Service-level agreement-based QoS analysis for web services discovery and composition

Quality-of-Service (QoS) in Web services considers a service’s nonfunctional characteristics during service specification, discovery, and composition. In order to encourage the development of QoS-aware Web services, we first develop a QoS-aware model, which contains a common set of QoS attributes including response time, throughput, reliability, availability and price etc. Then, based on the attributes, two alternative service selection methods, namely absolute and relative matchmaking, are presented. Finally, according to the formal semantics of different workflow patterns, we utilize the aggregative effects of QoS attributes to help service consumers perform QoS-aware service composition.