基于UML的面向对象通信协议建模技术研究

协议描述是协议开发进程和协议工程中非常重要的一步。提出使用UML来对协议的行为、结构和体系建模,包括了协议的静态和动态2个方面,并以一个简单的通信协议和服务作为实例来说明将UML用于协议描述的技术。     

Modeling UML sequence diagrams using extended Petri nets

Unified modeling language (UML) sequence diagrams combined with the UML profile for modeling and analysis of real-time and embedded (MARTE) systems are used to represent systems?? requirements. To enhance formal analysis abilities, sequence diagrams annotated with MARTE stereotypes are mapped into timed colored Petri nets with inhibitor arcs (TCPNIA). The mapping rules for the fragments of sequence diagrams and MARTE stereotypes are proposed respectively. They are proposed both in graphical and formal forms. The soundness of mapping rules is analyzed. The data related issues are handled through colored properties in TCPNIA models, guard functions and operational functions. A mapping rule for state invariant is proposed based on data related information. Through state invariant, complicated control relations can be expressed. Formal definitions for morphing and substitution in TCPNIA models are given. They provide modular and hierarchical modeling methods for TCPINA models. To show the applicability and feasibility of our method, an application example in vehicular ad hoc networks (VANETs) domain is studied.     

Protocol verification using database technology

A novel application of databases in communications networks, namely, protocol verification on a parallel database machine, is described. An approach to protocol verification that uses database algorithms executing on a commercially available, parallel architecture called a hypercube multicomputer is introduced. The goal is to achieve the high degree of computational parallelism necessary to explore rapidly the global state space of even very complex protocols, significantly reducing the time required to verify a protocol and allowing formal verification to be included as part of the process of protocol design. An overview is provided of the relational model of protocol verification used, and extensions to the model are described. The hypercube multicomputer and the algorithms for relational database operations designed to execute in that environment are then described. Estimates of the performance improvements achievable by parallel executing of verification algorithms in the proposed system are given     

Protocol conformance testing using multiple UIO sequences

Automatic generation of conformance test sequences for communication protocols by means of unique input/output (UIO) sequences is addressed. It is shown that if multiple minimum-length UIO sequences are computed for each state of the finite-state-machine (FSM) specification, then the length of the resulting test sequence is significantly reduced without an appreciable increase in the time needed to compute the sequence. An algorithm for assignment of the multiple UIO sequences is given. This algorithm, which is based on network flow, is polynomial in the number of states and transitions of the FSM and is effective in reducing the overall length of the test sequence     

基于UML的嵌入式系统设备驱动分析技术

提出一种使用UML(统一建模语言)对Linux设备驱动进行分析的方法,借助UML对设备驱动程序模型进行建模并分析,从而明晰设备驱动组件之间的依赖关系,明确设备驱动开发的重点。在此基础上对SDWiFi设备驱动程序模型进行了研究,设计处理器与Wi-Fi芯片之间的SDIO通信接口,移植SDWiFi设备驱动程序。最后使用无线工具包对SDWiFi无线网卡设备进行了配置和测试,测试结果表明SDWiFi无线网卡设备工作正常,通过使用UML对设备驱动程序模型进行建模和分析,可以提高设备驱动程序开发效率。     

UML在VPN业务管理中的应用和实现

分析了当前网络／业务管理中管理信息建模方法的不足,指出UML建模方法的,优点,具体研究了UML建模方法在VPN业务管理信息建模方面的应用。     

Deploying Internet Protocol Security in satellite networks using Transmission Control Protocol Performance Enhancing Proxies

Applications that use the reliable Transmission Control Protocol (TCP) have a significant degradation over satellite links. This degradation is mainly a consequence of the congestion control algorithm used by standard TCP, which is not suitable for overcoming the impairments of satellite networks. To alleviate this problem, two TCP Performance Enhancing Proxies (PEPs) can be deployed at the edges of the satellite segment. Then these PEPs can use different mechanisms such as snooping, spoofing and splitting to achieve a better TCP performance. In general, these mechanisms require the manipulation of the Internet Protocol (IP) and TCP headers that generates a problem when deploying the standard IP security (IPsec) protocol. The security services that IPsec offers (encryption and/or authentication) are based on the cryptographic protection of IP datagrams, including the corresponding IP and TCP headers. As a consequence, these cryptographic protections of IPsec conflict with the mechanisms that PEPs use to enhance the TCP performance in the satellite link. In this article, we detail the reasons that cause this conflict, and we propose three different approaches to deploy IPsec in a scenario with TCP PEPs. Our proposals provide different trade‐offs between security and TCP performance in some typical scenarios that use satellite networks. Copyright © 2012 John Wiley & Sons, Ltd.     

Traffic engineering standards in IP-networks using MPLS

The explosive growth of the Internet over the last few years has made the IP protocol suite the most predominant networking technology. Furthermore, the convergence of voice and data communications over a single network infrastructure is expected to happen over IP-based networks. Traditional IP-networks offer little predictability of service, which is often unacceptable for applications such as telephony, as well as for emerging and future real-time applications such as telemedicine. One of the primary goals of traffic engineering is to enable networks to offer predictable performance. Due to the need for better traffic control by network service providers, there has been considerable activity in the Internet Engineering Task Force to develop standards for traffic engineering in IP-based networks. This article discusses the direction taken by the IETF and some of the recent standardization efforts for traffic engineering using multiprotocol label switching (MPLS). Our primary focus is on the signaling protocols developed for this purpose     

Re-evaluating systems engineering concepts using systems thinking

Humans (individually, on teams, and in organizations) can follow simple processes to increase their probability of success. Many authors, both technical and nontechnical, have described processes for doing various things like designing a system, attaining business excellence, and solving personal and professional problems. The amazing similarities in these diverse processes suggest that there is a general process that might be closely related to human thinking. This general process was abstracted into the SIMILAR Process. This paper shows how the SIMILAR Process was used to help redescribe the requirements discovery process and system design process     

面向对象方法与UML

在计算机软件产业界，目前流行使用面向对象方法和UML开发软件系统。阐述面向对象方法的现状以及UML在面向对象方法中的地位。     

Efficient and flexible password authenticated key agreement for Voice over Internet Protocol Session Initiation Protocol using smart card

Providing a suitable key agreement protocol for session initiation protocol is crucial to protecting the communication among the users over the open channel. This paper presents an efficient and flexible password authenticated key agreement protocol for session initiation protocol associated with Voice over Internet Protocol. The proposed protocol has many unique properties, such as session key agreement, mutual authentication, password updating function and the server not needing to maintain a password or verification table, and so on. In addition, our protocol is secure against the replay attack, the impersonation attack, the stolen‐verifier attack, the man‐in‐the‐middle attack, the Denning–Sacco attack, and the offline dictionary attack with or without the smart card. Copyright © 2013 John Wiley & Sons, Ltd.     

A guide to engineering workstations: using workstations efficiently

The development of a distributed computing environment that ties together diverse design operations is discussed. A vast array of computer-aided engineering tools and related software is being integrated into a fully distributed, data-driven environment called the Grumman Computer/Information Integrated Enterprise (CIE). The decision was made to maintain Grumman's CAD/CAM capabilities while controlling operating costs through effectively linked workstations. Crucial to the plan is the definition and implementation of a local-area network (LAN) strategy to link all the different types of machines together. The network tasks are defined, the current set-up is described, and past problems are reviewed. The plan for migration to an integrated electronic design system based on lower-cost, high-powered workstations operating in an open-architecture environment is discussed. An accompanying table gives an extensive sampling of commercially available workstations     

一种基于AODV的QoS路由协议

对Ad Hoc网络中具有代表性的路由协议AODV路由协议进行了研究,提出一种利用AODV的HELLO协议包在路由层测试带宽的方法,并提出一种以带宽作为主要度量参数的QAODV路由协议以支持QoS路由.详细介绍了QAODV,并采用NS 2网络模拟仿真工具对相同场景下AODV与QAODV路由协议进行了仿真模拟,仿真结果表明:在网络负载比较重时,QAODV的包接收率优于AODV.     

Analytical modeling of Transmission Control Protocol NewReno using Generalized Stochastic Petri Nets

This paper presents a novel analytical model of Transmission Control Protocol (TCP) using a generalized stochastic Petri net (GSPN). Extensive simulation work has been done for the performance evaluation of TCP NewReno protocol. In view of the limitations of the simulation technique, we present an analytical approach using GSPN. A GSPN is a useful mathematical tool that solves continuous time Markov chains for complex systems and evaluates the stationary behavior. In this paper, we analyze the slow‐but‐steady variant of TCP NewReno. The model captures the behavioral aspects of the slow start and the congestion avoidance phase together with the fast retransmit and recovery capabilities of TCP NewReno. Performance metrics such as throughput, goodput, and task completion time of the system are obtained. The effect of variation in the model parameters on the performance is studied. The results are validated using the network simulator, and their accuracy is verified by evaluating the confidence interval. The performance of the proposed model is compared with that of TCP Reno. The performance of the proposed model is also compared with one of the previous models. The numerical illustrations and comparison of the proposed technique with simulation validates the accuracy, efficiency, and competence of the GSPN technique. While GSPN modeling for TCP is investigated in depth for the TCP NewReno and TCP Reno variant in this paper, other protocols could be also analyzed similarly. Copyright © 2013 John Wiley & Sons, Ltd.     

UML Statecharts的切片模型检验方法

统一建模语言UML已被广泛应用于软件设计和开发中,而验证UML模型是否满足关键的性质需求成为一个重要问题.由于空间爆炸和语义的复杂性,对Statecharts进行模型检验受到软件规模和设计精化程度的制约.本文在用扩展层次自动机(EHA)结构化的表示UML Statecharts后,通过分析EHA中存在的层次、并发和事件同步等特征定义了一组依赖关系.对于由状态和迁移组成的切片准则,给出对EHA进行切片的算法.该算法能保证切片后的EHA与原来的Statecharts对性质具有相同的可满足性,且删除了与被验证性质无关的层次和并发状态,缓解了空间爆炸问题.     

基于UML的面向对象设计

近年来，面向对象技术是软件设计的主流设计思想。UML作为一种面向对象的建模方法，一方面可方便地同大多数面向对象的设计语言链接；另一方面可运用到除软件设计以外的其他方面，如商业、信息系统、甚至是面向对象设计语言的开发等。     

基于UML的面向对象的系统建模

UML是一种通用的可视化建模语言，用于对软件进行描述、可视化处理、构造和建立软件系统的文档。它是面向对象分析和设计过程中重要的建模工具。本文以办公自动化系统的建模为实例，介绍了一种基于UML的面向对象的系统建模方法。