Subtyping Supports Safe Session Substitution

Gay, Simon J.

doi:10.1007/978-3-319-30936-1_5

Cited by 17 publications

(14 citation statements)

References 23 publications

(26 reference statements)

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“…Our structural preorder on processes mimics the subtyping relation between session types of [7], which is a restriction of the subtyping of [11]. This choice is justified by the fact that the subtyping of [11] allows process substitution, while the subtyping of [14] allows channel substitution, as observed in [13].…”

Section: Related Workmentioning

confidence: 99%

Open Multiparty Sessions

Barbanera

Dezani‐Ciancaglini

2019

Electron. Proc. Theor. Comput. Sci.

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Multiparty sessions are systems of concurrent processes, which allow several participants to communicate by sending and receiving messages. Their overall behaviour can be described by means of global types. Typable multiparty session enjoy lock-freedom. We look at multiparty sessions as open systems by a suitable definition of connection transforming compatible processes into gateways (forwarders). A relation resembling the standard subtyping relation for session types is used to formalise compatibility. We show that the session obtained by connection can be typed by manipulating the global types of the starting sessions. This allows us to prove that lock-freedom is preserved by connection. * Partially supported by the project "Piano Triennale Ricerca" DMI-Università di Catania. † Partially supported by Ateneo/Compagnia di San Paolo 2016/2018 project "MnemoComputing -Components for Processing In Memory". Definition 2.3 (LTS for Multiparty Sessions) The labelled transition system (LTS) for multiparty sessions is the closure under structural congruence of the reduction specified by the unique rule: [COMM] makes the communication possible: participant p sends message ℓ to participant q. This rule is non-deterministic in the choice of messages. The condition msg(Λ) ⊆ msg(Λ ′ ) assures that the sender can freely choose the message, since the receiver must offer all sender messages and possibly more. This allows us to distinguish in the operational semantics between internal and external choices.We use M λ − → M ′ as shorthand for M pℓq − − → M ′ . We sometimes omit the label writing −→. As usual, −→ * denotes the reflexive and transitive closure of −→.Example 2.4 Let us consider a system (inspired by a similar one in [1]) with participants p, q, and h interacting according the following protocol. Participant p keeps on sending text messages to q, which

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Section: Related Workmentioning

confidence: 99%

Open Multiparty Sessions

Barbanera

Dezani‐Ciancaglini

2019

Electron. Proc. Theor. Comput. Sci.

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“…Lange and Yoshida [11] reduce Turing machine termination into a notion of compatibility for communicating automata and, then, transfer 5 The Gay and Hole subtyping is contravariant on outputs and covariant on inputs. This is because a channel-based subtyping [9] is considered instead of our process-oriented subtyping. (Figure 3) is much simpler than the encoding we need to use here.…”

Section: Bounded Asynchronous Subtypingmentioning

confidence: 99%

“…Anyway, such output/input types can be seen as an output selection/input branching with only one choice. 2 Here, we focus on the so-called process-oriented subtyping, as opposed to channel-based subtyping [9].…”

Section: Introductionmentioning

confidence: 99%

On the boundary between decidability and undecidability of asynchronous session subtyping

Bravetti

Carbone²,

Zavattaro³

2018

Theoretical Computer Science

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Session types are behavioural types for guaranteeing that concurrent programs are free from basic communication errors. Recent work has shown that asynchronous session subtyping is undecidable. However, since session types have become popular in mainstream programming languages in which asynchronous communication is the norm rather than the exception, it is crucial to detect significant decidable subtyping relations. Previous work considered extremely restrictive fragments in which limitations were imposed to the size of communication buffer (at most 1) or to the possibility to express multiple choices (disallowing them completely in one of the compared types). In this work, for the first time, we show decidability of a fragment that does not impose any limitation on communication buffers and allows both the compared types to include multiple choices for either input or output, thus yielding a fragment which is more significant from an applicability viewpoint. In general, we study the boundary between decidability and undecidability by considering several fragments of subtyping. Notably, we show that subtyping remains undecidable even if restricted to not using output covariance and input contravariance.

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“…We note that the subtyping relation is inverted w.r.t. the "process-oriented" subtyping [26], because, for convenience, we adopt the "channel-oriented" ordering [17]; an analysis of the two subtyping relations is given in Gay [27].…”

Section: Definition 24 (Partial Projection)mentioning

confidence: 99%

Interconnectability of Session-Based Logical Processes

Toninho

Yoshida

2018

ACM Trans. Program. Lang. Syst.

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In multiparty session types, interconnection networks identify which roles in a session engage in communication (i.e., two roles are connected if they exchange a message). In session-based interpretations of linear logic the analogue notion corresponds to determining which processes are composed, or cut, using compatible channels typed by linear propositions. In this work, we show that well-formed interactions represented in a session-based interpretation of classical linear logic (CLL) form strictly less-expressive interconnection networks than those of a multiparty session calculus. To achieve this result, we introduce a new compositional synthesis property dubbed partial multiparty compatibility (PMC), enabling us to build a global type denoting the interactions obtained by iterated composition of well-typed CLL threads. We then show that CLL composition induces PMC global types without circular interconnections between three (or more) participants. PMC is then used to define a new CLL composition rule that can form circular interconnections but preserves the deadlock-freedom of CLL.

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Subtyping Supports Safe Session Substitution

Cited by 17 publications

References 23 publications

Open Multiparty Sessions

Open Multiparty Sessions

On the boundary between decidability and undecidability of asynchronous session subtyping

Interconnectability of Session-Based Logical Processes

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