A Feasibility-Enhanced Approach for QoS-Based Web Service Composition in Cloud Environment

The number of Web service in cloud environment is increasing explosively. These independent services can be integrated into value-added service through composition technology as long as their interfaces are subject to standard protocols. Now more and more services providing the same function but different in QoS are available in cloud, so service composition strategy is needed to obtain the optimal composition scheme. Furthermore, service level agreement (SLA) plays an important role in the process of service delivery. Users´ request for the performance of composite service, such as price and response time, is defined in SLA. A composite service is feasible only if its QoS satisfies user´s request. In this paper, we first propose a QoS evaluation method which takes the SLA satisfaction into account. Then we design a service selection algorithm based on our QoS evaluation method. The simulation results show that our approach performs well in guaranteeing composite services´ feasibility and optimality.