One of the new controls introduced with ASP.NET 2.0 was the Substitution control. By using this control, you can create pages that participate in output caching but also have regions designated to contain dynamic content that will be updated on every page request. This type of setup is referred to as Post-Cache Substitution (or Donut Caching) and is aimed at optimizing the development experience for this mostly-cached page scenario. Rather than requiring page developers to mark page regions (user controls) as cached, post-cache substitution allows them to output cache an entire page and then simply identify regions of the page that should be exempt from caching. It also allows control developers to prevent their rendering from being cached. For example, an AdRotator control that takes advantage of post-cache substitution would be able to serve a different advertisement on each request even if its parent page were cached.
Revision number 3, Monday, February 18, 2008 7:21:01 AM by mbanavige