The Study Of Workplace Selection Method In Migrating Workflow System

With the computer network systems developing gradually, the complex businesses required by many users are accomplished cooperatively in a distributed environment, which make the migrating workflow become a hot issue in recent years. Migrating workflow includes the migrating workflow engine, the workplace and the migrating instance, is a new model of the workflow management. When created, the migrating instance migrates from one workplace to another, using service to execute the business process. A migrating workflow engine creates migrating instances according to business processes. The migrating instance migrates from one workplace to another, using run-time service and workflow service to execute the business process.Due to advantages such as its support to business execution with distributed information storage and processing method as well as reducing network load and network latency, migrating workflow is particularly suitable for the business process with complex and large tasks, multi-node cooperation and frequent information exchange. It has drawn considerable attention of people in both the laboratory and the business.Path planning is a critical issue in migrating workflow system. Dynamic path planning method takes the environmental variability into account, so the flexibility problem of migrating workflow can be solved to some extent. As a part of path planning process, each time of workplace selection is the concrete step in developing a workflow path. However, in most practical applications, the mobile agent not only expects the final result to complete a service, but also considers spending time, money, reputation, etc., which are the necessary factors in decision. Without considering the cost for completing task means the quality of the task result can not be ensured. Thus, the service completing efficiency of the working position selected by the mobile agent may not be the most appropriate. In order to achieve the dynamic planning for the entire workflow path, mobile agent should dynamically choose workplace according specific analysis in the current environment.In large-scale network environment, the number of workplaces is gradually increasing. Inevitably, many service providers with the same functionality of services, but tend to have different service qualities. Referencing to the quality-oriented problem of service composition in Web service, this paper presents a more comprehensive workplace evaluating method with evaluation items system. It makes workplace selection in path planning more flexible and suitable.This paper introduces bidding mechanism into establishing selecting relationship between mobile agent and workplace. Referencing to the contract net protocol, mobile agent communicates and consults with workplaces for the specific quality of service factors. Then, the agent takes the appropriate choice strategy according to the specific requirements of user tasks. Based on the commitment of non-functional properties on the candidate workplace, the appropriate workplace is selected for the mobile agent. Then a contract is signed between mobile agent and workplace in order to achieve the service, mobile agent migrates and completes the task at last. This method is a reliable protocol mechanisms and services guarantee for users receiving services, and it also improves the efficiency and flexibility of the migrating workflow.