基于构件软件的可靠性通用模型

工作流管理的最终目的是实现适当的人在适当的时间执行适当的活动.企业要获得竞争力,需要在工作流模型中考虑与业务过程相关的时间约束.一个考虑时间因素的工作流模型,需要在投入运行前进行时间规范与验证,以保证工作流执行的时间协调.通过为工作流网元素扩展时间属性,得到集成业务过程时间约束的工作流模型??时间约束工作流网(TCWF-nets).基于对业务活动的可调度性分析,提出了时序一致性验证方法,确保工作流执行中活动之间时间交互的安全性.在所附加的时间约束下,该可调度分析方法不仅能够检测某一给定工作流调度的时间可行性,还能对特定的实例给出一个最优调度,使工作流执行延迟最小.研究结果表明,该方法支持业务过程的时间建模与分析,对于丰富现有工作流系统的时间管理功能以及增强现存工作流软件对动态业务环境的适应性具有重要意义.     

基于时间约束Petri网的工作流可调度性分析

引入时间参数控制工作流高效执行是工作流技术研究的重要内容之一。在工作流的Petri网模型中引入时间参数,不仅可以对工作流中的活动进行时间约束,而且能建立相应的工作流时间约束Petri网模型。文中在分析该模型的时间约束和可调度性的基础上,提出了对工作流可调度性分析验证方法及其相应的算法,最后通过一个实例说明了分析验证的过程。     

基于时间约束Petri网的工作流可调度性分析

引入时间参数控制工作流高效执行是工作流技术研究的重要内容之一。在工作流的Petri网模型中引入时间参数，不仅可以对工作流中的活动进行时间约束，而且能建立相应的工作流时间约束Petri网模型。文中在分析该模型的时间约束和可调度性的基础上，提出了对工作流可调度性分析验证方法及其相应的算法，最后通过一个实例说明了分析验证的过程。     

基于资源和时间限制的多工作流网及可调度性验证

工作流建模阶段的验证工作对工作流的成功执行具有重要意义.首先分析了与工作流执行密切相关的资源和时间特性,考虑到工作流应用系统中总是有若干工作流并发执行,于是综合考虑结构、时间、资源限制三个层面,提出一个工作流应用系统一般性限制框架.基于该框架提出了多工作流网原型,并进一步给出了多工作流网下资源冲突和可调度性的概念,最后给出了多工作流网可调度性验证算法及其冲突解决方案.     

基于TCPN的协同设计过程资源约束可调度性分析

设计资源的有限性和设计活动的并发性会导致产品协同设计过程中的资源冲突.针对具有时间属性的产品协同设计过程资源约束的可调度性问题,采用时间约束Petri网理论提出一种产品协同设计过程资源约束网模型,定义了具有单一资源库所输入和多个资源库所输入的设计活动变迁的可调度性概念及其判定规则.把协同设计的资源约束可调度性划分为弱可调度和强可调度2类,通过引入变迁序列的token到达资源库所时间上下界的概念,给出了产品协同设计过程资源约束的可调度性规则及算法.最后通过一个链式输送机传动系统的协同设计资源约束模型,验证了文中方法的有效性.     

基于TCPN的LBS动态服务组合建模与验证

针对位置服务的动态服务组合过程中对位置的动态性和实时性考虑少的问题,本文运用时间约束Petri网对位置服务进行动态服务组合建模,设计了位置服务动态服务组合模型的执行时间、计算方法和库所可调度性分析算法.并对该模型的可达性进行了验证,同时引入实例说明了运用时间约束Petri网对位置服务动态服务组合建模方法的可靠性和可行性.     

基于图形展开及图形归约的过程模型验证方法

工作流过程模型是业务过程的形式化定义，在业务过程的分析、运行和重组方面起着关键性的作用．为了实现预期的业务目标，需要正确地定义工作流过程模型，它的正确性直接影响业务目标的实现，WfMS开始调度执行之前必须对其进行分析．针对大规模复杂应用的特点和业务过程执行的实际需要，对复杂工作流过程模型的正确性验证进行了研究；基于有向有环图(DCG图)详细讨论工作流过程模型的局部错误以及过程逻辑错误；给出了过程建模中避免错误的相关约束规则；另外了提出了一种新型的图形归约和图形展开相结合的验证方法及过程模型验证算法．     

一种基于UML的实时工作流建模方法研究

实时系统由于其业务对时间要求的特殊性,使得传统工作流技术难以满足其需求.在传统工作流的基础上,针对实时系统提出了实时工作流的概念,并建立了实时工作流元模型.与传统的工作流相比,主要对工作流的时间约束和异常处理进行了考虑.在活动上扩展了启动时间和执行时间,在工作流过程上扩展了执行时间,在并发活动上扩展了并发时间约束等,此外,元模型中还考虑了活动的超时异常以及应用程序和活动之间的执行关系.为了能够利用实时工作流元模型进行实时工作流建模,通过扩展UML定义了一种实时工作流描述语言,并分别从设计要求、定义技术和profile三个方面对实时工作流描述语言进行了阐述,给出了实时工作流的建模规则.最后结合船舶指控系统的具体实例,对建模方法进行了说明.     

时间约束工作流的可调度性分析

提出一种时间约束工作流的可调度性分析方法。针对时间约束Petri网（Timing Constraint Petri Nets,TCPN）为普通Petri网无法建模多参与资源的不足,给出了扩展的时间约束Petri网（w-TCPN）的定义;结合w-TCPN的拓扑结构,从模型和实例两个层次,给出了w-TCPN变迁可调度的判定定理;提出了时间约束的调整策略。w-TCPN的研究使得时间约束工作流的建模和可调度性分析更加合理。     

基于TC-Net的工作流模型研究

时间要素作为工作流管理的重要部分,是影响企业业务流程部署实施的关键因素。基于工作流中任务具有时间限制的特点,分析任务的时间要素,抽象出任务的形式化描述,定量计算两个连续任务执行的最大时间约束,提出可控时间约束Petri网模型（Time Constraint-Net,TC-Net）。该模型在任务节点中添加时间信息,从任务开始执行时间到任务的执行结束时间及最大约束时间,提高任务时间信息描述精度;利用TC-Net模型表示工作流过程中各项任务,基于任务间顺序、同步和并行关系的传递模型,细化实际业务流程中分析粒度。应用TC-Net模型进行实例分析,实验结果表明该工作流建模方法对时间违反而导致违规操作具有高敏感性,解决了单个任务违规和流程周期不合理两类问题,实现业务过程的管理和监控。     

Dynamic checking of temporal constraints for concurrent workflows

At present, workflow management systems have not sufficiently dealt with the issues of time, involving time modelling at build-time and time management at run-time. They are lack of the ability to support the checking of temporal constraints at run-time. Although some approaches have been devised to tackle this problem, they are limited to a single workflow and use only static techniques to verify temporal constraints. In reality, there are multiple workflows executing concurrently in a workflow management system. There may well exist resource constraints between these concurrent workflows, which affect significantly the verification of temporal constraints at run-time. This paper proposes a novel approach for dynamic verification of temporal constraints for concurrent workflows. We first investigate resource constraints in workflow management systems, and then define concurrent workflow executions. Based on these definitions, we propose a verification method by analysing the temporal relationship and resource constraints between activities among concurrent workflows.     

Timing constraint workflow nets for workflow analysis

The analysis of the correctness and rationality of a workflow model plays an important role in the research of workflow techniques and successful implementation of workflow management. This paper points out the relevant problems in the verification and analysis of a workflow model. It discusses two important properties: schedulability and boundedness of a workflow model considering timing constraints. To specify the timing constraints, WorkFlow net is extended with time information, leading to timing constraint workflow net (TCWF-net). This paper presents a model mapping method to convert a directed network graph (DNG) based workflow model, which is built by a graphic process modeling language extended with time information, into a TCWF-net. It then discusses its schedulability verification and synthesis. An algorithm to decompose an acyclic and free-choice TCWF-net into a set of T-components is presented, followed by a boundedness verification method. The usefulness of the research results is illustrated by an example.     

建立工作流数据仓库

工作流管理系统(WfMS)是允许定义、执行、监视和管理商业过程的软件平台。一个WfMS记录了在过程执行中发生的每一个事件,因此,工作流的日志包含了相当多的重要信息。通过分析这些信息,可以评估工作流的性能,了解影响工作流性能高低的原因,从而对工作流进行调整。本文提出一种方案对工作流的日志信息进行加工、综合,建立工作流数据仓库(WDW),然后根据在WDW中进行OLAP的结果,调整WfMS的运行。     

一种基于日志数据仓库的工作流监控方法

工作流管理系统是允许定义、执行、监视和管理商业过程的软件平台。一个工作流管理系统记录了在过程执行中发生的每一个事件,因此,工作流的日志包含了相当多的重要信息。通过分析这些信息,可以评估工作流的性能,了解影响工作流性能高低的原因,从而对工作流进行调整。本文提出一种方案对工作流的日志信息进行加工、综合,建立工作流数据仓库,然后根据在工作流数据仓库中进行OLAP的结果,调整工作流管理系统的运行。     

Integrating constraints to support legally flexible business processes

Flexible collaboration is a notable attribute of Web 2.0, which is often in the form of multiple users participating different activities that together complete a whole business process. In such an environment, business processes may be dynamically customized or adjusted, as well as the participants may be selected or attend uncertainly. So how to ensure the legitimacy of a business process for both security and business is increasingly critical. In this paper, we investigate this problem and introduce a novel method to support legally flexible business processes. The proposed Constraint-based Business Process Management Model incorporates constraints into the standard activities composing a business process, where the security constraints place restrictions on participants performing the activities and business constraints restrict the dependencies between multiple activities. By the assembly operations, business processes can be dynamically generated and adjusted with activities, that are obliged to the specified constraints. Several algorithms are presented to verify the consistency of constraints and the soundness of the generated business processes, as well as to perform the execution planning to guarantee the correct execution of a business process on the precondition of satisfying all constraints. We present an illustrative example and implement a prototype for the proposed model that is an application of property rights exchange for supporting legal business processes.     

允许违反局部时间约束的科学工作流调度策略

提高科学工作流在云环境中的执行效率、降低执行费用受到广泛关注。用户期望的局部QoS约束与工作流的总体执行效率之间往往存在矛盾。针对该现象,在前期的研究基础上提出一种允许违反局部时间约束的科学工作流调度策略。通过对已聚簇的工作流任务集使用任务后向优先合并的方法,可实现任务间空闲时间片的合理利用,进而优化科学工作流的执行时间;另外,为充分利用任务的松弛时间,提高工作流的整体执行效率,允许部分任务的调度违反局部最晚完成时间的约束。实验结果表明,该策略能提前科学工作流的最早完成时间,提高处理机的利用率,并最终降低工作流的执行费用。     

On Schedulability Analysis of AADL Architecture with Storage Resource Constraint

Embedded systems have been widely applied in real-time automatic control systems, and most of these systems are safety-critical, for example, the engine control systems in an automobile and the avionics in an airplane. It is very important to verify the schedulability of such a real-time embedded system in its early design stages, so as to avoid unexpected loss for the debugging of architecture design problems. However, it has been proved to be a tough challenge to evaluate the schedulability of a Preemptive-Scheduling Real-Time (PSRT) system, especially when the constraints of system resources are taken into consideration. The cache memory built inside the processor is an exclusive-accessing resource shared by all the tasks deployed on the processor. In addition, the Cache-Related Preemption Delay (CRPD) caused by preemptive task scheduling will bring extra time to the execution time for all the tasks. Thus, the CRPD should be taken into consideration when the Worst-Case Execution Time (WCET) of tasks is estimated in a real-time system. A model-based evaluation and verification method of architecture schedulability, which is designed for priority-based PSRT systems, is proposed in this study to make cache resource constrained and CRPD related schedulability evaluation based on the AADL system architecture model. In the first step, the study enhances the property set of AADL storage elements to make it compatible with cache memory properties in a system architecture model. Secondly, the study proposes a set of algorithms to estimate the CRPDs of a task before it is completed; run system schedule simulation and construct the schedule sequence with the constraint of cache resources and CRPDs involved; and make WCET estimation of the tasks in such a CRPD considered, preemptive-scheduling execution sequence. Finally, the methods mentioned above are implemented within a prototype software toolkit, which is designed to make evaluation and verification of system schedulability within CRPD constraints. The toolkit is tested with a use case of aircraft airborne open-architecture intelligent information system. The result shows that, compared with the schedule sequence constructed without cache memory resource constraints, the WCET estimated for most tasks is extended, and the sequence order is changed. In some extreme cases, when CRPD is taken into consideration, some tasks are evaluated to be incompletable. The test shows that the method and algorithms proposed in this study are feasible.     

工作流管理系统中一种概率性分析和调整时间约束的方法

时间管理是工作流管理系统应提供的重要功能,其中一个关键问题是分析时间约束的可行性,并调整时间约束以避免可能出现的违反.然而,在高度不确定的工作流环境下,传统定性的时间约束分析结果过于严格.因此,提出概率时间约束工作流网来描述时间约束下的工作流流程.基于该网提出一种方法,以随机的形式分析活动满足时间约束的概率.该概率能帮助流程管理者灵活地分析时间约束的可行性,进一步为时间约束调整提供精确的指导.此外,用一个实际工作流管理系统中的例子验证工作的有效性.