On the role of time in distributed systems

The role of time in distributed systems has been neglected for a long time. Outside the real-time arena, time has been ignored, mostly because of the asynchronous nature of the models currently used in distributed systems research. Even in real-time systems, time provision has stayed in the realm of centralised, unique system clocks. The situation is changing, though. The author presents an overview of the role of time in distributed systems. The author addresses the issue of the utility of time, that is, why and where time is used, namely its relationship with order and ordering protocols. The author reports on recent evolutions that may drastically change the current scenario of the use of time distributed systems.