Abstract: The authors tackle the problem of the efficient and scalable execution of the services composition execution engine for differentiated Quality of Service.On the basis of decoupling the execution of the processes from the execution of their activities,the authors design and implement the flow executive architecture with dual feedback control loops,which located in the process executor and service proxy respectively.The experiment results demonstrate that decoupling method improves the efficiency and throughput of the engine,and the feedback control mechanism enables the engine to provide response time guarantees for differentiated services even when workload varies significantly.

Key words: Web services composition execution engine, feedback control, service class, Quality of Service

摘要： 在Web服务组合执行引擎中解耦流程执行和成分Web服务调用,设计和实施了带有双控制反馈控制环的流程执行结构,反馈控制环分别位于流程执行器与服务代理之上。仿真结果表明：解耦流程执行和成分Web服务调用提高了引擎资源的使用效率,增加了流程执行的并发性,提高了引擎的吞吐量;引入QoS反馈控制结构,使得引擎在组合服务负荷变化时,可为不同的请求服务等级提供服务响应时间保障。

关键词: Web服务组合执行引擎, 反馈控制, 服务等级, 服务质量