A QoS-Aware Service Composition Optimization Based on Logical Structure

Abstract

Web Service composition integrating several single services by logical structure can fulfill users' complex requests while a single one cannot do this. As one of service's non- functional components, Quality of Service (QoS) can be used as the criteria for service selection process and evaluation of composition results. However, so far there is no suitable method to estimate composition result and existing approaches on QoS- aware Service Composition don't concern the effect of composition logic on composition consequences. This paper presents an approach to optimize a QoS-aware Service Composition based on the logical structure. With our approach, a global optimization consequence can be attained by displacing the single service component in a composition process, which is according to the flexibility of service execution duration under parallel logic. Moreover some experimental results illustrate that the proposed approach works effectively. Web service, one technology on Service-Oriented Architecture (SOA), is a software system built on a series of technologies such as UDDI, WSDL, SOAP and OWL-S. Users can publish or call a web service on Internet effectively and conveniently. However, according to the development of web service and the complexity of users' requirements one single service usually cannot fulfill customers' complex requirements. So Web service composition is proposed to solve these successfully. Web service composition is a kind of flexible and automatic business process which is produced by integrating several single services selected by customers' functional requirements into a whole one and orchestrating by particular logical structures and data dependence. But a great number of similar-functional services exist on network, so it is eager to develop an effective method to select a service which has better quality than anyone else from the view of the composition plan. Quality of Service (QoS) is a broad concept that includes a number of non-functional descriptions such as price, execution duration, reliability and reputation. These properties that apply both to stand-alone Web services and to composite Web