Grid Workflow Scheduling Algorithm And Prototype Using Customized Qos Mode

Grid Service is one kind of Web Service based on the WSDL definition, implementing a series of interfaces and following several behavioral standards for client interaction. As the development of the grid service application, complex tasks in grid workflow can be finished by combining individual services into a competent composite service. The grid workflow emphasizes the quality of service, but current description of the quality of grid service is lack of flexibility, it can't satisfy different uses' requirement. In another aspect, current grid workflow uses DAG to describe the process. DAG is weak in describing complex process and very difficult to handle the complex application requirement.This paper presents a customized quality of service model in grid workflow that is different from the traditional one. In the paper, it gives the definition and calculation of the customized quality of service model in workflow. The user is more flexible to describe his customized quality in new model. Also, this paper used BPEL to describe the process to combine the grid service, using the WS-Addressing Method. This paper make the new BPEL workflow engine support the grid service and job submission.In the customized quality of service model, this paper improves the original workflow scheduling algorithm. Through the experiment the new algorithm have higher correct percentage in complex environment and have the similar scalability as the original algorithms in complex environment.To prove the customized quality of service model and the grid workflow presented in this paper practical, this paper implements a prototype using the customized quality of service model and the execution BPEL that supports gird service and quality of service description.