Distributed Behavioural Adaptation for the Automatic Composition of Semantic Services
Services are developed separately and without knowledge of all possible use contexts. They often mismatch or do not correspond exactly to the end-user needs, making direct composition without mediation impossible. In such a case, software adaptation can s
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´ IBISC FRE 2873 CNRS – Universit´e d’Evry Val d’Essonne, France [email protected] 2 INRIA/ARLES project-team, France {pascal.poizat,sonia.ben mokhtar}@inria.fr
Abstract. Services are developed separately and without knowledge of all possible use contexts. They often mismatch or do not correspond exactly to the end-user needs, making direct composition without mediation impossible. In such a case, software adaptation can support composition by producing semi-automatically new software pieces called adaptors. Adaptation proposals have addressed the signature and behavioural service interface levels. Yet, taking also into account the semantic level is mandatory to enable the fully-automatic retrieval of adaptors from service interfaces. We propose a new adaptation technique that, compared to related work, supports both behavioural and semantic service interface levels, works system-wide, and generates automatically distributed adaptors. Keywords: Model-Based Adaptation, Behavioural Adaptation, Semantic Adaptation, Services, Input Output Labelled Transition Systems.
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Introduction
Service Oriented Architectures (SOA) [22] have introduced a new organizing of software, based on services, self describing and loosely coupled interacting software components that support the rapid and low-cost composition of distributed applications. An important issue in SOA is service composition and its automation [22,16], either to fulfill a user task or to have services collaborating in added-value composite services. Techniques that support the composition in component or service based systems rely on four interface description levels: signature (operations), behaviour (protocols), non functional (time, QoS) and semantics [23]. In SOA, service composition takes place after services have been discovered. It is often assumed that discovered services conform at the different interface levels, and first, at the signature one where syntactic matching is used to put in correspondence required and provided functionalities. Approaches that support the behavioural (called conversation) and semantics levels assume one-to-one functionality correspondences [5,3]. These assumptions do not yield
This work is supported by the project “PERvasive Service cOmposition” (PERSO) of the French National Agency for Research, ANR-07-JCJC-0155-01.
J. Fiadeiro and P. Inverardi (Eds.): FASE 2008, LNCS 4961, pp. 146–162, 2008. c Springer-Verlag Berlin Heidelberg 2008
Distributed Behavioural Adaptation of Semantic Services
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in practice in open heterogeneous environments where services are developed by different organizations. Software adaptation [11] has provided solutions for component interoperability through the computation – from component interfaces and user-defined adaptation specifications called mappings – of adaptors that operate in-between components to ensure their correct1 composition at the signature and behavioural levels [11,6,2,19], and more recently at the non-functional level [25]. Yet, while automatic adaptation is high
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