Language primitives and type discipline for structured communication-based programming

Abstract

ABSTRACT.•Ve introduce basic language constructs and a type discipline as a foundation of structured communication-based concurrent programming. The constructs, which are easily translatable into the summation-less aSynchronous It-calculus, allow prograznmers to organise programs as a combination of multiple flows of (possibly unbounded) reciprocal interactions in a simple and elegant way, subsuming the preceding communication primitives such as method invocation and rendez-vous. The resulting s3mtactic structure is exploited by a type discipline ~t la ML, which offers a high-level type abstraction of interactive behaviours of programs as well as guaranteeing the compatibility of interaction patterns between processes in a well-typed program. After presenting the formal semantics, the use of language constructs is illustrated through examples, and the basic syntactic results of the type discipline are established. Implementation concerns are also addressed.

A Distributed Object-Oriented Language with Session Types

“…Thus, the type system can statically check the consistent composition of communication protocols. The soundness of our system is weaker than that of all systems of session types for π-calculus processes [4,5,13,15,17,25]. In fact all these systems assure a perfect pairing between processes willing to communicate.…”

“…1. It is an extension of FJ [18], MJ [3] and DJ [1] (while omitting the new distributed primitives introduced in [1]), augmented with primitives for session communication [5,15,17,27]. The metavariable t ranges over types for channels and expressions, C ranges over class names, s ranges over session types.…”

“…Session types have been successfully applied to theoretical settings such as the π-calculus [4,5,13,15,17,25], a multi-threaded functional language [27], to practical settings such as CORBA [26] and a web-services description language [29]. With L doos we aimed to link language development to engineering and standardisation practice.…”

“…for π-calculus-based formalisms [4,5,13,15,17,25], for CORBA [26], for a λ-calculus with side-effects [14], for a multi-threaded functional language [27], and recently, for a W3C standard description language for web services called Choreography Description Language (CDL) [29]. To our knowledge, the integration of session types into an object-oriented language (even a small, core calculus, as in [3,10,18]) has not been attempted so far.…”

“…Through a combination of remote method invocation (RMI), a standard distributed primitive in objects, session-based distributed primitives [17,25] and linear interactions [16,19], we obtained a flexible high-level programming style for remote communication. We also found that the functionality of branching and selection constructs in session types [4, 5, 13-15, 17, 25-27] can be compensated by methods, a natural notion of branching in objects.…”