Unfortunately, there is really no good way you can tell if content displayed by your browser was GZIP compressed or not. Part of the process working is that it is unnoticeable if the content was compressed or not. In order to test out the compression, we need to spoof some HTTP requests and see what exactly is returned.
This can be done relatively easily by tossing some code in a JSP; here is such a JSP.
OSCache comes with a servlet filter that enables you to transparently cache entire pages of your website, and even binary files. Caching of binary files is extremely useful when they are generated dynamically, e.g. PDF files or images. In addition by using the last modified header the transaction overhead and server load is reduced excellently which speed ups the server response time.
How to configure OSCache to cache entire servlet responses is described in the configuration page of the CacheFilter. This short tutorial should demonstrate how to make your web site more responsive, and save load on your server. Using the CacheFilter the user will appreciate a faster loading site and will visit it more often.
Major improvements have been made to the CacheFilter in the releases 2.2 and 2.3: