How can I count the number of online users on my site? I have implemented my application as follows. Whenever a user logs in, I increment the count field in my database by 1 in Session_Begin and on Session_End I decrement it by 1.Though the code works fine in normal circumstances, I noticed a few anamolies: 1. If the user refreshes his browser, the Session_Begin is called again and the counter is incremented again. To overcome this, I used cookies. The first time the user logs in, I create the cookie. When the user refreshes his browser, it checks if the cookie exists, if it doesnt it treats it as a new request and updates the counter accordingly. 2. The problem arises on log out. Whenever the user refreshes his browser, Session_End is called that many times, and my counter is decremented more than once. How can I get Session_End to run only once for each instance of the browser? 3. I'm using Forms Authentication and on Session_End I want to call FormsAuthentication.SignOut since the user can still access the pages after the session ends,causing a new session to be started. But this function does not work in Session_End.

How can I keep track of the number of online users to implement concurrency metering? So far I have implemented as follows: When a user logs in, I add an entry to a Status table in the database and store a cookie in his machine.Every time he refreshes his browser, it checks if the cookie exists.If it doesnt exist, it treats it as a new login and updates the status table. Now I need to remove/decrement the status by 1 when the user logs out. I included this code in Session_End. But there is a problem, I need to call this fucntion only when the user closes his browser. If the user leaves his system idle or refreshes his browser again, Session_End is called twice and the status is decremented by 1 two times, which is incorrect. How should I implement concurrency metering? Is there any other way other than using session, since most users would probably log out by closing the browser instead of clicking the Log Out button.