The Design And Realization Of Web Service Composition QoS Fault-Tolerant Framework

As the most popular platform of resource conform, webservice can aggregate variety of resource and service via different platforms. W3C defines webservice as 'application of software under URI'. Webservice Composition put other services together through specific functional and logistic relationship, after then, a new service is set up. Because webservice could apply the strong function of resource integration and extensive services, it is being wildly used in integrate application and e-business. However, problems come out with the great development of WebService. Growth of application scale and the instability of network environment lead faults took place in the running of the webservice. It is so important to adjust the webservice Composition to handle fault in time to guarantee QoS that to make the service go on.Fault Handling in Webservice Composition is a valid method to improve the usability and reliability of the service. The paper classifies problems often take place in the service by order of severity, suggests the Fault Handling framework of the WebJetFlow at runtime, in which designed and achieved relevant online handling policy pointedly, which guarantees the function and the quality of service.The most important property of quality of service is the delay of service system response, so the key problem of Web QoS is the guarantee of timeliness. The paper is based on SLA protocal, designed a set of Fault Handling framework from user interface to WebJetFlow executing Engine, which applies guarantee of time, as well as cost and mission success rate, in order to guarantee the carrying out of WebService Composition under the guarantee of QoS. In the end, a set of actual test is given to prove the validity of the framework.