Top Most How can I prevent the expiration of a Session

You can change the "timeout" value in two ways.

1. To change one or more session (but on a per-session basis), use the setMaxInactiveInterval(int interval) method of the javax.servlet.http.HttpSession interface, passing any value in seconds. If you use a negative value, the session will never expire.
2. To change all the sessions, use the web application descriptor (web.xml):
   ...
   <session-config>
     <session-timeout>[MINUTES]</session-timeout>
   </session-config>
   ...
   If you want the container to never timeout a session, use a [MINUTES] value 0 or less.