Hi Bala,
When you will chose Stateful session bean and Stateless session bean?
In theory SFSBs can maintain state for every client, while SLSBs don�t, etc, etc. I�m not going to bore you with details that you can find in every EJB book.
In practice though the answer is quite different and sounds very simple: stay away from SFSBs as much as you can. One very important treason is that SFSBs don�t scale very well though. Another good reason is that using HttpSession is more efficient solution and you might achieve the same goals. However, there are situation when SFSBs are required and a good example is when developing an application that has rmi clients as well (and you cannot make use of HttpSession).
Regards.