Research On Design And Implementation Of Workplace Service In Migrating Workflow System

Migrating workflow is a new technology applying mobile computing to workflow management, which is explained as a mechanism combining static workflow specification with local strategy and user strategy at runtime. Three essential factors of a migrating workflow system include migrating workflow management engine, migrating instance and workplace. The management engine is in charge of workflow procedure definition, migrating instance's generation and the coordination of many migrating instances. The workplace refers to the MI server and work-machine network, while the MI server is the executing place of migrating instance, and work-machine provides workflow services to migrating instances. A migrating instance accesses workflow services through MI server by means of object reference. Migrating instances complete the whole business goal by migrating and cooperation with the support of MI server.In a migrating workflow system, workflow services are provided by the workplaces with different structures. So the migrating workflow service is different from the workflow executing service in traditional workflow systems. It has its own characteristic. Firstly, the workplace is a distributed environment with different structures. How to organize and use workflow services is important in the workplace because it impacts the executing efficiency and the reliability of the workflow executing service. Secondly, the workflow services of semantic affinity for migrating instances and workplaces is needed in favor of making the migrating decision and realizing the mapping from the task specification to the workflow service.The paper summarized the actual service strategies in the workflow management system, including the service deployment, providing, publication and security. These strategies could help the workplace to organize, manage and use the workflow services effectively. A dynamic service supplying and querying strategy was proposed to describe how to query services, and the relationship between tasks, services, sub services and workplaces. This strategy solved how to change input/output parameters of services dynamically at runtime.Based on the characteristic of services, some stable, common services were classified as MI service, such as migrating in/out service, communicating service, logging service and so on; some special services were classified as workflow service, which was related to a business application and must be queried to find out its details. According to whether MI should request the services on its own initiative, the paper classified the services into transparent services and non-transparent services. In the implementation, the workflow service supporting module (WSSM for short) provided services to MI Server, and we designed two types of WSSMs, synchronously calling workflow service module and asynchronously calling workflow service module. According to the experiment result, the paper compared these two modules.Then we discussed the MI Server and its work-machine network how to provide local workflows. According to the migrating workflow system framework, the application server in the work-machine network, which was independent to the MI Server, was the service executor, and a workflow participant could connect to the application server with a browser on a work-machine. We deployed some business process modules on an application server for the MI Server to use. In the application, we used the JBoss Application Server, an open source server, as the application server. According to the session facade design pattern, we developed a stateless session bean named ServiceProxyBean, which provided a uniform interface and shielded the complexity of the business layer for MI Server.We took a book ordering process for example, implementing the service querying and management. According to the experiment result, we compared the synchronously calling workflow service supporting module and asynchronously calling workflow service supporting module. Finally we showed how the MI Server and its work-machine network provided a local workflow by a class one examining and approving process.