A Decentralized Analysis of Multiparty Protocols

TL;DR

This paper introduces a decentralized method for analyzing multiparty protocols in distributed systems, ensuring protocol conformance and deadlock freedom through novel router processes and relative types within an asynchronous π-calculus framework.

Contribution

It presents a new decentralized analysis approach using router processes and relative types to verify multiparty protocol conformance and deadlock freedom.

Findings

Enables sound and complete transfer of properties from binary to multiparty protocols.

Uses APCP type system to ensure protocol conformance and deadlock freedom.

Provides a scalable analysis method for complex distributed protocols.

Abstract

Protocols provide the unifying glue in concurrent and distributed software today; verifying that message-passing programs conform to such governing protocols is important but difficult. Static approaches based on multiparty session types (MPST) use protocols as types to avoid protocol violations and deadlocks in programs. An elusive problem for MPST is to ensure both protocol conformance and deadlock freedom for implementations with interleaved and delegated protocols. We propose a decentralized analysis of multiparty protocols, specified as global types and implemented as interacting processes in an asynchronous $\pi$-calculus. Our solution rests upon two novel notions: router processes and relative types. While router processes use the global type to enable the composition of participant implementations in arbitrary process networks, relative types extract from the global type the intended interactions and dependencies between pairs of participants. In our analysis, processes are typed using APCP, a type system that ensures protocol conformance and deadlock freedom with respect to binary protocols, developed in prior work. Our decentralized, router-based analysis enables the sound and complete transference of protocol conformance and deadlock freedom from APCP to multiparty protocols.