JAASRealm and Subject

[Rogerio Baldini das Neves]

 Hi!
 
 I'm using the Tomcat 5 JAASRealm for authenticating users with my own 
LoginModule. 
In my LoginModule I am populating the Subject object delivered by the Realm 
with Principals, Role Principals and Credentials.
 
 The authentication and the mapping of my user defined roles to tomcat roles 
work fine, but I can´t get a reference to the Subject object in
 my servlets.

I have tried:

AccessControlContext context = AccessController.getContext();
Subject subject = Subject.getSubject(context);

But it´s not working... subject = null;

Can anybody help me, please ?

Rogerio.