If you're on a unix system, look at cron.

The basics of scheduling are as such:

1. Define a schedule and put it into some storage mechanism. (RDBMS's are usually used for this.)
2. A process every so often (usually, every second or minute) checks this storage mechanism and launches every action that should be taken at the time of checking.

That's the whole of scheduling. *shrugs* Of course, getting it done correctly is why my current employer has purchased a million+ dollar system that doesn't do much more than what I described above. :-)

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.