QoS-Enhanced Broker for Composite Web Service Selection

The paper proposes a layered system for web service composition. The input for the system is the specification of the desired service, including both functional and non-functional requirements. The composition operation takes as input a generic composition graph defined based on the functional requirements. Then, the set of potential compositions is identified based on "hard" non-functional requirements. This set is represented in terms of an extended version of the composition graph that permits to take into account the different BPEL constructors. Finally, best composition(s) are identified by solving a biobjective shortest path problem on the transformed composition graph.