Asynchronous session subtyping as communicating automata refinement

Abstract

We study the relationship between session types and behavioural contracts, representing Communicating Finite State Machines (CFSMs), under the assumption that processes communicate asynchronously. Session types represent a syntax-based approach for the description of communication protocols, while behavioural contracts, formally expressing CFSMs, follow an operational approach. We show the existence of a fully abstract interpretation of session types into a fragment of contracts that maps session subtyping into binary compliance-preserving CFSMs/behavioural contract refinement. In this way, on the one hand, we enrich the theory of session types with an operational characterization and, on the other hand, we use recent undecidability results for asynchronous session subtyping to obtain an original undecidability result for asynchronous CFSMs/behavioural contract refinement.

Refinements for Open Automata

“…Defining refinement of open systems as trace inclusion is addressed as a notion of subtyping in type theory (e.g. [14,9]). The definition of refinement is based on a connection between session types and communicating automata theories -a notion of session automata based on Communicating Finite-State Machines, that are used for modelling processes communicating through FIFO channels.…”

A Session Subtyping Tool

“…Only recently, sound (but not complete) algorithms for asynchronous session subtyping have been proposed [7,5,9]. However, the theory behind asynchronous session types (see [11] for a gentle introduction) and related algorithms is rather intricate and this could limit their dissemination in the research community, as well as their adoption in practical applications.…”