具有区分服务等级的可扩展并行服务器集群

采用并行Web服务器集群技术实现高性能的WEB服务器服务已经成为一种趋势,该技术具有性能高,可扩展性好,可靠性高、成本低等特点。文章介绍了目前Web服务器集群的结构和几种关键技术,在此基础上设计一种具有区分服务等级的Web服务器集群,并给出结构描述和资源管理的策略。     

基于COM的Apache Web Server参数在线调节系统

该文在WindowsNT平台下,针对开放源码的ApacheWebServer设计并实现了一种Web服务器的参数在线调节系统。该系统对ApacheWebServer进行了扩展,能够在线调节Web服务器的关键参数,从而提高Web服务器的性能。由于该系统采用了COM体系结构,它具有广泛的扩展性和互操作性。     

利用基于内容的缓存代理提高Web服务器性能

分布式Web服务器系统(DWSS)是提高网络服务性能的一种前沿方式.文中分析了当前几种在客户端、主机端提升Web服务性能的方法,提出了一种基于内容的缓存代理协作分布式Web服务器系统模型.该模型可以有效减少用户获得响应的时间,避免了服务器之间不必要的通信,提高了Web服务器整体的性能.     

基于Web服务器性能的TPC-W基准测试

随着Intemet的飞速发展,Web服务器日益重要,为了及时掌握Web服务器的性能,需要对其进行公证的测试.介绍了基于Web服务器性能的TPC-W基准测试系统的整体架构,根据此架构给出了系统的具体设计及实现方法,利用可变数据库实现了对被测系统进行多线程并发访问的测试系统,测试结果给出了被测服务器最主要的两个性能指标吞吐率和响应时间,为改善Web服务器的性能提供重要参考.     

嵌入式Web服务器中动态Web技术的研究

为了实现嵌入式Web服务器中的动态Web功能,讨论了适用于嵌入式环境的CGI与SSI技术,在分析其优缺点的基础上提出了CGI与SSI技术相结合的"扩展CGF解决方案.该方法克服了CGI方式可维护性差的缺点,减少了服务器生成动态页面时的开销.在成功设计扩展CGI的基础上,给出了嵌入式Web服务器的具体实现方法.实验结果表明了设计的可行性和有效性.该方法具有结构清晰、合理利用嵌入式系统资源和易于开发与维护的特点.     

一种基于入侵容忍技术的Web服务器系统设计

在SITAR模型基础上,设计Web服务器入侵容忍模型,并阐述工作原理.建立敖学模型,确定Web服务器最优个数;对性能进行测试,表明Web服务器入侵容忍系统具有更高的安全性.     

嵌入式Web服务器的设计研究

研究了多种嵌入式操作系统,分析了嵌入式Web服务器在多种嵌入式操作系统应用问题,通过对多平台的嵌入式Web服务器体系结构的设计研究,实现了一个模块化、通过模块配置可以适合的几种嵌入式操作系统的嵌入式Web服务器.该服务器能够对不同种类操作系统目标多平台的异构性进行屏蔽,并分析了Windows CE操作系统下实现嵌入式Web服务器注意事项,给出该系统下嵌入式Web服务器的具体实现方案.     

Web服务器负载压力模型及其优化原则

分析了HTTP协议交互原理以及Web服务器对一次HTTP请求做出响应的处理机制,并建立层次化的Web服务器负载压力模型.通过对该模型的分析,提出缓解Web服务器压力的方法与原则.实验表明,这些缓解Web服务器压力的方法与原则能充分提升服务器性能,适应更大并发量的访问请求.     

TPC-W基准测试中客户端设计的关键技术

Web服务器性能测试是对服务器的综合性能测试．简要介绍了TPC-W基准测试系统的整体结构,详细论述了TPC-W基准测试系统在客户端设计中所采用的关键技术——线程内按比例访问技术．测试结果分析表明：利用线程内按比例访问技术,可以使客户端机器的资源得到充分利用,根据大量用户访问Web服务器真实行为的统计特性,进行细粒度的模拟,从而更好的对Web服务器的性能进行综舍测试．     

基于模糊算法的远程嵌入web空调控制技术

本文通过嵌入式web技术设计了Web服务器.设计并实现了一种基于模糊控制算法的远程监控模拟空调控制系统.通过对该控制系统进行测试,证明了其具有良好的性能.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate