基于部件设计的运行时验证

研究软部件设计中的可靠性问题,对这一问题主要诉是,当一个已存软部件的正确性无法得到确认时,在具具体实现不可知的情况下,如何提高它的运行时可靠性？为解决这一问题,该文首先构造一个能够用于软部件动态语义检测的抽象模型;然后通过在设计中系统地引入一些运行时技术以保证基于部件软件的可靠性。这些运行时技术包括：（１）包裹部件。作为额外的一层设计,根据软部件的接口说明自动生成,用于检测运行时错误;（２）虚拟部     

利用WinPcap实现一个小型的数据包回放系统

在离线情况下利用数据包回放模拟一个真实的网络环境是一种常用方法,因而寻找一种方法对网络数据包进行可靠地回放变得尤为重要。本文概述了WinPcap的结构组成和实现原理,简单介绍了数据包回放操作的重要部件,通过一个应用实例,说明了如何利用WinPcap发包功能进行网络数据包回放。     

基于构件设计的正确性验证

本文研究基于构件设计的正确性问题,我们首先建立一个构件描述的模型：（１）接口：通过对ＣＯＲＢＡ的ＩＤＬ进行扩展,使其能够在构件的接口中同时描述构件的语法和语义信息,（２）实现,通过引入一个简单的程序模型,阐述如何利用子构造一个新的构件,然后我们考虑如何将构件的接口和实现联系起来,利用Ｈｏａｒｅ逻辑,验证一个构件的实现是否满足其接口中所给出的语义要求。     

基于CHNN聚类算法的款式部件生成模型

对智能化服装款式设计系统中的款式部件的自动获取功能进行了研究.采用基于连续Hopfield神经网络(CHNN)的聚类算法提出了一个款式部件的风格生成模型.提取表现部件造型特征的特征要素构造一个空间点集,利用CHNN网络对该点集进行聚类,分析部件类别与款式设计风格之间的关系,建立基于款式风格设计的部件搭配规则.并将该模型应用于款式的衣片部件上,实现了衣片部件的聚类.实验结果表明,该模型设计合理,分类清晰,具有可扩展性.     

基于NiosII的SOPC多处理器系统设计方法

详细地阐述基于NiosII和FPGA的多处理器系统的实现机制,讨论利用硬件互斥核实现多处理器资源共享的方法,并给出硬件设计的具体步骤以及软件设计、调试方法和关键技术;利用Altera公司提供的QuartusII、SOPC Builder和NiosII IDE等开发工具,通过一个3处理器系统设计实例,验证了设计方法的正确性,实现了3处理器对存储器资源的共享。     

一个实用的多点通信部件的设计与实现

从工程实现的角度出发,阐述了如何利用自行研制的多媒体会议系统ＭＭＭ２０００中的多点通信模型,研制开发一个实用的多媒体通信部件的设计与实现方法。     

基于NiosⅡ的SOPC多处理器系统设计方法

详细地阐述基于NiosⅡ和FPGA的多处理器系统的实现机制,讨论利用硬件互斥核实现多处理器资源共享的方法,并给出硬件设计的具体步骤以及软件设计、调试方法和关键技术;利用Altera公司提供的QuartusⅡ、SOPC Builder和NiosⅡ IDE等开发工具,通过一个3处理器系统设计实例,验证了设计方法的正确性,实现了3处理器对存储器资源的共享.     

基于ProActive的容错调度器设计与实现

在分布式计算系统中保证并行应用计算的正确性及提高计算系统中动态资源的利用率是一个重要的研究问题。在原有的基于ProActive的并行计算平台上,引入呼吸通信机制、故障节点发现机制和子任务重新调度机制,设计和实现了一个容错调度系统。实验表明该调度器在部分节点出现故障的情况下,能保证并行计算的正确性,并具有较好的性能。     

网络环境中软件RAID的设计与实现

本文构造了一个在设备驱动层上实现网络RAID的模型。主要目的是探讨在对原有系统仅做少量修改的情况下，如何利用现有资源实现网络RAID，以提高系统的IO性能。文章对模型的实现进行了深入的讨论，并给出了利用iSCSI技术实现该模型的例子，例子本身也证明了模型的正确性和可行性。     

EDA领先企业Cadence让你实现“设计即所得”

你是否还记得一场被称为“所见即所得”的计算机技术重大突破？只要在电脑屏幕上打开一个文件．就可以精确地看到打印出来的页面会是什么样的，这曾被称作WYSIWYG。现在，25年时间转瞬即逝，将打印的图像面积缩小到一千万分之一，你就会知道半导体产业所面临的挑战：如何确保芯片的关键部件能够按照其设计被准确地生产出来－或者说，如何实现“设计即所得”或WYDIWYG签收？全球电子设计创新领先企业Cadence设计系统公司（NASDAQ：CDNS）今天在每年一度的CDNLive!用户会议中发表讲话，指出这是一个十分艰巨的任务。尖端半导体设备中的一个部件可能比过去用于打印的激光的波长还薄，这本身就代表了一系列的工程难题。[第一段]     

Recording concerns in source code using annotations

A concern can be characterized as a developer׳s intent behind a piece of code, often not explicitly captured in it. We discuss a technique of recording concerns using source code annotations (concern annotations). Using two studies and two controlled experiments, we seek to answer the following 3 research questions: (1) Do programmers׳ mental models overlap? (2) How do developers use shared concern annotations when they are available? (3) Does using annotations created by others improve program comprehension and maintenance correctness, time and confidence? The first study shows that developers׳ mental models, recorded using concern annotations, overlap and thus can be shared. The second study shows that shared concern annotations can be used during program comprehension for the following purposes: hypotheses confirmation, feature location, obtaining new knowledge, finding relationships and maintenance notes. The first controlled experiment with students showed that the presence of annotations significantly reduced program comprehension and maintenance time by 34%. The second controlled experiment was a differentiated replication of the first one, focused on industrial developers. It showed a 33% significant improvement in correctness. We conclude that concern annotations are a viable way to share developers׳ thoughts.     

高校非计算机专业计算机教育探讨

非计算机专业的计算机教育是高等教育改革的重要组成部分,对它如何定位？如何确定教学目标？如何规划新的课程体系？如何推进实施？是非计算机专业计算机教学改革的中心议题。文章主要介绍我校在非计算机专业计算机教学改革的经验。     

应用框架的层次泛化模型研究

随着构件技术的发展,构件粒度对于构件组装的复杂性变化起着不可忽视的作用。如何进行大粒度构件的组装,及同领域的构件以何种方式结合在一起,对这些问题的研究现在逐渐浮出水面,框架技术的研究已经提到了议事日程。构造应用框架是软件复用技术的飞跃。但是如何构造应用框架才能使框架具有较高的复用程度,才能实现以积木搭接式方法构造应用系统。结合当前应用框架研究,提出了应用框架的层次泛化模型,将应用框架分成不同的层次结构,居于不同层次的应用框架相对不同的解决方案,层次越高变化的概率也相应降低。     

基于偶然正确性概率的错误定位技术

基于代码覆盖的错误定位技术是一种常用的错误定位方法,被用来识别与故障相关的程序元素.然而,有研究工作表明基于代码覆盖的错误定位技术的有效性受到了偶然正确性现象的影响.偶然正确性现象是指程序中包含的错误被执行,但没有产生错误结果的情况,它在实际场景中是非常普遍的.在以往的研究工作中,我们提出了一种估算发生偶然正确性现象的概率的方法.该方法从程序运行时内存中值的定义-使用关系出发,对各语句的执行对程序输出的影响进行估计.基于偶然正确性概率,本文对基于代码覆盖的错误定位技术中可疑度的计算方法进行了修正,以消除偶然正确性现象对错误定位技术的影响.本文在Software-artifact Infrastructure Repository （SIR）中提供的西门子测试套件上进行了实验,这也是偶然正确性相关工作中常被使用的目标程序.实验结果表明,相对于基于代码覆盖信息的错误定位技术,本文提出的方法提高或至少维持了原有的安全性,并较好地提高了错误定位的精确度.     

Application design for wearable and context-aware computers

To effectively integrate wearable computers into ubiquitous computing environments, we must address several important challenges. How do we develop social and cognitive application models? How do we integrate input from multiple sensors and map them to users' social and cognitive states? How do we anticipate user needs? How do we interact with users? To address mobile-application design challenges, the authors created four user interface models that map problem-solving capabilities to application requirements.     

基于符号模型检测的Web服务组合形式化验证

随着经济的发展和市场竞争的加剧,企业必须能够快速且准确地满足市场和用户的各种需求。Web服务组合正是由于单个Web服务不能满足企业及用户的需求而产生的一种技术,而如何确保组合的正确性来实现服务增值是一个尚未完全解决的问题。针对此问题,提出了一种基于符号模型检测器NuSMV对Web服务组合进行验证的方法,并提出了基于消息会话的Web服务有限状态自动机的形式化定义。最后实例验证了Web服务组合交互的正确性和有无死锁状态现象,进一步证明了方法的可行性。     

Strategic reasoning about business models: a conceptual modeling approach

Strategic reasoning about business models is an integral part of service design. In fast moving markets, businesses must be able to recognize and respond strategically to disruptive change. They have to answer questions such as: what are the threats and opportunities in emerging technologies and innovations? How should they target customer groups? Who are their real competitors? How will competitive battles take shape? In this paper we define a strategic modeling framework to help understand and analyze the goals, intentions, roles, and the rationale behind the strategic actions in a business environment. This understanding is necessary in order to improve existing or design new services. The key component of the framework is a strategic business model ontology for representing and analyzing business models and strategies, using the i* agent and goal oriented methodology as a basis. The ontology introduces a strategy layer which reasons about alternative strategies that are realized in the operational layer. The framework is evaluated using a retroactive example of disruptive technology in the telecommunication services sector from the literature.     

Probabilistic Model Checking of Deadline Properties in the IEEE 1394 FireWire Root Contention Protocol

The interplay of real time and probability is crucial to the correctness of the IEEE 1394 FireWire root contention protocol. We present a formal verification of the protocol using probabilistic model checking. Rather than analyse the functional aspects of the protocol, by asking such questions as ‘Will a leader be elected?’, we focus on the protocol's performance, by asking the question ‘How certain are we that a leader will be elected sufficiently quickly?’ Probabilistic timed automata are used to formally model and verify the protocol against properties which require that a leader is elected before a deadline with a certain probability. We use techniques such as abstraction, reachability analysis and integer-time semantics to aid the model-checking process, and the efficacy of these techniques is compared. Received July 2001/Accepted in revised form November 2002 Correspondence and offprint requests to: Marta Kwiatkowska, School of Computer Science, University of Birmingham, Birmingham B15 2TT, UK. Email: M.Z.Kwiatkowska@cs.bham.ac.uk     

Reader Feedback

Abstract

Several ROI (return on investment) methods have been addressed in the business world. They include Net Present Value (NPV) and Internal Rate of Return (IRR). How do we know which methods are good for managing risks? How do we know when ROI methods need to be changed due to, for example, organizational restructuring, merger, or acquisition? How do we compare? Once we know, what criteria should we use to select values for input to an ROI method for a particular organizational environment?     

Making components contract aware

Components have long promised to encapsulate data and programs into a box that operates predictably without requiring that users know the specifics of how it does so. Many advocates have predicted that components will bring about widespread software reuse, spawning a market for components usable with such mainstream software buses as the Common Object Request Broker Architecture (CORBA) and the Distributed Component Object Model (DCOM). In the Windows world, at least, this prediction is becoming a reality. Yet recent reports indicate mixed results when using and reusing components in mission-critical settings. Such results raise disturbing questions. How can you trust a component? What if the component behaves unexpectedly, either because it is faulty or simply because you misused it? Before we can trust a component in mission-critical applications, we must be able to determine, reliably and in advance, how it will behave. In this article the authors define a general model of sofware contracts and show how existing mechanisms could be used to turn traditional components into contract-aware ones