Abstract: In service oriented architecture (SOA), the goal of consumers is to discover and use services which lead to them experiencing the highest quality. With the increasing number of Web services, recommending and selecting the optimal Web services for users has become one of the most important challenges in the service computing field. Traditional approaches to quality evaluation in SOA deem that consumers will be most satisfied when they receive the highest absolute performance. However, adopting such approach does not consider the consumers’ individual needs. So it will not necessarily lead to consumers receiving services that meet their requirements. In the service selection and recommendation process we need to consider not only the functional requirements of the service, but also non-functional requirements service account. In addition, the change of service quality can only be found in the service operated process. In order to solve this problem, this paper presents a QoS evaluation approach based on monitoring which fully considers functional and non-functional properties of service. We build a unified model and evaluate the quality of service based on the monitoring data. This approach provides the basis for the selection and recommendation services in dynamic environment. At last we describe the implementation framework of this approach.

Key words: Web service, QoS, evaluation model, monitoring