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Proxying with Apache

The standard Apache module mod_proxy supports both types of proxy operation. Under Apache 1.x, mod_proxy only supported HTTP/1.0, but from Apache 2.0, it supports HTTP/1.1. This distinction is particularly important in a proxy, because one of the most significant changes between the two protocol versions is that HTTP/1.1 introduces rich new cache control mechanisms.

This article deals with running a reverse proxy with Apache 2. Users of earlier versions of Apache are encouraged to upgrade and take advantage of the altogether richer architecture and improved application support. At the time of writing, the reason most commonly cited for not upgrading is difficulties running PHP on Apache 2. I cannot speak from personal experience, but several well-informed sources tell me the difficulty lies with non-thread-safe code in PHP, and that it works well with Apache 2 if it is built with the non-threaded Prefork MPM.