Foundations of Session Types and Behavioural Contracts

Abstract

Behavioural type systems, usually associated to concurrent or distributed computations, encompass concepts such as interfaces, communication protocols, and contracts, in addition to the traditional input/output operations. The behavioural type of a software component specifies its expected patterns of interaction using expressive type languages, so types can be used to determine automatically whether the component interacts correctly with other components. Two related important notions of behavioural types are those of session types and behavioural contracts. This article surveys the main accomplishments of the last 20 years within these two approaches.

Relating Process Languages for Security and Communication Correctness (Extended Abstract)

“…To our knowledge, this is the first integration of sessions (in the sense of [11]) within process languages for security protocol analysis. Indeed, research on security extensions to behavioral types (cf.…”

“…These models support cryptography and term passing, but lack support for high-level communication structures. (b) Process models for session-based communication, such as [10] (see also [11]), use π-calculus variants equipped with type systems to enforce correct message-passing programs. Security extensions of these models target properties such as information flow and access control (cf.…”

Context-Free Session Type Inference

“…Session types [9,10,12] are an established formalism for the enforcement of communication protocols through static analysis. Recently, Thiemann and Vasconcelos [22] have proposed context-free session types to enhance the expressiveness of conventional session types.…”

Retractable and Speculative Contracts

“…Binary behavioral contracts [14,27,15] and binary session types [22] are abstractions of programs used to statically ensure that a client and a server interact successfully (see the survey in [24]). Along the years, the basic theory has been extended to deal with many features of clients and servers, such as exceptions [12], time [9], and so on.…”