《计算机专业英语》电子教案第9章.ppt

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1、计算机专业英语,9-1,Computer English,Chapter 9 The World Wide Web,9-2,理解万维网(World Wide Web)的工作原理；能够描述Internet和万维网的特征及其服务；了解学术论文写作的有关知识。,Requirements:,9-3,The invention of the Web brought an extraordinary expansion of digital services to millions of amateur computer users,including color text and pages,forma

2、tted text,pictures,animations,video,and sound.In short,the Web makes nearly all the rich elements of human expression needed to establish a commercial marketplace available to nontechnical computer users worldwide.,万维网的发明带来了为数以百万计的业余计算机使用者提供的数字化服务的非常扩展,包括彩色文本和网页、格式化文本、图片、动画、视频和声音。简而言之，万维网使建立商业化市场必需的

3、人类表达方式的几乎所有丰富要素对非技术计算机使用者成为可能。,9-4,New Words&Expressionsanimation n.动画browse v.n.浏览Hypertext n.超文本protocol n.草案,协议extension n.扩展名supplant vt.排挤掉,代替browser n 浏览器surf vi.作冲浪运动,vt.在.冲浪extension n.扩展名supplant vt.排挤掉,代替browser n 浏览器surf vi.作冲浪运动,vt.在.冲浪Netscape 美国Netscape公司，以开发Internet浏览器闻名,Abbreviations

4、GML(Generalized Markup Language)通用置标语言SGML(Standard Generalized Markup Language)标准通用置标语言XML(Extensible Markup Language)可扩展链接标示语言SSL(Security Socket Layer)加密套接字协议层FTP(File Transfer Protocol)文件传输协议PDA(personal digital assistant)个人数字助理,9-5,9.1 HYPERTEXT,Web pages can be accessed through the Internet be

5、cause the Web browser software operating your PC can request Web pages stored on an Internet host server using the HTTP protocol.Hypertext is a way of formatting pages with embedded links that connect documents to one another,and that also link pages to other objects such as sound,video,or animation

6、 files.When you click on a graphic and a video clip plays,you have clicked on a hyperlink.,因为操作个人计算机的网络浏览器软件能使用HTTP协议对储存在因特网主机服务器上的一个网页发出请求,所以能通过因特网访问万维网网页。超文本是使用嵌入式链接形成格式化网页的一种方法，这些链接将文档彼此联结，而且将网页链接到其他对象如声音、视频或动画文件。当你点击一个图形和一个视频剪辑播放按钮的时候,你在点击一个超链接。,9-6,HTTP is the first set of letters at the start

7、of every Web address,followed by the domain name.The domain name specifies the organizations server computer that is housing the document.Most companies have a domain name that is the same as or closely related to their official corporate name.The directory path and document name are two more pieces

8、 of information within the Web address that help the browser track down the requested page.Together,the address is called a Uniform Resource Locator,or URL.When typed into a browser,a URL tells it exactly where to look for the information.,HTTP是每个网址的第一个字母组合，位于网址的起始位置,紧跟着它的是域名。域名指定组织的服务器计算机，而文件收藏于服务器

9、计算机之上。大多数公司有一个与其官方公司名字相同或接近的域名。目录路径和文件名在网址中是出现较多的两个信息，它帮助浏览器捕捉被请求的网页。同时，网址叫做统一资源定位符,或URL。当把网址键入一个浏览器内时，URL准确分辨到哪里找寻数据。,9.1 HYPERTEXT,9-7,Although the most common Web page formatting language is HTML,the concept behind document formatting actually had its roots in the 1960s with the development of Ge

10、neralized Markup Language(GML).,虽然最常见的网页格式化语言是HTML,实际上文档格式的概念早在20世纪60年代随着通用置标语言(GML)的发展就形成了。,9.2 HYPERTEXT,9-8,SGML.In 1986,the International Standards Organization adopted a variation of GML called Standard Generalized Markup Language,or SGML.The purpose of SGML was to help very large organizations

11、 format and categorize large collections of documents.The advantage of SGML is that it can run independent of any software program but,unfortunately,it is extremely complicated and difficult to learn.Probably for this reason,it has not been widely adopted.,SGML(标准通用置标语言)。在1986年，国际标准组织正式通过了GML的一种变体叫做

12、标准通用置标语言,或SGML。SGML的目标是帮助特大型组织对大量文档格式化并归类。SGML的优点是它能独立于任何软件程序运行，但不幸的是，它极端复杂和难学。或许因为这个理由，它没有被广泛地采用。,9.2 HYPERTEXT,9-9,HTML.HTML(HyperText Markup Language)is a GML that is relatively easy to use.HTML provides Web page designers with a fixed set of markup“tags”that are used to format a Web page.When th

13、ese tags are inserted into a Web page,they are read by the browser and interpreted into a page display.You can see the source HTML code for any Web page by simply clicking on the“Page Source”command found in all browsers.,HTML(超文本链接标示语言)。HTML是相对容易使用的一种GML。HTML为网页设计者提供一组固定的标示“标签”用于格式化网页。当这些标签被插入一个网页之

14、中时,他们被浏览器阅读并翻译为网页显示。你可以看见任何网页的HTML源代码，只需点击一下所有浏览器中都能找到的 网页源文件指令。,9.2 HYPERTEXT,9-10,HTML functions to define the structure and style of a document,including the headings,graphic positioning,tables,and text formatting.5 Since its introduction,the two major browsersNetscapes Navigator and Microsofts I

15、nternet Explorerhave continuously added features to HTML to enable programmers to further refine their page layouts.Unfortunately,many of the enhancements only work in one companys browser,and this development threatens the attainment of a universal computing platform.,HTML的功能是定义文件的结构和风格,包括标题、图形定位、表

16、格和本文格式。从HTML引入以来,两个主要的浏览器Netscape(网景公司)的Navigator和Microsoft(微软公司)的Internet Explorer不断地把特征加入HTML之中，使程序员能够进一步改进他们的页设计。不幸的是，许多功能的加强只有在一个公司的浏览器中起作用，而且这种发展威胁到通用计算机平台的实现。,9.2 HYPERTEXT,9-11,HTML Web pages can be created with any text editor,such as Notepad or Wordpad,using Microsoft Word(simply save the W

17、ord document as a Web page)or any one of several Web page editors.,HTML网页可以使用微软的Word或几种网页编辑器中任何一种通过本文编辑器生成,例如Notepad(记事本)或 Wordpad(写字本)(只需把Word文件保存为一个网页)。,9.2 HYPERTEXT,9-12,XML.Extensible Markup Language(XML)takes Web document formatting a giant leap forward.XML is a new markup language specificati

18、on developed by the W3C(the World Wide Web Consortium).XML is a markup language like HTML,but it has very different purposes.Whereas the purpose of HTML is to control the“look and feel”and display of data on the Web page,XML is designed to describe data and information.,XML(可扩展标示语言)。XML使网络文件格式化发生了一次

19、巨大的飞跃。XML是由万维网联合会开发的一种新型置标语言规范。XML是像HTML一样的一种置标语言，但是它又有非常不同的目的。XML是用于描述数据和信息,而HTML的目的是控制表现与感觉 并将数据在网页上显示。,9.2 HYPERTEXT,9-13,For instance,if you want to send a patients medical recordincluding diagnosis,personal identity,medical history information,and any doctors notesfrom a database in Boston to a

20、 hospital in New York over the Web,it would be impossible using HTML.However,with XML,these rich documents(database records)for patients could be easily sent over the Web and displayed.,比如，如果你想要把一个病人的病历卡包括诊断、个人身份、病史信息和任何医生笔记通过网络从一个在波士顿的数据库发送到位于纽约的一所医院，使用HTML是不可能的。然而，使用XML，这些有关病人的富文件(数据库记录)可以容易通过网络发送

21、并显示。,9.2 HYPERTEXT,9-14,XML is“extensible,”which means the tags used to describe and display data are defined by the user,whereas in HTML the tags are limited and predefined.XML can also transform information into new formats,such as by importing information from a database and displaying it as a ta

22、ble.With XML,information can be analyzed and displayed selectively,making it a more powerful alternative to HTML.This means that business firms,or entire industries,can describe all of their invoices,accounts payable,payroll records,and financial information using a Web-compatible markup language.On

23、ce described,these business documents can be stored on intranet Web servers and shared throughout the corporation.,XML是 可扩展的,意味着用于描述并显示数据的标签被使用者定义,而在HTML中标签是有限制的，而且是预先定义的。XML也能把信息转变成新的格式,例如从一个数据库输入信息并显示为一张表格。使用XML，数据能被有选择性地分析且显示,使它成为比HTML更有力的可选方案。这意味着商业公司,或整个行业,全部能使用与网络兼容的置标语言通过发票、可支付帐户、薪资记录和财政信息来描述

24、。一旦完成描述,这些商业文件可以被储存在内联网网络服务器上并在整个公司共享。,9.2 HYPERTEXT,9-15,XML is not yet a replacement for HTML.Currently,XML is fully supported only by Microsofts Internet Explorer 5,and is not supported by Netscape(although this may change).Whether XML eventually supplants HTML as the standard Web formatting spec

25、ification depends a lot on whether it is supported by future Web browsers.Currently,XML and HTML work side by side on the same Web pages.HTML is used to define how information should be formatted,and XML is being used to describe the data itself.,XML仍然不能替换HTML。当前，只有微软的Internet Explorer 5完全支持XML,而Net

26、scape(网景公司)不支持(虽然这种现象可能改变)。XML能否最终替代HTML作为标准的网络格式规范，在很大程度上仰赖于将来的网络浏览器是否支持它。目前,XML和HTML在相同的网页上并肩工作。HTML用来定义应该如何格式化信息，而XML用来描述数据它本身。,9.2 HYPERTEXT,9-16,We have already described client/server computing and the revolution in computing architecture brought about by client/server computing.You already kn

27、ow that a server is a computer attached to a network that stores files,controls peripheral devices,interfaces with the outside worldincluding the Internetand does some processing for other computers on the network.,我们已经描述了客户机/服务器计算技术及其在计算机技术结构中引起的革命。你已经知道服务器是一台联接到网络的计算机，用于储存文件、控制外设、与外界包括因特网接口，且为网络上的

28、其他计算机进行一些处理。,9.3 WEB SERVERS AND CLIENTS,9-17,But what is a Web server?Web server software refers to the software that enables a computer to deliver Web pages written in HTML to client machines on a network that request this service by sending an HTTP request.The two leading brands of Web server sof

29、tware are Apache,which is free Web server shareware that accounts for about 60%of the market,and Microsofts NT Server software,which accounts for about 20%of the market.,但什么是网络服务器？网络服务器软件是一种使计算机能够向网上客户机传递HTML网页的软件，而客户机通过发出HTTP请求申请这种服务。网络服务器软件的两种主要品牌是Apache和微软的NT服务器软件,前者是一种免费的网络服务器共享软件，约占有60%的市场；后者约占

30、有20%的市场。,9.3 WEB SERVERS AND CLIENTS,9-18,Aside from responding to requests for Web pages,all Web servers provide some additional basic capabilities such as the following:File Transfer Protocol(FTP)This protocol allows users to transfer files to and from the server.Some sites limit file uploads to t

31、he Web server,while others restrict downloads,depending on the users identity.,除了回应网页请求之外，所有的网络服务器还提供一些附加的基本能力，例如下列各项:文件传输协议(FTP)这个协议允许使用者从服务器来回移动文件。根据使用者的身份不同，一些网站限制文件上传到网络服务器,而其他网站限制下载。,9.3 WEB SERVERS AND CLIENTS,9-19,Security servicesThese consist mainly of authentication services that verify th

32、at the person trying to access the site is authorized to do so.For Web sites that process payment transactions,the Web server also supports Secure Sockets Layer(SSL),the Internet protocol for transmitting and receiving information securely over the Internet.When private information such as names,pho

33、ne numbers,addresses,and credit card data need to be provided to a Web site,the Web server uses SSL to ensure that the data passing back and forth from the browser to the server is not compromised.,安全服务主要由认证服务组成，确认人们试图对网站进行的访问是经过授权的。对于处理支付交易的网站，网络服务器也支持加密套接字协议层(SSL)用于在因特网上安全地传输与接收信息的因特网协议。当私人信息如姓名、电

34、话号码、地址和信用卡数据等需要向一个网站提供时，网络服务器使用SSL确保从浏览器到服务器来回传递的数据不被损害。,9.3 WEB SERVERS AND CLIENTS,9-20,Search engineJust as search engine sites enable users to search the entire Web for particular documents,search engine modules within the basic Web server software package enable indexing of the sites Web pages

35、and content,and permit easy keyword searching of the sites content.When conducting a search,a search engine makes use of an index,which is a list of all the documents on the server.The search term is compared to the index to identify likely matches.,搜索引擎正如搜索引擎网站使用户能够为特殊的文件搜寻整个万维网,基本网络服务器软件包中的搜寻引擎模块允

36、许对网站的网页和内容进行索引,并允许网站内容的关键词搜索。当进行搜寻时,搜索引擎使用索引,索引是服务器上所有文件的列表。将搜寻项与索引进行比较，确定可能的匹配,9.3 WEB SERVERS AND CLIENTS,9-21,Data captureWeb servers are also helpful at monitoring site traffic,capturing information on who has visited a site,how long the user stayed there,the date and time of each visit,and whic

37、h specific pages on the server were accessed.This information is compiled and saved in a log file,which can then be analyzed by a user log file.By analyzing a log file,a site manager can find out the total number of visitors,average length of each visit,and the most popular destinations,or Web pages

38、.,数据捕获网络服务器还有助于监测网站访问量，捕获有关谁访问某个网站、用户在那里停留多久、每次访问的日期和时间、和服务器上哪个特定网页被存取等信息。这个信息被汇编并保存在一个日志文件中,然后能通过用户日志文件进行分析。通过分析一个日志文件，网站管理员能找出访客总数、平均访问时间长度和最流行的目的地或网页。,9.3 WEB SERVERS AND CLIENTS,9-22,The term Web server is sometimes also used to refer to the physical computer that runs Web server software.Leadin

39、g manufacturers of Web server computers are IBM,Compaq,Dell,and Hewlett Packard.Although any personal computer can run Web server software,it is best to use a computer that has been optimized for this purpose.To be a Web server,a computer must have the Web server software described above installed a

40、nd be connected to the Internet.Every Web server machine has an IP address.,术语网络服务器有时也被用于指运行网络服务器软件的实际计算机。网络服务器计算机的领先制造商是IBM(国际商用机器公司)、Compaq(康柏)、Dell(戴尔)和Hewlett Packard(惠普)。虽然任何个人计算机都能运行网络服务器软件，但是最好使用一部为这个目的最佳化的计算机。作为一个网络服务器,一部计算机必须安装上述网络服务器软件且联接到因特网。每部网络服务器计算机有一个IP地址。,9.3 WEB SERVERS AND CLIENTS,

41、9-23,Aside from the generic Web server software packages,there are actually many types of specialized servers on the Web,from database servers that access specific information with a database,to ad servers that deliver targeted banner ads,to mail servers that provide mail messages,and video servers

42、that provide video clips.At a small e-commerce site,all of these software packages might be running on a single machine,with a single processor.At a large corporate site,there may be hundreds of discrete machines,many with multiple processors,running specialized Web server functions described above.

43、,除了一般的网络服务器软件包之外，网络上其实还有许多类专用服务器,从访问数据库特定信息的数据库服务器,到递特定标题广告的广告服务器,到提供邮寄信息的邮件服务器,以及提供视频剪辑的视频服务器。在一个小型电子商务网站，所有的这些软件包可能在一部具有一个处理器的机器上运行。在一个大公司的网站,可能有数百台分布的机器,多数具有多个处理器,运行上述特定的网络服务器功能,9.3 WEB SERVERS AND CLIENTS,9-24,A Web client,on the other hand,is any computing device attached to the Internet that i

44、s capable of making HTTP requests and displaying HTML pages.The most common client is a Windows PC or Macintosh,with various flavors of UNIX machines a distant third.,另一方面，网络客户机是指任何一种联接到因特网、能够发出HTTP请求并显示网页的计算装置。最常见的客户机是采用Windows操作系统的个人计算机或麦金托什机,各种不同风格的UNIX机远远排在第三。,9.3 WEB SERVERS AND CLIENTS,9-25,Th

45、e primary purpose of Web browsers is to display Web pages,but browsers also have added features,such as e-mail and newsgroups(an online discussion group or forum).,网络浏览器的主要目的是显示网页，但浏览器还有更多的功能,例如电子邮件和新闻讨论组(在线讨论组或论坛)。,9.4 WEB BROWSERS,9-26,Currently 94%of Web users use either Internet Explorer or Nets

46、cape Navigator,but recently some new browsers have been developed that are beginning to attract attention.The browser Opera is becoming very popular because of its speedit is currently the worlds fastest browserand because it is much smaller than existing browsers(it can almost fit on a single diske

47、tte).It can also remember the last Web page you visited,so the next time you surf,you can start where you left off.And like the big two,you can get it for free;the catch is that you have to watch blinking ads in one corner,or pay$40 for the ad-free version of Opera.,目前，94%的网络用户使用Internet Explorer或Ne

48、tscape Navigator浏览器，但是最近已开发出的一些新浏览器开始吸引人们的注意力。Oprea浏览器正在变得非常流行，因为它的速度它是目前世界上最快的浏览器，而且因为它比现有浏览器小得多(它几乎可以装在一张软盘上)。它也能记得你访问过的最后一个网页,因此下回漫游时,你能从你停止的地方开始。而且像那两个大浏览器一样,你能免费得到它；其陷阱是你不得不看一个角落中可恶的广告,否则要支付40美元购买无广告版。,9.4 WEB BROWSERS,9-27,The browser NeoPlanet is also gaining new fans,primarily because of the

49、 500+skins,or design schemes,that come with it.Using skins,you can design the browser to look and sound just the way youd like it to,rather than being limited to the standard look provided by Navigator and Internet Explorer.However,NeoPlanet requires Internet Explorers technology in order to operate

50、,so you must also have IE installed on your computer.,浏览器NeoPlanet也正在获得新的爱好者,主要因为它带有500多套界面或设计方案。使用不同界面,你能根据你喜欢看或听的方式设计浏览器，而不是被限于Netscape Navigator和Internet Explorer浏览器提供的标准外观。然而,NeoPlanet 需要Internet Explorer的技术来运行,因此你也必须在计算机上安装IE。,9.4 WEB BROWSERS,9-28,学术论文的英文写作简介,一篇完整规范的学术论文结构如右所示：其中，Title，Abstrac