Multiparty Session Actors

TL;DR

This paper introduces a framework integrating multiparty session types into actor models, enabling type-safe, concurrent actor communication with runtime verification, demonstrated through a Python library.

Contribution

It presents a novel approach to actor coordination using MPST protocols, adding minimal extensions like roles and mailboxes for verification and concurrency.

Findings

Supports actor-like syntax with runtime verification

Ensures type safety and progress in actor communication

Allows actors to implement multiple roles concurrently

Abstract

Actor coordination armoured with a suitable protocol description language has been a pressing problem in the actors community. We study the applicability of multiparty session type (MPST) protocols for verification of actor programs. We incorporate sessions to actors by introducing minimum additions to the model such as the notion of actor roles and protocol mailbox. The framework uses Scribble, which is a protocol description language based on multiparty session types. Our programming model supports actor-like syntax and runtime verification mechanism guaranteeing type-safety and progress of the communicating entities. An actor can implement multiple roles in a similar way as an object can implement multiple interfaces. Multiple roles allow for inter-concurrency in a single actor still preserving its progress property. We demonstrate our framework by designing and implementing a session actor library in Python and its runtime verification mechanism.