互联网环境下运行的组合服务易受到资源故障和组件失效影响而导致失效.已有的失效恢复措施在提高服务可用性的同时也会对服务的性能产生负面影响.为了对失效可恢复情况下的组合服务性能进行量化,通过综合组合服务失效类型和恢复策略,给...互联网环境下运行的组合服务易受到资源故障和组件失效影响而导致失效.已有的失效恢复措施在提高服务可用性的同时也会对服务的性能产生负面影响.为了对失效可恢复情况下的组合服务性能进行量化,通过综合组合服务失效类型和恢复策略,给出一种考虑失效恢复的组合服务性能分析模型.采用排队Petri网(queueing Petri net,简称QPN)描述组合服务的失效发生及其恢复处理过程,重点研究实施重试和替换策略的服务运行情况.详细描述了考虑失效恢复的服务节点和链路QPN模型的内部结构,在此基础上,通过服务交互机制构建组合服务分散执行的性能模型.最后,采用QPME工具仿真和比较不同失效发生率、失效类型分布和恢复策略下组合服务模型的性能表现.结果表明,该方法能够定量分析失效恢复对组合服务性能的影响,有助于指导不确定网络环境下的信息服务系统失效恢复策略实施方案的设计.展开更多
为了满足在组合W eb服务中提供服务质量支持,提供有保证的QoS(Quality of Service)的需要,以及针对目前在组合服务中,很少提供对服务质量支持的问题,建立了一个W eb服务质量的模型.该模型为所有服务建立了一系列的质量指标,并对它们进...为了满足在组合W eb服务中提供服务质量支持,提供有保证的QoS(Quality of Service)的需要,以及针对目前在组合服务中,很少提供对服务质量支持的问题,建立了一个W eb服务质量的模型.该模型为所有服务建立了一系列的质量指标,并对它们进行量化,得到量化值.最后在此模型的基础之上,在组合服务中建立了一个服务质量驱动的服务选择机制,从而可以实现所有在组合服务中的服务都是最优的.已经基于M icrosoft.NET实现了一个原型系统.展开更多
How to compose existing web services automatically and to guarantee the correctness of the design （e.g. freeness of deadlock and unspecified reception, and temporal constraints） is an important and challenging probl...How to compose existing web services automatically and to guarantee the correctness of the design （e.g. freeness of deadlock and unspecified reception, and temporal constraints） is an important and challenging problem in web services. Most existing approaches require a detailed specification of the desired behaviors of a composite service beforehand and then perform certain formal verification to guarantee the correctness of the design, which makes the composition process both complex and time-consuming. In this paper, we propose a novel approach, referred to as AutoSyn to compose web services, where the correctness is guaranteed in the synthesis process. For a given set of services, a composite service is automatically constructed based on L＊ algorithm, which guarantees that the composite service is the most general way of coordinating services so that the correctness is ensured. We show the soundness and completeness of our solution and give a set of optimization techniques for reducing the time consumption. We have implemented a prototype system of AutoSyn and evaluated the effectiveness and efficiency of AutoSyn through an experimental study.展开更多
文摘互联网环境下运行的组合服务易受到资源故障和组件失效影响而导致失效.已有的失效恢复措施在提高服务可用性的同时也会对服务的性能产生负面影响.为了对失效可恢复情况下的组合服务性能进行量化,通过综合组合服务失效类型和恢复策略,给出一种考虑失效恢复的组合服务性能分析模型.采用排队Petri网(queueing Petri net,简称QPN)描述组合服务的失效发生及其恢复处理过程,重点研究实施重试和替换策略的服务运行情况.详细描述了考虑失效恢复的服务节点和链路QPN模型的内部结构,在此基础上,通过服务交互机制构建组合服务分散执行的性能模型.最后,采用QPME工具仿真和比较不同失效发生率、失效类型分布和恢复策略下组合服务模型的性能表现.结果表明,该方法能够定量分析失效恢复对组合服务性能的影响,有助于指导不确定网络环境下的信息服务系统失效恢复策略实施方案的设计.
基金the National High-Tech Research & Development Program of China (Grant No. 2007AA010301)the National Basic Research Program of China (Grant No. 2005CB321803)+2 种基金the National Natural Science Foundation of China for Distinguished Young Scholar (Grant No. 60525209)the National Natural Science Foundation of China (NSFC)/Research Grants Council (RGC) Joint Research Project (Grant No. 60731160632)the Program for New Century Excellent Talents in University (Grant No. NCET-05-0186)
文摘How to compose existing web services automatically and to guarantee the correctness of the design （e.g. freeness of deadlock and unspecified reception, and temporal constraints） is an important and challenging problem in web services. Most existing approaches require a detailed specification of the desired behaviors of a composite service beforehand and then perform certain formal verification to guarantee the correctness of the design, which makes the composition process both complex and time-consuming. In this paper, we propose a novel approach, referred to as AutoSyn to compose web services, where the correctness is guaranteed in the synthesis process. For a given set of services, a composite service is automatically constructed based on L＊ algorithm, which guarantees that the composite service is the most general way of coordinating services so that the correctness is ensured. We show the soundness and completeness of our solution and give a set of optimization techniques for reducing the time consumption. We have implemented a prototype system of AutoSyn and evaluated the effectiveness and efficiency of AutoSyn through an experimental study.
