Aspectual session types

Abstract

Multiparty session types allow the definition of distributed processes with strong communication safety properties. A global type is a choreographic specification of the interactions between peers, which is then projected locally in each peer. Well-typed processes behave accordingly to the global protocol specification. Multiparty session types are however monolithic entities that are not amenable to modular extensions. Also, session types impose conservative requirements to prevent any race condition, which prohibit the uniform application of extensions at different points in a protocol. In this paper, we describe a means to support modular extensions with aspectual session types, a static pointcut/advice mechanism at the session type level. To support the modular definition of crosscutting concerns, we augment the expressivity of session types to allow harmless race conditions. We formally prove that well-formed aspectual session types entail communication safety. As a result, aspectual session types make multiparty session types more flexible, modular, and extensible.

Global Types for Open Systems

“…The general aim of enhancing the expressive power of global type formalisms has been variously pursued in the literature. For example, in [15] the authors define a formalism where global types with initial and end points can be combined. The results in [14] are slightly more related to our approach.…”

A Theory of Composing Protocols

“…[4] look at direct composition and decomposition on global types in the setting of multiparty session types. Inspired by aspect-oriented programming, [32] support protocol extensions with 'aspectual' session types, that allow messages in session types to be matched and consequently introduce new behaviour in addition to, or in place of, the matched messages. [29] look at composition in the setting of choreographies.…”

“…The resulting composition relation given in this work is not characterizable as one of the synchronizations of Team Automata (discussed further in Section 7). Another related line of work defines composition as run-time weaving, for example applying principles of aspect-oriented programming to protocol composition [32]. Unlike the aforementioned work, we statically derive protocol compositions that enable (human/automated) reasoning and verification of their properties.…”