Résumé en anglais

Web services composition has been gaining interest over the last years as it leverages the capabilities to offer complex operations resulting from the aggregation of Web services offered by different organizations. As composite Web services are often long-running, loosely coupled and cross-organizational applications, advanced transactional support is required to ensure reliable execution. In addition, in the presence of multiple Web services with equivalent functionality, users will discriminate the alternatives based on their quality of service (QoS). This paper address the issue of selecting and composing Web services not only according to their functional requirements but also to their transactional properties and QoS characteristics defined using a quality model. In this model, Web services are selected in a way that satisfies user preferences. These preferences are expressed as weights over QoS criterion and as risk level defining semantically the transactional requirements.