数字通信原理的虚拟实验室系统的设计与实现

本文提出了基于CORBA技术的网上虚拟实验系统模型，该模型以Java Applet作为客户端，CORBA作为中间通信桥梁，能够集成JavaBean、Matlab、COM／DCOM作为计算后台，大大提高了专业虚拟实验室的开发效率。基于这个平台，开发了通信原理实验需要的信号发生器、信号叠加器、滤波器以及示波器四种设备。同时，通信原理虚拟实验室为学生提供了学习通信原理的实验环境，学生能够在互联网上根据需要完成各种通信原理实验。     

基于Internet的计算机网络虚拟实验环境架构

提出了基于Internet的计算机网络虚拟实验室的开发模型。该模型的客户端是Java Applet，计算后台以NS为核心，辅以JavaBean来完成辅助计算，中间的通信桥梁是CORBA，通过CORBA实现NS与Java的数据传输。该模型具有Java语言的优点，客户端简单安全，服务器端利用了第三方工具NS，能够大大缩短开发周期，确保系统的正确性。     

基于ColdFusion的虚拟实验室设计

提出一个基于ColdFusion的虚拟实验室开发模型。该模型以Flash作为客户端,改善实验体验和表现效果,以ColdFusion为服务器,集成ColdFusion组件、Matlab、COM/DCOM、JavaBean作为计算后台,以提高专业虚拟实验室的开发效率。实验结果证明,该模型可以使设计人员快速开发与实现虚拟实验室,并为用户提供一种不受时间、地点、实验设备限制的实验环境。     

基于NS2的计算机网络远程虚拟实验室的设计与实现

文章提出了基于NS2模拟器的计算机网络虚拟实验室系统的设计模型和实现方法。该实验室以JavaApplet实现客户端,使用NS2多协议模拟器作为服务器的后台计算平台,Nam作为客户端的可视化工具,通过JavaRMI远程调用机制实现了客户端的远程调用。该系统客户端以JavaApplet实现,具有Java语言的平台独立性和安全性,以JavaBean实现虚拟实验设备(如节点,链路等);以组件的形式开发实验库,易于扩充实验库,提高了开发效率,实现了软件重用。服务器端以NS2作为后台计算平台,提供了强大的模拟仿真能力。该系统基于Web环境在用户和NS2网络模拟器之间提供了实验室平台,既使用户省去难以学习NS2的困难,又可以让用户利用NS2模拟器强大的系统仿真能力进行网络模拟试验,让用户可以更加深入理解网络中的复杂行为。     

基于Internet的密码学虚拟实验室的设计与实现

本文提出了一种采用组件技术构架的基于Internet的密码学虚拟实验室的设计模型和实现方法.该虚拟实验室以Java Applet实现客户端,具有Java语言的平台独立性和安全性,以JavaBeans的形式开发组件,提高了系统的开发效率,实现了软件重用,使得系统容易维护和扩充.利用该实验系统,用户能进行可视化的实验流程定制、仿真实验保存,对算法进行验证和性能分析实验,用户还可以加入自己编写的算法进行验证及扩充实验组件,为科研、教学等提供了一个很好的密码学虚拟平台.     

基于WWW的"计算机网络"虚拟实验室的设计与实现

论述了基于WWW的“计算机网络”虚拟实验室系统的设计和实现.该实验室以Java Applet的形式实现客户端,使用Java RMI远程调用机制实现了客户端和服务器方的通信,采用JavaBean的形式实现虚拟设备(如节点、主机和链路),以组件的形式开发实验库.系统采用NS2作为服务器方模拟器,客户端采用Nam作为可视化工具,既充分了利用了NS2多协议模拟器的强大功能,又省去了普通学生难于学习使用NS2模拟器的缺点.系统为用户远程学习计算机网络课程提供了良好的实验平台.     

基于Java与Matlab集成的虚拟实验平台的设计与实现

提出了采用JMatLink实现Java与Matlab之间联接的虚拟实验平台，Matlab作为计算后台提高了平台的仿真能力。详细介绍了该平台的设计与实现，讨论了服务器方与Matlab进行通信的服务器应用程序（VLS）的实现，并以数字通信原理虚拟实验室中低通滤波器的设计为实例介绍了整个平台的通信过程和实现机制。     

基于Web的虚拟物流实验室设计与实现

通过对虚拟物流实验室设计特点的分析,提出了基于Web的虚拟物流实验室构架,并设计了实现方案.运用3D 软件结合VRML建立虚拟场景模型,通过Java 3D对模型文件的调用实现虚拟场景的构建.调用Java 3D类库实现场景漫游、人机交互等功能,并对虚拟模型进行优化、重组.最后建立一个虚拟实验室的场景实例,验证了该设计方法具有良好的开发效率以及系统的沉浸性与交互性.     

基于Web的网络化虚拟仪器库

将虚拟仪器库与Web技术相结合,介绍了虚拟控件、仪器库、智能虚拟控件的原理和建模;提出了基于Java框架下的Web虚拟仪器库系统;系统被分为界面、中间和后台服务三层结构;利用组件技术实现系统登录、应用和系统维护等功能;信息被下载并嵌入到客户端浏览器运行。     

基于Java／CORBA架构的分布式综合信息检索平台

介绍了一个分布式检索系统的设计与实现,该系统基于Object Web理论,采用Java/CORBA架构。系统包含接口定义、服务器端服务对象、客户端查询对象等几个部分。     

Quantitative survivability evaluation of three virtual machine-based server architectures

Virtual machine-based services have become very popular in data centers and cloud computing in recent years. Efficient redundancy technology of virtual machine provides good availability for services; thus, it has become possible to provide continuous services even if the system suffers intrusions. So far, many intrusion tolerant server architectures have been developed based on virtual machine technology in academia and industry. Unfortunately, to the best of our knowledge, there is very little work done on evaluating the survivability of virtual machine-based server architectures in the literature.In this paper, we focus on analyzing and evaluating the survivability of three virtual machine-based architectures, which are load balance server architecture (LBSA), isolated component server architecture (ICSA), and Byzantine fault tolerant server architecture (BFTSA). As a reference, a traditional server cluster without virtual machines is also analyzed and compared. We model different architectures with Continuous Time Markov Chain (CTMC). We analyze the transient behaviors and steady states of different virtual machine-based architectures. Furthermore, the costs of the traditional server cluster and the virtual machine-based architectures are compared in terms of processing costs, memory costs, communication costs, and fail-safe fault tolerance. The results show that BFTSA has better survivability than LBSA and ICSA, but with longer time to reach the steady states and higher communication costs.     

The implementation and evaluation of the use of CORBA in an engineering design application

Many computer applications today require some form of distributed computing to allow different software components to communicate. Several different commercial products now exist based on the Common Object Request Broker Architecture (CORBA) of the Object Management Group. The use of such tools, however, often requires the modification of existing systems, rather than the development of new applications. The objective of this research has been to integrate the use of a CORBA tool into an existing engineering design application for the purpose of (1) evaluating the amount of re‐engineering that is involved to effectively integrate distributed object computing into an existing application, and (2) evaluating the use and performance of distributed object computing in an engineering domain, which often requires the transfer of large amounts of information. The results of this work demonstrate that CORBA technology can be easily integrated into existing applications. The ease of the integration as well as the efficiency of the resulting system, however, depends upon the degree of modification that developers are willing to consider in the re‐engineering process. The most transparent approach to the use of CORBA requires less modification and generally produces less efficient performance. The less transparent approach to the use of CORBA can potentially require significant system modification but produce greater performance gains. This work outlines issues that must be considered for the partitioning of functionality between the client and the server, development of an IDL interface, development of client and server‐side wrappers, and support for concurrent, multi‐user access. In addition, this work also provides performance and implementation comparisons of different techniques for the use of wrappers and for the transfer of large data files between the client and the server. Performance comparisons for the incorporation of concurrent access are also presented. Copyright © 1999 John Wiley & Sons, Ltd.     

一种移动数据库管理系统的体系结构

移动计算的网络环境具有其鲜明的特点：移动性、断接性、带宽多样性、可伸缩性、弱可靠性、网络通信的非对称性、电源能力局限笥等等。而现有的DBMS不能很好地解决移动计算环境中的数据库管理问题,因此有必要设计适于移动计算的数据库管理系统,首先分析了移动计算环境数据库系统的本质,指出移动数据库是一种动态分布式数据库。由于运动是相对的,即客户机被假定静止时,则服务器是动态变化的,通过引入虚拟服务器的概念可以将客户机的“移动”转换为服务器的“移动”,在此基础上,提出了一种移动数据库管理系统的体系结构,这种结构具有一定的通用性,该结构由虚拟服务器和局部DBMS组成,其中虚拟服务器是核心,对它的功能进行了详细的讨论,最后还介绍了基于此体系 结构和自主开发的分布式数据库管理系统DM2上的一个移动DBMS原型。     

Human-assistance robotic system based on distributed computing technology

Population aging is becoming an increasingly pressing problem for society. Thus, the timely development of supporting systems to improve care cost and the quality of life of the elderly is becoming particularly important. Because of the dispersal of the elderly and disabled, a standard software architecture that can implement network-distributed software sharing and improve the cost of writing and maintaining software is in high demand. This paper proposes using distributing computing technology CORBA to integrate network-distributed software and robotic systems for supporting the aged or disabled. Using CORBA as a communication architecture, we implemented a networkdistributed human-assistance robotic system. We developed a hardware base including a robot arm and an omnidirectional mobile robot, developed key technologies such as localization of a mobile robot, real-time recognition, real-time multimedia, and implemented several CORBA servers including a Web user management server, a task-level robot arm control server, a live image and video feedback server, a mobile robot control server, and an indoor Global Positioning System server. With the user controlling a robot arm with 5 d.o.f. to cooperate with an omnidirectional mobile robot, the developed system can provide basic services to support the aged and disabled.     

CC-NUMA架构下4路龙芯3B服务器设计与实现

针对特定领域中服务器的高性能计算、高带宽通信以及自主可控需求,在分析龙芯3B3000处理器架构特点的基础上,设计了基于CC NUMA并行处理架构的4路龙芯3B3000高性能服务器核心模块,通过使用TOE芯片提高了网络响应效率,同时大幅降低了10G以太网接口对处理器资源的占用消耗,有效提高了服务器的综合性能。通过测试验证,该服务器能够实现高效的并行计算能力和10G以太网通信能力,且国产元器件种类占比和数量占比均可达95%以上。     

CORBA构件模型研究与实现

对几种构件模型进行了比较分析，研究了CORBA构件模型体系结构，提出了CCM构件平台实现技术及方法，并给出了采用国防科大计算机学院研制的CCM构件平台进行程序开发的步骤，体现出CORBA构件模型可以简化CORBA服务器方的应用开发过程，并能够提高CORBA的易用性。     

虚拟企业环境下基于CORBA的分布式组件调度

1 引言信息集成技术一直是企业为增强竞争而追寻的一种新的信息管理技术,而组件调度的思想也正来源于此。但伴随着Internet和虚拟企业的发展,传统的信息集成技术已不再能满足新的需求。传统集成方法一般归纳为两类:点对点转换方法和公共数据模型转换方法。点对点转换方法如图1(a)所示。系统要使用一些精确的转换规则或算法,将一个模型表示的模式转