Apache: The Definitive Guide, 3rd Edition

Inward Caching

Another reason for using a proxy server is to cache data from the Web to save the bandwidth of the world’s clogged telephone systems and therefore to improve access time on our server. Note, however, that it in practice it often saves bandwidth at the expense of increased access times.

The directive CacheRoot, cunningly inserted in the Config file shown earlier, and the provision of a properly permissioned cache directory allow us to show this happening. We start by providing the directory ... / site.proxy/cache, and Apache then improves on it with some sort of directory structure like ... /site.proxy/cache/d/o/j/gfqbZ@49rZiy6LOCw.

The file gfqbZ@49rZiy6LOCw contains the following:

320994B6 32098D95 3209956C 00000000 0000001E
X-URL: http://192.168.124.1/message
HTTP/1.0 200 OK
Date: Thu, 08 Aug 1996 07:18:14 GMT
Server: Apache/1.1.1
Content-length: 30
Last-modified Thu, 08 Aug 1996 06:47:49 GMT

I am a web site far out there

Next time someone wants to access http://192.168.124.1/message, the proxy server does not have to lug bytes over the Web; it can just go and look it up.

There are a number of housekeeping directives that help with caching.