Behavioural Contracts with Request-Response Operations

Abstract

Abstract. In the context of service-oriented computing, behavioural contracts are abstract descriptions of the message-passing behaviour of services. They can be used to check properties of service compositions such as, for instance, clientservice compliance. Previous formal models for contracts consider unidirectional send and receive operations. In this paper, we present two models for contracts with bidirectional request-response operations, in the presence of unboundedly many instances of both clients and servers. The first model takes inspiration from the abstract service interface language WSCL, the second one is inspired by Abstract WS-BPEL. We prove that client-service compliance is decidable in the former while it is undecidable in the latter, thus showing an interesting expressiveness gap between the modeling of request-response operations in WSCL and in Abstract WS-BPEL.

Automata for Analysing Service Contracts

“…In [14,1] behavioural contracts are expressed via suitable process algebras, where the interactions between services are modelled via I/O actions. Two different choice operators, namely internal and external, describe how two services interact.…”

“…Previous work have tackled similar issues. We only mention a few that use the λ-calculus [4,5,8], process calculi [14,15,1], non-classical logics [7].…”

A Note On Compliance Relations And Fixed Points.

“…Must-testing compliance. The notion of compliance in [3] is inspired to must-testing [14]. Must testing requires a contract to reach success in all (sufficiently long) traces.…”

“…Behavioural contracts and compliance relations have been studied in several works and contexts, e.g. service-oriented computing [2,3,11,13,18,19,1] and session types [5,6,9]. Testing preorders have been studied in [14,18,21].…”

Combining Techniques to Verify Service-based Components

“…A contract is the agreement between clients and providers and the interesting point is that it includes clauses that can focus on the heterogeneous aspects (rights and duties, quality of service...) (Beugnard et al, 1999). The notion of multi-level contract that we promote here can be an unifying paradigm for the functional contracts of Meyer (Meyer, 2003) or the behavioural contracts (Acciai et al, 2013;Fenech et al, 2009). …”