Apress © 2003 (1200 pages)

Chapter 18: ASP.NET Web Pages and Web Controls

This comprehensive text starts with a brief overview of the

C# language and then quickly moves to key technical and

This chapter begins your study of Web technologies supported under the .NET platform. ASP.NET is a architectural issues for .NET developers.

completely new approach for building Web applications and has absolutely nothing to do with classic (COM-based) ASP. For example, server-side scripting code has been replaced with "real" object-oriented

languages (such as C#, VB.NET, managed C++ and the like). This chapter introduces you to key

Table of Contents

ASP.NET topics such as working with (or without) code behind files, the role of ASP.NET Web controls

C# and the .NET Platform, Second Edition

(including the mighty DataGrid), validation controls, and interacting with the base class libraries from

Introduction

*.aspx files.

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

ChapterChapter2 - Building19: ASPC# Applications.NET Web Applications

Part Two - The C# Programming Language

This chapter extends your current understanding of ASP.NET by examining various ways to handle state

Chapter 3 - C# Language Fundamentals

management under .NET. Like classic ASP, ASP.NET allows you to easily create cookies, as well as

Chapter 4 - Object-Oriented Programming with C#

application-level and session-level variables. However, ASP.NET also introduces a new state

Chapter 5 - Exceptions and Object Lifetime

management technique: the application cache. Once you examine the numerous ways to handle state

with ASP.NET, you then learn the role of the System.HttpApplication base class (lurking within the

Chapter 7 - Callback Interfaces, Delegates, and Events

Global.asax file) and how to dynamically alter the runtime behavior of your Web application using the

Chapter 8 - Advanced C# Type Construction Techniques web.config file.

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 20: XML Web Services

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

In this final chapter of this book, you examine the role of .NET XML Web services. Simply put, a Web

Part Four - Leveraging the .NET Libraries

serviceis an assembly that is activated using standard HTTP requests. The beauty of this approach is the

Chapter 12 - Object Serialization and the .NET Remoting Layer

fact that HTTP is the one wire protocol that is almost uni-versal in its acceptance and is, therefore, an

Chapter 13 - Building a Better Window (Introducing Windows Forms)

excellent choice for building platformand language-neutral distributed systems. You also check out

Chapter 14 - A Better Painting Framework (GDI+)

numerous surrounding tech-nologies (WSDL, SOAP, and UDDI) which enable a Web service and external

Chapter 15 - Programming with Windows Forms Controls client to communicate in harmony.

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

All of the code examples contained within this book (minus small code snippets here and there) are

Apress © 2003 (1200 pages)

available for free and immediate download from the Apress Web site. Simply navigate to

This comprehensive text starts with a brief overview of the

http://www.apress.com and look up this title by name. Once you are on the homepage for C# and

C# language nd then quickly moves to key technical and

the .NET Platform,architecturalSecond Edition,issues youf r .mayNET developersdownload.a self-extracting .zip file. After you unzip the contents, you will find that the code has been logically divided by chapter. Do be aware that the following icon:

Table of Contents

C# andSOURCEthe .N T Platform,is your cueSecondthatEditionthe example under discussion may be loaded into Visual Studio .NET for

CODE further examination and modification. To do so, simply open the *.sln file found in the

Introduction

correct subdirectory.

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

Note All of the source code for this book as been compiled using Visual Studio .NET 2003. Sadly,

Chapter 2 - Building C# Applications

*.sln files created with VS .NET 2003 cannot be open using VS .NET 2002. If you are still

currently running Visual Studio .NET 2002, my advice is to simply create the appropriate project

Chapter 3 - C# Language Fundamentals

work-space, delete the auto-generated C# files, and copy the supplied *.cs files into the project

Chapter 4 - Object-Oriented Programming with C#

using the Project | Add Existing Item menu selection.

Chapter 5 - Exceptions and Object Lifetime Chapter 6 - Interfaces and Collections

Chapter 7 - Callback Interfaces, Delegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

Obtaining UpdatesC# and the .NETforPlatform,This BookSecond Edition

As you read over this text, you may find an occasional grammatical or code error (although I sure hope

Apress © 2003 (1200 pages)

not). If this is the case, my apologies. Being human, I am sure that a glitch or two may be present, despite

This comprehensive text starts with a brief overview of the

my best efforts. IfC#thislanguageis the case,and youthencanquicklyobtainmovesthe currentto key echnicalerrata listandfrom the Apress Web site (located once again on thearc"homepage"itectural issuesfor thisfor book).NET developersas well as. information on how to notify me of any errors you might find.

Table of Contents

C# and the .NET Platform, Second Edition

Introduction

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

Chapter 2 - Building C# Applications

Part Two - The C# Programming Language

Chapter 3 - C# Language Fundamentals

Chapter 4 - Object-Oriented Programming with C#

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

Chapter 7 - Callback Interfaces, Delegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

ContactingC#Meand the .NET Platform, Second Edition

If you have any questions regarding this book's source code, are in need of clarification for a given

Apress © 2003 (1200 pages)

example, or simply wish to offer your thoughts regarding the .NET platform, feel free to drop me a line at

This comprehensive text starts with a brief overview of the

the following e-mailC# addresslanguage(toandensurethen quicklyyour messagesmoves to keydon'ttechnicalend up andin my junk mail folder, please include "C# SE" in the titlearchitecturalsomewhere!):issues<atroelsen@intertechfor .NET developers. -inc.com>.

Please understand that I will do my best to get back to you in a timely fashion; however, like yourself, I get

TablebusyoffromContentstime to time. If I don't respond within a week or two, do know I am not trying to be a jerk or don't C#careandtothetalk.NETto youPlatform,. I'm justSecondbusy (orEditionif I'm lucky, on vacation somewhere).

Introduction

So then! Thanks for buying this text (or at least looking at it in the bookstore, trying to decide if you will buy

Part One - Introducing C# and the .NET Platform

it). I hope you enjoy reading this book and put your newfound knowledge to good use.

Chapter 1 - The Philosophy of .NET

Chapter 2 - Building C# Applications

Take care,

Part Two - The C# Programming Language

ChapterAndrew3Troelsen- C# Language Fundamentals

Minneapolis, MN

Chapter 4 - Object-Oriented Programming with C#

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

Chapter 7 - Callback Interfaces, Delegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

Part One:C#Introducinga d the .NET Platform,C#SecondandEditionthe .NET Platform

Apress © 2003 (1200 pages)

Chapter ListThis comprehensive text starts with a brief overview of the C# language and then quickly moves to key technical and architectural issues for .NET developers.

Chapter 1: The Philosophy of .NET

Table of Contents

Chapter 2: Building C# Applications

C# and the .NET Platform, Second Edition

Introduction

Part One - Introducing C# and the .NET Platform

Chapter 1 - The Philosophy of .NET

Chapter 2 - Building C# Applications

Part Two - The C# Programming Language

Chapter 3 - C# Language Fundamentals

Chapter 4 - Object-Oriented Programming with C#

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

Chapter 7 - Callback Interfaces, Delegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

Chapter C#1:andThethe .NETPhilosophyPlatform, Second Editionof .NET

Overview This comprehensive text starts with a brief overview of the C# language and then quickly moves to key technical and

Every few years ora chitecturalso, THE modernissues forday.NETprogrammerdevelope smust. be willing to perform a self-inflicted knowledge transplant to stay current with the new technologies of the day. The languages (C++, Visual Basic 6.0, Java), frameworks (MFC, ATL, STL), and architectures (COM, CORBA, EJB) that were touted as the silver

Tablebulletsof Contentsof software development, eventually become overshadowed by something better or at very least

C#somethingand the .NETnew.Platform,RegardlessSecondof theEditionfrustration you can feel when upgrading your internal knowledge base,

Introductionit is unavoidable. Microsoft's .NET platform represents the latest wave of (positive) changes coming from

PartthoseOnekind- Introducingfolks RedmondC# a .the .NET Platform

Chapter 1 - The Philosophy of .NET

The point of this chapter is to lay the conceptual groundwork for the remainder of the book. It begins with a

Chapter 2 - Building C# Applications

high-level discussion of a number of .NET-related atoms such as assemblies, the common intermediate

language (CIL), and just-in-time (JIT) compilation. In addition to previewing some key features of the C#

Chapter 3 - C# Language Fundamentals

programming language, you will also come to understand the relationship between various aspects of the

.NET Framework, such as the common language runtime (CLR), the Common Type System (CTS), and

Chapter 5 - Exceptions and Object Lifetime

the Common Language Specification (CLS). As you would hope, many of these topics are explored in

Chapter 6 - Interfaces and Collections

further detail throughout the remainder of this text.

Chapter 7 - Callback Interfaces, Delegates, and Events

ChapterThis chapter8 - Advancedalso providesC# TypeyouConstructionwith an overviewT chniquesof the functionality supplied by the .NET base class

Partlibraries,Threesometimes- Programmingabbreviatedwith .NETasAssthemblies"BCL" or alternatively as the "FCL" (being the Framework Class ChapterLibrary)9. Finally,- Understandingyou examine.NETaAssembliesnumber of helpful utilities (such as ildasm.exe and wincv.exe) that may be

used to investigate the structure of these libraries at your leisure.

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables

Enter Java. The Java programming language is (almost) completely object oriented and has its syntactic

independence. Java (as a language) cleans up the unsavory syntactical aspects of C++. Java (as a

Apress © 2003 (1200 pages)

platform) provides programmers with a large number of predefined "packages" that contain various class

This comprehensive text starts with a brief overview of the

and interface definitions. Using these types, Java programmers are able to build "100% Pure Java"

C# language and then quickly moves to key technical and

applications complete with database connectivity, messaging support, Web-enabled front ends, and a rich- architectural issues for .NET developers.

user interface.

Although Java is a very elegant language, one potential problem is that using Java typically means that

Table of Contents

you must use Java front-to-back during the development cycle. In effect, Java offers little hope of

C# and the .NET Platform, Second Edition

language independence, as this goes against the grain of Java's primary goal (a single programming

Introduction

language for every need). In reality however, there are millions of lines of existing code out there in the

Part One - Introducing C# and the .NET Platform

world that would ideally like to commingle with newer Java code. Sadly, Java makes this task problematic.

Chapter 1 - The Philosophy of .NET

ChapterPure Java2 -isBuildingsimply notC# Aappropriatelications for many graphically or numerically intensive applications. For Partexample,Two - Theif youC#areProgrammingbuilding a graphicsL nguageintensive product (such as a 3D-rendered video game), you will find

Java's execution speed will leave something to be desired. A better approach for such programs would be

Chapter 3 - C# Language Fundamentals

to use a lower-level language (such as C++) where appropriate. Alas, while Java does provide a limited

Chapter 4 - Object-Oriented Programming with C#

ability to access non-Java APIs, there is little support for true cross-language integration.

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

ChaptLifer As7 - aCallbackCOMInterfaces,ProgrammerDelegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

The truth of the matter is, if you are not currently building Java-based solutions, the chances are very good

Part Three - Programming with .NET Assemblies

that you have invested your time and energy understanding Microsoft's Component Object Model (COM).

Chapter 9 - Understanding .NET Assemblies

COM is an architecture that says in effect, "If you build your classes in accordance with the rules of COM,

Chapter 10 - Processes, AppDomains, Contexts, and Threads

you end up with a block of reusable binary code."

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

The beauty of a binary COM server is that it can be accessed in a language-independent manner. Thus,

Chapter 12 - Object Serialization and the .NET Remoting Layer

C++ programmers can build COM classes that can be used by VB. Delphi programmers can use COM

Chapter 13 - Building a Better Window (Introducing Windows Forms)

classes built using C, and so forth. However, as you may be aware, COM's language independence is

Chaptsomewhatr 14 -limitedA B tter Painting Framework (GDI+)

. For example, there is no way to derive a new COM type using an existing COM type (no

Chasupportter 15for- classicalProgramminginheritance)with Windows. Rather,FormsyouControlsmust make use of the more cumbersome "has-a"

Chaprelationshiper 16 - Theto reuseSystemCOM.IO Namespacetypes.

Chapter 17 - Data Access with ADO.NET

Another benefit of COM is its location-transparent nature. Using constructs such as application identifiers

Part Five - Web Applications and XML Web Services

(AppIDs), stubs, proxies, and the COM runtime environment, programmers can avoid the need to work

Chapter 18 - ASP.NET Web Pages and Web Controls

with raw sockets, RPC calls, and other lowlevel details. For example, ponder the following Visual Basic 6.0

Chapter 19 - ASP.NET Web Applications

COM client code:

Chapter 20 - XML Web Services

Index

' This block of VB 6.0 code can activate a COM class written in

List of Figures

' any COM-aware language, which may be located anywhere

List of Tables

c.DoSomeWork

Although COM is a very dominant object model, it is extremely complex under the hood (at least until you have spent many months exploring its plumbing...especially if you happen to be a C++ programmer). To help simplify the development of COM binaries, numerous COM-aware frameworks have come into existence. For example, the Active Template Library (ATL) provides another set of C++ -based classes, templates, and macros to ease the creation of classic COM types.

Many other languages (such as Visual Basic 6.0) also hide a good part of the COM infrastructure from view. However, language support alone is not enough to hide the complexity of classic COM. Even when you choose a relatively simply COM-aware language such as VB 6.0, you are still forced to contend with fragile registration entries and numerous deployment-related issues (collectively termed DLL hell).

Life As a WindowsC# and the .DNANET Platform,ProgrammerSecond Edition

Finally, there is aAprlittlessthing© 2003called(1200 thepages)Internet. Over the last several years, Microsoft has been adding more Internet-awareThisfeaturescomprehensiveinto itstextfamilystartsof operatingwith a briefsystemsoverview. It ofseemsthe that the popularity of Web applications is everC#expandinglanguage and. Sadly,thenbuildingquickly movesa completeto k yWebtechnicalapplicationand using classic Windows DNA

architectural issues for .NET developers.

(Distributed iNternet Architecture) is also very complex.

Some of this complexity is due to the simple fact that Windows DNA requires the use of numerous

Table of Contents

technologies and languages (ASP, HTML, XML, JavaScript, VBScript, COM(+), as well as a data access C#APIandsuchtheas.NETADO)Platform,. One problemSecond Editionis that many of these items are completely unrelated from a syntactic

Introductionpoint of view. For example, JavaScript has a syntax much like C, while VBScript is a subset of Visual Basic

Papropert One. The- IntroducingCOM serversC# andthattheare.NETcreatedPlatformto run under the COM+ runtime have an entirely different look

Chapterand feel1 from- ThethePhilosoASP pageshy of .thatNETinvoke them. The result is a highly confused mishmash of technologies. ChapterFurthermore,2 - Buildingand perhapsC# Applicationsmore important, each language and/or technology has its own type system Part(thatTwotypically- The C#looksProgrammingnothing likeLanguagethe other type systems). An "int" in JavaScript is not the same as an "int" in

C, which is different from an "Integer" in VB proper.

Chapter 3 - C# Language Fundamentals

Chapter 4 - Object-Oriented Programming with C#

Chapter 5 - Exceptions and Object Lifetime

Chapter 6 - Interfaces and Collections

Chapter 7 - Callback Interfaces, Delegates, and Events

Chapter 8 - Advanced C# Type Construction Techniques

Part Three - Programming with .NET Assemblies

Chapter 9 - Understanding .NET Assemblies

Chapter 10 - Processes, AppDomains, Contexts, and Threads

Chapter 11 - Type Reflection, Late Binding, and Attribute-Based Programming

Part Four - Leveraging the .NET Libraries

Chapter 12 - Object Serialization and the .NET Remoting Layer

Chapter 13 - Building a Better Window (Introducing Windows Forms)

Chapter 14 - A Better Painting Framework (GDI+)

Chapter 15 - Programming with Windows Forms Controls

Chapter 16 - The System.IO Namespace

Chapter 17 - Data Access with ADO.NET

Part Five - Web Applications and XML Web Services

Chapter 18 - ASP.NET Web Pages and Web Controls

Chapter 19 - ASP.NET Web Applications

Chapter 20 - XML Web Services

Index

List of Figures

List of Tables