A combination of services QoS model customized for choosing design and implementation

Web service is an application program, which is based on internet, distributed, self-included, self-described and modular. It possesses the attributes of well encapsulation and loose coupling. With the prevailing of Web service, how to select a set of services among large body of services with the same function in order to make the Composite Web Service achieve better performance and better quality is a hot issue in recent research. At the same time, with the dynamic environment of the Internet and business, it is difficult to choose the better and more precise service for the simple and static service choice model .So the dynamic choice of web service is quite important for the task. AS the research of Web Service gets deeper and deeper, the single service can´t meet the need of the client. As the result, the Composite Web Service which can provide value-added functions has received a lot of attentions. So, the Web Service Composition emerges as the times require. In the study of QoS thesis analyzes current QoS models´ advantages and disadvantages, which proposes a new, objective, reliable QoS model called the Dynamic QoS model (D-QoS model). There is a way which supports the management in the thesis. The approach is based on genetic algorithm and uses the D-QoS model to solve the composite optimization, there is a diminutive system in which we could prove that the model is feasible and ensure the deep popularization of the model.