Time in Distributed Real-Time Systems

A real-time music system is responsible for deciding what happens when, when each task runs and each message takes effect. This question becomes acute when there are several classes of tasks running and intercommunicating: user interface, control processing, and audio, for example. We briefly examine and classify past approaches and their applicability to distributed systems, then propose and discuss an alternative. The shared access to a sample clock that it requires is not trivial to achieve in a distributed system, so we describe and assess a way to do so.