Chapter 12. Real Time

A system is real time when timeliness is a dimension of correctness; that means a correct answer delivered late is the same as an answer that has never been delivered. Real-time systems abound in the real world. To a degree, all systems are real time, because they have real-world deadlines: an airline ticketing program needs to issue tickets before the plane leaves, for example. Meeting deadlines is one aspect of real-time systems; the other is that the system behaves in a predictable manner. If the aforementioned airline reservation system issues tickets within 24 hours and does so for every ticketing request, the system can be considered real time.

Real-time systems that can tolerate missing an occasional deadline, with ...

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