Tracking logged in users and visitors

[gil]

I'm trying to track how many users are visiting a site and how may are
logged in, using application sessions like so:

Sub Session_OnStart
Session.Timeout = 20
Session("Start") = Now
Application.Lock
Application("ActiveUsers") = Application("ActiveUsers") + 1
Application.UnLock
End Sub

Sub Session_OnEnd
Application.Lock
Application("ActiveUsers") = Application("ActiveUsers") - 1
Application.UnLock
End Sub


The problem is that I don't know whose session is ending, a logged in user
or a visitor and therefore can't decrement when one or the others session
ends.

Is it possible to identify the session that is ending by name so I can track
two different sets of data, one for visitors and one for users? What is a
good way to go about this consdering that users won't always click the
"logout" button when ending their visit?




Thank you