Communications in Choreographies, Revisited

TL;DR

This paper extends choreographic programming to include grouped interactions, enabling more realistic multi-party communications, and proves that such programs are correct and deadlock-free by construction.

Contribution

It introduces a new model for choreographic programming with grouped interactions, unifying various multi-party communication scenarios.

Findings

Formal semantics for grouped interactions established

Choreographic programs with grouped interactions are correct by construction

Deadlock freedom is guaranteed in the new model

Abstract

Choreographic Programming is a paradigm for developing correct-by-construction concurrent programs, by writing high-level descriptions of the desired communications and then synthesising process implementations automatically. So far, choreographic programming has been explored in the monadic setting: interaction terms express point-to-point communications of a single value. However, real-world systems often rely on interactions of polyadic nature, where multiple values are communicated among two or more parties, like multicast, scatter-gather, and atomic exchanges. We introduce a new model for choreographic programming equipped with a primitive for grouped interactions that subsumes all the above scenarios. Intuitively, grouped interactions can be thought of as being carried out as one single interaction. In practice, they are implemented by processes that carry them out in a concurrent fashion. After formalising the intuitive semantics of grouped interactions, we prove that choreographic programs and their implementations are correct and deadlock-free by construction.