Improving Performance Through Caching

The best way to improve the performance of an ASP.NET application is through caching. The e-commerce application takes extensive advantage of the new caching features of the ASP.NET 2.0 Framework.

The list of products, list of featured products, and list of categories are displayed with three user controls named ProductView.ascx, FeaturedProductView.ascx, and CategoryView.ascx. All three of these user controls include an <%@ OutputCache %> directive that includes a SqlDependency attribute.

All three user controls use a Polling SQL Cache dependency. The user controls cache data in memory until the data changes in the underlying database. For example, the list of featured products displayed on the home page (Default.aspx) is cached by the FeaturedProductView.ascx user control. The rendered output of this user control is cached in memory until the contents of the Products database table is changed.

The product information displayed by the ProductDetails.aspx page is also cached. However, in this case, the caching is performed at the level of the DataSource control rather than at the level of a User Control. The product information is retrieved from an ObjectDataSource control. The ObjectDataSource control is configured to use a Polling SQL Cache Dependency.

Warning

The e-commerce application is configured to poll the database for changes every 15 seconds so data can be up to 15 seconds out of date. You can configure a shorter interval by modifying the pollTime attribute of the <sqlCacheDependency> element in the web configuration file.

Finally, the customer shopping carts are cached in Session state. When a shopping cart is first retrieved from the database for a customer, the shopping cart is added to Session state and remains there until the shopping cart is modified or the customer leaves the website.