Java Servlet store with Rails session

I want to avoid coupling between my rails application and JAVA SERVLET session Store. Let me explain.
What I do is that initially ( only for authentication and authorization i use java hence session created in java) the session data created from java i get through
jee_req = request.env['java.servlet_request']
abc= jee_req.get_session.get_attribute("abc")
Then next step i put the data obtained in rails session :

session[:abc] = abc

However in my other controllers I am getting session[:abc] as nil. As per my knowledge ( working properly in rails 2.3.5 and jruby 1.5.0 in production), putting data in rails session created an object in tomcat session store as _current_rails_session with the data .

Now with the new version i see the same object created in java servlet store (in tomcat) however it is not able to get the sesion data from rails session directly . For example:
abc = session[:abc]
gives abc as nil
I believe there is something broken in between wherein java session is not updating data in rails session

I want this de coupling because if at any point I decide to deploy it as a standalone rails aplication ( not Jruby on rails) i should be able to do so with very minimal changes.