Haroldo Try to separate ServletContext and HttpSessions, ServletContext is the
java representation of the application, and HttpSession is the java representation of a stateless session (statless protocol, HTTP). A session is just shared between contexts if you are inside a distributable application, also notice that the session will only transfer between context (the full object), there is no way to have parts of the session shared between containers, Take a look at HttpSessionActivationListener.
feel free to send me an e-mail, or a private message, in Portuguese if you preffer, maybe I can have more chances to help you using your native language (Portuguese isn't it?).