嵌入式高可用性数据管理的设计与实现

论述了在个人数字助理上如何设计一个高可用性数据管理软件来保证数据的高可用性.该软件具有可扩展性、可移植性,容易升级.     

新软物语

推荐理由：去除下载、安装常用软件的烦恼简介：根据绝大多数电脑用户的软件使用习惯和需求,默认提供各种常用软件,方便的同时还在安全角度把好关．即使是新手用户也不会在网上误中恶意软件的下怀。此外,该工具还自带了软件卸载功能,让用户有一个统一而又干净的软件卸载方法,而其提供的软件统一升级功能也非常有用。     

Ubuntu再战Vista

在上一期中,笔者从操作系统安装．软件安装以及硬件即插即用的三个角度对Ubuntu及Vista做了横向对比,此二者在不同方面各有优势,为了能够给大家呈现双方更多层面的差异性,本期我们将从网络、字处理、搜索引擎、多媒体及备份恢复的几个角度进行进一步对比。     

怎样保证网络的高可用性

一、网络高可用性应用分析 目前,保证网络高可用性一般是从两个方面同时入手,即硬件备份和软件容错。硬件备份需要消耗大量的备份硬件设备,大大提高了组网投资。软件容错只需要性能较高、功能全面和管理简单的系统即可,而且既使硬件备份齐全,也需要较好的容错软件管理备份系统,从而保证网络系统在工作运行中的可用性和稳定性。所以从这个方面来讲,网络系统的高可用性需要从硬件配置到软件选用全面考虑和合理采用。     

软件安装测试的内容和方法

软件是否能正常且方便地安装和卸载是软件能否顺利推广的关键之一,软件安装测试是软件测试的一个重要组成部分.本文从"安装和卸载的功能测试"、"安装和卸载的易用性测试"、"安装手册的测试"三个方面系统地阐述了软件安装测试的内容和方法,并给出一些实例.     

打造智能的ACDSee 6．0安装程序

AGDSee 6．0是我们常用的看图软件，它以其功能强大、操作方便受到了大家的欢迎。同其它软件一样，ACDSee 6．0在安装时也要根据安装向导一步一步进行，我们需要为它设王安装目录，输入序列号，选择安装组件等，而且在安装完成后还要重新启动计算机，整个过程非常的麻烦。其实我们可以自已动起手来修改ACDSee 6．0的安装程序，使其安装时自动又智能。     

高可用性系统框架设计与实现

高可用性要求是指当某个节点出现故障或失效时,整个系统仍能正常运行,而且要求在最短的时间内恢复故障。该文主要提出了高可用性的系统框架结构,从硬件结构出发,结合软件模型设计。该框架能够适合双节点、多节点系统。通过实验,证明该系统能应用到实际环境中,它具有很高的可用性。     

双机容错系统

双机容错系统是非常容易安装和管理的低成本、高可用性的全光纤集群解决方案。该方案设计是用来在两结点环境下为服务器提供失效自动切换功能。既可以实现基于SAN的全冗余，也可以实现低成本的JBOD直连，兼有低成本、易使用、简单管理和方便配置的特点。     

DEC筑起Internet安全墙

Digital最近推出了两个高可用性Internet安全解决方案:AltaVista高可用性防火墙系统和AltaVista高可用性隧道系统。这两个解决方案把Digital 64位的AlphaServer 800系统、强大的集群技术和著名的AltaVista Firewall 97或AltaVista Tunnel 97软件结合在一起,保证企业的Internet网关和虚拟私有网络具有最大的连续运行时间,满足了     

Check Point与Resilience联手升级防火墙

近日，Check Point公司与美国高可用性平台生产商Resilience睿智高用科技有限公司，在上海宣布将以“弃旧迎新，共建安全IT网络”为目标联手为国内企业提供高可用性防火墙升级方案。此方案将会通过睿智高用在国内的总代理ACA Pacific Technology Limited，为现有非Check Point用户推出防火墙竞争升级捆绑销售合作计划及相关的讲座。Check Point与睿智高用提供的解决方案中，包括Check Point防火墙软件，睿智高用高可用性平台，一年免费保养及安装。其中睿智高用的持续安全保证服务（CSO）将为企业提供永久产品保用及升级计划，随时升级到更高容量产品，保障投资，同时提供99．999％网络不停机服务。     

巧用VB模拟倒计时器

利用VB软件中计时器控件以及其他控件开发出可重复使用的倒计时软件,并给出相应的源程序。     

单片机在交通信号倒计时器的应用

详细介绍了基于AT89C2051单片机的交通信号倒计时器的基本工作原理,并对其在硬件设计、软件设计和实现方法中的注意事项进行了详细的阐述。     

单片机在交通信号倒计时器的应用

详细介绍了基于AT89C2051单片机的交通信号倒计时器的基本工作原理,并对其在硬件设计、软件设计和实现方法中的注意事项进行了详细的阐述。     

基于AT89C51单片机的交通灯系统设计

以单片机AT89C51作为城市交通灯的控制核心,模拟定周期交通信号灯的工作状态;针对复杂多变的路况环境,特别增设了路段遇忙调整、紧急情况处理、特种车检测、语音提示等模块,进一步完善了交通灯控制系统。     

An introduction to the NASA Shuttle ground operations simulator (SGOS)

The Shuttle ground operations simulator (SGOS) simulation software introduced in this paper is used to train NASA ground controllers and to certify launch countdown readiness. The SGOS executive and its subsystems have been an integral component of the Shuttle Launch Safety Program for almost 30 years. It is usable (via a LAN) by over 2000 NASA employees at the Kennedy Space Center and 11 000 contractors. SGOS supports over 800 models comprised of several hundred thousand lines of code and over 1000 Model Control Procedures. Copyright © 2007 John Wiley & Sons, Ltd.     

实时自适应交通信号倒计时显示控制方法

针对目前各城市的交通堵塞现象日益严重,传统的定配时交通控制方法因不够灵活而难以适应当前交通需求,提出了一种实时自适应交通信号倒计时显示控制方法,该方法能够将全程倒计时、无跳变、计时与实际时间相符合集中于一身,可根据各相位车流情况实时调整目标相位绿灯倒计时时间,不仅可使人们获知真实的倒计时时间,还能有效缓解交通拥堵,具有良好的实用性。     

基于nRF24L01的无线抢答器设计

该设计是一款无线抢答器,它在保证抢答器灵敏度的前提下解决了有线抢答器布置会场的复杂度。该次设计的无线抢答器由硬件部分和软件部分组成,硬件部分分为抢答主机和抢答分机。上位机界面的功能包括启动界面、试题选择功能、倒计时功能、分值选择功能、显示试题功能、显示答案功能、选手调试功能、选手犯规和忽略功能等。     

A study of N-version programming and its impact on software availability

N-version programming is a useful approach to improve the quality of software, especially for safety-critical systems. Positive performance in enhancing software availability is an expected result. In this paper, a software availability model for the study of the impact of N-version programming technique is proposed and investigated. The characteristics of the N-version software system and its operation and failure process are analysed. Based on this analysis, the time-dependent behaviour of the software system, which alternates between online and offline states, is described using a Markov chain. This model derives quantitative measures of software availability. Numerical examples and comparisons are also presented in this paper to directly illustrate N-version programming's positive impact on software availability measures. N-version programming generally provides a positive impact on the system. However, it does not always guarantee a higher availability performance. General recommendations are provided on N-version software structure design based on cost-effective criteria.     

A model for availability analysis of distributed software/hardware systems

System availability is a major performance concern in distributed systems design and analysis. A typical kind of application on distributed systems has a homogeneously distributed software/hardware structure. That is, identical copies of distributed application software run on the same type of computers. In this paper, the system availability for this type of system is studied. Such a study is useful when studying optimal testing time or testing resource allocation. We consider both the case of simple two-host system, and also the more general case of multi-host system. A Markov model is developed and equations are derived to obtain the steady-state availability. Both software and hardware failures are considered, assuming that software faults are constantly being identified and removed upon a failure. Although a specific model for software reliability is used for illustration, the approach is a general one. Comparisons show that system availability changes in a similar way to single-host based software/hardware systems. Sensitivity analysis is also presented. In addition, the assumptions used in this paper are discussed.     

Predicting operational software availability and its applications to telecommunication systems

It is essential to predict customer-perceived software availability during software development and determine when to release the software to maintain a balance among time-to-market, development cost and software quality. This paper presents methods and procedures to predict software failure rates from a user perspective in system test phases and to reverse-engineer in order to estimate software release time for given availability targets. Software reliability analysis is conducted based on non-homogenous Poisson process models. Software system test data of current release are used to estimate the number of residual faults by the end of system tests and data of previous releases or similar products (including system test data, post-system test data and field failure data) provide a means to predict a user-perceived average failure rate of a fault. Software system availability can be predicted from these estimates. Both execution and calendar times are considered. A software resource utilization model is developed to transfer one testing time to another. A telecommunications application illustrates how to calculate the failure rate and testing time to meet the software availability requirements.