The problem you have is that you can count logins and logouts, via the WebHandler method, SetSessionLoggedIn, but that
doesn't account for sessions which are just deleted in .NotifyDeleteSession. And you don't have access to the .SessionLoggedIn() method when doing a DeleteSession.
So the best option is likely just to count the items in the queue set to Logged in.
but that's a bit tricky to do, and depends on where you are when you are counting. So, hence the question, when exactly do you "need" this information? when you are validating a user's login perhaps?
cheers
Bruce