Theory of how Who's Online Feature Works

Hi Peeps.

I am interested in adding a feature like who's online to my website. I am fairly confident in coding with PHP. What I need is basically the theory of how the Who's Online Feature works and more importantly how it realises a user is not looking at the board no more etc.

Thanks for any help which can be offered.

[Mark Hensler]

ascii flow chart (sort of)

updating session table..
--
ENTER

sql: DELETE FROM session_table WHERE timestamp>(now()-$session_timeout)

sql: UPDATE INTO session_table SET timestamp=now() AND session_id=$your_session_id

RETURN
--

reading sessions table..
--
ENTER

sql: SELECT * FROM session_table
php: print all returned records

RETURN
--

You'll have to define $session_timeout as an integer constant. This will signify how long to keep a session before killing it.

You'll also have to generate a unique $your_session_id and use it to track users.

Ahhh cool m8ty that helps a lot. One final question tho. When does the function to delete from the session table get executed and in which script? For Eg. Is that run everytime the forumlist is loaded?

[Admin]

There was a script for this at EvilWalrus.com (http://evilwalrus.com/) but the they have seem to delete all the snippets.

[Mark Hensler]

Depending on your traffic, you may run it everytime a page is hit, or once every X times. Or you could put it in a cron job and set it off every 5 minutes.