A theory of contracts for web services

Contracts are behavioural descriptions of Web services. We devise a theory of contracts that formalises the compatibility of a client to a service, and the safe replacement of a service with another service. The use of contracts statically ensures the successful completion of every possible interaction between compatible clients and services. The technical device that underlies the theory is the definition of filters, which are explicit coercions that prevent some possible behaviours of services and, in doing so, they make services compatible with different usage scenarios. We show that filters can be seen as proofs of a sound and complete subcontracting deduction system which simultaneously refines and extends Hennessy's classical axiomatisation of the must testing preorder. The relation is decidable and the decision algorithm is obtained via a cut-elimination process that proves the coherence of subcontracting as a logical system. Despite the richness of the technical developme...

• Type: Conference
• Year: 2008
• Where: POPL
• Authors: Giuseppe Castagna, Nils Gesbert, Luca Padovani
• Keywords: Complete Subcontracting Deduction, Future Research, POPL 2008, Possible Practical Impact, Programming Languages