面向动态工作流的Web服务组合模型研究

Study on Dynamic-Workflow Oriented Web Service Composition Model

把Web服务与工作流相结合,将Web服务作为工作流中的各项任务,通过Web服务的动态组合技术,建立面向动态工作流的服务组合模型。对Web服务描述进行了扩展,提出了一个基于层次结构的服务发现模型,支持Web服务开发与部署的分离,并通过Web服务的动态查找,对符合要求的可用服务器,引入服务评价函数,根据服务器服务份额、价格策略以及信任度等因素对服务器进行综合评定,实现复合服务在运行时的动态部署与绑定。并通过工作流引擎对各项子任务的交互与完成进行相应控制,最终实现Web服务的动态绑定模型的执行框架。

Combined with workflow,the Web services are assigned as the tasks in the workflow process. A dynamic- workflow oriented service composition model is established according to the dynamic composition technology. The description to the Web service is expanded, a hierarchy-based service discovery model is proposed. This model also supports the separation of exploration and disposition. The service evaluation function is introduced to the usable server by dynamic lookup of the Web service. The server is evaluated according to the service share of the server and the price strategy and the trust level in order to realize the dynamic disposition and binding of the combined service when running. Finally, the execution frame of the dynamic binding to the Web service is realized by the engine of the workflow which controls the interaction and the accomplishment of the subtask.