Timed Runtime Monitoring for Multiparty Conversations

Abstract

We propose a dynamic verification framework for protocols in real-time distributed systems. The framework is based on Scribble, a tool-chain for design and verification of choreographies based on multiparty session types, developed with our industrial partners. Drawing from recent work on multiparty session types for real-time interactions, we extend Scribble with clocks, resets, and clock predicates constraining the times in which interactions should occur. We present a timed API for Python to program distributed implementations of Scribble specifications. A dynamic verification framework ensures the safe execution of applications written with our timed API: we have implemented dedicated runtime monitors that check that each interaction occurs at a correct timing with respect to the corresponding Scribble specification. The performance of our implementation and its practicability are analysed via benchmarking.Comment: In Proceedings BEAT 2014, arXiv:1408.556

Explicit Connection Actions in Multiparty Session Types

“…This is in contrast to the range of primarily theoretical extensions (e.g, time [6,33], asynchronous interrupts [15], nested subsessions [14], assertions [5], role parameterisation [46], event handling [29], multi-process roles [16], etc. ), which complicates tool implementation because each has its own specific restrictions to treat the subtleties of its setting.…”

Monitoring Networks through Multiparty Session Types

“…We are continuing the development of Scribble, its toolsuite and associated environments towards an integration into [44]. The theoretical framework developed in this article is extensible as a basis for other applications as demonstrated in our recent dynamic monitoring implementations for distributed actors [42] and timers [41]. For instance, the work in [41] extends run-time monitoring to real-time processes: monitors verify the punctuality of interactions against time constraints expressed as a timed extension of Scribble based on timed MPST [10].…”

Compliance and Subtyping in Timed Session Types

“…In this basic form, session types cannot faithfully capture a natural and relevant aspect of interaction protocols, i.e., the timing constraints among the communication actions. While formal methods for time have been studied for at least a couple of decades, they have approached the realm of session types very recently [9,22].…”

“…We have that p q, while in the semantics of [9] (ν 0 , (p, q, w 0 )) − → * (ν , (!a{x ≤ 1}, ?a{y ≤ 1}, w 0 )) with ν (x) = ν (y) > 1, which is a deadlock state. Dynamic verification of timed multiparty session types is addressed by [22], where the top-down approach to service composition is pursued [19]. Our middleware instead composes and monitors services in a bottom-up fashion [6].…”