Compositional Message Sequence Charts (CMSCs) Are Better to Implement Than MSCs

Abstract. Communicating Finite States Machines (CFMs) and Mes-sage Sequence Graphs (MSC-graphs for short) are two popular spec-ification formalisms for communicating systems. MSC-graphs capture requirements (scenarios), hence they are the starting point of the de-sign process. Implementing an MSC-graph means obtaining an equiva-lent deadlock-free CFM, since CFMs correspond to distributed message-passing algorithms. Several partial answers for the implementation have been proposed. E.g., local-choice MSC-graphs form a subclass of deadlock-free CFM: Testing equivalence with some local-choice MSC-graph is thus a partial answer to the implementation problem. Using Compositional MSCs, we propose a new algorithm which captures more implementable models than with MSCs. Furthermore, the size of the implementation is reduced by one exponential.