Chapter 16. ASP.NET: A Better ASP

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As noted in Chapter 1, the dominant application model in use today is a multitiered application with a Web-based interface. This model enjoys widespread acceptance in both the Microsoft .NET and Java 2 Enterprise Edition (J2EE) camps. Any framework that provides a foundation for such development must offer good support for developers of the Web- facing parts of the application. At the very least, it must provide abstractions of the low-level interaction between a client and a Web server.

Server-side Web components such as Microsoft Active Server Pages (ASP) running under Microsoft Windows and Java servlets in J2EE provide life-cycle management and object-based interfaces for interacting with the underlying HTTP messages being sent and received. These server-side frameworks also provide easy access to application functionality such as data access, security services, and other custom components written for the application.

However, the expectations surrounding Web-oriented applications are constantly increasing. For example, Web developers are expected to produce rich and powerful browser-based applications in a shorter and shorter time. This means that they need a much more standard infrastructure to help speed up the development of Web-based user interfaces. Another expectation is that an application's functionality should be easily adaptable to new channels and new types of client application and hardware. The clients might include specialist browsers running on handheld, mobile devices as well as Web services that allow other applications to exploit the functionality of your application.

The ASP.NET framework provides support for Web-oriented development in this demanding environment. ASP.NET supports two main types of applications: Web Forms applications, which produce HTML to be rendered in a browser, and Web service applications, which exchange data in XML format.

This chapter describes how the ASP.NET model works and explains the structure of a typical ASP.NET application. We'll concentrate on Web Forms applications and the delivery of content to a Web browser. Web service applications under ASP.NET will be covered in the next two chapters. In examining Web Forms, we'll look at essential aspects of ASP.NET that provide a good foundation for both Web Forms and Web services, such as the ASP.NET life cycle, application-level code, application configuration, and session management. All of the code shown in this chapter is from sample files that are part of the FourthCoffee and ErrorHandling sample projects.

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