AFAIK, it is not possible, as a session is identified by the browser/
client and not the real human being. There is no way for the Server to
know that session X, Y and Z are from the same machine but different
browser instances. You might want to reconsider the UI design and/or
the session management (do not use session variables that change often
- like transactional attributes) and/or provide a link for the users
to spawn out separate windows from within the application's web pages
as then they'd share the same session. The resource usage due to
sessions depends on how much and what data you stick in there. Ideally
they should be lightweight, and not hold information that is transient
across requests. Session scoped variables are mostly read-only or
relatively constant like a user's profile.

-cheers,
Manish

polilop wrote :

Well you cannot bind two session together. What you can do is make sure
that the information stored in each of the sessions assigned to a
particular user is the same.

The web.xml definition allows for a hook into the session
creation/destruction process. Use the web.xml <listener-class> tag to
have your application handle this.

Then you can link the sessions together for a single user using
whatever mechanism you want.