Verifying liveness properties of multifunction composite protocols

Abstract

In protocol composition techniques, component protocols are combined in various ways to obtain a complex protocol whose execution sequences consist of interleaved execution sequences of the component protocols. In this paper, we investigate the problem of verifying liveness properties of the composite protocol from the known properties of its components. We first characterize a class of composite protocols that encompasses almost every composite protocol appeared in the literature. For verifying liveness properties of a composite protocol in the class, we then develop a sufficient condition to ensure that certain liveness properties of the component protocols carry over to the composite protocol. A verification technique, based on this sufficient condition, is then used to determine whether the liveness properties of the component protocols also hold for the composite protocol. The technique is applicable to any transition based protocol model as long as the model is susceptible to reachability analysis for the sake of correctness proofs. To demonstrate the usefulness of our technique, we apply it to a class of protocols that involves certain synchronizing constraints. This work shows a promising integration of a synthesis technique with an analytic method. (C) 2003 Elsevier Science B.V. All rights reserved.