adding support for PHP to a web server

Hello, I've written a small web server and I'd like to add support for php to the server. Could anyone direct me to documentation or examples and give me some sense of how hard this would be. Put another way, if I have a working PHP installation and a web server how do the two communicate? The webserver is written in javascript running on rhino which in turn runs on java so probably the access would be through java. Thanks Terry