Abstract: With the increase of Web services with the similar or same functionality, QoS (Quality of Service) has become the important criteria for users to select the appropriate Web services. At present, most approaches to the QoS-based Web services selection suffer from the purely syntactic matchmaking, which could not meet the requirements of complicated QoS matchmaking in semantic level. In this paper, we proposed a based on semantic QoS-aware Web service discovery scheme. Initially, a QoS ontology was presented to define QoS data into service descriptions. hhen, the ontology reasoning was adopted to change previous syntactic matchmaking into a semantic way. Through confirming the compatibility of concepts, complicated QoS conditions were solved as constraints via constraints programming. The optimization algorithm based on QoS was proposed to obtain the appropriate service to users. Finally, case study was given to illustrate the effectiveness of discovery scheme.

Key words: Web services discovery, QoS aware, Constraints programming, Semantic Web