| With the enhance of computer and Internet,and with the population of web services,a single web service has not met the need of the requirement,so web service composition has become an inexorable trend.The currently existing web services can be composed to a service flow according to application requirement - functional and dysfunctional requirement,and they coordinate to complete the task.In the composition process,a single web service may be chosen automatically from a group of web services with the same function.However,there are so many equivalent web services on the Internet,which are from deferent providers and whose QoS are deferent.Usually,in composition process,web service is chosen in according to its QoS.In this paper,the writer designs a web service composition model thinking of service quality factor,and build the guide function to choose web service.The function's arithmetic has been improved to enhance the choice efficiency on base of traditional arithmetic.The improved service quality arithmetic has been written in the paper named web service discovery based on abstract service and probability that has been confirmed by a core journal.This paper,at first,put forward a web service dynamic composition model based on colored Petri net(WSC-CPN) thinking of QoS,after analyzing the crucial issues,the related solution and the practical technology about web service composition.It introduces each element of WSC-CPN in details,especially designs the color set and guide function, and elaborates their purpose in composition.Then it makes up the modes for web service using WSC-CPN.During the period,the paper put forward a place's two-stage theory and a gate transition conception.On the base of the signal web service,the writer designs six composition modes including sequential mode,XOR-split mode,AND-split mode, AND-join mode,XOR-join mode and loop mode.Then,after analyzing the traditional QoS arithmetic,the paper puts forward a service general quality evaluation method thinking of customers' strategy and probability.Then,it verifies the service composition model using WSC-CPN,and put forward the method of calculating the QoS for the composed service. Finally,the writer realizes the tool to calculate the QoS for the composed web service with java,which will help to analyze the models using WSC-CPN. |
