ABSTRACT
Currently, most approaches that deal with Qos of Web services only address some generic criteria such as execution cost, execution time, reliability and availability, etc [2, 3, 4]. Their Qos information is often advertised by service providers in a subjective and unneutral manner. Furthermore, in order to meet Qos requirements of different applications and business, such generic criteria might not be sufficient. On the other hand, the number of services providing a similar functionality may be large and constantly changing. It is inappropriate to assign randomly a component service to each execution task of composite service. Existing service selection approaches have not considered a set of criteria (other than execution cost) for selecting component services. It is neglected that different users may have different preferences or requirements on different Qos attributes (criteria). In order to avoid all above
disadvantages, we present an extensible set of Qos criteria and decision model DQos for evaluating Web services. Some key features of DQos model are: (1) Using fidelity criterion to enhance the open and fair characteristics of generic Qos criteria; (2) Formulating service selection as Multiple Attribute Decision Making (MADM) problem which can be solved using subjective weight mode, objective weight mode, and subjective-objective integrated mode; (3) Embodying different users' requirements on Qos criteria and objective characteristic of Qos information.
