嵌入式Internet中TCP／IP协议栈的研究与设计

目前大多数嵌入式设备是8位或16位的MCU,要将Internet与嵌入式设备进行结合,其主要困难在于,相对于8／16位低速处理器本身资源的限制,Internet的TCP／IP协议簇过于复杂,因此不可能实现完整的TCP／IP协议栈,必须根据实际需求进行精简。针对8位或16位的低档MCU接入Internet,采用MCU＋软件嵌入TCP／IP协议的方法加以实现。对嵌入式Internet中TCP／IP协议栈的实现进行了研究与分析,针对每一层的具体协议,提出了设计方法和精简方案。由于嵌入式设备自身资源的限制,使得在嵌入式Internet中TCP／IP协议栈的实现存在功能简单、安全性不高等问题。但是随着嵌入式硬件设备和Internet技术的不断发展,嵌入式TCP／IP协议栈的实现也将会越来越完善。     

使用CAsyncSocket类实现异步网络通信

TCP／IP协议是Internet网最重要的协议，VC＋＋的MFC提供了两个Socket类用于在ICP／IP的基础上进行网络通信。文中结合实际开发经验，阐述了使用CAsyncSocket类实现局域网的异步通信机制和编程技术。     

SSL协议分析及实现

目的:该文主要讨论SSL协议的组成和工作过程,应用SSL实现Internet上的安全。方法:先了解SSL协议的体系结构,并通过SSL通信过程和握手协议的工作过程完全了解SSL协议的工作过程。结果SSL协议是在TCP/IP套接层的安全协议,SSL协议很好的解决了Internet上信息的安全传输,弥补了TCP/IP协议的不足,使得我们在网络上传输数据得到安全保障。结论:该文通过对SSL协议的分析及实现过程的讨论,使得我们对SSL实现Internet上的安全有一个全面的了解,并提出其不足之处并加以完善。     

基于事件驱动的边界网关协议BGP-4的设计与实现

边界网关协议BGP(border gateway pr otocol)是Internet上用于自治系统之间交换路由信息的动态路由协议.介绍了在清华大学研 制的国产高性能路由器中分布式路由协议BGP-4的具体实现.为了实现这一复杂的动态协议, 提出基于事件驱动的设计和实现方法.事件驱动机制能够精确地反映网络报文交换行为的实 现机制,因而很适合Internet高层协议的实现.该方法也可以用于实现其他的Internet高层协议.     

基于Internet的实时控制系统的传输协议

为了在Internet实现实时控制，需要开发基于Internet的实时控制系统的传输协议。提出了该协议的设计方案，完全符合TCP／IP协议标准，并且在运输层同时支持TCP协议和UDP协议。以该协议为基础，开发了基于Internet的实时控制系统实验平台，实验表明该协议能在Internet上进行远程控制。     

嵌入式Internet中TCP协议的设计与实现

介绍了嵌入式Internet技术的概念和研究现状,以网络传感器为应用背景,对TCP/IP协议栈中的主要协议TCP进行了机制裁减和编程实现。该研究对于Internet技术能否在8位单片机上实现和应用有着重要而现实的意义。     

Internet路由关联分析与监测系统设计

Internet已经从一个学术性网络演化成为具有商业意义的公共信息基础设施的重要组成部分,路由系统是其基础和关键部分,对Internet路由层面的监测与分析有着重要的理论和现实意义.Internet路由结构被划分成为域内路由和域间路由,两者紧密联系并相互作用,但是目前路由监测和分析的工作主要基于单一协议进行,无法给出包含多种路由协议的全面监测视图,也不能很好地解决由于协议交互带来的问题.针对这个不足,探索了域内和域问路由的关联分析技术,并在此基础上成功设计实现了Internet路由监测系统IRMS(Internet routing monitoring system).IRMS在对主流路由协议OSPF,BGP的监测基础上,可以提供包括全局路由拓扑构造、协议交互分析在内的路由关联分析能力.实际网络路由监测实验表明,IRMS使网络管理人员可以更加深入和全面地进行路由监测分析.     

单片机嵌入式Internet技术研究及系统开发①

实现MCS-51单片机嵌入式接入Internet技术。单片机通过ATL8019AS以太网控制器实现与Internet的交互。利用开源代码的TCP／IP协议栈uIP实现对底层设备的驱动,同时通过uIP协议的应用程序接口实现各种应用服务。给出了硬件设计图,编写了单片机主程序。应用此技术实现了一个城市中心停车监测系统。     

Ad Hoc网络Internet接入协议的仿真与研究

目前的无线Ad Hoc网络路由协议只能适用于无线局域网本身,而没有实现与Inernet的连接。为了实现AdHoc网络与Internet的连接,通过改进原有的AODV协议来实现无线局域网节点与Internet上节点的互连。在新的协议中,无线局域网内的节点使用原AODV协议互相通讯,无线节点使用改进的AODV协议通过网关与Internet网络上的固定节点进行通讯。在AODV路由协议的基础上提出了三种网关发现算法,并在NS2仿真平台上对这三种网关发现算法的性能进行了比较。从仿真结果来看,基于AODV协议上的网关发现算法是可行的。     

面向Internet的IPsec安全体系

介绍了一种新型的Internet安全体系结构-IPsec体系。并描述了IPsec体系结构的一些协议,例如IPsec协议和验证报头协议(AHP)、封装安全有效负荷协议(ESPP)、Internet密钥管理协议(IKMP)。阐述了这些协议的特点和实现要求。     

Java实体传输在网上采购系统中的应用

实体传输可以在网络中直接传递或者存储对象，因而在网络编程中具有很重要的作用。文章介绍了Java实体传输的实现方法，Applet与Servlet之间的远程方法调用(RMI)以及Java实体传输在网上采购系统中的应用。     

Measuring Internet usage: The Israeli case

The article describes two instruments for measuring Internet Usage and the changes in subjects’ Internet usage following a controlled intervention. It focuses on the use of usage and lack of usage for measuring the digital gap. The “digital gap” is defined as the gap between individuals with and without access to technology (telephones, computers, Internet access) and related services. Since its emergence, the Internet has become the most important form of information and communication technology (ICT).The goal of the present research was to develop ways of measuring Internet usage for different segments of the Israeli population (it can also be used to measure Internet usage outside Israel). For the past few years, the Israeli government has sponsored programs designed to increase Internet usage in specific segments of the Israeli population. Some of these programs have been “controlled programs”. Controlled Internet Usage Programs are planned and monitored programs, which use research methods to discover whether they have increased Internet usage and changed Internet habits.The population of Internet users in Israel is presently 45.8% (compared with 68.2% in the US population). The past 5 years has witnessed a significant rise in the number of Internet users in the West in general and in Israel specifically: an increase of 152% in the number of Israeli households connected to the Internet during the period 2000–2005.However, large differences are apparent between the stronger and weaker sections of the Israeli population where the Internet is concerned, and controlled intervention is therefore a very important means of reducing these discrepancies.The present article describes two measurement instruments: the first instrument examines on-line proficiency, while the second determines patterns of Internet use and the status of respondents’ “Internet awareness”.The instruments were built to determine the reduction in the digital divide associated with Internet usage following controlled intervention, and the population's Internet usage status before and after intervention. The difference between the two measurements represents the increase or decrease in Internet usage.These two instruments may be used by agencies making decisions about resource disbursement to reduce the digital divide in a variety of populations.     

基于J2ME的移动互联网信息安全监控管理机制的研究

以移动互联网中信息安全为研究对象,从J2ME的体系结构出发,研究了移动互联网中的安全需求、信息安全监控管理机制、及J2ME对应用安全支持的分析。从移动互联网应用安全方面、MIDlet程序和Servlet服务器端构建一个信息安全监管试验系统。     

A Historical Overview of Internet Reference Services for Distance Learners

SUMMARY

The advent of library services and collections on the Internet revolutionized reference services to students enrolled in distance learning programs. Prior to the Internet, reference librarians who supported distance learning programs had few methods, and many of them costly, to provide the equivalent library services advocated by the ACRL Guidelines. Through the Internet, these librarians were able to approximate the services and resources that had always been available to students who came into the library. This article describes the development of reference services on the Internet in a variety of libraries that support distance learners.     

高性能网络爬虫:研究综述

网络爬虫是一种自动下载网络资源的程序,是搜索引擎的基础构件之一.系统地介绍了网络爬虫的工作原理和发展现状,详细地阐述了一个高性能、可伸缩、分布式的网络爬虫的系统架构和所面临的关键问题.     

Security at the Internet layer

The Internet Engineering Task Force is standardizing security protocols (IPsec protocols) that are compatible with IPv6 and can be retrofitted into IPv4. The protocols are transparent to both applications and users and can be implemented without modifying application programs. The current protocol versions were published as Internet drafts in March 1998. The article overviews the proposed security architecture and the two main protocols-the IP Security Protocol and the Internet Key Management Protocol-describes the risks they address, and touches on some implementation requirements. IPsec's major advantage is that it can provide security services transparently to both applications and users. Also, the application programs using IPsec need not be modified in any way. This is particularly important when securing application programs that are not available in source code, which is common today. This transparency sets IPsec apart from security protocols that operate above the Internet layer. At present, IPsec is likely to be used in conjunction with and complemented by other security technologies, mechanisms, and protocols. Examples include firewalls and strong authentication mechanisms for access control, and higher layer security protocols for end-to-end communication security. In the near future, however, as virtual private networking and corporate intranets and extranets mature, IPsec is likely to be deployed on a larger scale     

Ethics of Collecting and Using Consumer Internet Data

A wealth of information concerning a consumer's Internet use and preferences can, with rela-tive ease, be gathered and disseminated. Sometimes, a consumer may willingly give personal information to enhance the browsing experience at a favorite Web site. Other times, Internet monitoring programs may be surreptitiously gathering this information so it can be used to commit identify theft. in another instance, information willingly given to one site is sold to a third party that uses it to promote its own Web services. the ethics of these first two scenarios is clear: the first is good and the second is bad. the third, however, is not so clear. the consumer may feel that private information has been violated while industry may feel it is doing good by better serving the consumer. These are just a small sampling of the range of ethical situations data collection on the Internet creates. This article identifies the ways Internet information about consumers is collected and examines the ethical issues created by the collection process and its consequences.     

Memory allocation costs in large C and C++ programs

Dynamic storage allocation is an important part of a large class of computer programs written in C and C + +. High-performance algorithms for dynamic storage allocation have been, and will continue to be, of considerable interest. This paper presents detailed measurements of the cost of dynamic storage allocation in 11 diverse C and C + + programs using five very different dynamic storage allocation implementations, including a conservative garbage collection algorithm. Four of the allocator implementations measured are publicly available on the Internet. A number of the programs used in these measurements are also available on the Internet to facilitate further research in dynamic storage allocation. Finally, the data presented in this paper is an abbreviated version of more extensive statistics that are also publicly available on the Internet.     

探索物联网人才培养模式

物联网在众多领域有着广泛的应用,产业空间巨大。物联网人才的培养变的尤为重要。根据国家和东莞经济结构的调整及发展战略,本着服务地方经济的理念,调整高等院校的专业方向和专业结构;根据社会经济的需要和安排,制订高等院校的专业人才培养方案和课程标准;根据地方经济环境,建设物联网专业,培养企业需求的人才。