Purpose
The server libraries are an important part of Ajax IM’s flexibility. Depending on the server library you use, you can run Ajax IM purely on PHP and MySQL or using the (much better option of the) Node.js server.
Additionally, you can implement your own server library that works with your existing authentication system and the Node.js server (or just Ajax IM’s MySQL database).
Building your own library
Creating a new server library is easy! Head over to the Custom Server page to learn how to build your own PHP library.
Using something other than PHP?
It is possible to use another language besides PHP (as the Node.js server uses the Memcache protocol for its API), however, Ajax IM currently only officially supports PHP. If there is significant enough interest, other languages may be considered for support.
JSP and/or Servlet support please! Thousands of JSP/Servlet-based systems exist around the world and I am sure many would take advantage of this great library. (No offense to PHP; but there are other very popular server platforms that continue to grow)