Enterprise Social Network (ESN) is an open-source project to develop a framework of a social network in Java EE 5, EJB 3.0. The objective is to build a basic framework that models a social network graph in Java EE. This basic framework will provide some basic functions of a social network. It can be further extended according to client needs to incorporate a bigger set of end-user functionality. In future, ESN may be developed into a full-fledged out-of-box Java EE based social network product.

The project is released under LGPL. 

Website: http://code.google.com/p/esn/
SVN: http://esn.googlecode.com/svn/
Start wiki page: http://code.google.com/p/esn/wiki/ESN

ESN is not just another public social network such as, MySpace or Orkut.