Capture browser close - IHttpSessionManagerUnboundListener

TimDonovan

Hi,

Using DFC/WDK 5.3, I am trying to capture when the user closes the browser.

IHttpSessionManagerUnboundListener is supposed to be used for this. I have done the following:

My component extends IHttpSessionManagerUnboundListener
Added the listener: SessionManagerHttpBinding.addHttpSessionUnboundListener(this);
Implemented unbound(IDfSessionManager idfsessionmanager) - that is supposed to be called when the user closes the browser (or the HTTP session is cleared up).

However unbound() is rarely/never executed (I have seen it executed *once* despite many runs of the code)

Any advice would be greatly appreciated.

Regards,

Tim

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Comments

mszurap

Hi,

The UnboundListener work only when the application server destroys the http session object. This is not done if you do not invalidate your session (e.g. explicitly logout from a wdk application), which is not done when you "unexpectedly" close the browser window.

The solution could be to use an async javascript (AJAX) call in such cases. If you have some luck, you can do so with setting the window.onbeforeunload function (look at the example: http://jebberwocky.spaces.live.com/blog/cns!E6B47C4A2931B4B5!731.entry )

Mike

TimDonovan

I don't think this is quite right Miklos; while I agree it might only work when the app server destroys the HTTP session, the few times I have had it work I have not explicity logged off or invalidated the session. Also, if you shut the browser "unexpectedly" the app server must destroy the HTTP session at some point; it wouldn't persist it forever.

mszurap

If you shut down the browser, the application server is not notified about that. There is an HTTP session timeout setting in every application server, after that idle time the session gets destroyed (except if you turn off this timeout).

So something/somebody must notify the application server on this event (closing the browser), as you asked.

TimDonovan

Granted the app server doesn't know that the browser was shut down, but it will destroy the HTTP session after a period of time, as you state, which is when HttpSessionManagerUnboundListener should be triggered. I have set webtops session-timeout to 1 in web.xml.

sunshine

This is a known issue if you are on Tomcat. Tomcat will only remove HTTPSessions if it suffers from low memory (call the HTTPSession.invalidate() method). When it does that all objects will be de-references and the next garbage collection act will remove them from memory.

You can make a AJAX call to session.invalidate() explicitly, when a browser window is closed. Webtop has devised similar mechanism to address browser close events. See <client_shutdown_session_timeout> configurable parameter and its implementation.