一种基于Petri网化简的工作流过程语义验证方法

过程验证是保证工作流过程定义正确性的重要手段.针对过程定义中控制流、数据流和资源三维元信息相结合的冲突检测问题,研究了过程的语义验证方法.首先根据语义验证的需求,定义3DWFN网作为过程描述的形式化模型,然后基于该模型阐述了完成语义验证的化简规则.并通过与其他相关化简规则的比较,说明了这些规则在语义验证层面的优势.  

Semantic Issues in the Verification of Agent Communication Languages

This article examines the issue of developing semantics for agent communication languages. In particular, it considers the problem of giving a verifiable semantics for such languages—a semantics where conformance (or otherwise) to the semantics could be determined by an independent observer. These problems are precisely defined in an abstract formal framework. Using this framework, a number of example agent communication frameworks are defined. A discussion is then presented, of the various options open to designers of agent communication languages, with respect the problem of verifying conformance.  

Real-time system = discrete system + clock variables

This paper introduces, gently but rigorously, the clock approach to real-time programming. We present with mathematical precision, assuming no prerequisites other than familiarity with logical and programming notations, the concepts that are necessary for understanding, writing, and executing clock programs. In keeping with an expository style, all references are clustered in bibliographic remarks at the end of each section. The first appendix presents proof rules for verifying temporal properties of clock programs. The second appendix points to selected literature on formal methods and tools for programming with clocks. In particular, the timed automaton, which is a finite-state machine equipped with clocks, has become a standard paradigm for real-time model checking; it underlies the tools HyTech, Kronos, and Uppaal, which are discussed elsewhere in this volume.  

Towards the Semantics and Verification of BPEL4WS

In this paper, we discuss the semantics of BPEL4WS language which is a de facto standard for specifying and execution workflow specification for web service composition and orchestration. We propose a language μ-BPEL that includes most primitive and structured activities of BPEL4WS, and define its semantics. As the Timed Automata (TA) is powerful in designing real-time models with multiple clocks and has well developed automatic tool support, we define a map from μ-BPEL into composable TA. Therefore, the properties we want to check can be verified in TA network correspondingly. Furthermore, we prove that the mapping from μ-BPEL to TA is a simulation, which means that the TA network simulates correctly the corresponding μ-BPEL specification. The case study with model checker Uppaal shows that our method is effective, and a Java supporting tool based on Uppaal model checker engine has been developed.  

Advanced Features of Duration Calculus and Their Applications in Sequential Hybrid Programs

Duration Calculus was introduced as a logic to specify real-time requirements of computing systems. It has been used successfully in a number of case studies. Moreover, many variants were proposed to deal with various features of real time systems, including sequential communicating processes, sequential hybrid systems and imperative programming languages. This paper aims to integrate several variants of Duration Calculus, and to provide a semantic framework for real-time programming languages and sequential hybrid programs. A shortversion of this paper appeared in J. Davis, A.W. Roscoe and J.C.P. Woodcock editors, Millennial Perspectives in Computer Science,Proceedings of the 1999 Oxford-Microsoft Symposium in Honour ofProfessor C.A.R. Hoare.  

A Verification Framework for Agent Communication

In this paper, we introduce a verification method for the correctness of multiagent systems as described in the framework of ACPL (Agent Communication Programming Language). The computational model of ACPL consists of an integration of the two different paradigms of CCP (Concurrent Constraint Programming) and CSP (Communicating Sequential Processes). The constraint programming techniques are used to represent and process information, whereas the communication mechanism of ACPL is described in terms of the synchronous handshaking mechanism of CSP. Consequently, we show how to define a verification method for ACPL in terms of an integration of the verification methods for CCP and CSP. We prove formally the soundness of the method and discuss its completeness.  

基于条件约束的工作流语义验证方法及应用

针对业务流程在动态执行时,由于业务环境、资源的复杂性和多变性会给流程的正确执行带来影响的问题,提出一个用于描述基于业务目标实现的流程、业务资源,以及三者协作争约束关系的四维元模型;并且基于流程模式对业务过程进行表示,利用XML进行流程知识表示的优势,通过在流程模式的XML Schema中对实现业务目标所依赖的资源、环境等进行条件约束的设计,根据业务目标、流程和资源三者之间的逻辑条件约束关系,采用条件匹配算法对动态规划出的流程文件进行解析和语义检查,减少了工作流引擎在执行时会发生错误的概率.  

一种基于报文序列分析的半自动协议逆向方法

基于报文序列分析的协议逆向方法在自动化分析过程中缺乏对人工知识的引入.为此,提出一种半自动协议逆向方法.通过人工输入的方式,将先验知识加入到报文分析中,用于指导报文的语义推断,并对分析结果进行人工纠正.实验结果表明,该方法能提高报文分析的效率和准确率.  

面向移动云服务系统的形式化语义描述方法

针对移动云服务系统构建过程中架构设计和语义描述等方面存在的问题,以类型范畴理论为基础,为基于Agent的移动云服务系统建立了一种形式化语义描述模型。Agent作为范畴理论中的对象结点,Agent之间的交互和依赖关系作为态射,将整个云服务系统描述为一个类型范畴图表。在此基础上,对Agent交互与协作、架构设计与精化、Agent迁移、Agent可替代性以及应用请求的可满足性等进行了分析和讨论。该形式化模型增强了系统架构的语义描述能力,有助于对移动云服务系统的规约进行分析和验证。  

Beyond contracts for concurrency

SCOOP is a concurrent programming language with a new semantics for contracts that applies equally well in concurrent and sequential contexts. SCOOP eliminates race conditions and atomicity violations by construction. However, it is still vulnerable to deadlocks. In this paper we describe how far contracts can take us in verifying interesting properties of concurrent systems using modular Hoare rules and show how theorem proving methods developed for sequential Eiffel can be extended to the concurrent case. However, some safety and liveness properties depend upon the environment and cannot be proved using the Hoare rules. To deal with such system properties, we outline a SCOOP Virtual Machine (SVM) as a fair transition system. The SVM makes it feasible to use model-checking and theorem proving methods for checking global temporal logic properties of SCOOP programs. The SVM uses the Hoare rules where applicable to reduce the number of steps in a computation. P. J. Brooke, R. F. Paige and Dong Jin Song This work was conducted under an NSERC Discovery grant.