hqa?khha_pekj of the postback variables.

CapLkop>]_gBkniNabanaj_a

Returns a DHTML code fragment that the client browser can use to reference the form on the page that was posted.

CapN]`ek>qppkjo>uCnkql

Retrieves a collection of radio button controls specified by cnkqlJ]ia. Takes the name of a Ouopai*Sa^*QE*Sa^?kjpnkho* N]`ek>qppkj group and returns an E?khha_pekj object with N]`ek>qppkj instances.

CapOp]paLanoeopan

Returns a L]caOp]paLanoeopan object used by the web page to maintain the control and view states.

NaceopanN]`ek>qppkj

Adds a radio button control to the collection for a specified radio button group.

Naj`an>acejDulanhejg

2ENDERSANOPENINGHYPERLINKTAG INCLUDINGTHETARGET52, TOTHE response stream. It takes the current PatpSnepan instance to write the data. This method is overloaded in order to support different sets of parameters.

Naj`anAj`Dulanhejg

Renders a closing hyperlink tag to the response stream.

Naj`anLkop>]_gArajp

Renders a postback event to the response stream as a hyperlink, including the encoded and possibly encrypted view state, and the event target and argument. This method is overloaded to support different sets of parameters.

Pn]jobkniPatp

Transforms text for the target browser.

Device-Specific Filter for Adaptive Behavior A device filter recognizes a client device and assigns a device-specific adapter to its controls. The filter can also identify control properties, user defined attributes and templates, and can be controlled with nksoano Browser files are used to create the Dppl>nksoan?]l]^ehepeao object that exposes the device’s properties. The definitions form a hierarchy, preventing the files from redefining basic definitions. For instance, the ie.browser file contains several IE-related definitions. The following snippet shows settings specific to Internet Explorer: 8^nksoano: 8^nksoane`9EAl]najpE@9Ikvehh]: 8e`ajpebe_]pekj: 8qoan=cajpi]p_d9ZIkvehh]WZ$Y&X$W?x_Ykil]pe^ha7Xo&IOEA Download at WoweBook.Com

381

382

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

$;#ranoekj#$;#i]fkn#X`'%$;#iejkn#X*X`'%$;#happano#Xs&%%$;#atpn]#WZ%Y&%+: 8qoan=cajpjkjI]p_d9Klan]xCkX*Sa^xSej`kso?AxAq`kn]Sa^+: 8+e`ajpebe_]pekj: 8_]lpqna: 8+_]lpqna: 8_]l]^ehepeao: 8_]l]^ehepuj]ia9^nksoanr]hqa9EA+: 8_]l]^ehepuj]ia9atpn]r]hqa9 watpn]y+: 8_]l]^ehepuj]ia9eo?khknr]hqa9pnqa+: 8_]l]^ehepuj]ia9happanor]hqa9 whappanoy+: 8_]l]^ehepuj]ia9i]fknranoekjr]hqa9 wi]fkny+: 8_]l]^ehepuj]ia9iejknranoekjr]hqa9 wiejkny+: 8_]l]^ehepuj]ia9o_naaj>ep@alpdr]hqa94+: 8_]l]^ehepuj]ia9pular]hqa9EA wi]fkny+: 8_]l]^ehepuj]ia9ranoekjr]hqa9 wranoekjy+: 8+_]l]^ehepeao: 8+^nksoan: 8^nksoane`9EA1pk5l]najpE@9EA: 8e`ajpebe_]pekj: 8_]l]^ehepuj]ia9i]fknranoekji]p_d9ZW1)5Y+: 8+e`ajpebe_]pekj: 8_]lpqna: 8+_]lpqna: 8_]l]^ehepeao: 8_]l]^ehepuj]ia9]_perat_kjpnkhor]hqa9pnqa+: 8_]l]^ehepuj]ia9^]_gcnkqj`okqj`or]hqa9pnqa+: 8_]l]^ehepuj]ia9_kkgeaor]hqa9pnqa+: 8_]l]^ehepuj]ia9_oo-r]hqa9pnqa+: 8_]l]^ehepuj]ia9_oo.r]hqa9pnqa+: 8_]l]^ehepuj]ia9a_i]o_nelpranoekjr]hqa9-*.+: 8_]l]^ehepuj]ia9bn]iaor]hqa9pnqa+: 8_]l]^ehepuj]ia9f]r]]llhapor]hqa9pnqa+: 8_]l]^ehepuj]ia9f]r]o_nelpr]hqa9pnqa+: 8_]l]^ehepuj]ia9fo_nelpranoekjr]hqa91*,+: 8_]l]^ehepuj]ia9io`kiranoekj± r]hqa9 wi]fknranoekjy wiejknranoekjy+: 8_]l]^ehepuj]ia9oqllknpo?]hh^]_gr]hqa9pnqa+: 8_]l]^ehepuj]ia9oqllknpoBehaQlhk]`r]hqa9pnqa+: 8_]l]^ehepuj]ia9oqllknpoIqhpehejaPatp>kt@eolh]ur]hqa9pnqa+: 8_]l]^ehepuj]ia9oqllknpoI]ejp]ejO_nkhhLkoepekjKjLkop^]_g± r]hqa9pnqa+: 8_]l]^ehepuj]ia9oqllknpoR?]n`r]hqa9pnqa+: 8_]l]^ehepuj]ia9oqllknpoTihDpplr]hqa9pnqa+: 8_]l]^ehepuj]ia9p]^haor]hqa9pnqa+: 8_]l]^ehepuj]ia9p]csnepan± r]hqa9Ouopai*Sa^*QE*DpihPatpSnepan+: 8_]l]^ehepuj]ia9r^o_nelpr]hqa9pnqa+: 8_]l]^ehepuj]ia9s/_`kiranoekjr]hqa9-*,+: 8_]l]^ehepuj]ia9tihr]hqa9pnqa+: 8+_]l]^ehepeao: 8+^nksoan: *** 8+^nksoano: Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

The filter consists of two parts. First, the qoan=cajp tag provides a i]p_d attribute which contains a regular expression. This expression is matched against the user-agent HTTP header sent by each client device. The capabilities section contains a setting for the preferred p]csnepan, which you can use to assign a particular behavior when creating tags. This is much less common than using a full-blown adapter, but is expedient if you simply want to write XHTML instead of HTML (see Figure 9-3).

Figure 9-3. User Agent settings for Internet Explorer

NCaution

As the User Agent string can be fake, don’t trust the settings for security-related activities.

Adding client device filters can be accomplished on a per-application basis using the App_Browsers folder (see Figure 9-4). This is a special folder which can be added to any Web application project. Place a custom browser file into this folder and define device-specific settings there.

Figure 9-4. Adding a *.browser file to the current project’s App_Browsers folder Download at WoweBook.Com

383

384

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

The browser file has a similar structure to the default ones. The inheritance behavior is crucial. By using the right l]najpE@ attribute, you can inherit all common settings from an existing device and add or change a few values to match your current device. A typical file contains the following tags, at a minimum: 8^nksoano: 8^nksoane`9Jas>nksoanl]najpE@9Ikvehh]: 8e`ajpebe_]pekj: 8qoan=cajpi]p_d9QjemqaQoan=cajpNacqh]nAtlnaooekj+: 8+e`ajpebe_]pekj: 8_]lpqna: 8qoan=cajpi]p_d9Jas>nksoan$;#ranoekj#X`'X*X`'%+: 8+_]lpqna: 8_]l]^ehepeao: 8_]l]^ehepuj]ia9^nksoanr]hqa9IuJas>nksoan+: 8_]l]^ehepuj]ia9ranoekjr]hqa9 wranoekjy+: 8+_]l]^ehepeao: 8_kjpnkh=`]lpanoi]ngqlPatpSnepanPula9: 8]`]lpan]`]lpanPula9 _kjpnkhPula9+: 8+_kjpnkh=`]lpano: 8+^nksoan: 8^nksoannabE@9Ikvehh]: 8_]l]^ehepeao: 8_]l]^ehepuj]ia9tihr]hqa9pnqa+: 8+_]l]^ehepeao: 8+^nksoan: 8+^nksoano: The types defined in the _kjpnkh=`]lpano tag build the relationship between controls and adapters. They are specific to the current device. However, by using a common matching pattern, you can assign the filter to any device. While the ]`]lpanPula is a type derived from the Ouopai*Sa^*QE*=`]lpano*?kjpnkh=`]lpan, the _kjpnkhPula must derive from Ouopai*Sa^*QE*?kjpnkh. The i]ngqlPatpSnepanPula attribute defines the writer to render the content. This type is instantiated and the object passed to the Naj`an and Naj`an?deh`naj methods of the control adapter. For an embedded control, this looks like the following: 8_kjpnkh=`]lpanoi]ngqlPatpSnepanPula9Ouopai*Sa^*QE*TdpihPatpSnepan: 8]`]lpan_kjpnkhPula9Ouopai*Sa^*QE*Sa^?kjpnkho*Iajq ]`]lpanPula9Ouopai*Sa^*QE*Sa^?kjpnkho*=`]lpano*Iajq=`]lpan: 8+]`]lpan: 8+_kjpnkh=`]lpano:

NNote

The browser capabilities file does not function for certain browser settings. The file matches the user agent string against a predefined set of properties. For instance, Internet Explorer supports JavaScript, hence the Dppl>nksoan?]l]^ehepeao object returns pnqa for that setting. If, however, a user disables JavaScript, this action does not change the property. You should read the object’s name literally—as a capability rather than as actual behavior.

Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

Using Control Adapters There are several usage scenarios for adapters. In fact, adapters are one of the most powerful tools for extending control behavior.

Device-Friendly Adapters The main purpose of control adapters is to support specific client devices that do not function well with the standard HTML created by built-in controls. The intended behavior is defined within the .browser configuration file.

CSS-Friendly Adapters When you readABOUTADAPTERS YOULLOFTENSEETHETERMh#33 FRIENDLYCONTROLADAPTERSv4HIS WRONGLYIMPLIESTHATTHEADAPTERSUPPORTS#33CASCADINGSTYLESHEETS !NADAPTERISSIMPLYAN extensibility technique that allows page developers to alter the render behavior for all or particular CLIENTDEVICES2EPLACINGPURE(4-,WITH#33SUPPORTISACOMMONSCENARIO BUTITISNOTTHEONLY ONESUPPORTEDBYADAPTERS4HEREASONFORTHENAMEISTHELACKOF#33SUPPORTIN!30.%4 ANDTHE development of adapters to overcome this limitation. For a sophisticated example of the usage of ADAPTERSTOSUPPORT#33 REFERTOTHE7EBSITEsss*]ol*jap+?OO=`]lpano. This site offers a complete set of adapters using specific style definitions to format controls. The Iajq=`]lpan shows how the replacement of 8p]^ha: tags with nested 8qh:TAGSAND#33STYLES SAVESALOTOFSPACEANDRESULTSIN AFREELYCONFIGURABLEMENUCONTROL/THEREXAMPLESINTHEPACKAGESUPPORTCOMPLEXCONTROLS such as BkniReas and PnaaReas.

Other Adapter Ideas An adapter can output any kind of markup. It’s not limited to HTML or XHTML, and you can even create XAML to support WPF applications or Silverlight. (As this does sound strange, I’ll reiterate it so that you know it’s not a mistake.) It is possible to write a regular ASP.NET page consisting entirely of ASP.NET controls and render them in XAML—or anything else. The PatpSnepan class, used to add content to the output stream, writes text, whether or not it consists of markup. You can also use adapters to expose the source of a page by replacing the tags with "hp7 and "cp7 entities.

Writing a Custom Control Adapter The following example shows how a custom control derived from a built-in control can be modified with an adapter.

Steps for Creating the Example The example consists of the following parts:

s !CUSTOMCONTROLTHATADDSTWOPROPERTIESTOTHEBUILT IN#HECK"OX,IST



s !NADAPTERTHATCHANGESTHERENDERBEHAVIORUSINGTHESEPROPERTIES



s !PAGETHATUSESTHECUSTOMCONTROL



s !BROWSERFILETHATASSIGNS the adapter to the control

Download at WoweBook.Com

385

386

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

The Example Code Listing 9-1 shows the custom control. The two properties store the names of the image resources. The purpose of the control is to display an image list. The control takes HeopEpai members, and instead of rendering ?da_g>ktELEMENTS TWOIMAGESAREUSEDˆAN/N)MAGEIFTHEITEMISSELECTED CHECKED ANDAN/FF)MAGEOTHERWISE The control behaves as any standard ?da_g>ktHeop would. You can add HeopEpaio and fill in the appropriate data. However, the adapter changes the render behavior to just display images. There is no treatment of content because the list is read-only, and the user can’t change anything or post back the data. Imagine that the adapter is used to render the control for devices that don’t allow interaction, such as a kiosk application. In that situation, a disabled ?da_g>kt would look unprofessional. Listing 9-1. A Custom Control That Modifies a Built-In One lq^he__h]ooIu?da_g>ktHeop6?da_g>ktHeop w W>nkso]^ha$pnqa%Y lq^he_opnejcKbbEi]ca w cap w eb$ReasOp]paWKbbEi]caY99jqhh% w KbbEi]ca97 y napqnj$opnejc%ReasOp]paWKbbEi]caY7 y oap w ReasOp]paWKbbEi]caY9r]hqa7 y y W>nkso]^ha$pnqa%Y lq^he_opnejcKjEi]ca w cap w eb$ReasOp]paWKjEi]caY99jqhh% w KjEi]ca97 y napqnj$opnejc%ReasOp]paWKjEi]caY7 y oap w ReasOp]paWKjEi]caY9r]hqa7 y y y This control has two additional properties. The images the properties refer to can be defined as embedded resources. To achieve this, use the Sa^Naokqn_a=ppne^qpa as follows: W]ooai^hu6Sa^Naokqn_a=ppne^qpa$± =lnaoo*Atpajoe^ehepu*=`]lpano*Naokqn_ao*KjEi]ca*ljc(ei]ca+flc%Y Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

W]ooai^hu6Sa^Naokqn_a=ppne^qpa$± =lnaoo*Atpajoe^ehepu*=`]lpano*Naokqn_ao*KbbEi]ca*ljc(ei]ca+flc%Y Furthermore, we’ll need a simple test scenario in order to get the control working. The following code is a snippet from an ASPX page. The attribute goes anywhere but inside a class. Specifically, the AssemblyInfo.cs file is a great place, as shown in Listing 9-2. Listing 9-2. A Simple Usage Scenario 8bknie`9bkni-nqj]p9oanran: 8`er: 8__-6Iu?da_g>ktHeopE@9Iu?da_g>ktHeop-nqj]p9oanran ?kjpnkhKneajp]pekj9Dknevkjp]h>]_g?khkn9Na`Bkna?khkn9>hqa: 8+__-6Iu?da_g>ktHeop: 8+`er: 8+bkni: The code-behind file contains only the data source. To see the control in action, add a few HeopEpaio, and choose images via the Oaha_pa` property. If Oaha_pa` equals pnqa /N)MAGEIS SHOWNˆOTHERWISE ITS/FF)MAGESEE,ISTING   Listing 9-3. The Code-Behind File Adds a Few Items for Testing Purposes lq^he_l]npe]h_h]oo[@ab]qhp6Ouopai*Sa^*QE*L]ca w lnkpa_pa`rke`L]ca[Hk]`$k^fa_poaj`an(Arajp=ncoa% w eb$EoLkop>]_g% w r]nhe_9jasHeop8HeopEpai:$%7 he_*=``$jasHeopEpai$R]hqa-(-%wOaha_pa`9pnqay%7 he_*=``$jasHeopEpai$R]hqa.(.%wOaha_pa`9b]hoay%7 he_*=``$jasHeopEpai$R)]hqa/(/%wOaha_pa`9pnqay%7 he_*=``$jasHeopEpai$R]hqa0(0%wOaha_pa`9b]hoay%7 Iu?da_g>ktHeop-*Epaio*=``N]jca$he_*Pk=nn]u$%%7 y y y Last, but not least, the adapter is required. This renders the control through a reference to the control, using the appropriate Render methods, as shown in Listing 9-4. Listing 9-4. The Adapter Creates Images and Labels Instead of Checkbox Controls lq^he__h]ooIu?da_g>ktHeop=`]lpan6± Ouopai*Sa^*QE*Sa^?kjpnkho*=`]lpano*Sa^?kjpnkh=`]lpan w lner]paIu?da_g>ktHeop?da_g>ktHeop?kjpnkh w cap w napqnj$$Iu?da_g>ktHeop%?kjpnkh%7 y y lnkpa_pa`kranne`arke`Naj`an>acejP]c$Ouopai*Sa^*QE*DpihPatpSnepansnepan% Download at WoweBook.Com

387

388

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

w snepan*SnepaHeja$%7 snepan*Snepa>acejP]c$p]^ha%7 snepan*Snepa$DpihPatpSnepan*P]cNecdp?d]n%7 snepan*Ej`ajp''7 y lnkpa_pa`kranne`arke`Naj`anAj`P]c$Ouopai*Sa^*QE*DpihPatpSnepansnepan% w snepan*SnepaAj`P]c$p]^ha%7 snepan*SnepaHeja$%7 snepan*Ej`ajp))7 y lnkpa_pa`kranne`arke`Naj`an?kjpajpo$Ouopai*Sa^*QE*DpihPatpSnepansnepan% w osep_d$?da_g>ktHeop?kjpnkh*Nala]p@ena_pekj% w _]oaNala]p@ena_pekj*Dknevkjp]h6 snepan*Snepa>acejP]c$pn%7 snepan*Ej`ajp''7 snepan*Snepa$DpihPatpSnepan*P]cNecdp?d]n%7 bkn$ejpe9,7e8?da_g>ktHeop?kjpnkh*Epaio*?kqjp7e''% w snepan*Snepa>acejP]c$p`%7 snepan*Snepa$DpihPatpSnepan*P]cNecdp?d]n%7 Naj`an?da_g^kt$snepan(e%7 snepan*SnepaAj`P]c$p`%7 y snepan*SnepaAj`P]c$pn%7 snepan*Ej`ajp))7 ^na]g7 _]oaNala]p@ena_pekj*Ranpe_]h6 bkn$ejpe9,7e8?da_g>ktHeop?kjpnkh*Epaio*?kqjp7e''% w snepan*Snepa>acejP]c$pn%7 snepan*Snepa$DpihPatpSnepan*P]cNecdp?d]n%7 snepan*Snepa>acejP]c$p`%7 snepan*Snepa$DpihPatpSnepan*P]cNecdp?d]n%7 Naj`an?da_g^kt$snepan(e%7 snepan*SnepaAj`P]c$p`%7 snepan*SnepaAj`P]c$pn%7 y ^na]g7 y y lner]parke`Naj`an?da_g^kt$DpihPatpSnepansnepan(ejpe% w Ei]caeic9jasEi]ca$%7 H]^ahh9jasH]^ah$%7 eb$?da_g>ktHeop?kjpnkh*EpaioWeY*Oaha_pa`% w eic*Ei]caQnh9L]ca*?heajpO_nelp*CapSa^Naokqn_aQnh$pdeo*CapPula$%( Opnejc*Bkni]p$=lnaoo*Atpajoe^ehepu*=`]lpano*Naokqn_ao*w,y*ljc( ?da_g>ktHeop?kjpnkh*KjEi]ca%%7 h*Patp9Opnejc*Bkni]p$w,y$kj%( Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

?da_g>ktHeop?kjpnkh*EpaioWeY*Patp%7 y ahoa w eic*Ei]caQnh9L]ca*?heajpO_nelp*CapSa^Naokqn_aQnh$pdeo*CapPula$%( Opnejc*Bkni]p$=lnaoo*Atpajoe^ehepu*=`]lpano*Naokqn_ao*w,y*ljc( ?da_g>ktHeop?kjpnkh*KbbEi]ca%%7 h*Patp9Opnejc*Bkni]p$w,y$kbb%( ?da_g>ktHeop?kjpnkh*EpaioWeY*Patp%7 y eic*PkkhPel9?da_g>ktHeop?kjpnkh*EpaioWeY*R]hqa7 eic*Naj`an?kjpnkh$snepan%7 h*Naj`an?kjpnkh$snepan%7 y y A ?da_g>ktHeop supports a Naj`an@ena_pekj property, which has several more features not fully supported by this example. To obtain the right render direction, a table is used that either grows to the right by adding 8p`: tags, or downwards using 8pn:8p`: pairs. The private Naj`an?da_g^kt method is used to create the content. To simplify this, built-in controls are employed and their internal Naj`an method is used through the public Naj`an?kjpnkh method. This ensures that the other adapters responsible for Ei]ca and H]^ah controls will work as expected. In Listing 9-4, an embedded resource is used, and the properties the custom control exposes are accessed in order to obtain the correct resource. The assembly attributes (Sa^Naokqn_a=ppne^qpa) described previously define the embedded resources, which are retrieved by means of the CapSa^Naokqn_aQnh method. When building HTML, it’s often necessary to write parts of a tag, empty lines, or other characters. The DpihPatpSnepan class has several public constant values to support such characters. Table 9-4 explains the characters returned by the constants. Table 9-4. Constant Characters and Strings As Defined in HtmlTextWriter

Constant

Character Description

DefaultTabString

Represents a single tab character

$OUBLE1UOTE#HAR

"

Represents the quotation mark (") character

%ND4AG,EFT#HARS


Represents the left angle bracket and slash mark of the closing tag

%QUALS#HAR

=

Represents the equals sign

EqualsDoubleQuoteString

=""

Represents an equals sign with a double quotation mark

3ELF#LOSING#HARS

/

Represents a space and the self-closing slash mark of a markup tag

3ELF#LOSING4AG%ND

/>

Represents the closing slash mark and right angle bracket of a self-closing tag

3EMICOLON#HAR

;

Represents a semicolon

3INGLE1UOTE#HAR

'

Represents an apostrophe

3LASH#HAR

/

Represents a forward slash

3PACE#HAR

Represents a space character

3TYLE%QUALS#HAR

:

Represents the style equals character used to set style attributes equal to values

4AG,EFT#HAR

<

Represents the opening angle bracket of a markup tag

4AG2IGHT#HAR

>

Represents the closing angle bracket of a markup tag Download at WoweBook.Com

389

390

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

The code should now run as expected. Figure 9-5 illustrates the output of the preceding example.

Figure 9-5. A CheckBoxList that displays images Although the result may seem unimpressive, my intention was to demonstrate how to modify the render behavior of an existing control. The benefit here is that the other parts of the control that do not affect rendering still function as expected. Developers can choose between using this or another render behavior, depending on their application’s needs or device capabilities. )MAGINETHATAVERYBASICCLIENTCANTRENDERCHECKBOXES BUTITCANRENDERIMAGES#REATING a new ?da_g>ktHeop control would require a lot more work than simply editing the adapter.

Why Use HtmlTextWriter? You may be wondering why the DpihPatpSnepan plays such an important role. After all, when building HTML, the Opnejc>qeh`an is frequently the better and faster alternative. There are several reasons. First, the DpihPatpSnepan has a number of useful predefined characters and strings, as shown in Table 9-4. Second, it handles indentation well when formatting HTML line by line. This would require additional code with Opnejc>qeh`an. Third, it is associated with the output stream, which means that the content is written directly to the output (Naolkjoa*KqplqpOpna]i). This is the fastest way to transmit the response to the Web Server. However, there are some disadvantages to the DpihPatpSnepan. If you create your own DpihPatpSnepan, you might associate it with a OpnejcSnepan/Opnejc>qeh`an pair in order to retrieve the content. But using the writer exposed by the adapter classes, you can’t access the stream with anything but write access, and any attempt to read the content will fail.

Configure the Example To configure the code, you only need to make an entry in a .browser file. For this example, I define a file called MyClient.browser and place it in the default folder for browser definition files, App_Browser. 8^nksoano: 8^nksoannabE@9@ab]qhp: 8_kjpnkh=`]lpano: 8]`]lpan]`]lpanPula9=lnaoo*Atpajoe^ehepu*=`]lpano*Iu?da_g>ktHeop=`]lpan _kjpnkhPula9=lnaoo*Atpajoe^ehepu*=`]lpano*Iu?da_g>ktHeop+: 8+_kjpnkh=`]lpano: 8+^nksoan: 8+^nksoano: This is everything you need. Launch the application and the adapter will start working.

Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

Writing a Custom Page Adapter A L]ca=`]lpan is like a ?kjpnkh=`]lpan in that it’s the preferred way to change the behavior of a page without altering either markup or code. As explained previously, pages are responsible not only for the rendering process but also for saving view state and for several life cycle events. A typical usage scenario involves the view state behavior under specific circumstances. For example, if a client device has a low-bandwidth connection, sending the view state to the client and back during postback will result in disappointed users. However, to demonstrate creating a custom page adapter I will tackle a simplified scenario.

Steps for Creating the Example The L]ca=`]lpan functions exactly like the ?kjpnkh=`]lpan. You’ll need the adapter class and a .browser file in order to configure it. Listing 9-5 shows the code which writes the page’s source at the end of the page. Listing 9-5. Simple PageAdapter to Append Page Source lq^he__h]ooOkqn_aL]ca=`]lpan6L]ca=`]lpan w lnkpa_pa`kranne`arke`Aj`Naj`an$Ouopai*Sa^*QE*DpihPatpSnepansnepan% w Opna]iNa]`anon9Beha*KlajPatp$± pdeo*L]ca*Oanran*I]lL]pd$pdeo*L]ca*Namqaop*Qnh*Hk_]hL]pd%%7 snepan*SnepaBqhh>acejP]c$lna%7 pdeo*L]ca*Oanran*DpihAj_k`a$on*Na]`PkAj`$%(snepan%7 on*?hkoa$%7 snepan*SnepaAj`P]c$lna%7 ^]oa*Aj`Naj`an$snepan%7 y y The writer is used to write the page’s content from a Opna]iNa]`an object. This contains page code read directly from the disk. Figure 9-6 assumes that the page is available.

NNote

The example writes the content after all regular content, including the closing 8+dpih: tag. This results in invalid HTML. However, all common browsers render this, despite the discrepancy.

The configuration activates this for all clients. Imagine a workstation that you have configured FORTESTINGPURPOSES/NITYOUHAVESETTHE5SER AGENTSTRINGMANUALLYINORDERTOSENDAPRIVATEKEY to the server. The .browser file recognizes this private key and activates the adapter only for requests from the testing computer. It will be the only client to receive the content rendered with source. Everyone else will see only the conventional page output. You won’t need to set anything in web.config, or in code, or anywhere else.

NCaution

Several examples recommend calling the Naj`an?deh`naj method in order to send the rendered content of a page to a private PatpSnepan. This would not work with an adapter, as the adapter would be summoned again for the subsequent call, which would lead to an endless loop and eventually to a Op]_gKranbhksAt_alpekj.

Download at WoweBook.Com

391

392

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

Figure 9-6. The page used for the ControlAdapter example and content exposed by the page adapter Listing 9-6 shows another way to play with DpihPatpSnepan. Instead of exposing the server-side source, I want expose the HTML sent to the client below the page. Listing 9-6. PageAdapter to Append Rendered Page Source lq^he__h]oo?heajpOkqn_aL]ca=`]lpan6L]ca=`]lpan w DpihPatpSnepanejpanj]hSnepan7 DpihPatpSnepanjasSnepan7 Opnejc>qeh`ano^7 lnkpa_pa`kranne`arke`>acejNaj`an$DpihPatpSnepansnepan% w ejpanj]hSnepan9snepan7 o^9jasOpnejc>qeh`an$%7 jasSnepan9jasDpihPatpSnepan$jasOpnejcSnepan$o^%%7 ^]oa*>acejNaj`an$jasSnepan%7 y lnkpa_pa`kranne`arke`Naj`an$DpihPatpSnepansnepan% w ^]oa*Naj`an$jasSnepan%7 opnejcdpih9o^*PkOpnejc$%7 snepan*Snepa$dpih%7 snepan*Snepa>acejP]c$lna%7 snepan*Snepa$DpihPatpSnepan*Ol]_a?d]n%7 snepan*Snepa=ppne^qpa$opuha(^kn`an6okhe`-lt^hqa%7 snepan*Snepa$DpihPatpSnepan*P]cNecdp?d]n%7 snepan*SnepaAj_k`a`Patp$dpih%7 snepan*SnepaAj`P]c$lna%7 y y

Download at WoweBook.Com

C H A P T E R 9 N C O N T R O L E X T E N S I B I LI T Y

The original writer is now replaced by a custom one in the >acejNaj`an method. In Render it allows you to access your own writer instance and write the content to a string using PkOpnejc of the Opnejc>qeh`an object. First, the string is written back to the original writer. The remaining part creates a 8lna: tag and a border style to place the encoded content in, as shown in Figure 9-7.

Figure 9-7. The page used for the ControlAdapter example and rendered content exposed by the page adapter Both examples are very limited in their capabilities. They show the basic principles as well as the power you get when dealing on a low level with the content. However, keep in mind that changing the render behavior is an option to extend ASP.NET when needed.

NCaution Before considering the usage of adapters, the common techniques should be tried first. The complete render framework is complex, and you might experience weird behavior if it is not implemented completely or correctly.

Configure the Examples To configure the code, you’ll just need to make an entry in a .browser file. In the first example, I define a file called MyClient.browser and place it in the default folder for browser definition files, App_Browser. 8^nksoano: 8^nksoannabE@9@ab]qhp: 8_kjpnkh=`]lpano: 8]`]lpan]`]lpanPula9=lnaoo*Atpajoe^ehepu*=`]lpano*Okqn_aL]ca=`]lpan _kjpnkhPula9Ouopai*Sa^*QE*L]ca+: 8+_kjpnkh=`]lpano: 8+^nksoan: 8+^nksoano: This is everything you need. Launch the application and the adapter will start working. If you combine the L]ca=`]lpan with the ?kjpnkh=`]lpan example shown previously, you can put two

Download at WoweBook.Com

393

394

CH APT ER 9 N C ONTR OL EX TENS IB IL ITY

8]`]lpan: tags within the same 8_kjpnkh=`]lpano: section. The only reason to split it into several sections or files is to activate it for different kinds of client devices. For the second example, simply replace the class name Okqn_aL]ca=`]lpan with ?heajpOkqn_aL]ca=`]lpan to activate this.

Summary In this chapter, you looked at a method of extending a core part of ASP.NET—control renderING5SINGADAPTERS YOUCANASSIGNRELATIONSHIPSBETWEENACONTROLANDITSADAPTER!DAPTERSCAN change render behavior, persistence of view state and control state, and the treatment of controls during specific states of their life cycle. Page adapters are specialized control adapters supporting alternative behavior of the page’s render and state persistence processes. Adapters can be used in conjunction with device filters in order to render controls differently for devices that can’t handle ordinary HTML. Mobile devices especially suffer when it comes to large view states, complex content with several levels of nested TABLES OROTHERCONTENTORIGINALLYDESIGNEDFORPOWERFULMACHINES5SINGCONTROLADAPTERSALLOWS you to replace render behavior with a lean, device-specific version, without changing application code, page markup, or your custom controls.

Download at WoweBook.Com

Index

Special characters pattern, 181 = (EqualsChar constant), 389 ="" (EqualsDoubleQuoteString constant), 389 /> (SelfClosingTagEnd constant), 389 > (TagRightChar constant), 389 " (DoubleQuoteChar constant), 389 / (SelfClosingChars constant), 389 / (SlashChar constant), 389 ; (SemicolonChar constant), 389 ' (SingleQuoteChar constant), 389 : (StyleEqualsChar constant), 389

A ABC mnemonic, 298 access control lists (ACLs), 348 AcquireRequestState pipeline state, 257 actionFlags parameter, 265 adaptive control behavior control adapters, 376–379 default behavior, 374–375 device-specific filter for adaptive behavior, 381–384 overview, 373–374 page adapters, 379–380 add command, 55 Add method, 52 AddEditorControl method, 227 AddNode method SiteMapProvider, 346 StaticSiteMapProvider, 352 AddOnPreRenderCompleteAsync method, 141–142 AddUsersToRoles method, 280 AJAX (Asynchronous JavaScript and XML), 325 allowPathInfo attribute, 145 AnonymousAuthenticationModule module, 109 AnonymousIdentificationModule class, 112 App_Browsers folder, 383 App_GlobalResources folder, 197 App_LocalResources folder, 197 AppDomainAppVirtualPath property, 218 AppDomains enumerating, 63–64 HttpApplication instances, 17

loading .NET runtime, 10–11 overview, 60 unloading all, 62 unloading specific, 60–61 AppendTrailingSlash property, 358 AppInitialize method, 355 Application collection, 246 application pipeline overview, 21–22 request arrival HttpApplication class, 24 IIS6 versus IIS7, 23–24 overview, 22–23 request processing, 24 request receiving, 23 response objects, 23 application pool, 7 ApplicationManager class, 23 ApplicationName method PersonlizationProvider base class, 330 Profile Provider class, 311 ApplicationName property Membership Provider classes, 279 Role Provider classes, 281 ApplicationPhysicalPath property, 357 ApplicationPool property, 57 ApplicationVirtualPath property, 357 AppSettingsExpressionBuilder class, 181 ArgumentNullException, 160 .asax extension, 4 .ascx extension, 122 .ashx extension, 4 .asmx extension, 3–4, 122 ASP.NET application pipeline overview, 21–22 request arrival, 22–24 control state, 33 data binding events, 30–31 defined, 2 dynamic control events, 29–30 IIS7 integrated pipeline, 21 login control events, 31 .NET runtime, 9–10, 13 overview, 1 page life cycle considerations, 29 events, 27–28 395

Download at WoweBook.Com

396

NINDEX

ASP.NET (continued) Master page, 25 overview, 25 page request stages, 26–27 from view state perspective, 33–43 request handling HttpApplication class, 13–17 HttpContext class, 13–14 HttpHandler class, 19 HttpModule class, 19 life cycles, 20–21 .NET runtime, 8 pipeline, 18–19 request arrival, 7 request lifetime, 2–6 view state anti-patterns, 44–52 overview, 31–33 role of, 43–44 aspnet_Configurations property, 170 aspnet_isapi.dll, 3 Aspnet_regsql.exe tool, 262 aspnetdb.mdf database, 348 AspNetHostingPermission attribute, 356 .aspx extension, 3–5, 19, 122 Assembly Resource Loader (WebResource.axd), 122 Asynchronous JavaScript and XML (AJAX), 325 asynchronous operations, threading ASP.NET, 77–81 custom thread pool asynchronous handlers, 81–87 creating, 87–105 overview, 77 asynchronous pages configuring default Web Server, 144 development environment, 144 IIS7 settings, 144–145 overview, 143 using generic handlers, 146 using IIS Management Console, 145 overview, 138 preparing pages for asynchronous operation, 138–139 using public Web Service, 140–141 Attributes property, 347 Authenticate event, 31 AuthenticateRequest event, 273 authentication modules, 116–117, 276 preparing, 333–334 authorization modules, 276–277 techniques, 274 AuthorizationStoreRoleProvider class, 280

AuthorizeRequest event, 273 AutoEventWireup attribute, 27 .axd extension, 4

B base classes implementing security, 348 overview, 344–346 sitemap nodes in code, 347 basePath attribute, 272 BasicAuthenticationModule module, 109 Begin/End pattern, 141–142 BeginMethod method, 142 BeginProcessRequest method, 82, 85 BeginRender method, 393 BeginRender property, 377 BinaryFormatter type, 257 Browser property ControlAdapter base class, 377 HttpRequest class, 374 built-in handlers, 122 built-in providers, 156–157

C CacheRefreshInterval property, 281 CacheVaryByHeaders property, 381 CacheVaryByParams property, 381 caching modules, 110, 112 CalculateSHA1 method, 289, 294 CallbackValidator attribute, 176 section, 324 CertificateMappingAuthenticationModule module, 109 CfgExpressionEditor type, 190 CfgExpressionEditorSheet type, 190 CgiModule module, 110 _Change events, 42 change tracking, 39 ChangePassword method, 279 ChangePasswordQuestionAndAnswer method, 279 CheckBoxList class, 389 child controls, initializing, 48–49 ChildNodes property, 347 Class attribute, 146 classKey parameter, 208 client side-driven Profile provider exposing profile settings to AJAX, 325 JavaScript, 327–328 overview, 325 user interface, 326 clientConnectedCheck attribute, 66, 70 ClientState property, 381 CodeBehind attribute, 146 CodeExpression method, 187 CodeMethodInvokeExpression method, 187

Download at WoweBook.Com

NI N D E X

CodePrimitiveExpression method, 187 CodeTypeReferenceExpression method, 187 ColorElement class, 178 Combine property, 358 CommitChanges method, 57 CompilerOptions attribute, 146 CompleteRequest method, 117 compression modules, 110 ComVisible attribute, 10 .config (Forbidden Handler), 122 config parameter, 160 element, 159 configuration, accessing declaratively advanced expressions, 188–189 creating expression builders, 183–187 design-time support, 189–190 expression syntax, 181–183 extending expression binding syntax, 181 implementing expression builders with design-time support, 190–195 non-compiled pages, 187–188 overview, 181 configuration sections anatomy of, 174 attributes, 176 class model, 175 defining, 176–179 overview, 153, 174 scaffolding, 174 using, 180 ConfigurationElement class, 174–175 ConfigurationManager class, 180 ConfigurationProperty attribute, 172 ConfigurationSection class, 174–175 ConfigurationValidationModule module, 111 ConnectionStringsExpressionBuilder class, 181 content modules, 109 content parameter, 222 context parameter, 188 control adapters CSS-friendly, 385 device-friendly, 385 overview, 385 using, 376–379 writing custom configuring example, 390 creating example, 385 example code, 386–390 HtmlTextWriter, 390 overview, 385 Control events, 28 control extensibility adaptive control behavior default behavior, 374–375 device-specific filter for adaptive behavior, 381–384

overview, 373–374 using control adapters, 376–379 using page adapters, 379–380 control adapters CSS-friendly, 385 device-friendly, 385 overview, 385 writing custom, 385–390 overview, 373 page adapters, writing custom, 391–394 Control property ControlAdapter base class, 377 WebControlAdapter, 378 control state, 33, 247–249 ControlAdapter base class, 376, 377 ConvertFromString method, 324 ConvertToString method, 324 cookies, 246, 258–259 cpuMask attribute, 66 CreateChildControls method, 52 CreateChildControls property, 377 CreateDesignTimeLocalResourceWriter method, 211 CreateNewStoreData method, 265 CreateRole method, 280 CreateSessionID method, 260 CreateSupportedUserCapabilities method, 330 CreateUninitializedItem method, 265–266 CreateUser method, 279, 290 CreateWorkerRequest method, 12 CSS adapters friendly to, 385 reading dynamic from resource, 131 ctrlId parameter, 222 culture parameter, 222 Cultures.xml file, 220 CurrentCulture property, 212 CurrentNode property, 345 CurrentNotification property, 23 CustomDesignTimeResourceProviderFactory type, 209 CustomErrorModule module, 109 CustomLoggingModule module, 111 CustomResourceWriter, 201 CustomThreadPool class, 88

D -d databasename option, 262 data binding events, 30–31 data stores, 154 DataBinding event, 31 DataBound event, 31 DataContract attribute, 292 DataMemberAttribute attribute, 292 DataReader object, 352 DataSourceID property, 28

Download at WoweBook.Com

397

398

NINDEX

Debug attribute, 146 debugging design-time extensions, 218–219 modules and handlers overview, 146 using IIS, 147–151 declare prefix, 182 DecryptPassword method, 279 DefaultAuthenticationModule class, 112 DefaultDocumentModule module, 110 DefaultTabString class, 389 DefaultValue attribute, 176 delete command, 55 DeleteInactiveProfiles method, 311 DeleteProfiles method, 311 DeleteRole method, 280 DeleteUser method, 279 Description method, 330 Description property Role Provider class, 281 SiteMapNode, 347 SiteMapProperty, 345 WebHandler directive, 146 DeserializationSection method, 160 Deserialize method, 257 deserializing, 252, 312 DesignerHost class, 211 design-time stage, 199 design-time support overview, 209 registering debugging, 218–219 overview, 209–218 DesignTimeResourceProviderFactory base class, 209 DetermineInitialScope method, 330 DeterminePostBackMode member, 381 DetermineUserCapabilities method, 330 devenv.exe file, 219 device-friendly adapters, 385 device-specific filter, 381–384 diagnostic modules, 111 Dictionary value, 206 DigestAuthenticationModule module, 109 DirectoryExists method, 370 DirectoryListingModule module, 110 Dispose member, 264 Dispose method, 116–117 Domain Name System (DNS), defined, 3 DoubleQuoteChar constant ("), 389 do-while loop, 207 downloading IIS7 managed modules starter kit, 113 DropDownList control, 29 dynamic control events, 29–30

dynamic controls attaching, 50–51 initializing, 51–52 view state, 39 DynamicCompressionModule module, 110 DynamicMethod method, 372

E ECB (Extension Control Block), 9–10 edit.gif image, 227 EditIndex property, 248 editing resources at runtime function of, 219–223 online editor, creating, 223–242 overview, 219 EditorAttribute class, 190 embedded resources, 386 enable attribute, 66 Enabled attribute, 332 EnableLocalization property, 345 EnablePasswordReset property, 279 EnablePasswordRetrieval property, 279 EnableSessionState="ReadOnly" attribute, 264 EncryptPassword method, 279 End method, 117 EndRender property, 377 EndRequest method, 86, 264 EndTagLeftChars constant ( element, 182 ExpressionEditorSheet class, 190 ExpressionPrefix parameter, 189 ExpressionValues class, 186 Extension Control Block (ECB), 9–10 extension mapping, 5–6 extensions, ISAPI, 5, 9

Download at WoweBook.Com

NI N D E X

F FailedRequestsTracingModule module, 111 FastCgiModule module, 110 file operation classes, 357–358 FileAuthorizationModule class, 112 file-based session state persister configuring provider, 271–272 overview, 271 FileCacheModule module, 110 FileCleanupProvider class, 255 FileExists method, 370 FileStream class, 132 FindChildren method, 367 Findfiles method, 367 FindInactiveProfilesByUserName method, 311 FindProfilesByUserName method, 311 FindSiteMapNode method, 346 FindSiteMapNodeFromKey method, 346 FindState method, 330 FindSubDirectories method, 367 FindUsersByEmail method, 279 FindUsersByName method, 279 FindUsersInRole method, 280 FontElement class, 177 Forbidden Handler (.config), 122 forcing defaults, 46 FormsAuthenticationModule class, 112, 276 FromBase64String method, 338

G gate keepers, 273 GetAllInactiveProfiles method, 311 GetAllNodes property, 347 GetAllProfiles method, 311 GetAllRoles method, 280 GetAllUsers method, 279 GetAncestor method, 352 GetCacheDependency method, 370 GetCfg method, 186–187 GetChildNodes method, 346 GetCodeExpression method, 182–183, 186 GetCountOfState method, 330 GetCurrentNodeAndHintAncestorNodes method, 346 GetCurrentNodeAndHintNeighborhoodNodes method, 346 GetDataSourceView property, 347 GetDirectory method, 367, 370 GetDirectory property, 358 GetExplicitResourceString property, 347 GetExtension property, 358 GetFile method, 367, 370 GetFileName property, 358 GetHandler method, 135–136 GetHierarchicalDataSourceView property, 347 GetImplicitResourceString property, 347

GetInvariantResxPathAtDesignTime method, 215, 217 GetItem method, 258, 264, 265 GetItemExclusive method, 264–265 GetNumberOfInactiveProfiles method, 311 GetNumberOfUsersOnline method, 279, 290 GetObject method, 201, 207 GetParentNode method, 346 GetParentNodeRelativeToCurrentNodeAndHintDownFromParent method, 346 GetParentNodeRelativeToNodeAndHintDownFromParent method, 346 GetParentSiteMapNode method, 352 GetPassword method, 279 GetPossibleResourceList method, 230 GetPostBackFormReference property, 381 GetPropertyValues method, 311, 324 GetRadioButtonsByGroup property, 381 GetRequests method, 59 GetResources method, 206 GetResourceWriter method, 201 GetResxPath method, 218 GetRolesForUser method, 281 GetRoot method, 352 GetRootNodeCore method, 346 GetRootNodeCoreFromProvider method, 346 GetStandardValues method, 194 GetStandardValuesSupported method, 194 GetStatePersister property, 380–381 GetString method, 352 GetUser method, 279, 285 GetUserNameByEmail method, 279 GetUserProfile method, 324 GetWebResourceUrl method, 389 global resources, 198 global.asax file, 355 GridView property, 248

H Handler property, 137 handlers advanced usage of, 136–138 asynchronous pages configuring, 146 overview, 138 preparing pages for asynchronous operation, 138–139 using public Web Service, 141 building entry point, 125–126 handlers that don't create content, 131–133 image handler, 126–128 overview, 124 reading dynamic CSS from resource, 131 using IHttpHandlerFactory to perform URL rewriting, 133–136

Download at WoweBook.Com

399

400

NINDEX

handlers (continued) built-in, 122 debugging overview, 146 using IIS, 147–151 defined, 107 HTTP, 122–124 overview, 19, 107–108, 122 tracing, setting up for, 151 HasChildNodes property, 347 Headers property, 23 health monitor, 254–256 HiddenField control, 254 HiddenFieldPageStatePersister base class, 249 HideDisabledControlAdapter class, 378 HierarchicalDataBoundControlAdapter class, 378 HierarchyId column, 349 HierarchyId data type, 348, 352 Hint methods, 346 HintAncestorNodes method, 346 HintNeighborhoodNodes method, 346 HostingEnvironment class, 23, 358 HtmlForm control, 34 HtmlTextWriter class, 374, 389–390 HTTP handlers defined, 1 overview, 122–124 scenarios for using, 123 HTTP modules, 109 HTTP runtime, 2 HttpApplication class, 13–17, 24, 115 HTTPCacheModule module, 110 HttpContext class, 13–14, 23, 88 HttpHandler class, 19 HttpLoggingModule module, 111 HttpModule class, 19, 115–116 HttpRedirectionModule module, 109 HttpRequest object, 23–24 HttpResponse object, 23 HttpRuntime object, 256 tag, 71 HttpStaticObjectsCollection type, 257

I IAsyncResult interface, 83, 142 Id property, 63 Identity property, 274 IDesignerHost interface, 210 IDesignTimeResourceWriter interface, 212 Idle property, 63 idleTime attribute, 66 idleTimeout attribute, 69 IFRAME element, 131–133 IHttpAsyncHandler interface, 81, 123 IHttpHandler interface, 5, 123 IHttpHandlerFactory interface, 133–136

IHttpHandlerFactory2 interface, 134 IHttpModule interface, 5, 24 IIS Management Console configuring asynchronous pages using, 145 configuring modules using, 122 IIS6 (Internet Information Services 6) versus IIS7, 23–24 thread usage, 70–71 IIS7 (Internet Information Services 7) versus IIS6, 23–24 integrated pipeline, 21 modules managed, 111–115 native, 108–111 overview, 108 thread usage busy server, 73 configuring ThreadPool, 72–73 overview, 71–72 worker process AppDomains, 60–64 basic tasks, 56–57 configuration backup, 55 configuring, 64–68 prerequisites, 54 retrieving information about, 57–60 specific tasks, 68–70 task management, 54–55 IISCertificateMappingAuthenticationModule module, 109 image handler, 126–128 ImageDataDataContext class, 168 ImageProvider class, 171 ImageProviderSection class, 172 impersonation, 277 includeExceptionDetailInFaults attribute, 300 Init event, 27, 29, 39 Init method, 116–117 InitComplete event, 27 Initialize method Membership Provider class, 279 overview, 157, 160–162, 168 Profile Provider class, 311 RegisterVirtualPathProviderInternal class, 356 SiteMapProvider class, 346 InitializeCulture method, 27 InitializeRequest member, 264 InProcSessionStateStore class, 261 instantiation, 34–38 IntegerValidator attribute, 176, 178 internal session state providers InProcSessionStateStore class, 261 OutOfProcSessionStateStore class, 262 overview, 260–261 SqlSessionStateStore class, 262–263 internal site map provider, 341–343

Download at WoweBook.Com

NI N D E X

internationalization, 197 Internet Information Services 6. See IIS6 Internet Information Services 7. See IIS7 Internet Service API (ISAPI), 2, 4–5 IPostBackDataHandler interface, 40–42 IpRestrictionModule module, 109 IPrincipal interface, 274 IReadOnlySessionState interface, 136–137 IRequiredSessionState interface, 136 IResourceProvider interface, 212 IsAbsolute property, 358 IsAccessibleToUser method, 346 IsAccessibleToUser property, 347 ISAPI (Internet Service API), 2, 4–5 IsapiFilterModule module, 110 IsapiModule module, 110 ISAPIRuntime class, 10 ISAPIWorkerRequest object, 12–13 ISAPIWorkerRequestInProc class, 13 ISAPIWorkerRequestInProcForIIS7 type, 13 IsAppRelative property, 358 IsApproved property, 295 IsDefaultCollection attribute, 176 IsDescendantOf property, 347 IsDesignerViewLocked property, 212 IsEnabled property, 378 IServiceProvider interface, 210 ISessionIDManager interface, 259 IsInRole method, 274 IsKey attribute, 176 IsLoading property, 212 IsLockedOut property, 295 IsPostBack property, 26–27 IsPostNotification property, 23 IsRequired attribute, 176 IsReusable property, 124 IsUserInRole method, 281 Item property, 347 ItemCreated event, 31 ItemDataBound event, 31 IWebFormsDocumentService interface, 212, 214

J JavaScript, 327–328

K Key property, 347

L Language attribute, 146 life cycles, 20–21. See also page life cycle lifetime provider, 161 request, 2–6 list command, 55 LiteralControl controls, 34

Load event, 28–29 Load method, 254 load page request stage, 26 LoadAdapterControlState property, 377 LoadAdapterViewState property, 377 LoadComplete event, 28 LoadControl class, 371–372 LoadMe function, 240 LoadPersonalizationBlobs method, 330 LoadPersonalizationState method, 330 LoadPostData method, 40–41 LoadProviders method, 165 LoadResource method, 222 localization, 343 lock statement, 161–162 Log Request state, 22 LoggedIn event, 31 logging modules, 111 LoggingIn event, 31 login control events, 31 LoginError event, 31 logLevel attribute, 66 LongValidator attribute, 176

M machine.config file, 64–65 MakeRelative property, 358 managed modules overview, 111–113 starter kit benefits of, 113–115 downloading, 113 overview, 113 ManagedEngine module, 111 Map Handler state, 22 MapPath property, 357 markupTextWriterType attribute, 384 Master page life cycle, 25 maxAppDomains attribute, 66 maxconnection attribute, 74–75 MaxInvalidPasswordAttempts property, 279 maxIoThreads attribute, 66, 74 maxWorkerThreads attribute, 66, 74 MeasureString method, 128 Membership providers developing configuring provider, 308 configuring services, 298–300 implementing provider, 300–308 overview, 282 testing provider, 308–309 Web service-driven, 282–298 extending, 281–282 Membership service, 155–156, 277 MembershipUser class, 306 memoryLimit attribute, 66, 68 MemoryStream object, 130

Download at WoweBook.Com

401

402

NINDEX

Menu control, 341–342 MenuAdapter class, 378 MenuItemClick event handler, 333 meta:resourcekey attribute, 223 mexHttpBinding attribute, 299 minFreeThreads attribute, 71, 74 minIoThreads attribute, 66 minLocalRequestFreeThreads attribute, 71, 74 MinRequiredNonAlphanumericCharacters property, 279 MinRequiredPasswordLength property, 279 minWorkerThreads attribute, 66, 74 MissHandler method, 207 mode attribute, 276 modules building checking for specific headers, 117–119 defining, 115–116 overview, 115 writing simple authentication module, 116–117 configuring, 120–122 debugging overview, 146 using IIS, 147–151 IIS7 architecture managed modules, 111–115 native modules, 108–111 overview, 108 interaction between, 119–120 overview, 18–19, 107–108 modules attribute, 145 Modules property, 120 Monitor method, 162 Multi Threaded Apartment (MTA), 17

N name attribute, 121 Name method, 330 Name property Membership Provider class, 279 overview, 157 SiteMapNode, 347 SiteMapProvider class, 345 NameValueCollection class, 160 native modules, 108–111 NavigateControl method, 225 NavigateUrl property, 347 .NET Reflector, 8 .NET runtime handling requests within, 12–13 loading, 10–11 overview, 8–9 processes, 9–10 threads, 9–10 NextSibling property, 347 NotImplementedException method, 163

O onError function, 327 OnInit event, 47–48 OnInit method, 376 OnInit property, 377 online editor, creating, 223, 242 OnLoad event, 28, 47 OnLoad property, 377 onLoadSuccess function, 327 OnPreInit event, 49 OnPreRender property, 377 OnUnload property, 377 OperationContract attribute, 283, 285 Options attribute, 176 OutOfProcSessionStateStore class, 262 OutputCacheModule class, 112

P page adapters adaptive control behavior, 379–380 writing custom configuring example, 393–394 creating example, 391–393 overview, 391 Page Handler (.aspx), 122 page initialization, 26 page life cycle considerations, 29 events, 27–28 Master page, 25 overview, 25 page request stages, 26–27 from view state perspective initializing, 39 instantiation, 34–38 loading postback data, 40–41 loading step, 42 loading view state, 39–40 overview, 33 raising postback events, 42 rendering page, 43 storing view state, 43 page management control state, 247–249 overview, 245 page state persister, 245–246 page state provider, 251–256 view state, 247 Page property, 377 page request stages, 26–27 load, 26 overview, 26 page initialization, 26 postback event handling, 26 rendering, 26 start, 26

Download at WoweBook.Com

NI N D E X

unload, 27 validation, 26 page state persister, 245–246 page state provider default, 250–251 developing custom analyzing, 252 data storage, 252 extending, 254 health monitor, 254–256 implementing, 252–254 overview, 251–252 PageAdapter property, 377 PageHandlerFactory, 107, 133 pageId parameter, 222 PageIndex property, 248 Pagename.resx file, 197 PageStatePersister base class, 249 PageStatePersister property, 251 parentID attribute, 384 ParentNode property, 347 ParentProvider property, 345 ParseExpression method, 182–183, 186, 188 partial keyword, 34 PassportAuthenticationModule, 276 PasswordAttemptWindow property, 280 PasswordFormat property, 280 PasswordStrengthRegularExpression property, 280 path attribute, 144 path operation classes, 357–358 Path property, 347 Performance Counter, installing, 75–77 persisting cheap data, 46–48 constant data, 46 personalization providers authentication, 333–334 configuring, 339 creating, 334–339 implementing, 331–339 overview, 331 Portal page, 331–333 Web Parts implementing, 331–339 overview, 329–331 testing, 339 PersonalizationState class, 329 PhysicalPath property, 63 pingFrequency attribute, 67, 69 pingTimeout attribute, 67, 69 Portal page, 331–333 PositiveTimespanValidator attribute, 176 postback event handling, 26 precompiled sites, 372 preCondition attribute, 121, 145 PreInit event, 27, 222

PreLoad event, 28 PreRender event, 28 PreviousHandler property, 137 PreviousSibling property, 347 ProcessEvent method, 256 ProcessGuid method, 57 processing pipeline, defined, 1 <processModel> tag, 65, 68, 72, 77 ProcessRequest method, 9, 12, 33, 123, 125, 173 Profile class, 317 profile handling modules, 112 Profile providers client side-driven exposing profile settings to AJAX, 325 JavaScript, 327–328 overview, 325 user interface, 326 configuring, 314 extending configuring, 314 defining profile settings, 312–313 overview, 310 Profile service, 310 serializing and deserializing, 312 using Profile data, 313 implementing, 319–325 overview, 314 preparation steps, 314–319 Profile service, 155–156, 278, 310 element, 325 ProfileAuthenticationOption parameter, 312 ProfileModule class, 112 ProfileService class, 327 PropertyGrid control, 324 propertyType parameter, 189 Protected Configuration service, 155–156 ProtocolSupportModule module, 109 provider element, 255 ProviderBase class, 157, 165–166, 267 ProviderCollection class, 170 ProviderException class, 160 ProviderHelper class, 165 providers anatomy of configuring, 158–160 making available, 158 overview, 157 built-in extending, 156–157 overview, 156 configuring, 308 considerations initialization procedure, 160 lifetime, 161 overview, 160 thread safety, 161 custom provider-based service

Download at WoweBook.Com

403

404

NINDEX

providers (continued) configuring providers, 170–172 creating provider, 165–170 creating service, 164–165 limitations of code samples, 163 overview, 163 using service, 172–173 default, 154–155 goals of, 154 implementing, 300–308 Membership developing, 282–309 extending, 281–282 overview, 153 page state default, 250–251 developing custom, 251–256 personalization authentication, 333–334 configuring, 339 creating, 334–339 implementing, 331–339 overview, 331 Portal page, 331–333 Web Parts, 329–339 Profile client side-driven, 325–328 configuring, 314 extending, 310–314 implementing, 319–325 overview, 314 preparation steps, 314–319 resource configuring, 208 extending provider model, 198–199 implementing, 201–208 overview, 198 prerequisites for, 200 using, 208 Role developing, 282–309 extending, 281–282 session state internal, 260–263 overview, 256 session state service, 256–258 session state store file-based session state persister, 267–272 handling expired data, 266 locking session-store data, 266 overview, 264 session state module, 264–266 setting application name, 266 sitemap base classes, 344–348 internal, 341–343 localization, 343

overview, 341, 344 prerequisites, 344 reasons to customize, 343 security, 343 SQL server-based navigation, 348–353 testing, 308–309 <providers> section, 319 public Web Service, 140–141

R raising postback events, 42 ReadAllText class, 254 ReaderWriterLock class, 133, 162 ReadOnly property, 263, 347 ReferenceManager property, 212 referrers, 117–118 regenerateExpiredSessionId="true" attribute, 259 RegexStringValidator attribute, 176, 179 RegisterAsyncTask method, 141 registering design-time support debugging, 218–219 overview, 209–218 RegisterRadioButton property, 381 RegisterRequiresControlState method, 248 RegisterVirtualPathProvider property, 357 ReleaseItemExclusive method, 265–266 RemapHandler property, 137–138 RemoteOnly property, 177 RemoveItem method, 258, 265–266 RemoveNode method, 346 RemoveTrailingSlash property, 358 RemoveUsersFromRoles method, 281 Render method, 26, 377 Render property, 378 RenderBeginHyperlink property, 381 RenderBeginTag property, 378 RenderCheckbox method, 389 RenderChildren method, 376 RenderChildren property, 377 RenderContents property, 378 RenderControl method, 374, 389 RenderDirection property, 389 RenderEndHyperlink property, 381 RenderEndTag property, 378 rendering page request stage, 26 RenderPostBackEvent property, 381 request arrival ASP.NET, 7 HttpApplication class, 24 IIS6 versus IIS7, 23–24 overview, 22–23 request processing, 24 request receiving, 23 response objects, 23 request handling HttpApplication class, 13–17

Download at WoweBook.Com

NI N D E X

HttpContext class, 13–14 HttpHandler class, 19 HttpModule class, 19 life cycles, 20–21 .NET runtime handling requests within, 12–13 loading, 10–11 overview, 8–9 threads, 9–10 pipeline, 18–19 request arrival, 7 request lifetime extension mapping, 5–6 ISAPI, 4–5 overview, 2–4 RequestFilteringModule module, 109 requestLimit attribute, 67–68 RequestMonitorModule module, 111 RequestNotification enumeration, 22 requestQueueLimit attribute, 67, 73 requireAccess attribute, 144 RequiresQuestionAndAnswer property, 280 RequiresUniqueEmail property, 280 ResetPassword method, 279 ResetPersonalizationBlob method, 330 ResetPersonalizationState method, 330 ResetState method, 330 ResetUserState method, 331 ResolveSiteMapNode method, 346 resource management principles fallback strategy, 197–198 global resources, 198 limitations of existing provider, 198 overview, 197 resource model, extending design-time support, 209–219 editing resources at runtime, 219–242 overview, 197 resource management principles, 197–198 resource provider, programming custom, 198–208 resource providers configuring, 208 extending provider model, 198–199 implementing, 201–208 overview, 198 prerequisites for, 200 using, 208 resource reader, 207–208 ResourceExpressionBuilder class, 181 ResourceKey property, 345, 347 ResourceReader class, 201 ResourceReader property, 215 ResourceTuple class, 206 resourceType attribute, 144–145 responseDeadlockInterval attribute, 67, 69 restartQueueLimit attribute, 67

restore command, 55 .resx files, 198–199, 206, 219 resx.gif image, 227 ResXResourceReader class, 208 ResXResourceWriter class, 218 RetrieveImage method, 164–166, 168, 170, 173 Role providers developing configuring provider, 308 configuring services, 298–300 implementing provider, 300–308 testing providers, 308–309 Web service-driven, 282–298 extending, 281–282 Role service, 155–156, 278 RoleExists method, Role Provider classes, 281 RoleManagerModule class, 112 roles attribute, 277 Roles elements, 295 Roles property, 347 RoleService class, 298 RootComponent property, 211 RootNode property, 345, 347 RootProvider property, 345 RowCreated event, 31 RowDataBound event, 31 rules element, 255

S -S servername option, 262 Save method, 254, 298 SaveAdapterControlState property, 377 SaveAdapterViewState property, 377 SavePersonalizationBlob method, 331, 338 SavePersonalizationState method, 331 SaveResource method, 222 SaveStateComplete event, 28 ScopeName property, 281 Script resource handler (ScriptResource.axd), 122 ScriptManager control, 231 scriptProcessor attribute, 144 ScriptResource.axd (Script resource handler), 122 SectionAttribute attribute, 165, 172 security. See also user management base classes, 348 modules, 109, 112 site map providers, 343 SecurityTrimmingEnabled property, 345, 348 select clause, 64 SelfClosingChars constant (/), 389 SelfClosingTagEnd constant (/>), 389 SemicolonChar constant (;), 389 serialization method, 252 SerializationSection method, 160 Serialize method, 257

Download at WoweBook.Com

405

406

NINDEX

serializeAs attribute, 313 serializing, 312 serverErrorMessageFile attribute, 67 ServerManager class, 57 ServerSideIncludeModule module, 110 ServerVariables property, 24 service oriented architectures (SOA), 281 service tier, 283 [ServiceContract] attribute, 283 services, defined, 154 Session collection, 246 session handling modules, 112 session management overview, 245 session state providers identifying session, 258–260 improving session state, 263 internal, 260 overview, 256 session state service, 256–258 session state store provider file-based session state persister, 267–272 handling expired data, 266 locking session-store data, 266 overview, 264 session state module, 264–266 setting application name, 266 session state handlers, 136–137 session state providers identifying session, 258–260 improving session state, 263 internal InProcSessionStateStore class, 261 OutOfProcSessionStateStore class, 262 overview, 260–261 SqlSessionStateStore class, 262–263 overview, 256 session state service, 256–258 session state service, 155–156, 256–258 session state store providers file-based session state persister configuring provider, 271–272 overview, 267–271 handling expired data, 266 locking session-store data, 266 overview, 264 session state module, 264–266 setting application name, 266 sessionIDManagerType attribute, 260 SessionPageStatePersister class, 251–252 sessionState element, 271 SessionStateItemCollection type, 257 SessionStateModule class, 112, 264 SessionStateStoreData class, 256 SessionStateStoreProviderBase class, 257 SetAndReleaseItemExclusive method, 265–266 SetItemExpireCallback method, 265–266

SetPropertyValues method, 311 shared resources, 198 shutDownTimeout attribute, 67, 69 Single Threaded Apartment (STA), 17 SingleQuoteChar constant ('), 389 site management overview, 341 sitemap providers base classes, 344–348 custom, 343 implementing SQL server based navigation, 348–353 internal site map provider, 341–343 localization, 343 overview, 341, 344 prerequisites, 344 reasons to customize, 343 security issues, 343 suggestions for extending example, 354 VirtualPathProvider limitations of, 371–372 overview, 354 path and file operation classes, 358 prerequisites for, 356 registering, 355–356 themes, getting from database, 358–371 using, 355 Site Map service, 155, 156 sitemap providers base classes implementing security, 348 overview, 344–346 sitemap nodes in code, 347 internal, 341–343 localization, 343 prerequisites, 344 reasons to customize, 343 security, 343 SQL server-based navigation configuring custom provider, 352–353 creating provider, 349–352 overview, 348 preparing database, 348–349 testing provider, 353 SiteMapDataSource control, 341–342 SiteMapPath control, 341–342 SiteMapProvider class, 344 SiteMapResolve event, 346 SiteName property, 357 SlashChar constant (/), 389 Sleep call, 16 Sleep method, 83 SOA (service oriented architectures), 281 SortDirection property, 248 SpaceChar constant, 389 SQL server based navigation configuring custom provider, 352–353

Download at WoweBook.Com

NI N D E X

creating provider, 349–352 overview, 348 preparing database, 348–349 testing provider, 353 SqlPersonalizationProvider class, 329 SqlProfileProvider class, 310 SqlSessionStateStore class, 262–263 -ssadd option, 262 -ssremove option, 263 -sstype c option, 263 -sstype p option, 263 -sstype t option, 263 STA (Single Threaded Apartment), 17 start page request stage, 26 State property, 57 state storage, 247 StateBag class, 39, 41, 50, 247, 252 StateFormatter class, 254 stateless protocol, 245 StaticCompressionModule module, 110 StaticFileModule module, 110 StaticObjects property, 257 StaticSiteMapProvider class, 344 stickiness, 41, 47 storing view state, 43 stress test tool, 79–81 StringValidator attribute, 176, 178–179 StyleEqualsChar constant (:), 389 SubclassTypeValidator attribute, 176 SubStatusCode property, 23 SupportsEvaluate class, 183, 187 .svc extension, 4 System.serviceModel section, 299

T TagLeftChar constant (<), 389 TagRightChar constant (>), 389 tagwriter, 383 testing providers, 308–309 TextWriter class, 385 theme parameter, 222 themes, getting from database configuring path provider, 371 creating VirtualPathProvider, 358–370 overview, 358 prepare project, 358 thread safety, 161 ThreadInfo class, 97, 99 ThreadPool class, 70–73 threads asynchronous operations ASP.NET, 77–81 custom thread pool, 81–105 overview, 77 IIS6, 70–71 IIS7, 71–73 .NET runtime, 9–10

overview, 53, 70 tune threading installing performance counter, 75–77 overview, 73 tasks, 73–75 ThreadWrapper class, 99 TimeExpressionEditor type, 192 TimeExpressionEditorSheet type, 193 timeout attribute, 67–68 TimespanValidator attribute, 176 Title property, 347 ToAbsolute property, 358 ToAppRelative property, 358 TokenCacheModule module, 110 TokenParser class, 186 Trace Handler (trace.axd), 122 tracing, 151 TracingModule module, 111 TransactionDescription property, 211 TransformText property, 381 TreeView control, 341–342 trigger events, 42 tune threading installing performance counter, 75–77 overview, 73 tasks, 73–75 type attribute, 121, 144–145 Type property, 347 typeConverter attribute, 194, 324 TypeConverterAttribute class, 190

U UICulture property, 26 unified request processing pipeline, 21 UniqueID property, 26 Unload event, 28 unload page request stage, 27 unloadFunc() method, 62 UnlockUser method, 279 UpdateUser method, 279, 306 UriCacheModule module, 110 Url property, SiteMapNode, 347 URL rewriting, 133–136 UrlAuthorizationModule class, 109, 112 UrlMappingsModule class, 112 useHostingIdentity attribute, 264 User Control Handler (.ascx), 122 user management authentication modules, 276 authorization modules, 276–277 interfaces extensibility issues, 278–281 overview, 277–278 Membership and Role providers configuring provider, 308 configuring services, 298–300 extending, 281–282

Download at WoweBook.Com

407

408

NINDEX

user management (continued) implementing provider, 300–308 overview, 282 testing providers, 308–309 Web service-driven, 282–298 overview, 273–275 Profile provider, custom client side-driven, 325–328 implementing provider, 319–325 overview, 314 preparation steps, 314–319 Profile providers configuring, 314 overview, 310–313 Profile service, 310 Web Parts personalization providers implementing, 331–339 overview, 329–331 testing, 339 UserAgent property, 130 userAgent tag, 383 UserData class, 290, 298 username attribute, 67 users attribute, 277

V Validate method, 26, 260 ValidateUser method, 279 ValidatingPassword event, 279 validation page request stage, 26 validator.gif image, 227 Value property, 347 verb attribute, 144, 277 view state anti-patterns attaching dynamic controls, 50–51 forcing defaults, 46 initializing child controls, 48–49 initializing dynamically created controls, 51–52 overview, 44 persisting cheap data, 46–48 persisting constant data, 46 overview, 31–33 page life cycle from perspective of initializing, 39 instantiation, 34–38 loading postback data, 40–41 loading step, 42 loading view state, 39–40 overview, 33 raising postback events, 42 rendering page, 43 storing view state, 43 role of, 43–44 __VIEWSTATE field, 33, 39, 43 ViewStateDecoder tool, 250

VirtualFile instance, 370 virtualPath parameter, 208 VirtualPath property, 63 VirtualPathProvider class limitations of, 371–372 overview, 354 path and file operation classes, 357–358 prerequisites for, 356 registering, 355–356 themes, getting from database configuring path provider, 371 creating VirtualPathProvider, 358–370 overview, 358 preparing project, 358 using, 355 VirtualPathProvider property, 357 VirtualPathUtility class, 358 VirtualThemeDirectory class, 360 VirtualThemeFile class, 359

W WarningLevel attribute, 146 WAS (Windows Process Activation Service), 54 WCF (Windows Communication Foundation), 282 Web Events service, 155 Web Parts personalization providers authentication, 333–334 configuring, 339 creating, 334–339 overview, 329–331 Portal page, 331–333 testing, 339 Web Parts service, 155–156 Web Service Handler (.asmx), 122 Web service-driven membership providers, 282–298 Web service-driven role providers, 282–298 web.config section, 314, 325 WebControlAdapter base class, 378 webGarden attribute, 67 WebHandler directive, 146 WebHeartbeatEvent class, 254, 255 webpart.gif image, 227 WebResource.axd (Assembly Resource Loader), 122 web.sitemap XML file, 341 where clause, 60, 62 Windows Communication Foundation (WCF), 282 Windows Management Instrumentation (WMI), 53–54 Windows Process Activation Service (WAS), 54 WindowsAuthenticationModule class, 109, 112, 276 WindowsTokenRoleProvider class, 280

Download at WoweBook.Com

NI N D E X

WMI (Windows Management Instrumentation), 53–54 worker process AppDomains enumerating, 63–64 overview, 60 unloading all, 62 unloading specific, 60–61 basic tasks, 56–57 configuration backup, 55 configuring attributes, 65–67 machine.config file, 64–65 overview, 64 processModel tag, 68 overview, 53 prerequisites, 54 retrieving information about executing requests, 59–60 overview, 57 state of worker process, 57–58

specific tasks checking client connection, 70 overview, 68 recycling, 68–69 shutting down, 69 task management, 54–55 WorkerProcess object, 57 WorkerProcesses property, 58 WorkRequest class, 102 WriteAllText class, 254 wsHttpBinding class, 299 WSRoleProvider class, 306

X XmlArrayItem attributes, 293 XmlElement attribute, 290 XmlResourceHelper class, 215 XmlSiteMapProvider provider, 341 XPath expressions, 338

Download at WoweBook.Com

409

Download at WoweBook.Com

Download at WoweBook.Com

Offer valid through 1/2010.

Download at WoweBook.Com