End of session operations

Question

Hi
I have this problem with Tomcat 6.0:
I have a bean in session scope that is responsible for executing some MySQL operations (creating tables, inserting rows, deleting...etc). All these operations are temporary and the tables created by the this bean have to be deleted when the session is invalidated. I added these two methods to my bean:
public class ResultsBean implements Serializable, HttpSessionBindingListener
  /* Bind / Unbind operations */
  public void valueBound(HttpSessionBindingEvent event)
    //System.out.println("resultsBean was loaded!");
    this.sessionID = event.getSession().getId();
    init();
  public void valueUnbound(HttpSessionBindingEvent event)
    //System.out.println("resultsBean was unloaded!");
    finish();
}finish(), cleans up the tables the bean has created during the session.
The problem is that i would always have leftovers in MySQL from past sessions (not all but some). I know that the problem is somewhere with the invalidation process because looking into the logs I cannot see any attempts to cleanup the database for the sessions that left the mess.
My webapp web.xml is configured with 2 minutes timeout.
How can I initiate a proper cleanup process whenever a session is invalidated?
Is it possible to make a background process in Tomcat similar to Java's garbage collector?
Thanks!

Answer 1

That's what I was missing I didn't know the web.xml had a <listener> tag.
SessionCleaner.java:
package listeners;
import javax.servlet.http.*;
public class SessionCleaner implements HttpSessionListener
  /* Session Listener */
  public void sessionCreated(HttpSessionEvent sessionEvent)
    System.out.println("Session created: " + sessionEvent.getSession().getId());
  public void sessionDestroyed(HttpSessionEvent sessionEvent)
    System.out.println("Session ended: " + sessionEvent.getSession().getId());
}web.xml:
<!-- Listeners -->
<listener>
     <listener-class>listeners.SessionCleaner</listener-class>
</listener>
.Works like a charm.
stdout log:
Session created: 0E953FC8AEA6B5BE37F714D72F33DF1F
Session ended: 0E953FC8AEA6B5BE37F714D72F33DF1FThanks for the hint bandarurm!
Edited by: exkor5000 on Feb 27, 2009 5:20 PM