Sélection et composition flexible basée services abstraits pour une meilleure adaptation aux intentions des utilisateurs

摘要

The design approach of service oriented architectures (SOA) is based on standards which gives the possibility of creating an integrated IT infrastructure capable of rapidly responding to new user needs. Actually, it is not always easy to find services that meet user requests. Therefore, the service composition satisfying the user intention is a growing need. The composition of services implies the ability to select, coordinate, interact, and to interoperate existing services. The composition is considered as a complex task. This complexity is mainly due to the large number of available services and their heterogeneity as they are created by different organizations. This complexity is increased when services must be dynamically and automatically composed to meet requirements which are not satisfied by existing services. In fact, an approach for service composition must offer the potential to achieve flexible and adaptable applications, by selecting and combining services based of the request and the context of the user. In this perspective, different approaches have been developed for services composition. However, most of the existing composition approaches tend to be static and not flexible in the sense that they do not have the ability to adapt to user requirements. In this thesis, we propose a composition approach in which the generation of the composition schema is performed at runtime through the use of abstract services provided at design time. The use of abstract services allows flexibility and adaptability without having to build a service composition from scratch at run time. The composition process that we propose consists mainly of four steps. The first step takes a structure of user requirements materialized by a graph of intentions and enriches this graph to explicit the implicit relationships. The enriched graph is used to generate an initial composition scheme by building the control flow and selecting the appropriate abstract services. The selection of these services is based on the semantic matching and the degree of semantic affinity between abstract services. The third step is to generate the final composition schema with a refinement mechanism of abstract services using semantic matching techniques and taking into account user context and constraints. Finally, the execution plan is generated driven by non-functional constraints provided in the intentions specification.