| Web service is self-included and self-described application program based on web. With the increase of the number of companies that publish their applications as web services, the service users' requirement of the service function and service quality are becoming higher and higher; however single service from suppliers is difficult to meet the requirement of the users. So it will certainly course of web services composition with high quality in web services technology.Service composition is to combine the relative services dynamically according to users' requirement and publish as new service which can implement particular tasks. So that we can not only saves the developing cost of the services, but also improves reusability and availability of service components and essential services. The most difficult problem in the service composition is how to improve the quality service. It aims to find a group of optimal service under users' constrains and obtain the service which meets users' requirement best.This article is mainly targeted at the analysis the quality of web service. Article first introduced the definition of web services, architecture and related concepts of web services protocol stack. And described in detail the concept of web sercices, web services advantages, key technologies of the web services and methods of web services. Followed by the introduction of temporal Petri net, quoting temporal Petri net model, and use temporal Petri net to describe web services composition problem. Combination of temporal Petri nte logic formulas can receive combination system's reachable status and operation status, anslysis its safety, reachability and dead lock. At last, according to web services'quality parameters, calculate the quality of the web services composition. Finally give an example, through this example can know: temporal Petri net is a good tool of analysis web services, use temporal Petri net to describe web service's quality is fessible. |
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