QoS-Aware Service Composition in Dynamic Service Oriented Environments

Abstract. QoS-aware service composition is a key requirement in Ser-vice Oriented Computing (SOC) since it enables fulfilling complex user tasks while meeting Quality of Service (QoS) constraints. A challenging issue towards this purpose is the selection of the best set of services to compose, meeting global QoS constraints imposed by the user, which is known to be a NP-hard problem. This challenge becomes even more relevant when it is considered in the context of dynamic service environ-ments. Indeed, two specific issues arise. First, required tasks are fulfilled on the fly, thus the time available for services ’ selection and composi-tion is limited. Second, service compositions have to be adaptive so that they can cope with changing conditions of the environment. In this pa-per, we present an efficient service selection algorithm that provides the appropriate ground for QoS-aware composition in dynamic service envi-ronments. Our algorithm is formed as a guided heuristic. The paper also presents a set of experiments conducted to evaluate the efficiency of our algorithm, which shows its timeliness and optimality.