Constructing Weakly Terminating Interface Protocols

TL;DR

This paper develops generalized methods for constructing weakly terminating interface protocols to prevent deadlocks and livelocks in asynchronous systems, with practical tools for interface design.

Contribution

It extends existing theories to more broadly enable the design of weakly terminating interfaces using partial mirroring and embedding in modeling tools.

Findings

Generalized conditions for weak termination in interface compositions.

Method to derive client models from server specifications.

Integration of the theory into an open-source modeling tool.

Abstract

Interfaces play a central role in determining compatible component compositions by prescribing permissible interactions between a service provider (server) and its consumers (clients). The high degree of concurrency in asynchronous communicating systems increases the risk of unintentionally introducing deadlocks and livelocks. The weak termination property serves as a basic sanity check to avoid such problems. It assures that in each reachable state, the system has the option to eventually terminate. This paper generalizes existing results that, by construction, guarantee weakly terminating interface compositions. Our generalizations make the theory applicable more broadly in practice. Starting with an interface specification of a server satisfying certain properties, we show how a class of clients modeling different usage contexts can be derived using a partial mirroring relation. Furthermore, we discuss an embedding of our results in an open-source tool to guide modelers in designing weakly terminating interfaces.