多数据源集成系统中数据查询过程的π-演算模型

企业动态联盟对信息系统灵活性提出了更高的要求。我们开发的异构数据源集成系统，具有系统配置灵活和数据源的“即插即用”特点，。并给出了其简化的数据查询过程的π－演算模型，利用该模型研究了系统动态行为，表现其多层结构中多代理，多对象之间的互操作性，该模型显示了HDSI的并发性，分布性及适于动态联盟组织结构和软硬件平台多变性的灵活性，该形式化模型有利于系统的改进，维护和验证。     

航空订票业务的Web服务建模及组合兼容性验证

Web服务通过组合基本服务为解决复杂问题提供了方法,于是近年来越来越受到关注。当前交互式下的Web服务在实际组合中还存在诸多问题,其中就包括Web服务组合验证问题。运用Pi演算对航空订票业务的Web服务进行形式化建模,改进基于Pi演算的推理,提供一种验证多个Web服务组合是否兼容的方法。为证实该验证方法,进一步采用MWB工具展示了Web服务组合兼容性的验证过程。     

Separation of Synchronous and Asynchronous Communication Via Testing

One of the early results about the asynchronous π-calculus which significantly contributed to its popularity is the capability of encoding the output prefix of the (choiceless) π-calculus in a natural and elegant way. Encodings of this kind were proposed by Honda and Tokoro, by Nestmann and (independently) by Boudol. We investigate whether the above encodings preserve De Nicola and Hennessy's testing semantics. In this sense, it turns out that, under some general conditions, no encoding of output prefix is able to preserve the must testing. This negative result is due to (a) the non atomicity of the sequences of steps which are necessary in the asynchronous π-calculus to mimic synchronous communication, and (b) testing semantics's sensitivity to divergence.     

Fair Π

In this paper, we define fair computations in the π-calculus [Milner, R., Parrow, J. & Walker, D., A Calculus of Mobile Processes, Part I and II, Information and Computation 100 (1992) 1–78]. We follow Costa and Stirling's approach for CCS-like languages [Costa, G. & Stirling, C., A Fair Calculus of Communicating Systems, Acta Informatica 21 (1984) 417–441, Costa, G. & Stirling, C., Weak and Strong Fairness in CCS, Information and Computation 73 (1987) 207–244] but exploit a more natural labeling method of process actions to filter out unfair process executions. The new labeling allows us to prove all the significant properties of the original one, such as unicity, persistence and disappearance of labels. It also turns out that the labeled π-calculus is a conservative extension of the standard one. We contrast the existing fair testing [Brinksma, E., Rensink, A. & Vogler, W., Fair Testing, Proc. of CONCUR'95, LNCS, 962 (1995) 313–327, Natarajan, V. & Cleaveland, R., Divergence and Fair Testing, Proc. of ICALP '95, LNCS, 944 (1995) 648–659] with those that naturally arise by imposing weak and strong fairness as defined by Costa and Stirling. This comparison provides the expressiveness of the various fair testing-based semantics and emphasizes the discriminating power of the one already proposed in the literature.     

基于Pi-Calculus的跨组织工作流建模方法

针对跨组织协同环境下的业务流程建模技术的不足,提出了一个新的用于跨组织业务流程的形式化建模方法。首先根据工作流管理联盟（WfMC）的有关工作流过程定义接口规范,利用PiCalculus技术对跨组织业务流程结构进行了形式化定义。此外,利用PiCalculus特有机制对并发流程及其之间的通信进行描述。提出的方法可以有效用于不同业务流程间的协同工作,并且适合于对分布式协同环境下的工作流进行建模。     

Linearity, Persistence and Testing Semantics in the Asynchronous Pi-Calculus

In [C. Palamidessi, V. Saraswat, F. Valencia and B. Victor. On the Expressiveness of Linearity vs Persistence in the Asynchronous Pi Calculus. LICS 2006:59–68, 2006] the authors studied the expressiveness of persistence in the asynchronous π-calculus (Aπ) wrt weak barbed congruence. The study is incomplete because it ignores the issue of divergence. In this paper, we present an expressiveness study of persistence in the asynchronous π-calculus (Aπ) wrt De Nicola and Hennessy's testing scenario which is sensitive to divergence. Following [C. Palamidessi, V. Saraswat, F. Valencia and B. Victor. On the Expressiveness of Linearity vs Persistence in the Asynchronous Pi Calculus. LICS 2006:59–68, 2006], we consider Aπ and three sub-languages of it, each capturing one source of persistence: the persistent-input calculus (PIAπ), the persistent-output calculus (POAπ) and persistent calculus (PAπ). In [C. Palamidessi, V. Saraswat, F. Valencia and B. Victor. On the Expressiveness of Linearity vs Persistence in the Asynchronous Pi Calculus. LICS 2006:59–68, 2006] the authors showed encodings from Aπ into the semi-persistent calculi (i.e., POAπ and PIAπ) correct wrt weak barbed congruence. In this paper we prove that, under some general conditions, there cannot be an encoding from Aπ into a (semi)-persistent calculus preserving the must testing semantics.     

基于PI演算的反XML重写攻击安全模型验证

设计出一个安全模型后,要严格验证其是否满足安全需求是非常重要和必要的。利用形式化方法来检验模型是否满足了安全协议是一种有效的手段。本文针对XML重写攻击,设计出了一个反XML重写攻击的安全模型,然后运用Pi演算形式化方法验证了其有效性、真实性和安全性。