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A probabilistic approach to modeling and estimating the QoS of web-services-based workflows 总被引:1,自引:0,他引:1
Web services promise to become a key enabling technology for B2B e-commerce. One of the most-touted features of Web services is their capability to recursively construct a Web service as a workflow of other existing Web services. The quality of service (QoS) of Web-services-based workflows may be an essential determinant when selecting constituent Web services and determining the service-level agreement with users. To make such a selection possible, it is essential to estimate the QoS of a WS workflow based on the QoSs of its constituent WSs. In the context of WS workflow, this estimation can be made by a method called QoS aggregation. While most of the existing work on QoS aggregation treats the QoS as a deterministic value, we argue that due to some uncertainty related to a WS, it is more realistic to model its QoS as a random variable, and estimate the QoS of a WS workflow probabilistically. In this paper, we identify a set of QoS metrics in the context of WS workflows, and propose a unified probabilistic model for describing QoS values of a broader spectrum of atomic and composite Web services. Emulation data are used to demonstrate the efficiency and accuracy of the proposed approach. 相似文献
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工作流进程中的QoS受很多非功能性因素的影响,例如性能、可靠性以及安全性等等。对QoS度量的管理直接影响到参与工作流具体应用的服务能否顺利完成。因此,当服务被工作流或Web进程创建或管理时,底层的工作流引擎必须估计、检测并控制用户的QoS。基于已有的工作流模型分解算法,利用随机良构工作流网的数值分析,给出了分析工作流进程QoS的一种新方法,并结合实例加以验证。 相似文献
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Dimosthenis Kyriazis Konstantinos Tserpes Andreas Menychtas Ioannis Sarantidis Theodora Varvarigou 《Concurrency and Computation》2009,21(6):739-766
The advent of heterogeneous and distributed environments, such as Grid environments, made feasible the solution to computational‐intensive problems in a reliable and cost‐effective manner. In parallel, workflows with increased complexity that require specialized systems to deal with them are emerging, so as to carry out more composite and mission‐critical applications. In that rationale, quality‐of‐service (QoS) issues need to be tackled in order to ensure that each application satisfies the corresponding user requirements. Therefore, considering the quality provision aspect as fundamental for enabling Grid applications to become QoS compliant, we present an approach for service selection using QoS criteria. The latter is achieved with a suite of components that allow the different mappings of application workflow processes to Grid services that not only meet the user goals and requirements but also maximize his/her benefit in terms of the offered QoS level. We also demonstrate the operation of the aforementioned suite of components and evaluate its performance and effectiveness using a Grid scenario, based on a 3D image rendering application. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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目前存在的大多数基于QoS(quality of service)的Web服务选择方案都忽略了服务之间的关联关系, 认为服务之间是相互独立的, 使得组合服务的结果与实际有所偏差。为了提高组合Web服务QoS的精确性, 考虑到服务之间的关联关系对组合服务质量的影响, 分别对服务之间的接口关联、业务关联和统计关联三种关联关系进行研究, 提出了一种基于关联度的关联服务集合发现方法, 将支持服务关联的选择问题转换为混合整数规划模型进行求解。实验结果表明, 考虑服务之间的关联关系会提高组合Web服务的质量。 相似文献
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Christoph Riedl Tilo Böhmann Michael Rosemann Helmut Krcmar 《Information Systems and E-Business Management》2009,7(2):199-221
Service-oriented architectures and Web services mature and have become more widely accepted and used by industry. This growing
adoption increased the demands for new ways of using Web service technology. Users start re-combining and mediating other
providers’ services in ways that have not been anticipated by their original provider. Within organisations and cross-organisational
communities, discoverable services are organised in repositories providing convenient access to adaptable end-to-end business
processes. This idea is captured in the term Service Ecosystem. This paper addresses the question of how quality management
can be performed in such service ecosystems. Service quality management is a key challenge when services are composed of a
dynamic set of heterogeneous sub-services from different service providers. This paper contributes to this important area
by developing a reference model of quality management in service ecosystems. We illustrate the application of the reference
model in an exploratory case study. With this case study, we show how the reference model helps to derive requirements for
the implementation and support of quality management in an exemplary service ecosystem in public administration. 相似文献
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基于语义描述的Web服务工作流集成 总被引:9,自引:4,他引:5
Web服务是可以由其它软件在Internet上访问的一种软件接口。Web服务工作流则是一组按一定顺序执行的Web服务的集合。如何集成一个Web服务工作流,特别是如何运用对Web服务的语义描述来为一个工作流来自动寻找和匹配Web服务,这是目前所急需解决的问题。介绍如何用语义Web服务本体论来集成工作流,同时提出一个基于语义Web服务工作流集成的模型。 相似文献
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为实现制造网格应用的自动化,提出了一个基于领域本体(ontology)的服务自动组合体系结构及其相应的算法。领域本体基于TOVE、STEP、PSL三个成熟的制造本体和网格服务概念模型构建。体系结构以语义结构良好的用户目标作为输入,输出预约的可执行工作流;通过基于领域本体推理的反向递归组合算法,能够实现本地仓库中工作流的重用和网格范围内服务的新工作流组合;支持抽象、具体两个层面的松耦合工作流组合(对应于编排(Choreography)和编制(Orchestration));支持面向服务质量的工作流优化选择和工作流预约。实现了一个原型系统,实例的实验结果证明了该体系结构和算法的有效性。 相似文献
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随着Web服务在电子商务等应用领域的快速发展,Web服务中的QoS管理,特别是Web服务事务中的QoS管理,成了一个迫切需要解决的问题,它对于服务的提供商和用户都同样重要。但是Web的动态性、不可预见性等特点使得提供全面的QoS管理成为一个富有挑战性的工作。并且,现有的Web事务管理沿用了数据库的事务管理模式,不能提供深入全面的支持。为了加强QoS管理,该文提出了基于QoS管理的事务计算模型和基于QoS的主动两阶段提交协议QA-2PC。QA-2PC即使在操作系统和网络不能提供完全保障的前提下,也可以保证全面的质量服务。 相似文献
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Semantic E-Workflow Composition 总被引:39,自引:0,他引:39
Systems and infrastructures are currently being developed to support Web services. The main idea is to encapsulate an organization's functionality within an appropriate interface and advertise it as Web services. While in some cases Web services may be utilized in an isolated form, it is normal to expect Web services to be integrated as part of workflow processes. The composition of workflow processes that model e-service applications differs from the design of traditional workflows, in terms of the number of tasks (Web services) available to the composition process, in their heterogeneity, and in their autonomy. Therefore, two problems need to be solved: how to efficiently discover Web services—based on functional and operational requirements—and how to facilitate the interoperability of heterogeneous Web services. In this paper, we present a solution within the context of the emerging Semantic Web that includes use of ontologies to overcome some of the problem. We describe a prototype that has been implemented to illustrate how discovery and interoperability functions are achieved more efficiently. 相似文献
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基于QoS的语义Web服务发现研究 总被引:1,自引:0,他引:1
将QoS引入到语义Web服务中,分析了QoS本体的描述方法、Web服务的发现方法和语义Web服务发现方法,建立了一个通用的QoS模型,模型中的参数属性基本能描述QoS的衡量标准。提出了基于QoS语义Web服务发现框架,第一步通过功能来发现Web服务,第二步通过建立的QoS模型来评价发现的Web服务集合,找到QoS最佳的Web服务。最后通过实例建立了语义功能本体和QoS本体。 相似文献
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网络制造中Web Service的服务质量模糊排序方法 总被引:4,自引:0,他引:4
从WebService对质量的需求入手分析,给出服务质量模型,以及其中的几个重要指标入时间消耗、资源消耗、可靠性、可信度和安全性等的定量描述,在此基础上给出模糊排序算法.通过对上述指标的——建立模糊相似矩阵,确定服务间的相似程度,并对其相似度进行综合评价后,给出Web Service的模糊排序.该算法旨在提高UDDI上Web Service检索结果的质量,是UDDI有益的补充.该算法已在一个网络制造平台中得到应用,文末给出一个基于服务质量的Web Service模糊排序实例。 相似文献
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Today mobile network operators offer a wide variety of mobile Internet services to their customers including mobile email, banking, and news services. The acceptance of these services is heavily based on quality of service (QoS) experienced by the user. So far the discussion of QoS has been very network centric and the key to user satisfaction has been the network performance. In this paper we analyze the relationship between QoS perceived by the customer and network performance offered by the service provider. We conduct a lab experiment where network performance variables were controlled. Statistical analysis of the results indicates that there is no 1:1 correspondence or even truly linear relationship between network performance and perceived QoS as recommended by the International Telecommunications Union-Telecommunication (ITU-T). Instead the relationship varied from application to application. We examine several usability factors as potential reasons behind this phenomenon and make suggestions for future research. 相似文献
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随着Web的发展,可供选择的功能相同或相似的Web服务越来越多,因此有必要为用户提供一种高效的基于服务质量(QoS)的Web服务查询机制.然而现有的Web服务QoS管理模型并不能很好的支持如动态查询等查询需求,其查询性能也有待提高.鉴于此,本文提出一种新的Web服务管理模型——多维QoS模型(MQM:Multi-dimensional QoS Model),并介绍了该模型的创建方法和相关算法.MQM通过多维模型来管理QoS数据,提供查询和OLAP操作.实验证明MQM能够使用户能更准确和快速的按QoS查询现有服务,很好地解决了传统查询方法无法确定查询条件、无法动态改变查询区间、查询性能不高等问题,进而改善了用户体验. 相似文献
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在语义Web服务中,OWL-S虽然包括一些如质量保证等的有关服务质量参数的描述,但仍缺少一个较为完善的Web服务QoS模型描述,此外,语义Web服务质量的研究主要考虑服务质量的静态因素,而服务的QoS信息动态变化的情况较多,本文实现了对服务质量QoS的语义描述扩展,并在对语义Web服务QoS描述模型研究的基础上,充分考虑服务的QoS信息,提出了基于QoS约束的语义Web服务匹配算法。 相似文献
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为了实现企业间异构工作流系统的优势互补和信息共享,针对工作流呈现出的异构、分布等特点,提出了一种基于Web服务的异构工作流流程互联接口设计,以解决异构流程互联问题。从调用接口、调用方式、调用返回等三个方面描述了基于Web服务的流程互联解决方案;并以XPDL描述的SynchroFlow工作流流程与BPEL描述的ODE工作流流程为例,实现了这两种异构工作流的流程相互调用。 相似文献
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面对多个功能相同或相似的服务,服务的Qo S是服务选择中重要的考虑因素.将Qo S属性分为精确数型、区间数型和三角模糊数型.在此基础上,利用TOPSIS(technique for order preference by similarity to an ideal solution)条件下的多属性群决策模型给出了服务选择过程,该过程考虑了多个决策者在决策过程中所占的权重,以及多个决策者不同的Qo S偏好权重.通过一个实例验证了该方法的有效性. 相似文献