Deliverables of WP2 - Core |
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In this paper we show how service contracts can be extracted from the service behaviour, how service contracts can be used to check the compliance among the communication protocols of interacting services, and how service contracts can be used as the basis for the automatic discovery and correct composition of services. Two intertwined approaches have been followed in the design of core calculi for Service-Oriented Computing: bottom-up and top-down. The bottom-up approach consists of electing one specific service oriented technology as the starting point, and extract from it a corresponding core model. The opposite top-down approach consists of designing an abstract model of services that do not tight to a specific technology. The present deliverable reports on the research activities carried out during the first two years of the project and revolving around the notion of distribution in service oriented architectures. More specifically, we review the research on linguistic mechanisms, expressive power and reasoning techniques centred around the notion of locality in WP2’s core calculi. Accordingly, in the present deliverable we have (1) examined meaning and aspects of distribution in SOA; (2) singled out a few emergent dimensions of distribution in SOA; (3) classified and assessed proposals for core calculi within WP2 according to those dimensions. Two orthogonal issues of the service compositionality problem have been explored. The first issue concerns the way behavioural types can support and enforce high-level properties of the global service interactions. The second issue tackled the problem of formally representing the internal conversation rules between services, i.e. service sessions. |