I think the way it is mostly done is by using push events from the
server. Have a look at Mortbay Jetty servlet container if you are
really interested, It's supposed to handle continuations/push events
quite well. If you can no longer push server events out you could
make the assumption the client has disconnected.
Greg Wilkins had a video on it not too long ago that was interesting
- you should be able to find it on google easily. He's been working
on the whole connection scalability issue for quite some time ( I
think he had some experimental java.nio stuff back in v5.0).
Overall though, I agree you can't reliably trust the browser to
notify you of the end of session.
Oz
On 06/06/2007, at 12:42 AM, Roger Varley wrote:
Roger Varley wrote:
> I'm sure that I've read that it's possible, using Javascript, to
> detect if a client closes the browser & if that's true, then you
could
> use an AJAX call to invalidate the session.
This is possible, but you can't bet on it actually working. The user
might have javascript disabled, or the browser may not fire
javascript
events as it's closing itself entirely (instead of just closing one
window, for instance).
Basically, the only reliable way to destroy a session is to wait
for it
to time out (unless the user explicitly logs out, of course).
I would not disagree with this. However, you have to suspect that the
majority of clients don't have Javascript turned off, otherwise Ajax
wouldn't be the current favourite technology. :-)
Regards
Roger
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