Capture the Browser Close event

[Guest]

I need to capture the event when the user closes the browser in my
application. I have some code in the session_End event, which works fine
when the session times out, but I need to end the session immediately when
the user closes the browser.

Does anyone know a way of doing this?

 

[Ken Dopierala Jr.]

Hi Bill,

This is a tricky issue. The odds of you getting a succesful postback are
50/50
to say the best. I've had about a 95% success rate doing this:

1. Capture the onbeforeunload event in your body tag.
2. Incorporate the WebService.htc.
3. When the onbeforeunload event fires run a function that uses the
WebService.htc to tell a web service.

The browser will close before you get a response back but, about 95% of the
time, your web service will get hit and the user can successfully be logged
out. Note, that using the latest IE and Windows XP you will achieve almost
100% results. This is sort of complicated until you get the hang of it. If
this isn't something you want to try then here is another suggestion to
improve your chances but it might seem clunky to the user:

Have a main page that the user browses to. To run your app, they click a
button or link and then you use window.open() to create a new browser
window. This is the window your app runs from. Don't ask me why, but the
success rate of a postback from onbeforeunload seems to be much higher for
browsers launched from javascript than from browsers launched by the user.
Good luck! Ken.

 

[Guest]

Ken,

Thanks for the response. It turns out that my application already works the
way you suggested, with the app started from javascript, so your idea seems
to work. Everything would be fine except for the fact that the Session_Start
event seems to fire twice. I tried starting the main page directly, not
using the javas script but the Session_Start event still fires twice.

I am trying to keep track of the number of users logged in to our
application for purposes of enforcing a "concurrent user" license model. I
didn't want to wait until the session timed out to decrement the active user
count, which I am storing in a database. If I rely on the Session_Start
event to increment the user count, I am incrementing the count by two, which
is of course not desirable.

Any ideas on why the Session_Start event fires twice?

 

[Ken Dopierala Jr.]

Hi Bill,

Do your users need to log in? If so, are you using Forms or Windows
authentication? If you do then you could update a date/time field in your
database each time you authenticate them in the Application_BeginRequest.
Then you could write a query to automatically set people as logged off when
they are inactive for a set number of minutes. I have web apps that track
online users like you but all of my apps use client-side scripting to
constantly hit the server behind the scenes every couple of seconds to prove
that they are still online. This requires javascript to be enabled in the
browser. Ken.

 

[Guest]

Ken,

The users do login, when the application is isntalled they decide whether
they want to use Windows authentication or Forms authentication. I will
consider another stategy - keeping a table of logged in users in the
database. This might allow the possibility of users "sharng" a common login
to circumvent the license restriction, but maybe I'll live with that. I'll
give it some more thought.

Thanks for your help.