An Overview of Web Services Composition Approaches <s> Dynamic Web Services Composition Based on QoS Model <s> Web service composition lets developers create applications on top of service-oriented computing's native description, discovery, and communication capabilities. Such applications are rapidly deployable and offer developers reuse possibilities and users seamless access to a variety of complex services. There are many existing approaches to service composition, ranging from abstract methods to those aiming to be industry standards. The authors describe four key issues for Web service composition. <s> BIB001 </s> An Overview of Web Services Composition Approaches <s> Dynamic Web Services Composition Based on QoS Model <s> How to select the service components and coordinate services composition have become key problems in dynamic web services. Based on the original discrete probability distribution, we propose a QoS model to support dynamic Web services composition, develop a WS_TSC algorithm for services composition QoS. We finally carry out a simulation experiment via this algorithm. Compared with San-Yih Hwang's work, the experimental result shows that this model markedly reduces the response time and improves the rate of success and the rate of composition in dynamic Web services composition. <s> BIB002
DONG Rang-sheng et al propose in BIB002 a QoS model to support dynamic Web services composition, They identify two problems to work out immediately in dynamic Web service composition : (1) How to select the service components. BIB001 How to coordinate services composition. For that purpose this team propose a QoS model for selection and coordination problems which supports dynamic Web services composition, then develop a WS _ TSC algorithm to select the services according to the restrictions on the response time, the rate of the success and the rate of the composition and this approach mainly focuses on Response time T(a), Reliability R(a) and Composability C(a) in Web services. Using the principle of linear programming transformed QoS parameters' formula in Web services composition flow into a single objective function to solve the optimization of Web Services selection. One algorithm is designed based on the model to select services, then assess the QoS performance in the dynamic Web services composition such as the response time, the rate of success and the rate of composition. The QoS model presented in this approach has a certain degree of generality, so in the future the model and the algorithm can be applied to other service-oriented framework.