IIS app. like thing with php/apache?

[botsai]

I am wondering if there is anything possible like the IIS application concept with php:

I want to run a script every so and so much times to see if users reacted or not, and if they didn't react for say 10 mins, I want to remove them from my 'onlineusers' table in a mysql db.

I want to know if this exists, because if the browser of a user crashes I cannot tell php to do this for me . . .

Or what else can I do?

Any suggestions?