This chapter introduces the method in which ASP.NET manages configuration information. It gives a taste of how ASP.NET configuration works. We'll see details about ASP.NET configuration in later chapters. ASP.NET is a feature-rich system for developing and deploying Web sites. The features we'll see in more detail as we examine ASP.NET further include some the following:

• session state

• caching content to help optimize your Web site's responses

• tracing requests

• mapping specific file extensions to custom handlers

• authenticating users

Each of these features are controlled by a number of separate parameters. For example, when you enable session state for your application, you may choose where to locate your application's session state (in process, on a separate machine using a daemon process, or using SQL Server). You may also configure the lifetime of your session state and how your application tracks the session state (via a cookie or some other method).

A second feature controlled through the configuration file is caching output. When you cache the content of your site, you may vary the lifetime of your cached content and where it's cached (on the server, on the client, or on the proxy).

For both these features (and others) the configuration options are governed by various configuration files. Here we first examine the nature of Windows configuration, and then look specifically at how ASP.NET handles configuration. In ASP.NET 1.x, modifying the configuration of your application meant editing the XML-based configuration file by hand. Fortunately, ASP.NET 2.0 offers two tools that make configuration a much easier proposition. One tool is the ASP.NET configuration tab available through the normal IIS configuration panel. The second tool is the Web site Administration tool, available through the Web site | Web Administration menu in Visual Studio. We'll cover these tools as well.