Caching can be applied to dynamic documents. A large amount of client HTTP requests contain cookies, which are HTTP header elements typically indicating that a request be personalized. As web servers become more sophisticated and customizable, and as one-to-one marketing e-commerce strategies proliferate the Internet, the level of personalization is anticipated to rise. The increasing amount of personalized content makes caching such information difficult and not practical with current proxy designs.
Active caching uses applets, located in the cache, to customize objects that could otherwise not be cached. When a request for personalized content is first issued, the originating server provides the objects and any associated cache applets. When subsequent requests are made for that same content, the cache applets perform functions locally (at the cache) that would otherwise (more expensively) be performed at the originating server. Thus, applets enable customization while retaining the benefits of caching.