Service compositions are created by exploiting existing component services that are, in general, out of the control of the composition developer. The challenge nowadays is to make such compositions able to dynamically reconfigure themselves in order to address the cases when the component services do not behave as expected and when the execution context changes. We argue that the problem has to be tackled at two levels: on the one side, the runtime platform should be flexible enough to support the selection of alternative services, the negotiation of their service level agreements, and the partial replanning of a composition. On the other side, the language used to develop the composition should support the designer in defining the constraints and conditions that regulate selection, negotiation, and replanning actions at runtime. In this paper we present the SCENE platform that partially addresses the above issues by offering a language for composition design that extends the standard BPEL language with rules used to guide the execution of binding and re-binding self-reconfiguration operations.

Abstract. The diffusion of service-oriented computing is today heavily influencing many software development and research activities. Despite this, service-oriented computing is a relatively new field, where many aspects still suffer from a lack of standardization. Also, the service-oriented approach is bringing together researchers from different communities or from organizations having developed their own solutions. This introduces the need for letting all these people communicate with each other using a common language and a common understanding of the technologies they are using or building. This paper proposes a conceptual model that describes actors, activities and entities involved in a service-oriented scenario and the relationships between them. While being created for a European project, the model is easily adaptable to address the needs of any other service-oriented initiative.

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