valueUnbound() ?

[Laurent Rouvet <la...@roovay.com>]

Does someone can confirm if it works or not with Tomcat 5.x ?


Nikla Ratinen wrote:
> Hi,
> 
> Overriding valueUnbound() works in Jetty but not in 
> Tomcat (4.1.27). The reason is that Tomcat calls valueUnbound()
> of the old listener each time the new listener is set to the HTTP
> session. Tapestry engine gets stored to session after (almost) every
> request even if its already there, therefore resulting in valueUnbound()
> called at the end of each request. Jetty is wise enough to check
> for parameter equality and calls valueUnbound() on old parameter
> only if the new and old values are not equal.
> 
> If anybody knows a better way I would like to hear it, 
> but at least this works:
> 
> ----------- MyEngine.java ---------
> 
> public class MyEngine extends BaseEngine 
> {
>     public static String SESSION_LISTENER = "session_listener";
> 
>     public boolean service(RequestContext context)
>         throws ServletException, IOException
>     {
>         HttpSession session = context.getSession();
>         if (session != null &&
>             session.getAttribute(SESSION_LISTENER) == null)
>         {
>             session.setAttribute(SESSION_LISTENER, 
>                         new SessionEndListener(this));
>         }
>         return super.service(context);
>     }
> }  
> 
> --------- SessionEndListener.java ------------
> 
> public class SessionEndListener
>     implements HttpSessionBindingListener,
>                Serializable
> {
>     private IEngine engine;
>     public SessionEndListener(IEngine engine)
>     {
>         this.engine = engine;
>     }
>     
>     public void valueBound(HttpSessionBindingEvent hsbe)
>     {
>     }
> 
>     public void valueUnbound(HttpSessionBindingEvent hsbe)
>     {
>         if (engine != null)
>         {
>             // Cleanup code here
>         }
>         engine = null;
>     }
> }
> 
> -----------------------------------------------
> 
> 
> Rgds, 
> -- Nikla
> 
> 
> On Wed, 2004-06-16 at 00:49, Hensley, Richard wrote:
> 
>>I need to detect an invalidated session from a Tapestry application. The
>>purpose is to detect when the container times a session out so clean up work
>>can be done.
>>
>>I noticed that AbstractEngine implements the HttpSessionBindingListenter.
>>Can I simply extend BaseEngine override valueUnbound?
>>
>>That method would be implemented something like
>>
>>    public void valueUnbound(HttpSessionBindingEvent arg0) {
>>        super.valueUnbound(arg0);
>>        Visit visit = (Visit)getVisit();
>>        if (visit != null) {
>>            visit.cleanup();            
>>        }
>>    }
>>
>>I think this would mean that anytime the container discards the session, or
>>the session is invalidated by Tapestry, this method will get called.
>>
>>Is this the best way to detect this situation?
>>
>>According to the JavaDoc for Servlet 2.3
>>
>>"When an application stores an object in or removes an object from a
>>session, the session checks whether the object implements
>>HttpSessionBindingListener. If it does, the servlet notifies the object that
>>it has been bound to or unbound from the session. Notifications are sent
>>after the binding methods complete. For session that are invalidated or
>>expire, notifications are sent after the session has been invalidatd or
>>expired."
>>
>>So I think I have the right animal. :)
>>
>>Richard Hensley
>>
>>
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