The Selection Of Web Services For Composition Based On 3-layer Web Services Organization Model

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. So it becomes the focus in the area of industry and academia. Nowadays, compositing previous available Web services into incremental Web services with more powerful functions have been a new hotspot.However, with the prevailing of Web service, the number of services on the internet has been larger and larger. 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.The dissertation mainly researches the dynamic Composite Web Services selection.Firstly, in the study of QoS the dissertation analyzes current QoS models' advantages and disadvantages, based on which proposes a quality model, which regards the service level QoS, the domain level QoS and the relation QoS between business, such as duration , price, reliability, availability, reputation, domain quality etc.Secondly, the dissertation views Web services selection problem in Web services composition as combinational optimization problem and designs QoS-globally optimal model which can satisfy the users' constrains, then presents a dynamic Web services selection approach with QoS global optimal, the approach is based bidirectional dynamic programming. In order to improve the efficiency of the approach, the dissertation uses 3-layer Web Services Organization Model to support the selection of Web services. The match of service community's interface replace the match of service's interface, this improve the efficiency of the selection of web services.