云计算环境下大规模Web服务故障诊断技术研究

随着Web服务规模的不断增大,系统中往往会伴随着大量的噪音数据;为了提高Web服务诊断在噪音影响下的健壮性,文章研究了大规模Web服务下的故障诊断;首先,提出了一种Web服务自动诊断框架;其次,分别定义了转移矩阵和发射矩阵,并通过这两种矩阵来表达Web服务的状态转换过程;最后,提出了一种基于Viterbi方法的故障诊断算法;实验表明,文章提出的算法与其它相关的Web服务故障诊断算法相比准确性高,并且对噪音数据有着良好的健壮性。     

基于贝叶斯与多故障推理的Web服务诊断

Web服务组合进程规模的不断增加和复杂性的不断提高都有可能导致服务的运行失败,因此很难确保服务的可靠性。针对传统的基于模型的方法无法处理服务应用系统中状态和行为故障的不确定性问题,提出了一种基于贝叶斯与多故障逻辑推理的诊断方法。该方法使用历史数据构建服务执行矩阵,通过多故障逻辑推理技术获取候选诊断解并利用贝叶斯公式计算候选解的后验概率并排序,最终获得一个最优的诊断结果。相比于传统基于模型的Web服务诊断方法,该方法不仅可以同时定位多个故障,而且能够随着历史数据的增加不断优化诊断结果。实验证明该方法具有很好的诊断效果。     

基于SOA的设备综合故障诊断系统研究

针对分散、异构设备的故障诊断系统和设备全生命周期内故障诊断信息交互难的问题,建立了基于SOA(Service-Oriented Architecture)的设备综合故障诊断系统架构;采用XML信息建模和描述的方法,建立标准化的故障诊断信息模型,实现测试与故障诊断信息的统一描述;以诊断推理机服务的实现为例,介绍了故障诊断Web服务的开发方法,较好地解决了故障诊断信息交互和诊断资源共享、重用等问题,有效地提高设备故障的诊断能力.     

基于SE-CNN的服务机器人运动系统云端故障诊断方法

研究并设计了一种基于服务机器人云平台的故障诊断系统.传统算法只关注服务机器人某一时刻的状态数据,所提取的特征信息有限,因而难以较好地完成故障诊断任务.在这种背景下,提出了基于时间序列关联特征的故障诊断方法.首先,对采集的服务机器人数据进行归一化和后向差分预处理,消除数据量纲并获取数据变化特征;其次,利用滑动窗口来生成时间序列样本,保证每个样本包含足够的特征信息;然后,应用卷积神经网络(CNN)挖掘时间序列的关联特征,并在网络中引入通道注意力网络(squeeze-and-excitation network,SENet),构建了一种SE-CNN模型.该模型能够自适应调整特征通道的重要程度,聚焦于更有效的特征通道,从而提高了诊断精度.对比实验与实际场景下的综合测试证明了本文提出的故障自诊断方法的可行性和有效性.     

基于CPN模型的REST服务架构标准特征验证方法研究

当前REST服务架构广泛应用于大规模、可扩展的分布式Web系统中,若应用REST服务架构时不遵循其标准特征,则可能导致基于REST服务架构的Web系统出现性能下降、可扩展性低等问题。因此,实现基于REST服务架构的Web系统前,需要对该系统设计是否满足REST服务架构标准特征进行验证,以提升基于REST服务架构的Web系统的研发质量。提出一种基于CPN模型的REST服务架构标准特征验证方法,即对REST服务架构的五个标准特征约束进行CPN建模,并使用模型状态空间执行路径同步匹配的验证方法,以应用系统的CPN模型和标准特征约束的CPN模型为基础,对模型状态空间中的各自执行路径进行同步匹配,若路径可同步执行完毕,则说明该应用系统满足该REST标准特征约束。以基于REST服务架构的课程管理Web系统为例,验证上述方法的可用性和有效性。实验结果表明,本文所提验证方法可以有效确认基于REST服务架构的Web应用系统设计是否符合REST服务架构的标准特征约束,并在不符合标准特征约束时提供直观、可行的执行数据,便于后续完成应用系统设计缺陷定位及修正。     

Web服务故障的分类方法①

Web服务故障分类是实现故障诊断的基础。在分析了Web服务的故障管理流程的基础上,提出了Web服务类型和执行过程相结合的Web服务故障分类方法,构建了Web服务故障树,根据故障及其外部表现间的对应关系构造了Web服务故障矩阵,通过分析和验证说明Web服务分类方法能够有效支持快速、准确的Web服务故障诊断。     

基于SOA的综合故障诊断系统架构研究

针对分散、异构的故障诊断系统和设备全寿命周期内故障诊断信息交互难的问题,建立基于SOA的综合故障诊断系统的架构.采用XML信息建模和描述的方法,建立标准化的故障诊断信息模型,实现测试与故障诊断信息的统一描述.以诊断推理机服务的实现为例,介绍故障诊断Web服务的开发方法.所采用的相关技术较好地解决了故障诊断信息交互和诊断资源共享、重用等问题,有效地提高了设备的故障诊断能力.     

基于Web服务的工作流事务处理的研究与实现

事务处理是Web服务实现分布式信息集成的关键技术之一,利用工作流技术实现Web服务的事务处理是实现分布式事务的一种有效手段.提出一个能够处理分布式、异构应用下Web服务组合事务的模型,并详述Web服务事务在执行过程中抛出异常时,补偿事务的产生策略和执行机制.     

Web服务行为兼容性的判定与计算

确保Web服务行为兼容是实现Web服务无缝集成与协作的一个重要问题.在服务视图概念的基础上,给出了Web服务行为兼容性的相关定义.提出一种基于π演算的Web服务行为兼容性的定性判定与定量计算方法.该方法首先通过算法自动地将Web服务行为和Web服务间的交互行为表达成π演算进程,然后借助π演算的操作语义和形式化推演实现服务行为兼容性自动的定性判定;随后在π演算的进程变换理论的基础上提出算法实现服务兼容性自动的定量计算.该方法在服务动态组合与服务动态替换中的典型应用表明,该方法对于服务组合的正确建立和可靠执行具有重要作用.     

Web服务组合匹配框架研究

在现有服务发现方法中,单一考虑原子服务或服务组合的方式难以满足用户日益增长的需求。针对该问题,设计一个基于模型转换的Web服务匹配框架。在服务发现过程中综合考虑组合Web服务的执行过程信息和服务质量需求信息,为Web服务组合的匹配设计完整的过程:将UML模型转换为过程模型,再将过程模型转换为过程图,最后计算2个Web服务组合的相似度。实验结果表明,该服务匹配框架能够有效区分组合服务,提高服务发现的准确率。     

Web Service Diagnoser Model for managing faults in web services

Reliability is an important criterion to facilitate extensive deployment of web service technology for commercial business applications. Run-time monitoring and fault management of web services are essential to ensure uninterrupted and continuous availability of web services. This paper presents WISDOM (Web Service Diagnoser Model) a generic architecture for detecting faults during execution of web services. Policies have been proposed to describe the intended behavior of web services and faulty behavior would be detected as deviations or inconsistencies with respect to the specified behavior. The model proposes the use of monitoring components in service registries and service providers to detect run-time faults during publishing, discovery, binding and execution of web services. An independent fault diagnoser is proposed to coordinate the individual monitoring components and also act as a repository for the specified web service policies. The proposed model has been tested with a sample web service application and the results obtained are presented.     

A semantical framework to engineering WSBPEL processes

Web services promise the interoperability of various applications running on heterogeneous platforms over the Internet, and are gaining more and more attention. Web service composition refers to the process of combining Web services to provide value-added services, which has received much interest in supporting enterprize application integration. Industry standards for Web Service composition, such as WSBPEL, provide the notation and additional control mechanisms for the execution of business processes in Web service collaborations. However, these standards do not provide support for checking interesting properties related to Web Service and process behavior. In an attempt to fill this gap, we describe a formalization of WSBPEL business processes, that adds communications semantics to the specifications of interacting Web services, and uses a formal logic to model their dynamic behavior, which enables their formal analysis and the inference of relevant properties of the systems being built.     

基于用户视角的组合Web服务响应时间优化

针对响应时间,通过选择、调用合适的成员Web服务,对组合Web服务的QoS进行优化．该优化方法基于用户的视角,将组合Web服务运行时用户一次等待周期中需要执行的所有任务作为一个整体进行调度;同时根据组合Web服务流程的不同环节中用户对等待时间的不同敏感度,设置调度参数,降低关键环节超时的风险．实验表明,此方法可以有效地优化组合Web服务的响应时间,提高用户的满意度和QoS．     

Web服务合成研究综述

Web服务的发展将Web应用从信息交互领域扩展到了服务交互领域。Web服务诸多的特性使得它非常适合于商务应用集成，因此工业界和学术界都希望能够通过合成多个Web服务从而获得增值的新服务。在服务合成的过程中，不仅需要语义清晰的服务描述语言和直观的建模方法，并且应该能够动态地发现构件服务，顺利地执行复合服务以及对其进行事务处理。此外对Web服务合成的分析评估也将有助于理解复合服务中每一项活动的行为，从而促使不断改进服务合成技术。     

Efficient execution of composite Web services exchanging intensional data

Web service technologies provide a standard means of integrating heterogeneous applications distributed over the Internet. Successive compositions of new Web services using pre-existing ones usually create a hierarchical structure of invocations among a large number of Web services. For the efficient execution of these composite Web services, we propose an approach which exploits intensional XML data, i.e. an XML document that contains special elements representing the calls to Web services, in order to delegate the invocations of the external Web services to some relevant nodes. We formalize an invocation plan for composite Web services in which intensional data is used as their parameters and results, and define a cost-based optimization problem to obtain an efficient invocation plan for them. We provide an A∗ heuristic search algorithm to find an optimal invocation plan for a given set of Web services and also present a greedy method of generating an efficient solution in a short time. The experimental results show that the proposed greedy method can find a close-to-optimal solution efficiently and has good scalability for a complex call hierarchy of Web services.     

A holistic approach to model‐based testing of Web service compositions

The behavior of composed Web services depends on the results of the invoked services; unexpected behavior of one of the invoked services can threat the correct execution of an entire composition. This paper proposes an event‐based approach to black‐box testing of Web service compositions based on event sequence graphs, which are extended by facilities to deal not only with service behavior under regular circumstances (i.e., where cooperating services are working as expected) but also with their behavior in undesirable situations (i.e., where cooperating services are not working as expected). Furthermore, the approach can be used independently of artifacts (e.g., Business Process Execution Language) or type of composition (orchestration/choreography). A large case study, based on a commercial Web application, demonstrates the feasibility of the approach and analyzes its characteristics. Test generation and execution are supported by dedicated tools. Especially, the use of an enterprise service bus for test execution is noteworthy and differs from other approaches. The results of the case study encourage to suggest that the new approach has the power to detect faults systematically, performing properly even with complex and large compositions. Copyright © 2012 John Wiley & Sons, Ltd.     

A layered architecture for flexible Web service invocation

Web service composition is emerging as an interesting approach to integrate business applications and create intra‐organizational business processes. Single Web services are combined to create a complex Web service that will realize the process business logic. Once the process is created, it is executed by an orchestration engine that invokes individual Web services in the correct order. However, Web services composing the workflow sometimes become unavailable during the run‐time phase, blocking process execution. This paper describes an architecture that allows the flexible orchestration of business processes. With this approach, Web services composing the process can be automatically substituted with other compatible Web services during process execution. A methodology is defined to evaluate Web service compatibility based on interface matching, in order to select substitutable Web services. Copyright © 2005 John Wiley & Sons, Ltd.     

SFDCloud: top-k service faults diagnosis in cloud computing

With a variety of providers large and small delivering a number of cloud-based services, cloud computing is evolving into an important service delivery infrastructure. One of the challenges in this evolution is how to provide necessary fault handling for migration long-running or computationally-intensive application services into shared open cloud infrastructures. To minimize failure impact on services and application executions, we present a diagnostic architecture and a diagnosis method based on the service dependence graph (SDG) model and the service execution log for handling service faults. By decoupling diagnosis service components and sharing diagnosis resources, the scalability of diagnosis methods is improved by incorporating third-party diagnostic components into our architecture. By analyzing the dependence relations of activities in SDG model, our diagnosis method identifies the incorrect activities, and explains the root causes for the web service composition faults, based on the differences between successful and failed executions of composite service. Experimental results show that our method is effective in diagnosing faults in web service composition of various scales.     

The Weka4WS framework for distributed data mining in service‐oriented Grids

The service‐oriented architecture paradigm can be exploited for the implementation of data and knowledge‐based applications in distributed environments. The Web services resource framework (WSRF) has recently emerged as the standard for the implementation of Grid services and applications. WSRF can be exploited for developing high‐level services for distributed data mining applications. This paper describes Weka4WS, a framework that extends the widely used open source Weka toolkit to support distributed data mining on WSRF‐enabled Grids. Weka4WS adopts the WSRF technology for running remote data mining algorithms and managing distributed computations. The Weka4WS user interface supports the execution of both local and remote data mining tasks. On every computing node, a WSRF‐compliant Web service is used to expose all the data mining algorithms provided by the Weka library. The paper describes the design and implementation of Weka4WS using the WSRF libraries and services provided by Globus Toolkit 4. A performance analysis of Weka4WS for executing distributed data mining tasks in different network scenarios is presented. Copyright © 2008 John Wiley & Sons, Ltd.     

一个面向服务的LBS开放框架

随着面向服务体系结构的发展和Web服务技术的日益成熟,对现有的LBS体系框架提出了新的要求。本文以服务共享为核心,给出了包括数据层、服务层和应用层的LBS开放体系框架。对LBS中基本服务和复杂服务进行了讨论,数据获取,数据分析和移动终端的位置计算作为服务为各类LBS应用所共享。研究了通过服务组合技术对复杂服务和业务流程建模,以及服务流程执行中服务节点的具体实例选择。最后通过一个原型系统的实现,对本文研究的可行性和有效性进行了验证。