Composition de services et supervision : application aux Web Services

Stage de DEA. Rapport de stage.Le développement de l'Internet a favorisé l'échange de données entre partenaires et la multiplication de services en ligne. Des plateformes de services évoluées permettent aujourd'hui la conception, le déploiement et la mise en oeuvre de ces services dans des échelles de temps réduites. Au sein de ces plateformes, les services peuvent être perçus comme des composants, et des modèles de composition permettent de les combiner pour aboutir à des services plus élaborés. Ces services présentent par conséquent une forte dynamicité, d'où la nécessité de créer des plateformes de supervision qui soient adaptées. La richesse des spécifications fournies par les modèles de composition peut constituer un socle pour cette supervision. Ce stage de DEA consiste à trouver de nouvelles méthodes permettant d'exploiter les modèles de composition pour faciliter la supervision de services composés. Pour cela, nous nous sommes placés dans le cadre des Web Services et avons étudié une des fonctions de la supervision : la gestion de la qualité. Nous proposons d'étendre un langage de composition pour qu'il intègre des éléments de qualité de service et nous avons défini une plateforme qui exploite cette extension, et qui permet la gestion de la qualité des Web Services composés par recomposition dynamique

Managing Application Service Dependencies with XML and the Resource Description Framework

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Component-based Adaptation Methods for Service-Oriented Peer-to-Peer Software Architectures

Service-oriented peer-to-peer architectures aim at supporting application scenarios of dispersed collaborating groups in which the participating users are capable of providing and consuming local resources in terms of peer services. From a conceptual perspective, service-oriented peer-to-peer architectures adopt relevant concepts of two well-established state-of-the-art software architectural styles, namely service-oriented architectures (also known as SOA) and peer-to-peer architectures (P2P). One major argumentation of this thesis is that the adoption of end-user adaptability (or tailorability) concepts is of major importance for the successful deployment of service-oriented peer-to-peer architectures that support user collaboration. Since tailorability concepts have so far not been analyzed for both peer-to-peer and service-oriented architectures, no relevant models exist that could serve as a tailorability model for service-oriented peer-to-peer architectures. In order to master the adaptation of peer services, as well as peer service compositions within service-oriented peer-to-peer architectures, this dissertation proposes the adoption of component-oriented development methods. These so-called component-based adaptation methods enable service providers to adapt their provided services during runtime. Here, a model for analyzing existing dependencies on subscribed ser-vice consumers ensures that a service provider is able to adapt his peer services without violating any dependencies. In doing so, an adaptation policy that can be pre-arranged within a peer group regulates the procedures of how to cope with existing dependencies in the scope of a group. The same methods also serve as a way to handle exceptional cases, in particular the failure of a dependent service provider peer and, hence, a service that is part of a local service composition. In this, the hosting runtime environment is responsible for detecting exceptions and for initiating the process of exception resolution. During the resolution phase, a user can be actively involved at selected decision points in order to resolve the occurred exception in unpredictable contexts. An exception could also be the reason for the violation of an integrity constraint that serves as a contract between various peers that interact within a given collaboration. The notion of integrity constraints and the model of handling the constraint violation aim at improving the reliability of target-oriented peer collaborations. This dissertation is composed of three major parts that each makes a significant contribution to the state of the art. First of all, a formal architectural style (SOP2PA) is introduced to define the fundamental elements that are necessary to build service-oriented peer-to-peer architectures, as well as their relationships, constraints, and operational semantics. This architectural style also formalizes the above-mentioned adaptation methods, the exception handling model that embraces these methods, the analysis model for managing consumer dependencies, as well as the integrity constraints model. Subsequently, on this formal basis, a concrete (specific) service-oriented peer-to-peer architecture (DEEVOLVE) is conceptualized that serves as the default implementation of that style. Here, the notions described above are materialized based on state-of-the-art software engineering methods and models. Finally, the third contribution of this work outlines an application scenario stemming from the area of construction informatics, in which the default implementation DEEVOLVE is deployed in order to support dispersed planning activities of structural engineers