Temporal Uncertainty Time Warp: an implementation based on Java and Actor Foundry

This paper describes TUTW – Temporal Uncertainty Time Warp – a distributed control engine designed for an exploitation of temporal uncertainty (TU) in general optimistic simulations. Novel in TUTW is an event model where time intervals are attached to events instead of classical punctual or “precise” timestamps. All of this complies with system specifications where the occurrence time of events cannot be known with complete certainty. TUTW is able to take advantage of TU by resolving events in such a way to reduce the number of rollbacks. The simulator performance can thus be improved without necessarily compromising the accuracy of the results. An agent-based implementation of TUTW was achieved which enables simulations to be carried out over the Internet. The implementation depends on Java and the ActorFoundry middleware. The implementation is totally portable and simplifies configuration and control of a distributed simulation virtual computer which includes heterogeneous computing platforms. The paper reports performance and accuracy results of TUTW applied to a large QNET simulation model