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Internet
Computer networks are a popular topic these day,major newspapers,popular magazines,professional journals,even radio and television are talking about “Information Highways”and “National Information Infrastructure” . Let’s imagine what an international data superhighway might look like;
1) Users from around the globe will be able to connect to the network,there will be high-speed access at universities ,government agencies ,and business installations worldwide.
2) The network will use standard communication protocols.communication protocols are a series of formal statutes established for the cionsistency of data exchange (between processors and terminals ), providing access no matter what brand of computer one uses,no matter what operating system and no matter the size of the computer.
3) Users on this global network will be able to exchange electronic mail with one another,with message delivered instantaneously in a few seconds or minutes otherwise.The network will allow not just one-to-one communications ,but will also provide tolls to allow groups of individuals separated by distance and time to carry on discussions.
4) The network will provide a simple ,standard way for users to log into computers around the world. Individuals will take advantage of this not only from their homes of office ,but also will use the network when traveling so they can connect back home.
5) Navigation tools will make it easy for individuals to cruise the network ,glancing at information provided by universities ,businesses,libraries,foundation,and individuals.
6) Index tools will allow users to scan large databases ,quickly locating documents of interest.
7) Users will be able to retrieve and play back movies ,sounds ,and multimedia documents.
8) The network will support real-time communications; people will be able to talk to one another online (by tying ,or ,with the right equipment ,over audio links) and will even use the network to play real-time virtual reality game.
9) Finally ,the network will be two-way highway .Users would not think of themselves exclusively as consumers; instead ,tools will make it relatively easy for anyone to be become an information provider . Individuals could publish resumes ,papers they’s written ,photos of their families ,samples of their artworks .
That list of features seems rather futuristic .One might speculate that we’d see it by the year 2000 .In fact ,every feature listed above exists today ------on the Internet.
The Internet represents real ,functional , worldwide data network .So the Internet can be described as a “network of network”.
The fastest ,most capable network in the world wouldn’t be very uesful if it didn’t have valuable information for people to retrieve.The Internet is not just a medium for person-to-person electronic mail ; it’s also a repository of all sorts of information , “published” by information providers worldwide .Here are some examples of how information is exchanged over the Internet:
Many universities are building Campus-Wide Information Systems ,or CWISes , as a way of consolidating campus information and computing services in one place .Most CWISes are accessible via the Internet . Users form around the world can search course catalogs, read about campus services ,or examine the library’s online catalog.
Individual scientists and scientific institutes are building collections of papers and databasea and making them available for Internet access. Using tools such as Gopher ,World-wide Web ,and WAIS ,users can retrieve information on everything from astronomy to biodiversity to the human gnome project to epidemiology to zoology.
Classical works of literature are being made available freely on the Internet , through the efforts of a group called “Project Gutenberg ,” Titles online include the works of Shakespeare ,the Bible ,the Autobiography of Frederick Douglass and many more.
The written word isn’t all you’ll find; with the right equipment ,you can listen to audio documents over the Internet . You can find snippets of historical voices , samples of music,and longer audio documents such as presidential debates and interviews in a “radio” format.
Current weather forecasts and weather maps are available from several sources on the Internet .You can even find motion-picture versions of weather maps ,resembling the satellite loops seen on television .Earthquake reports are also made available daily .The Internet was even used to deliver advice to victims of the Mississippi River flood in mid-1933.
Government agencies are discovering the value of the Internet as away to disseminate information . Agencies with a scientific focus,such as NASA ,are perhaps further along in publishing information via the Internet.
A new mode for the 21st century manufacturing enterprises --------virtual companies are lightly to influence the manufacturing tremendously. A virtual company is a temporarily organized “productive facility” . Through the Internet it can share information about social manufacturing resources and market demands and hence realize the so-called “virtual manufacturing” or “remote manufacturing” .
1.2.1 Service Supported Internet
1. Electronic Mail
One of the earliest electronic mail systems was created in the early days of the ARPANET ,when two developer began sending notes to each other using the Mascot networks .Since those days electronic mail ,or E-mail ,has become a familiar concept. It has been deployed on large mainframe platforms such as the IBM PROFS ,provided on various local area networks .Today E-mail become basic service of Internet and important tools of user to send message each other.
2.Gopher
The Internet Gopher is named for the Mascot of its home ,the University of Minnesota .Gopher is a simple tool ,relatively implemented ,but it has caught the Internet by storm .It is described as a document delivery tool ; In fact ,Gopher can deliver documents ,lists of documents ,and indexes .Thus , Gopher servers can offer not only textual information ,but also organized browsing lists of resources on the Internet.
3.World Wide Web
This tool more ambitious in its model for delivering information on the Internet ,rather than offering simple folders with the Line-Description of documents ,WWW offers hypertext .In a nutshell ,this simply means that a document can have embedded links to other document anywhere within the text .A user clicks on such an embedded link ,and the other document appears on the screen . One tool ,called Mosaic ,is a multiplatform , multipurpose tool whose introduction has helped usher WWW from the hypertext mode into the hypermedia mode.
4.Wide-area Iformation Server(WAIS)
Whether is it a pile of unread articles on one’s desktop or a virtual pile of unread documents scattered across the global Internet ,users need a way to sift through large quantities of information . There are two sides to WAIS ; it is a tool that allows an information provider to prepare indexes of such digital piles of unstructured documents ,and it is a tool that lets users search these indexes with natural language questions.
1.2.2 Who Uses the Internet
As we will see ,the Internet has historically been associated with the U.S. Department of Defense ,and with research universities .While there are still many Internet users among those communities ,the base of Internet users has become much broader over the last several years .who uses the Internet?
1) Teachers and students at universities, community colleges ,and schools . They use the Internet as a virtual reference desk ,as a way for students and faculty to communicate with peers worldwide ,and as a way to share lesson plans.
2) Professors and other researchers at universities and in research divisions of corporations .These researchers are both consumers and producers of Internetbased information .Some universities are even teaching courses for credit over the Internet.
因特網
計算機網絡是近來比較流行的話題，主要的報紙，流行的雜志，專業(yè)的學報，甚至廣播和電視都在談論關于“信息高速公路”和“國家信息基礎設施”，讓我們想象一個國際數(shù)據(jù)超級高速公路可以看成像這樣：
1）用戶可以從地球的任何角落連接上網絡。那將提供高速的信息通道在大學，政府機關和全世界的商業(yè)網點。
2）網絡將運用標準的通信協(xié)議。通信協(xié)議是建立一系列的法規(guī)來穩(wěn)定地進行數(shù)據(jù)交換（在處理器和終端之間），提供數(shù)據(jù)通路，無論是人們用的電腦是什么樣的品牌，無 論什么樣的處理系統(tǒng)，無論計算機的尺寸的大小。
3）使用全球互聯(lián)網的用戶將能夠相互交換電子郵件和他人，能夠傳遞信息用很短的時間幾秒，不然幾分鐘?；ヂ?lián)網允許不僅僅一個對一個的單線傳遞，也提供網絡工具把個別的進行隔離通過距離和反映的時間。
4）互聯(lián)網將提供一個簡單的標準的通信信道為用戶登錄全球的計算機網絡。個別的將有利于不僅能從他們的家連接到辦公室，而且能夠使用互聯(lián)網在他們旅游的時候，能連接回到家中。
5）導航工具讓單獨在互聯(lián)網中游覽變得簡單，粗略的信息被高校，商業(yè)組織，圖書館，一些基礎設施，和個人提供。
6）搜索工具允許用戶去瀏覽大型數(shù)據(jù)庫，快速的查找處他們感興趣的文件。
7）用戶能夠去檢索和回放電影，音頻，和多媒體文件。
8）互聯(lián)網提供即時通信：人們可以在線和另一個人進行交流（用打字，或者用合適的設備，或建立的聲音的連接） 甚至能夠用互聯(lián)網玩即時的接近真實的網絡游戲。
9）最后，網絡將會變成雙線的通信高速公路。用戶不會認為那是他們自己專用的作為一個消費者，反而，網絡工具將使那變得相當?shù)暮唵危屓魏我粋€人成為信息的提供者。個體可以公開簡歷，他們寫的文學作品，他們家庭的照片，以及他們的藝術作品。
那些列舉的網絡特征看起來相當現(xiàn)代。一種可能的推測是我們可以見到那一天在2000年。實際上每個如上所述列舉的特征是存在的在今天——在因特網上。
因特網呈現(xiàn)出一個真正的，實用的，世界的數(shù)據(jù)網絡。所以，因特網可以被描述為“由網絡連接成的網絡”。
近來，世界上大多數(shù)工作能力強的網絡不會非常的有用如果它沒有有價值的信息為人們檢索的話。因特網不僅僅是一個人們相互發(fā)電子郵件的媒介，它也是存放各種各樣信息的倉庫，被信息提供者向全世界公開。這有一些關于在因特網上數(shù)據(jù)如何交換的例子：
許多大學都建立校園網絡信息系統(tǒng)，或被稱為CWISes，作為一個加強校園信息和數(shù)據(jù)的處理服務的方法在一些地點。大多數(shù)的CWISes線路經由因特網。全球的用戶能夠接觸到教育目錄，連接到關于校園屋內設施網，或者查詢圖書館的在線目錄。
一部分科學家和研究科學的機構建立起文件的收集庫，數(shù)據(jù)庫，以及為他們可用的因特網通路。采用網絡工具比如菜單式信息搜索查詢工具，萬維網，廣域信息服務，用戶可以得到任何信息從天文學到生物多樣性再到人類經濟學方案再到流行病學到動物學。
經典的文學著作被作為免費的可用文件在因特網上，盡管那盡力被叫做“”網絡上的標題包括 莎士比亞經典著作，圣經，弗雷德里克 道格拉斯的自傳，和其他更多的東西。
并不是所有的文學著作的文字你能夠看到，采用合適的設備，你能夠聽到聲音文件在因特網上。你可以發(fā)現(xiàn)一段歷史的聲音，音樂樣本，較長的音頻文件比如總統(tǒng)的辯論，和用廣播的格式傳遞會談。
當前的天氣預報和和氣象云圖可以從因特網的數(shù)個信息來源獲得。你甚至能夠發(fā)現(xiàn)移動的圖片描述關于氣象云圖，看起來像電視上看到的壯觀的圓環(huán)。地震的預報也會被變得每天就能獲得。因特網甚至被用來發(fā)布對災民的忠告，關于密西西比河的1993年中期的那次洪水。
政府服務機構發(fā)現(xiàn)因特網作為傳播信息的通道的巨大價值?？蒲兄行狞c的代表，比如NASA，大概是沿著未來的方向公布信息通過因特網。
在21世紀一個新的關于制造業(yè)企業(yè)的模式——虛擬企業(yè)很輕易地對制造業(yè)產生了巨大的影響。虛擬企業(yè)是一個臨時地組織出的“生產工廠”。盡管因特網可以同時使用關于社會生產資源和市場需求，因此可以理解被叫做“虛擬制造業(yè)”或者“遠程制造業(yè)”。
1.2.1 因特網提供的服務
1. 電子郵件
最早的一個電子郵件系統(tǒng)被組建在早先的阿帕網中，兩個開發(fā)者開始相互發(fā)送短信給用Mascot 網絡。直到近來電子郵件，或“E-mail”，才變成大眾觀念。那是進行調度通過大的主機計算機平臺就好像IBM PROFS一樣，被提供安放在各種地方區(qū)域的網絡，今天電子郵件成為因特網的基礎服務，也是用戶重要的相互傳遞信息的工具。
2. 菜單式信息搜索查詢工具
被叫做因特網菜單式信息搜索查詢工具因為，明尼蘇達州大學。菜單式信息搜索查詢工具是一個基本的工具，相當簡單的工具，但是它被暴風雨捕捉因特網。那是一個描述作為一個文件傳遞的工具；實際上，菜單式信息搜索查詢工具能夠傳遞文件，文件清單，和索引。如此，菜單式信息搜索查詢工具服務器歩僅僅能提供原文信息，也能有條理的瀏覽資源清單在因特網上。
3. 萬維網
這種工具為了傳遞信息在因特網中，是比較龐大的在它的體系描述中。而非提供基本的成行描述文件的文件夾，WWW 提供超文本。簡而言之，這簡單意思是一個文件能被嵌入（插入）鏈接到另一個文件的正文里面的任何地方。一個用戶點擊如此一個深入的鏈接，別的文件顯現(xiàn)在電腦屏幕上。一種工具，被叫做
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是否那是大量的非讀的描述在某人的桌面上或者一個虛擬的大量的非讀文件散播通過全球的因特網，用戶需要一種方法來區(qū)分大量的信息。這有WAIS的兩個特征：它是一種允許一個信息提供者準備索引關于數(shù)字信息系統(tǒng)中大量的無條理的文件的工具，那是容許用戶接觸那些自然的語言問題的索引的工具。
1.2.2 誰在使用因特網
就像我們看到的那樣，因特網在歷史上最早出現(xiàn)在美國人想象中。國家安全部門，防衛(wèi)部門，以及大學的研究院。這仍然有許多因特網的用戶在這些群體中，大眾化的因特網用戶變得十分普遍在以后的若干年里。誰在使用因特網？
1） 大學，地方學院，和中小學校的老師和學生。他們使用因特網作為一個虛擬的參考的平臺，用來作為一種學生和教員同全世界的同輩交流的平臺，也可以作為一個公示教育課程安排的平臺。
2） 教授，其他大學中的研究員和在公司的研究部門工作的人。這些研究員是因特網的用戶，也是因特網基礎技術的研究者和創(chuàng)造者。一些大學甚至開設了有學分的關于因特網的課程。
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