Connectors meet Choreographies

TL;DR

The paper introduces Cho-Reo-graphies (CR), a novel language that combines choreographic programming with user-defined connectors to enable flexible, deadlock-free concurrent process communication.

Contribution

CR is the first choreography calculus allowing mixed communication semantics via user-defined connectors, supported by static analysis and a compiler ensuring deadlock-freedom.

Findings

CR supports various communication semantics through user-defined connectors.

A static analysis guarantees choreography and connector compatibility.

The compiler ensures deadlock-free process implementations.

Abstract

We present Cho-Reo-graphies (CR), a new language model that unites two powerful programming paradigms for concurrent software based on communicating processes: Choreographic Programming and Exogenous Coordination. In CR, programmers specify the desired communications among processes using a choreography, and define how communications should be concretely animated by connectors given as constraint automata (e.g., synchronous barriers and asynchronous multi-casts). CR is the first choreography calculus where different communication semantics (determined by connectors) can be freely mixed; since connectors are user-defined, CR also supports many communication semantics that were previously unavailable for choreographies. We develop a static analysis that guarantees that a choreography in CR and its user-defined connectors are compatible, define a compiler from choreographies to a process calculus based on connectors, and prove that compatibility guarantees deadlock-freedom of the compiled process implementations.