Abstract: In order to provide composed Web services according to the quality of service (QoS) requirements of clients, firstly,an enhanced Web service description language (EWSDL) with rich QoS elements was proposed to describe the QoS properties of Web services based on the current Web service description language (WSDL), Secondly, a service composition management language (SCML) was also presented to management composition. Thirdly, a way to choose a proper service from the candidate services set was given based on the multi-object decision theory. Fourthly, an evolved Web service framework (E-WsFrame) was designed by adding a new role in the current Web service architecture. Finally, a prototype of E-WsFrame was implemented. Experiments show that the E-WsFrame can feasibly select and compose pre-existing Web services in terms of clients’ dynamic requirements at the run time.

Key words: Web Service, Service Composition, Quality of Service, Service Management