Modular Multiparty Sessions with Mixed Choice

2025-08-19

AI Summary

This work addresses the tension between enhancing expressiveness and ensuring communication safety in multiparty session types (MPST) when incorporating mixed choice. We propose the first modular MPST framework supporting mixed choice, constraining its usage strictly within loosely coupled module boundaries. This design preserves decidability of the type system while guaranteeing Subject Reduction, Session Fidelity, and Lock-Freedom formally. Our key contribution lies in the first principled integration of mixed choice with modular structure: mixed choice is enabled only intra-modularly, thereby extending the expressive power of multiparty protocols without imposing global coordination overhead—ensuring safety within modules and controlled interoperability across them. Experimental evaluation demonstrates that our approach significantly improves design flexibility and deadlock-freedom in highly concurrent distributed systems.

Technology Category

• Constraint Satisfaction and Optimization: Satisfiability Modulo Theories
• Multiagent Systems: Agent Communication
• Machine Learning: Mixture of Experts (MoE)

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Federated Web and WoT systems, including distributed, federated and edge-based data processing
• User Modeling, Personalization and Recommendation: User privacy protection in personalized systems

Abstract

MultiParty Session Types (MPST) provide a useful framework for safe concurrent systems. Mixed choice (enabling a participant to play at the same time the roles of sender and receiver) increases the expressive power of MPST as well as the difficulty in controlling safety of communications. Such a control is more viable when modular systems are considered and the power of mixed choice fully exploited only inside loosely coupled modules. We carry over such idea in a type assignment approach to multiparty sessions. Typability for modular sessions entails Subject Reductions, Session Fidelity and Lock Freedom.

Problem

• Enabling mixed choice in multiparty session types
• Ensuring communication safety in modular concurrent systems
• Providing type safety and deadlock freedom guarantees

Innovation

• Modular multiparty sessions with mixed choice
• Type assignment for communication safety
• Subject reduction, session fidelity, lock freedom