Time and Asynchrony in Interactions among Distributed Real-Time Objects

This paper presents a framework of specification and verification for distributed real-time object-oriented systems. An earlier paper [17] introduced a process calculus to describe distributed objects using local clocks. However, it is appropriately based on synchronous communication and thus cannot sufficiently model asynchronous communication in distributed systems. In this paper we propose a new process calculus with the ability to express asynchronous message passing, communication delay, and delayed processing. It can describe temporal and behavioral properties of distributed real-time objects. Based on the new calculus, we develop a verification method by means of algebraic order relations. The relations are speed-sensitive and can decide whether two distributed real-time objects are behaviorally equivalent and whether one of them can perform its behaviors faster than the other. They offer a suitable method to prove the correctness and the reusability of realtime objects in asynchronous communication settings. Some examples are shown to demonstrate utilities of the calculus and the relations.