This is surprisingly hard to get right on your first try, I ran into a similar issue not too long ago with a framework I had built myself. This page has a grea

This is surprisingly hard to get right on your first try, I ran into a similar issue not too long ago with a framework I had built myself. This page has a great synopses on how it should be done: http://www.mnot.net/cache_docs/ http://www.mnot.net/cache_docs/