(.NET - ASP.NET) Improved Caching in ASP.NET 2.0

Stephen Walther looks at the new caching features included in ASP.NET 2.0, and how you can use them to improve the performance and scalability of your ASP.NET applications.

The most dramatic way to improve the performance of a database driven Web application is through caching. Retrieving data from a database is one of the slowest operations that you can perform in a Web site. If, however, you can cache the database data in memory, then you can avoid accessing the database with every page request, and dramatically increase the performance of your application.

The one and only drawback to caching is the problem of stale data. If you cache the contents of a database table in memory, and the records in the underlying database table change, then your Web application will display old, inaccurate data. For certain types of data you might not care if the data being displayed is slightly out of date, but for other types of data—such as stock prices and auction bids—displaying data that is even slightly stale is unacceptable.

The initial release of the Microsoft ASP.NET framework did not provide a good solution to this problem. When using the ASP.NET 1.0 framework, you just had to live with this tradeoff between performance and stale data. Fortunately, the Microsoft ASP.NET 2.0 framework includes a new feature called SQL Cache Invalidation that solves this very problem.

In this article, you'll learn about many of the new caching enhancements in the ASP.NET 2.0 framework. First, you'll learn how caching support has been integrated into the new DataSource controls. Next, you'll learn how to configure and take advantage of SQL Cache Invalidation. Finally, we'll take a look at a new control introduced with the ASP.NET 2.0 framework, which enables you to inject dynamic content into a cached page: the Substitution control.