| With the rapid development of Internet technology, the needs for resource in the World Wide Web is getting stronger than ever before. Web services composition has rendered a very good solution for making good use of software component in the World Wide Web which makes Enterprise Application Integration and dynamically collaborating feasible.Web services composition ever almost works manually, which is time consuming and can't meet the dynamic of the web services. On the basis of analysis and comparing with the web services and semantic web technology, a model of secure semantic web services architecture is proposed. Some methods for web services discovery, execution, interpretation and composition using web services technology combining with semantic web technology is suggested.By dynamically composing existing web services, the existed resources can be utilized well, which according with the tide of software reusing and adapting well the constant evolution of client requests. At the same time, security is another issue for web services composition. So a framework of dynamic composition for web services is proposed according to secure semantic web services architecture, and based on it an improved algorithm for dynamic services composition is proposed. Based on BPEL4WS(Business Process Execution Language for Web Services), the method constructs a dynamic services composition graph, and optimizes it according to quality of service, and select a series services satisfied with the threshold of service composition as the result. The method is also satisfied with that several services are front or subsequence of the other services. The criterion of quality of service for web services is introduced, which ensure the quality of service composition.At last, a prototype system for dynamic composition of services is introduced, and a example indicates that the method is effective. |
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