QoS Based Ranking for Web Services: Fuzzy Approaches

Web service selection is one of important steps in many Web service applications such as Web service composition systems and UDDI registries. As more and more Web services are available on the Internet, there are often a number of Web services which are functionally matched with a service request. QoS plays a crucial role in selecting Web services in terms of their quality. According to userpsilas requirements on service quality, candidate Web services are ranked in order to find best Web services. In many cases, the value of a QoS property may be difficult to be precisely defined. Therefore fuzzy logic can be applied to support for representing imprecise QoS constraints. In addition, suitable ranking algorithms which can deal with fuzzy numbers have been proposed. In this paper, we will present an overview of current research works which concentrate on developing QoS based ranking algorithms by basing on fuzzy logic. These works are summarized and compared in order to assess their benefits and limitations. Such analysis contributes in developing more complete solutions in ongoing works in the field of Web service discovery and selection.