Using APE with PHP

I'm a little confused on how APE (Ajax Push Engine) works.

1. How do you know which connection to push to, making sure the user is correct, from a PHP application?
2. Is it a Apache extension? Independent server? ETc...

Some explanations would be awesome, thanks!

APE uses a independent HTTP/Comet server that allows, for example, long-polling. It needs some configuration made to the Apache server running beside it. It uses as server-side javascript framework for the development of modules.

On the client side of things it uses a javascript framework that receives information sent by the APE server, handles data, and send back the users requests. When the page is loaded a new client is created with var client = new APE.Client(); and from then on the client is connected to the server.

More information here