Best way to detect browser closing/navigation to other page and do logout

Question

I am writing an application in GWT and I need to detect when a user navigates away from my application or when he closes the browser window (onUnload event) and do a logout (session invalidation and few other cleanup tasks). The logout action is performed by a servlet.

I am currently doing this by hooking into the onUnload() event and opening a new window pointed to the logout servlet.

Is there a better way to do this? Any other suggestions are welcome.

Solution 1

Looks like GWT does have an event for exactly this.

ClosingEvent.

Looks like you need to implement a ClosingHandler

Solution 2

Why not just make a very short lived session cookie that is reset with each page load, then add a tracking cookie. When the user returns you notice the tracking cookie but no session cookie. Expire the session and clear everything up at that point.

Pop up blockers will prevent your session clean up when it blocks the onUnload window open, because this is something spammers use.

Solution 3

This is how the closing event works:

Window.addWindowClosingHandler(new Window.ClosingHandler()
{
 @Override
 public void onWindowClosing(ClosingEvent event)
 {
  event.setMessage("Are you sure?");
 }
});

Then GWT gives the user a chance to say yes or no. Of course you can also add a test in there to see if they've got any unsaved data or whatever you want. Not setting the message or setting it to null doesn't do anything.

Comments

[Carnell]

You should be able to send one last logout request to your server in your handler.

[Carnell]

I just ran a quick test to create a ClosingHandler and registered it. I made a simple one that just displays an alert. The code is getting fired when the tab/window is closed as well as when I browse to another page outside of the app.

[Saravanan M]

I am aware of this WindowCloseListener (equivalent of ClosingEvent in GWT 1.5), but was in the assumption that since a RequestCallback object is mandatory to make a Request, it may cause some problem on the callback events. But I tried with a RequestCallback doing nothing on the onResponseReceived event, and it is working fine. Thanks for the response.

[Jorden]

Answers like this are exactly why only linking to information shouldn't be allowed. Both of those are broken.