Preventing Multiple Logins in ASP.NET

http://www.eggheadcafe.com/articles/20030418.asp

We talked about the fact that the classic ASP Session_OnEnd handler is widely known to be pretty unreliable. However, in ASP.NET the corresponding Global class handler, Session_End, is very reliable. Then we talked about "what if" scenarios, such as what if the ASP.NET worker process was recycled? If so, I reasoned, it didn't matter whether you were using Session, Application or Cache, all of your stuff would be lost. The only exceptions to this would be if you were using the ASP.NET State Server service for your Session, or the SQL Server Session option. In particular, there is a second script available for the SQL Server Session option that does not use the TempDB, and this means that even if the whole machine goes down, when it comes back up, the Session data will still be there. Both StateServer and SQL Server Session options run out of process, so it really doesn't matter if the ASPNET_WP.EXE worker process is recycled - the sessions, which run out of the ASP.NET worker process and rely on the Session Cookie that's stored at the browser, will still be there.