how to do "online user"?

[Anon]

I'm programming my own forum but I'm stuck at one thing. That's the "Online User" feature. How can you track if a user has closed their browser or go to another website? That means they are not in the forum any more. I don't know how to do that. I think this has something to do with session as I looked at vBB. Please help. Thanks.

[Anon]

Actually there's no exact way to track if user closed browser or went to other site.
The simplest solution is to store each users's session ID with last page access time in database and to get 'online' users use query like:

select count(*) as users_online from sess_table where (unix_timestamp()-access_time) < 600

access_time here is in Unix time() format.

Also don't forget to purge old sessions (where access_time is more than a hour in past, for example).

[fitzbean]

Yup, just set up a timestamp field that tracks page access, and the way I do it is

SELECT count(id) FROM users WHERE lastpage > NOW() - INTERVAL 20 MINUTE

[Anon]

So it's possible to have wrong number of people who are online!! Because what if I stay on the forum for 2 hours but doing nothing, then it's considered that I'm offline already!! Right?

[mmilano]

maybe put in a meta-refresh for every half hour .. so if the user has the page still open, it's like they pressed refresh and their hour will start over again.