Screaming Penguin

Oreillys OnJava has a good article entitled Another Java Servlet Filter Most Web Applications Should Have. It contains a good overview of filters in general and also HTTP request and responses. Elementary stuff but still a good combination of putting it all together. The actual filter enumerated in the article is one that controls the cache-control HTTP header. It can be useful but I dont know about that "most should have" stuff. This can be implemented many ways and the level of granularity often required (some stuff to cache, some not, different headers for different browsers and browser versions, despite the HTTP spec, etc) while possible to do with a filter would be quite complicated, and it would IMHO be better handled by a reverse proxy server configured to take care of the task.