分层准则调控的服务协同保障机制

为了提高服务协同的可靠性和简化异常处理设计过程的复杂性,在基于服务协同的虚拟组织中引入分层准则调控的服务协同保障机制,在功能准则层通过各业务间依赖关系生成异常依赖关联,从而在异常处理中通过异常依赖关联指导保障准则层的运作,并结合高效可行的运行机制,保障服务的一致性和可靠性。首先给出准则的定义,然后给出了异常依赖关联的自动生成算法,以及分层准则调控的服务协同保障机制,阐述了异常处理步骤,最后结合详细实例进行了情景分析。     

结构化组合补偿抽象精化性质研究

为解决松耦合Web事务复杂业务流程的建模问题,确保组合事务的可靠性和一致性,提出一种基于配对Petri网的结构化组合补偿精化方法,实现复杂多伙伴业务流程的抽象层次建模.定义了4种基于配对Petri网的基本组合补偿结构:顺序、并行、选择和循环结构.引入组合流程精化和组合补偿抽象的定义,分析了复杂业务流程的精化和抽象过程,给出了精化流程应满足的性质.通过具体业务实例验证了该精化和抽象方法的可行性.     

面向组合服务动态自适应的事务级主动伺机服务替换算法

动态服务环境的各种异常随时会导致整个业务流程暂时无响应或服务中断,极大影响业务流程的可靠性.已有替换机制大多缺乏事务支持而适应性差,进而不能有效保证系统执行过程中事务服务的原子性和数据一致性,也无法保障替换过程要求的正确性、实时性和高效性.该文以"事务支持"为核心,充分考虑了服务间多关系以及Web服务的事务特性,提出一种事务级组合服务主动伺机替换算法.首先,该文给出了事务粒度的获取及替换范围识别算法.然后,提出事务级替换代价/收益QoS模型,将事务补偿代价与替换代价有机结合,保证以最少的代价实现服务替换.在此基础上,提出了全新的QoS驱动的事务级服务替换算法.为了提高替换的时效性,提出了早期预测模式挖掘算法,对运行的服务实时监控保证其识别失效服务的早期性.实验结果证明,该模型不仅保证了替换过程中业务流程的事务原子性和数据一致性,而且提高了系统的可靠性和时效性.     

BPEL文档基于DAG自动生成框架的研究与实现

针对目前服务之间组合的复杂性,提出一种基于有向无环图的业务流程执行语言文档生成框架。通过对框架模型的解析,提出一种能够自动生成服务组合所需各种文档的改进框架及其算法,有效地隐藏了专业的业务流程执行语言知识和繁琐的服务组合流程。实践表明,该框架简单、易用,不仅能够清楚地反应服务组合之间的流程,而且还不需要BPEL专业方面的知识,减少了服务组合的工作量。     

组合Web服务事务的补偿语义研究

Web服务组合需要可靠的事务处理机制,而目前仅依赖传统的ACID机制进行组合事务处理无法满足需要。为此提出一种基于配对Petri网的结构化补偿方法,该方法基于配对Petri网描述基本聚合结构的Web服务组合及其补偿行为。借助配对Petri网的动态执行推演技术分析了聚合结构补偿的执行语义,分析表明该方法可用于可靠业务流程组合、聚合补偿和组合流程优化等方面。     

基于两阶段规划模型的跨域服务流程动态构造方法

为了应对来自网络计算环境下业务流程跨越协同过程中层出不穷的业务需求,提出一种基于两阶段规划模型的跨域服务流程动态构造方法.第一阶段,利用跨域服务协同语义模型,基于层次任务网络规划方法,构建满足用户业务需求的跨域抽象业务流程;第二阶段,在各城内部对抽象业务流程确定的候选服务集应用图规划数据流验证模型,构建最终的跨域可执行服务流程.方法在保证了业务需求与跨域服务流程逻辑结构的语义一致性的同时,满足了跨域服务流程中数据流的一致性,为网络计算环境下管理域间的业务协同和互操作提供了更为实际可用的可执行服务流程.原型系统实验及实例验证说明该方法的正确性和有效性.     

面向服务的多参与者协调事务建模方法

为了保证Web服务组合执行获得正确一致的结果,用形式化方法研究Web服务事务处理的协调过程是很重要的。基于Web服务事务规范(Web services transaction,WS-TX),提出了一种由业务流程执行语言(business process execution language,BPEL)自动生成Web服务多参与者协调事务模型的方法。介绍了Web服务协调的Pi-演算建模方法,阐述了如何由BPEL描述的业务流程建立服务协调事务模型,进一步给出了自动生成该协调模型的算法描述,并通过具体实例说明了该方法的正确性及可行性。     

结构化组合事务补偿精化性质研究

针对复杂异构、松耦合Web组合事务执行失败时原子性和一致性保持的问题,提出一种基于配对Petri网的复杂组合业务流程的补偿和精化方法,解决复杂多伙伴业务流程的抽象建模问题。首先定义了4种基于配对Petri网的基本组合补偿结构：顺序、并行、选择和迭代结构;然后引入组合流程精化的概念,给出了精化后相关性质的证明,最后通过具体业务实例验证该精化方法的可行性。     

支持业务事务验证的服务协调模型

在Web服务业务流程中如何保证参与者之间的协调一致性是亟待解决的重要问题.Web服务事务规范中描述的参与者之间的交互消息缺乏严格的语义,无法精确地描述复杂的协调活动,本文用Pi-演算形式化描述WS -TX规范中定义业务活动事务的WS-BA协议,在此基础上建立了适用于多方参与的业务事务的服务协调模型;并利用基于等价自动机转换的HAL模型检测工具,验证分析了WS-BA协议的安全性和活性,给出一个多方参与的业务事务实例的验证过程,介绍如何利用模型检测技术来分析业务流程设计正确性的方法,有效地确保了业务事务执行的可靠性和一致性.     

分布式业务流程实时一致性分析方法

业务流程的实时性是业务流程可靠运行的重要指标,实时一致性分析是保证业务流程高效执行的关键。针对分布式业务流程对实时性的要求,提出时间业务流程图的概念,并规定协作业务流程的组合建模方法。定义时间业务流程图的结构正确性,并给出正确性分析方法。在结构正确的基础上,对业务流程的实时性进行分析,判断协作业务流程的时间执行是否满足一致性,从而为保证业务流程的实时可信提供了一种有效的技术途径。     

Dynamic execution planning for reliable collaborative business processes

Collaborative business processes, implemented and carried out via web services and enabling dynamic interaction among organizations, are becoming more indispensable to competitiveness in the global market. As dynamic collaboration prevails, the quality of service (QoS) of collaborative processes becomes more important. A critical requirement in cases where processes involve long-term activities is to guarantee successful completion within time constraints. In this study, we developed a methodology for dynamic planning of web service execution that imparts reliability to collaborative business processes. In order to ensure that processes successfully execute within time constraints and at minimum cost, the proposed method dynamically modifies execution plans at run-time by means of fault-tolerance techniques. Since generation of an execution plan of minimum cost while guaranteeing successful completion is classified as an NP-hard problem, a heuristic algorithm was developed. Additionally, to compare the proposed algorithm’s performance with those of the branch-and-bound method and the genetic algorithm (GA), a set of experiments was conducted.     

基于Internet工作流的复合Web服务框架

实现灵活方便的企业业务集成一直是信息领域的核心问题，也是B2B电子商务应用的关键．为此将Web服务和传统的工作流技术相结合，设计并实现了支持复合Web服务运行和管理的框架WSFlow．给出了WSFlow的总体结构，描述了其中的关键技术，包括Web服务与工作流活动的动态配置和绑定技术，复合Web服务流程的动态修改以及复合Web服务的运行监控等技术．     

Coordinating multiple agents for workflow-oriented process orchestration

Distributed component-based services and semantic web services are promising technologies for next generation inter-enterprise integration. The dynamic nature of this domain presents a complex problem for tools that intend to support this cross-organizational integration. However, the autonomy and adaptation of software agents represent a viable solution for the composition and enactment of cross-organizational services. Currently, there are few studies that measure the impact of the dynamic environmental effects on service composition. On an on-going basis, composite services or workflow processes of web services may be constantly changing in terms of responsiveness of services, accessibility of services and their meta-information, business process schema changes, etc. These conditions impact what interactions a team of agents must undergo to achieve a specific process derived of composite web services. This paper describes an approach, model, and supporting software toward the efficient design of interaction protocols for coordinating agent teams in the business process orchestration domain. This approach considers several environmental conditions related to the dynamism of the Internet.     

组合Web服务业务流程访问控制技术研究综述

业务流程访问控制是保证组合Web服务增值安全应用的关键技术,着重论述了组合Web服务业务流程访问控制技术的研究现状及问题。首先对组合Web服务业务流程安全需求进行了分析,然后从组合Web服务业务流程访问控制模型、业务流程运行时访问授权约束、业务流程协同访问授权的一致性检验3个方面分析了业务流程访问控制核心技术的研究进展。最后,结合已有的研究成果,指出了目前研究的挑战以及未来的发展趋势。     

Context aware exception handling in business process execution language

ContextFault handling represents a very important aspect of business process functioning. However, fault handling has thus far been solved statically, requiring the definition of fault handlers and handling logic to be defined at design time, which requires a great deal of effort, is error-prone and relatively difficult to maintain and extend. It is sometimes even impossible to define all fault handlers at design time.ObjectiveTo address this issue, we describe a novel context-aware architecture for fault handling in executable business process, which enables dynamic fault handling during business process execution.MethodWe performed analysis of existing fault handling disadvantages of WS-BPEL. We designed the artifact which complements existing statically defined fault handling in such a way that faults can be defined dynamically during business process run-time. We evaluated the artifact with analysis of system performance and performed a comparison against a set of well known workflow exception handling patterns.ResultsWe designed an artifact, that comprises an Observer component, Exception Handler Bus, Exception Knowledge Base and Solution Repository. A system performance analysis shows a significantly decreased repair time with the use of context aware activities. We proved that the designed artifact extends the range of supported workflow exception handling patterns.ConclusionThe artifact presented in this research considerably improves static fault handling, as it enables the dynamic fault resolution of semantically similar faults with continuous enhancement of fault handling in run-time. It also results in broader support of workflow exception handling patterns.     

面向业务人员的动态业务过程改变方法

针对目前业务过程修改和实例迁移系统对使用者的技术背景要求较高的问题,提出了一个面向业务人员的动态业务过程改变方法,进行了一致性分析,并给出了业务过程设计器。业务过程设计器基于业务过程模型和符号2.0规范。该规范易于业务分析人员掌握及建模,并具有可执行语义。针对由于业务过程重组导致的业务过程改变的常见模式,提出了业务过程改变操作类型。业务过程设计器支持业务过程改变操作类型,将IT人员解放出来,降低了业务人员与IT人员交流的成本。     

Terminability and compensatibility of cycles in business processes with a process-oriented trigger

BPTrigger is a process-oriented trigger model that provides economy of specification and efficient execution for complex business constraints. An essential part of trigger execution is detection and resolution of cycles. This paper presents an approach to determine the terminability of a cycle introduced by a BPTrigger in a business process and determine whether a cycle is allowable in terms of compensatibility. The foundation of the approach is a set of conditions for cycle termination derived from classifications of business processes by resource usage and activity types by compensation status. This paper formally presents cycle analysis procedures using the notion of cycle analysis graph. Further, a procedure is proposed which checks the terminability of multiple cycles using a composite cycle analysis graph constructed from the cycle analysis graphs of the associated cycles. The paper proves the correctness of the analysis and presents a validation example. The presented results extend some limitations of well-formed sphere which has addressed atomicity of workflow transactions.     

Web服务组合的马氏策略规划

针对Web服务存在的业务逻辑与服务质量的不确定性,以及时序、时间窗约束,本文提出了利用马尔可夫决策理论来解决Web服务组合中最优策略规划问题的方法。该方法首先将Web服务组合描述为有向无环图表示的任务网络,网络中每个节点代表一个任务。任务是由相应的Web服务来实现,任务之间的弧线代表任务间时序的约束,任务执行应满足时间窗的约束。在此基础上,建立Web服务组合的马尔可夫决策模型,从而获得Web服务组合的最优策略。     

Exception Handling for Conflict Resolution in Cross-Organizational Workflows

Workflow management systems (WfMSs) are being increasingly deployed to deliver e-business transactions across organizational boundaries. To ensure a high service quality in such transactions, exception-handling schemes for conflict resolution are needed. The conflicts primarily arise due to failure of a task in workflow execution because of underlying application, or controlling WfMS component failures or insufficient user input. So far, little progress has been reported in addressing conflict resolution in cross-organizational business processes, though its importance has been recognized. In this paper, we identify the exception handling techniques that support conflict resolution in cross-organizational settings. In particular, we propose a novel, bundled exception-handling approach, which supports (1) exception knowledge sharing--sharing exception specifications and handling experiences, (2) coordinated exception handling, and (3) intelligent problem solving--using case based reasoning to reuse exception handing experiences. A prototype of this exception handling mechanism is developed and integrated as a part of the METEOR Workflow Management System. An evaluation of our approach is also presented through some sample workflow applications.