Check if user is offline
<p>I have an online game. I wish to show how many user are online. The problem is to know when a user is offline.
Is there a way to perform a check on sessions cookie to acknowledge whether the session with the broswer was closed?
I was thinking about simply set a timeout on the server which launch a script that count how many session cookie are present, but how do I check if the session cookie is about somebody who's logged and not just a visitor? </p>

<p>How did you handle this?</p>

<p>1) I don't want to rely on a script fired with the logout button, since nobody ever logout... people simply close the browser.</p>

<p>2) About timestamps and registering activity? Since in my game users interact with an svg (not moving through pages), they generate a huge amount of clicks. Making a query for each click for each of them refreshing a record would be very expensive.</p>
