Real-Time Java™ Platform Programming

Underlying Mechanism

Real-time tasks must meet deadlines. Sometimes the deadline is expressed in terms of a time sequence that includes program events and real-world events—the control program must turn the current off before the wire overheats. Those are certainly deadlines in a strict sense of the word, but deadline scheduling requires deadline times.

First, applications need a way to communicate their timing requirements to the scheduler. The scheduler must know the next deadline for each task. This communication could use function calls like this:

setDeadline(time);

If all applications pass the scheduler the time of their next deadline and a ceiling on the processor time required to reach that deadline, the scheduler can tell the application ...