CODEWITHSUNDEEP
asp.net
Kthevar
Kthevar

Reputation: 1547

How to find how many people are online in a website

I have to show how many people are online in that site. The site has developed by using ASP.NET 2.0. Currently I am using the Session start (increase by 1) and Session End Event (decrease by 1) in Global.asax. But the Session_End Event not calling properly most of the times. Is there any better way to achieve this?

Upvotes: 4

Views: 1398

Answers (4)

Jonathan
Jonathan

Reputation: 1892

A quick Google search revealed a handy way of doing this with a HttpModule.

All in all, Yohann did a great job with this. It does implement a set timeout that was suggested above, but otherwise there is no set way of doing this accurately outside of checking the server's perfmon.exe and checking the WebService >> WebAppPool's count of current connections.

When I implemented this myself I used a SQL Server table to store a date/time and user info on authentication. I decremented the count by re-assesing and matching the IP addresses whenever I had to refresh the data cache (once every 10 mins).

Upvotes: 4

awl
awl

Reputation: 1559

I've done this before and can attest that Session_End will only be called if you manually destroy the session (Session.Abandon). When you think about it, it makes sense. If the user isn't on the website, the code never gets executed.

What I did was store a hashtable in Application state that contained the Username and a Datetime for the last time the user was seen on the site. For every page load I would call a function that would either insert or update this value for the current user. Then it would cull the entire list and remove all of the entries that are older than the session timeout (20 minutes or whatever). Remember to use lock or sync to avoid race conditions when making changes to this list.

This has the added benefit of not only knowing how many people, but specifically which users.

If you don't have something unique like a Username, you can use Session.SessionID instead. It should be unique per visitor of your site.

But be careful, using an Application or App Instance state variable has its own share of problems since it won't share between processes in "Web Garden Mode" or in a multi-server setup. You would need a more persistent medium such as a database or distributed cache for larger scale setups.

Upvotes: 3

John Rasch
John Rasch

Reputation: 63435

You're not going to get much better then incrementing in Session_Start and decrementing in Session_End unless you use some other means like a database.

When you are authenticating your requests you could update a timestamp in the database to show that the user has been active, and after a given time (say 15 minutes), the query that collects the number of concurrent users ignores that row in the database (thus decrementing the count).

Upvotes: 5

Fred
Fred

Reputation: 1234

We have the same issue in a project, after tried several methods, we end with tracking idle time of each user, when the idle time is over the session timeout, we consider the user is not online anymore. of course you also need to consider the other issue such as the user log off, or log back in after timeout...

Upvotes: 3

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