On the Expressiveness of Joining

The expressiveness of communication primitives has been explored in a common framework based on the pi-calculus by considering four features: synchronism (asynchronous vs synchronous), arity (monadic vs polyadic data), communication medium (shared dataspaces vs channel-based), and pattern-matching (binding to a name vs testing name equality vs intensionality). Here another dimension coordination is considered that accounts for the number of processes required for an interaction to occur. Coordination generalises binary languages such as pi-calculus to joining languages that combine inputs such as the Join Calculus and general rendezvous calculus. By means of possibility/impossibility of encodings, this paper shows coordination is unrelated to the other features. That is, joining languages are more expressive than binary languages, and no combination of the other features can encode a joining language into a binary language. Further, joining is not able to encode any of the other features unless they could be encoded otherwise.Comment: In Proceedings ICE 2015, arXiv:1508.04595. arXiv admin note: substantial text overlap with arXiv:1408.145

A Process Calculus of Atomic Commit

This article points out a strong connection between process calculi and atomic commit. Process calculus rendezvous is an abstract semantics for atomic commitment. An implementation of process-calculus rendezvous is an atomic commit protocol. Thus, the traditional correctness properties for atomic commit are entailed by a bisimulation proof of a calculus implementation. Actually, traditional rendezvous as found in the pi calculus corresponds to just a special case of atomic commit called a binary cohesion. If we take the general case of atomic commit, this induces a richer form of calculus rendezvous similar to the join calculus [10]. As an extended example of the analogy between calculus and atomic commit, we use the induced calculus to reformulate an earlier 2PCP correctness result by Berger and Honda [1]