Scheduled-task pattern

The scheduled task pattern is a design pattern used in software engineering. It is used to ensure that desired operations are performed at specific points in the future.

In Real-time systems, it is often necessary to ensure that something is done at a specific time. A scheduler object (note: not quite the same as scheduler pattern) keeps track of these actions, and invokes them at the appropriate times.

Times may be expressed as "wall time" or as some sort of internal time ("ticks", milliseconds-since-startup, etc.).

If highly accurate scheduling of tasks is needed (to milliseconds or less), the scheduler task needs to run at a very high priority, or be hooked into a high-frequency interrupt routine.

See also: Command pattern, Memento pattern

External Link

MartinFowler's Recurring Events document at PPR: http://c2.com/ppr/schedule.pdf