Recent traffic analysis suggests that a third of all documents carry cookies, almost a quarter contain queries, and many popular pages now carry rotating advertising banners. The problem with traditional web caches is that they treat pages as datagrams. However, due to dynamic content, they ought to be trated as objects comprising content plus code. Kevin proposed that mobile code should be attached to web pages in the form of cache applets which would be executed at caching proxies. A prototype based on this approach has been written in Java, the language chosen for practical reasons only.
Web servers mark URL as having an associated cache applet.
When the URL is requested the proxy invokes the cache applet. Examples of cache applets include those which log URL accesses and that generate client specific pages based on client preferences. This is done by using a type safe language, station examination of applet code and resource accounting so as to enforce consumption limitations. Each web server is a security entity and applets from different servers cannot collaborate. As a by-product of the work, it was noticed that string operations and file read accesses are not performant in existing applets.