Nondeterministic Probabilistic Petri Net — A New Method to Study Qualitative and Quantitative Behaviors of System

There are many variants of Petri net at present,and some of them can be used to model system with both function and performance specification,such as stochastic Petri net,generalized stochastic Petri net and probabilistic Petri net.In this paper,we utilize extended Petri net to address the issue of modeling and verifying system with probability and nondeterminism besides function aspects.Using probabilistic Petri net as reference,we propose a new mixed model NPPN(Nondeterministic Probabilistic Petri Net) system,which can model and verify systems with qualitative and quantitative behaviours.Then we develop a kind of process algebra for NPPN system to interpret its algebraic semantics,and an actionbased PCTL(Probabilistic Computation Tree Logic) to interpret its logical semantics.Afterwards we present the rules for compositional operation of NPPN system based on NPPN system process algebra,and the model checking algorithm based on the action-based PCTL.In order to put the NPPN system into practice,we develop a friendly and visual tool for modeling,analyzing,simulating,and verifying NPPN system using action-based PCTL.The usefulness and effectiveness of the NPPN system are illustrated by modeling and model checking an elaborate model of travel arrangements workflow.     

Synthesizing Distributed Protocol Specifications from a UML State Machine Modeled Service Specification

The object-oriented paradigm is widely applied in designing and implementing communication systems.Unified Modeling Language(UML) is a standard language used to model the design of object-oriented systems.A protocol state machine is a UML adopted diagram that is widely used in designing communication protocols.It has two key attractive advantages over traditional finite state machines:modeling concurrency and modeling nested hierarchical states.In a distributed communication system,each entity of the system has its own protocol that defines when and how the entity exchanges messages with other communicating entities in the system.The order of the exchanged messages must conform to the overall service specifications of the system.In object-oriented systems,both the service and the protocol specifications are modeled in UML protocol state machines.Protocol specification synthesis methods have to be applied to automatically derive the protocol specification from the service specification.Otherwise,a time-consuming process of design,analysis,and error detection and correction has to be applied iteratively until the design of the protocol becomes error-free and consistent with the service specification.Several synthesis methods are proposed in the literature for models other than UML protocol state machines,and therefore,because of the unique features of the protocol state machines,these methods are inapplicable to services modeled in UML protocol state machines.In this paper,we propose a synthesis method that automatically synthesizes the protocol specification of distributed protocol entities from the service specification,given that both types of specifications are modeled in UML protocol state machines.Our method is based on the latest UML version(UML2.3),and it is proven to synthesize protocol specifications that are syntactically and semantically correct.As an example application,the synthesis method is used to derive the protocol specification of the H.323 standard used in Internet calls.     

Design of bilinear observer for singular bilinear systems

In this paper, by analyzing the worm’s propagation model, we propose a new worm warning system based on the method of system identification, and use recursive least squares algorithm to estimate the worm’s infection rate. The simulation result shows the method we adopted is an efficient way to conduct Internet worm warning.     

Research of internet worm warning system based on system identification

In this paper, by analyzing the worm’s propagation model, we propose a new worm warning system based on the method of system identification, and use recursive least squares algorithm to estimate the worm’s infection rate. The simulation result shows the method we adopted is an efficient way to conduct Internet worm warning.     

Research on component-based ERP system

Conventional ERP （Enterprise Resource Planning） system is based on a software developing mode in which software reuse can be only achieved at class level. Such a developing mode results in inefficient development, low-quality software and poor variability of ERP system. By applying component technology, these problems are solved and the system becomes more reliable, reusable, extensible, and transplantable. In this paper, we firstly introduce the concept of component and two popular component models, based on which our own ERP component model is developed. Then we propose a layered, flexible and extensible architecture for component-based ERP system. Components performing different functions at different layers can be extracted and encapsulated conveniently according to the architecture. Finally, we focus on the application of the proposed architecture, illuminating how to extract, encapsulate and assemble components to a completed ERP system with examples.     

Event-Based Semantics of UML 2.X Concurrent Sequence Diagrams for Formal Verification

UML 2.X sequence diagrams(SD)are among privileged scenarios-based approaches dealing with the complexity of modeling the behaviors of some current systems.However,there are several issues related to the standard semantics of UML 2.X SD proposed by the Object Management Group(OMG).They mainly concern ambiguities of the interpretation of SDs,and the computation of causal relations between events which is not specifically laid out.Moreover,SD is a semi-formal language,and it does not support the verification of the modeled system.This justifies the considerable number of research studies intending to define formal semantics of UML SDs.We proposed in our previous work semantics covering the most popular combined fragments(CF)of control-flow ALT,OPT,LOOP and SEQ,allowing to model alternative,optional,iterative and sequential behaviors respectively.The proposed semantics is based on partial order theory relations that permit the computation of the precedence relations between the events of an SD with nested CFs.We also addressed the issue of the evaluation of the interaction constraint(guard)for guarded CFs,and the related synchronization issue.In this paper,we first extend our semantics,proposed in our previous work;indeed,we propose new rules for the computation of causal relations for SD with PAR and STRICT CFs(dedicated to modeling concurrent and strict behaviors respectively)as well as their nesting.Then,we propose a transformational semantics in Event-B.Our modeling approach emphasizes computation of causal relations,guard handling and transformational semantics into Event-B.The transformation of UML 2.X SD into the formal method Event-B allows us to perform several kinds of verification including simulation,trace acceptance,verification of properties,and verification of refinement relation between SDs.     

数字图书馆中基于Java的用户界面组件库研究与开发

It is one of the most important task in digital library to develop a universal and customized user interface for search and retrieval in heterogeneous,distributed environment.In this paper,we briefly introduce working principles and workflow of SiteSearch system developed by OCLC.Based on analyzing the functions of this system,we study and design composing elements and implementation mechanism of the customized interface.By analyzing and illustrating the examples,we develop Java based component library for dynamically generating the customized interface in Chinese information platform of SiteSearch system.Finally,we make some remarks on the difference of develop-ment of this system with other similar systems.     

基于Web的UML建模系统

针对目前异构网络环境下的异地开发和信息查询需求,结合MVC模式,设计并实现基于Web的UML建模系统。为了便于表示UML建模过程中的结构化数据和半结构化数据,将建模信息保存为XML文件,使系统具有更好的可扩展性、开放性、灵活性、自我描述性、可操作性及规范的层次结构。通过建立基于XML的信息查询提高了查询效率。     

基于UML的用户管理系统分析与设计

对UML产生的背景及其基本模型进行了阐述,以用户管理系统的UML建模为背景,探索了基于UML的管理信息系统建模及UML中多种模型图的使用方法,并对传统的访问控制模型做了改进。最后对系统效率进行了验证。     

Model transformations in the UPES/UPSoC development process for embedded systems

Model-based development (MBD) aims at combining modeling languages with model transformers and code generators. Modeling languages, like profiles of the Unified Modeling Language (UML), are increasingly being adopted for specific domains of interest to alleviate the complexity of platforms and express domain concepts effectively. Moreover, system development processes based on automatic model transformations are widely required to improve the productivity and quality of the developed systems. In this paper, we show how MBD principles and automatic model transformations provide the basis for the unified process for embedded systems (UPES) development process and its unified process for system-on-chip (SoC) (UPSoC) subprocess. They have been defined to foster in a systematic and seamless manner a model-based design methodology based on the UML2 and UML profiles for the C/SystemC programming languages, which we developed to improve the current industrial system design flow in the embedded systems and system-on-chip area. This work is supported in part by the project Model-driven methodologies and techniques for embedded systems design and analysis based on UML, Abstract State Machines, and SystemC at STMicroelectronics, AST R&I of Agrate Brianza (MI), Italy.     

应用对象过程图扩展UML建模环境

统一建模语言UML存在着面向对象建模的不足,例如,用多个模型表示系统,模型的一致性难以保证.UML的工作主要集中于面向对象的分析和设计阶段,在实现阶段并没有做过多的努力等等,给系统设计带来了不便.提出了在UML建模环境中引入对象过程图(object-process diagram,简称OPD),为多个模型的一致性提供了统一的标准,提高了程序文档的可理解性和可维护性,使得扩展后的UML具备从面向对象分析到程序设计的完全可视化的描述能力.     

光电干扰武器系统C3I可执行建模的研究

UML已经成为面向对象分析与设计建模事实上的标准。基于UML的C3I系统模型的设计结果是对系统的静态表述,而C3I系统的本质是动态的。着色Petri网(CPN)具有强大的描述能力及严密的数学基础和多种分析手段,并且是可以仿真运行的。提出了从UML产品映射到可用于逻辑、行为和性能方面体系结构评价的CPN可执行模型的方法,对光电干扰武器系统C3I进行了UML建模的一般描述,阐述了光电干扰武器系统C3I从UML产品映射到CPN建立可执行模型的过程。通过对可执行模型CPN的仿真可对光电干扰武器系统C3I进行完整准确的评价。     

基于UML的仿真应用系统映射方法研究

基于组件的仿真应用系统设计方法在视图建模时往往存在标准不统一的问题,提出了仿真应用系统向统一建模语言UML映射的解决思路,仅用两种视图实现了系统的完整建模,完成了系统静态组成结构向UML复合结构图的映射以及系统动态行为向UML活动图的映射。参考模型驱动架构MDA的开发过程,对完成映射的系统进行了代码自动生成,实现了用户的零编码。最后,通过某一海军作战仿真实例证明,此方法达到了基于组件的仿真应用系统视图建模标准化的目的,提高了系统的一致性。     

基于UML的农村社会养老保险精算系统设计

以农村社会养老保险精算的模型建立和方案设计为背景,利用面向对象建模技术UML分析了农村社会养老保险精算系统的组织和行为特性,并以Java语言实现了系统的原型;讨论了UML在编制开放性、复杂性系统过程中的优势;阐述了系统的创新点,并展望了其在“金保工程”中的应用前景。     

基于可视化的建模技术研究

简述了面向对象（O－O）的可视化的建模技术UML,应用UML提出了一个网络侵扰监测系统（IDS）的O－O概念层的模型,并对此模型作出评价,以希望能在更多领域充分利用O－O技术的特点及优势,达到系统开发高效率、高质量、低成本的目的。     

使用UML对μC/OS-II建模与分析

使用统一建模语言（UML）对嵌入式实时操作系统C/OS-II做静态建模和动态建模,进而利用UML的可视化模型来描述和分析C/OS-II的系统结构和工作机理。通过UML静态建模,为基于C/OS-II的嵌入式系统设计,提供了一个运用面向对象技术的框架;通过UML动态建模,详细分析了嵌入式实时操作系统（ERTOS）的关键方面,包括实时内核的调度机理、优先级反转问题及其解决办法等。     

VPN动态密码认证系统设计与实现

针对VPN接入的身份认证问题，提出了一种综合运用LDAP认证、应用系统认证和动态密码认证技术的多级认证模式，运用UML模式对动态密码认证系统进行设计，实现了多应用系统和多种用户管理模式环境中的统一用户认证管理和安全的远程访问。