A Graph-Based Characterization of Communications Modes In Distributed Executions

This paper studies message communication modes in distributed executions. It establishes a simple, hierarchical and homogeneous characterization of logically instantaneous, causally ordered and first-in-first-out communications. It is shown that a distributed computation obeys one of the previous communication modes if and only if a communication graph of messages does not include a cycle. This characterization plays a key role when one is interested in understanding asynchronous distributed computations. Further the homogeneity of our characterization contributes to a better comprehension of concepts and relations that rule communication modes of distributed computations; this is a crucial point to develop new communication protocols by adding software layers over an existing one. Finally, such a graph-based approach shows some unity in the characterization of deadlock, concurrency control, memory consistency and communication modes.