Practical interruptible conversations: distributed dynamic verification with multiparty session types and Python

Fundamental Approaches to Software Engineering

2017

Self Cite

Abstract. This work extends asynchronous multiparty session types (MPST) with explicit connection actions to support protocols with optional and dynamic participants. The actions by which endpoints are connected and disconnected are a key element of real-world protocols that is not treated in existing MPST works. In addition, the use cases motivating explicit connections often require a more relaxed form of multiparty choice: these extensions do not satisfy the conservative restrictions used to ensure safety in standard syntactic MPST. Instead, we develop a modelling-based approach to validate MPST safety and progress for these enriched protocols. We present a toolchain implementation, for distributed programming based on our extended MPST in Java, and a core formalism, demonstrating the soundness of our approach. We discuss key implementation issues related to the proposed extensions: a practical treatment of choice subtyping for MPST progress, and multiparty correlation of dynamic binary connections.

Section: Related Work and Concluding Remarksmentioning

confidence: 85%

Section: Modelling Mpsts By Cfsms With Dynamic Connectionsmentioning

confidence: 99%

Section: Related Work and Concluding Remarksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Explicit Connection Actions in Multiparty Session Types

Fundamental Approaches to Software Engineering

2017

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Featherweight Scribble

Neykova

Models, Languages, and Tools for Concurrent and Distributed Programming

2019

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This paper gives a formal definition of the protocol specification language Scribble. In collaboration with industry, Scribble has been developed as an engineering incarnation of the formal multiparty session types. In its ten years of development, Scribble has been applied and extended in manyfold ways as to verify and ensure correctness of concurrent and distributed systems, e.g. type checking, runtime monitoring, code generation, and synthesis. This paper introduces a core version of Scribble, Featherweight Scribble. We define the semantics of Scribble by translation to communicating automata and show a behaviouralpreserving encoding of Scribble protocols to multiparty session type.

Verifying Asynchronous Interactions via Communicating Session Automata

Lange

Lecture Notes in Computer Science

2019

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This paper proposes a sound procedure to verify properties of communicating session automata (csa), i.e., communicating automata that include multiparty session types. We introduce a new asynchronous compatibility property for csa, called k-multiparty compatibility (k-mc), which is a strict superset of the synchronous multiparty compatibility used in theories and tools based on session types. It is decomposed into two bounded properties: (i) a condition called k-safety which guarantees that, within the bound, all sent messages can be received and each automaton can make a move; and (ii) a condition called k-exhaustivity which guarantees that all k-reachable send actions can be fired within the bound. We show that k-exhaustivity implies existential boundedness, and soundly and completely characterises systems where each automaton behaves equivalently under bounds greater than or equal to k. We show that checking k-mc is pspace-complete, and demonstrate its scalability empirically over large systems (using partial order reduction).Definition 5 (Stable). S has the stable property ( sp) if @s P RS pSq : Dpq; ǫq P RS pSq : s Ý Ñ˚pq; ǫq.A system has the stable property if it is possible to reach a stable configuration from any reachable configuration. This property is called deadlock-free in [22]. The stable property implies the eventual reception property, but not safety (e.g., an automaton may be waiting for an input in a stable configuration, see Example 2), and safety does not imply the stable property, see Example 4.Example 2. The following system has the stable property, but it is not safe. M s : pq!b pq!a M q : pq?a pq?b qr!c M r : qr?cNext, we define two properties related to bound independence. They specify classes of csa whose branching behaviours are not affected by channel bounds.Definition 6 (k-obi). S is k-output bound independent (k-obi), if @s " pq; wq P RS k pSq and @p P P, if s pq!a ÝÝÑ k , then @pq p , pr!b, q 1 p q P δ p : s pr!b ÝÝÑ k .