Chapter 30 Web Technology and DBMSs

Chapter 30 Web and Technology and DBMSs 

chapter objectives /*本章目標*/

In this chapter you will learn: /*在本章中，你將會學到*/

• The basics of the Internet, web, HTTP, URLs and Web services. /*Internet, Web, Http, URLs 和 web 服務 的基礎。*/
• The advantages and disadvantages of the web as a database platform. /*web做爲數據庫平臺的優勢和缺點*/
Approaches for integrating databases into the web environment:/*集成數據庫成爲web環境的方法*/　　
• scripting languages ( JavaScrip, VBscript, PHP, and Perl); /*腳本語言( JavaScrip, VBscript, PHP, and Perl)*/
• common Gateway Interface (CGI);/*通用網關接口*/
• HTTP cookies; /* */
• extending the web server; /*網頁服務的擴展*/
• Java, JEE, JDBC, SQLJ,CMP,JDO,JPA,Servlets, and JavaServer Pages(JSP);/**/
• Microsoft Web Platform: .Net, Active Server Pages（ASP）, and ActiveX Data Objects (ADO);/*微軟的網頁平臺：.Net, Active Server Pages（ASP）, and ActiveX Data Objects (ADO)*/
• Oracle Internet Platform/*Oracle 網絡平臺*/

Just over two decade after its conception in 1989, the world wide web (the Web for short) is the most popular and powerful networked information system to date .

@ 1. decade/'dekeid/ n. a period of ten years. 十年期間；十年；@ 

/* 在1989年它的概念生成後的20年以上， www (網頁的縮寫)是迄今爲至最流行和網絡功能最強大的信息系統。*/

Its growth in the past few years has been near exponential and it has started an information revolution that will continue through the next decade. 

@2. exponention /,ekspənenʃə/ adj. technical using a sign that shows how many times a number is to be multipled by itself. (術語)指數的；含有指數的； @

/*在過去幾年裏，它的發展已經將近指數值， 而且 開始了一場信息革命， 那將持續到下一個十年*/

Now the combination of the web and database brings many new opportunities for creating advanced database application.

/*如今， 數據庫和網頁的結合催生了許多新的機遇，針對建立高級數據庫應用程序。*/

 

 

      The web is compelling platform for the delivery and dis-semination of data-centric, interactive applications. 

 

@3. compelling /,kəm'peliŋ/ adj. extremely interesing or exciting 極爲有趣的，使人激動的@

@4. dis-semination /di,semiə'neiʃən/ n. formal to spread information, ideas etc to as many people as possible, especiallly in order to influence them (正式)（尤指爲了影響他人而）散步，普遍傳播（消息，觀點等）@

@5. delivery /di'livəri/ n. the act or process of bringing goods, letters etc. to the person or place they have been sent to 送貨；送信；交付@

/*網頁是一個使人激動的平臺，對於物流和信息中心的傳播， 以及應用程序的交互。*/

The web's ubiquity provides global application availability to both users and organizations. 

@6. ubiquity /ju:'bikwiətəs/ adj. formal or humorous seeming to be everywhere (正式或幽默)廣泛存在的；無處不在的@

/*無處不在的網頁提供了一個對於用戶和組織全球可用的應用程序。*/

Because the architecture of the web has been designed to be a platform-independent, it has the potential to significantly lower deployment and training costs

@7. potential /pə'tenʃə/n. the possibility that something will develop in a certain way, or have a particular effect. 可能性；潛在性@

@8. deploy /di'plɔ:/ v. to organize people or things, especially soldiers, military equipment etc., so that they are in the right place and ready to be used 部署， 調動（尤指士兵、軍事裝備）@

/*因爲網頁架構已經被設計爲多獨立的平臺，對於低的部署和培訓成本，它具備潛在性。*/

Organizations are now rapidly building new database applications or reegineering existing ones to take advantages of web as a strategic platform for implementing innovative business solutions, in effect becoming Web-centric organizations .

@9.innovative /'inə,veitiv/ adj. an innovative process, method, plan etc is new, different, and better than those that existed before(程序，方法，計劃)新穎的，有創新精神的；using clever new ideas and method 運用新觀念和新方法的@

@10. strategic /strə'tidʒik/ adjd. done as part of a plan, especially in a military, business, or politial situation 戰略上的；策略上的@

/*如今，公司正在快速構建新的數據庫應用程序， 或者爲了實現新的商務方案，採起網頁優點做爲策略平臺，從新架構已經存在的數據庫應用程序， 在效應上已經變成了以網頁爲中心的公司。 */

　　Transcending its root in government agencies and educational institutious, the Internet (of which the web forms a part) has become the most siginificant new medium for communication between and among organization, educational and government institutions and individuals. 

@11. trancend /træn'send/ v. formal to go above or beyond the limits of something (正式)超越；超過；超出； @

@12. root /ru:t / n. = cause of a problem 問題的原由= the main cause of a problem (問題的)根源， 原由@

@13. medium /'mi:diəm/ adj. a way of communicating information and news to people 傳播媒介（如報紙、電視等）@

/*超出了因特網政府機構和教育研究所的根源，Internet (網頁造成了一部分)已經成爲最重要的新媒介， 對於公司，教育和政府機構，以及我的之間的通信。*/

Growth of the Internet and corporate intranets/extranets will continue at a rapid pace through the next decade, leading a global inter-connectedness on a scale unprecedented in the history of computing. 

@14. pace /peis/ n. keep pace (with) to move or change as fast as someone  or something else (與...)並駕齊驅；齊頭並進；跟上... @

@15. unprecedented /ʌnpresiədentiəd/ adj. never having happened before, or neve happen so much. 空前的；史無前例的；@ 

/*Internet 和 公司的 intranets/extranets 在下一個十年內將繼續同步進行，在整計算機歷史上，引領了一場規模空前的全球交互鏈接。  */

　　Many Web sites today are file-based; each Web document is stored in a separate file

　　/*今天， 許多網頁是基於文件形式，每個網頁文檔被存儲在一個分隔的文件內。*/

For small Web sites, this approach is not too much of a problem.  /*對於小型網站，這種方式不是一個太大的問題。*/

However, for a large site, this method can lead to significant management problem. /*不管如何，對於一個大型網站，這種方法可能致使極爲重要的管理問題。*/

For example, maintaining current copies of hundreds or hundreds of different documents in separent files is difficult enough, but maintaining links between these files ie even more formidable, particularly when the documents are created and maintained by different authors.

@16. formidable /'fɔ:miədəbəl/ adj. a formidable person etc. is one that  you feel respect for because they are very powerful, or impressive, 使人敬畏的，使人驚歎的；傑出的；different to deal with and needing a lot of effort or skill 難對付的；@

/*例如，在一個分隔的文件中，維護成百上千的不一樣文檔是足夠困難的，可是維護這些文件之間的連接也有少量難以對付， 特別是這些文件的製做和維護被不一樣的做者。*/ 

 

　　A second problem stem from the fact that many web sites now contain more information of a dynamic nature，such as product and pricing information. 

@17. stem / 'steim/  vt. stem from (T not in progressive  不用於進行時態)  to develop as a result of something else 源於...; 來自...; @

/*另外一個問題來自於這樣的事實：許多的網址包含有更多的信息是動態的, 例如產品和價格信息。*/

Maintaining such information in both a database and in separate HTML files (see section 30.2.2) can be an enormous task, and difficult to keep synchronized. 

@18.synchronize / ,siŋkrənaiz/  v. to arrange for two or more actions to happen at exactly the same time. 使同步；使同時發生； @

@19. enormous /i'nɔməs/ adj. 巨大的；龐大的； @

/* 在數據庫中和分隔的HTML 文件中，維護諸如此類信息，多是一個龐大的任務，也是很難去保持同步的。*/

For these and other reasons, the approach of allowing databases to be accessed directly from the Web is increasingly being adopted for the management of dynamic web content. 

/*對於這些和其它的緣由， 容許從Web 直接讀取數據庫的方式是增長了被採用率對於動態網頁內容的管理。*/

 

The storage of Web information in a database can replace or complement file storage. 

@replace vt. 取代；complement vt. 補充；補足；@

/*儲存在數據庫中的Web信息，可能取代或者補充文件存儲。*/

The aim of this chapter is to examine some of the current technologies for Web-DBMS integration to give a flavor of what is available. 

@20.flavor /'fleivə/ n. a quality or feature that makes something have a particular style or character 特點，特色@

/*本章的目標是學習一些實時技術（網頁數據庫管理系統集成所給予的可用特性。）*/

A full discussion of these technologies is beyond the scope of this book,  but the interested reader is reeferred to the additional reading material cited for this chapter at the end of the book .

@21. cite /sait/ v. to give the exact words of something that has been written in order to support an opinionor prove an idea. 引用；引述；  @

/*這些技術的充足討論是超出了本書的範圍，可是感興趣的讀者能夠參考在本書後關於本章的額外閱讀材料。*/

 

Structure  of this Chapter   /*本章架構*/ 

 

In section 30.1 and 30.2 we provide a brief introduction to Internet and Web technology and examine the appropriateness of the Web as a database application platform. 

/*在30.1和30.2節中， 咱們提供了一個簡短的介紹關於Internet 和 Web 技術， 而且學習做爲數據庫應用程序平臺的Web的適應性*/

In Section 30.3 to 30.9 we examine some of the different approaches to integrating databases into the Web environment. 

/*在30.3 到30.9節之間，咱們學習一些集成數據庫造成網頁平臺的不一樣方式。*/

The examples in this chapter are once again drawn from the DreamHome case study documented in section 11.4 and Appendix A. 

/*本章示例又一次引用 DreamHome Case 學習文檔在11.4節和附錄A.*/

To limit the exent of this chapter, we have placed lengthy examples in Appendix L . 

/*爲了限制本章的範圍， 在附錄L中，咱們設置了示例的長度。*/

In some sections we refer to the extensible Markup Language (XML) and its related technologies, but in the main we defer discussion of these until the next chapter.

@21. defer /'difæ/  v. to delay something until a later date. 延期， 推遲；@

/*在一些章節中，咱們推薦XML 和相關技術，可是直到下一章，咱們在主體部分纔開始討論。*/

However, the reader should note the important role that XML now has in the web environment. 

/*不管如何， 讀者應該記住：如今，XML 在web環境中的重要角色。*/

 

 

30.1  Introduction to the Internet and the Web 

Internet   A worldwide collection of inter-connected computer networks. 

/* Internet    世界範圍內交互連結的計算機網絡的集合。*/

 

The Internet is made up of many separate but inter-connected networks belonging to commerical, educational, and government organizations and Internet Service Provides（ISPs）. 

/*Internet 是由許多單獨而屬於商業、教育、和政府部門和Internet服務供應商相互網絡連結而成。*/

The services offered on the Internet include electronic mail (email), conferencing and collaboration services, as well as the ability to access remote computers and send and receive files. 

@22.conference /kɔnfərəns/ n. a large formal meeting where a lot of people discuss important matters such as business or politics, especially for serveral day. 會議（指不少人蔘加討論重要事宜的大型會議，尤指歷時數天的會議）@

@23.collaboration /kə,læbə'reiʃən/ n. the act of working together with another person or group to achieve something, especially in Science or art (尤指在科學或藝術方面的)合做、協做；@

/*在Internet上，提供的服務包括：電子郵件，大型會議和服務結盟， 還有能力去讀取遠程計算機的能力或者發送和接收文件。*/

It began in the late 1960s and early 1970s as an experimental US Department of Defense project called ARPANET (Advanced Research Projects Agency Network) investigating how to build networks that could withstand partical outages (like nuclear bomb attacks) and still survive.

@24. experimental /[ɪkˌsperɪˈmentl/ n. 實驗性的@

@25. defence / di'fens/ n. all the armies and weapons that are available to defense a place 防護力量；@

@26. investigate /in'vestiəgeit/ v. to try to find out the truth about something such as a crime, accident or scientific problem 調查；審查； @

@27. outage /'autidʒ/ n. a period when a service such as the electricty supply is not provided (電力等的)斷供期； @

@28. withstand /wið'stænd/ v. to be strong enough to remain unharmed by something such as great heat or cold, great pressure etc. 耐得住（酷熱、嚴寒、高壓等）承受住@

@29. partial  /'pa:ʃəl/ adj. not complete 部分的；不徹底的；@

/*它開始於20世紀60年代末和70年代初，做爲一項被稱做ARPANET（高級研究計劃署）的美國防護工程部實驗性調查： 怎樣去構建網絡，能夠承受部分電力斷供期（像原子彈襲擊）並且還能生存。*/

 

 

　　　　In 1982, TCP/IP  (Transmission Control Protocol/ Internet Protocol ) was adopted as the standard communications protocols for ARPANET. 

/* 在1982年， TCP/ IP ( 傳輸控制協議/ 因特網協議)被用做標準通訊協議對於ARPANET*/

Tcp is responsible for ensuring correct delivery of messages that move from one computer to another. 

/*TCP 是對於確實信息從一臺電腦傳到另外一臺電腦正確傳遞是負責任的。*/

IP manages the sending and reeiving of packets of data between machines, based on a four-byte destination address (the IP number), which is assigned to an organization by the Internet authorities.

/*IP 管理機器之間的數據包發送和接收，基於一個4字節的目標地址（IP號），那被Internet 受權組織管理。*/

The term TCP/IP  sometimes refers to the entire Internet suite of protocols that are commonly run on TCP/IP, such as FTP (File Transfer Protocol), SMTP( Simple Mail Transfer Protocol), Telnet(Tele-communication Network), DNS(Domain Name Service), POP (Post office Protocol), and so on.

/*TCP/IP 詞彙有時參考爲全部Internet的協議族， 它們一般運行TCP/IP, 例如： FTP (文件傳輸協議)，SMTP(簡單郵件傳輸協議)，Telnrt (網絡遠程登錄)， DNS (域名服務)，POP(郵件辦公服務)， 等等。*/

 

 

　　　　In the process of developing this technology, the military  forged strong links with large corporations and universities. 

　　@30. forge/fɔ:dʒ/ vt. forge  a relationship/ alliance/ links etc. to develop a strong relationship with other group or other copubntries (與它的國家或團體)創建關係、結盟、創建聯繫等@

　　/*在開發這項技術的協程中， 軍方創建強有力的連接和大的公司和大學。*/

As s result, responsibility  for the continuing research shifted to the National Science  Foundation (NSF) and, in 1986, NSFNET (National Science Foundation NETwork) was created, forming the new backbone of the network.

@backbone /'bækbəun/ n. the backbone of = the most important part of an organization, set of ideas etc. 骨幹，支柱，主力， 中堅；@

/*致使這樣的結果， 繼續研究的責任上升爲國家科學基金會， 而且，在1986年， NSFNET (國家科學基金網絡)已經被創建，造成了網絡的新骨架。*/

under the aegis of the NSF, the network become known as the Internet.

@32.aegis/'i:dʒiəs/ n.  under the aegis of formal with the protection or suppport of a person or organization. （正式）在...支持下（保護下）；@

/*在NSF的保護下，網絡變成爲著名的Internet.*/

However, NSFNET itself ceased to form the Internet backbone in 1995, and a fully commerical system of backbones has been created in its place. 

@cease/si:s/ vt. put an end to a state or an activity中止；@

/*不管如何， 在1995年NSFNET 自己中止了造成Internet主體， 而且一個全新的商業在它的空間中已經被創造。*/

The current Internet has been likened to an electronic city with virtual libraries, storefronts, bussiness offices, art galleries, and so on. 

@33. liken /'laikən/ v. liken sb./ sth. to sb./sth. [T usually passive 通常用被動態] formal to describe something or someone as being similar to an person or thing (正式)將某人或某物比做（另外一人或物）@

@34 . gallery /' gæləri/ n. a large buliding where people can see famous pieces of art. 美術館；@

/*如今的Internet已經看起來更像是一座電子城市， 包括虛擬的圖書館，臨街商鋪，商業辦公，和藝術館等。 */

 

　　Another term that is popular, particularly with the mediu, is the "Information Superhighway".

/*另外一個詞彙是流行的， 特別是在媒體上，是「信息高速公路。」*/

This is a metaphor for the future worldwide network that will provide connectivity, access to information, and online services for users around the world.

@35. metaphor /'metəfə/ n. something in book, painting, film etc. that is intended to represent a more general idea or quality, symbol. ( 書、畫、電影等中的)象徵（+ for） @

/*這是對將來萬維網的象徵，它將提供鏈結，讀取信息，全球網上服務*/

 The term was first used in 1993 by then-vice President AL Gore in a speech outlining plans to build a high-speed national data communications network, of which the Internet is a prototype. 

@37. ptototype /'prəutətaip/ n. the first form that a new design of a car, machine etc has (新型汽車、機器等的)原型，雛形； @

/*這個詞彙首次被使用在1993年， 被當時的副總統阿爾·戈爾， 在一次演講中描繪了去計劃建設一條高速國家數據交流網絡，它是Internet的雛形*/

In his book The Road Ahead， Bill Gates (chairman and co-founder of Microsoft) likens the United States, where the Internet represent the starting in the construction of a new order of networked communication (Gates 1995).

/*在他的書《將來之路》中， Bill Gates (主席和微軟前共同創造者)類比美國，Internet 表明了一種新的網絡通訊秩序建築的開端。*/

  The Internet began with funding from the NSF as a mean to allow American univerisities to share the resources of five national supercomputing centers.

@37. funding /'fʌndiŋ/  n. an amount of money used for a specific purpose. 專款；撥款；@

/*Internet 開始從NSF 取專項資金爲了實現容許美國大學能夠共享五個國家級超級計算機中心資源的方法。*/

Its numbers of users quickly grew as access became cheap enough for domestric users to have their own links on PCs. 

@38. domestic /də'mestil/ adj. about family and home= concerning family relationships and life in home涉及家庭關係和生活的；家事的 @

/*用戶數量快速增長因爲對於家庭用戶使用他們自已電腦上的連接使讀取信息變的更便宜。*/

By the early 1990s, the wealth of information made freely available on this network had increased so much that a host of indexing and  search services sprang up to answer user demand such as Archie, Gopher, Veronica, and WAIS (Wide Area Information Service), which provided services through a menu-based interactive.

@39. spring up = to suddenly appear or share to exist 忽然出現，開始存在；@

/*截止20世紀90年代初，在這個網絡上，大量的信息被無償使用增長，以至於指針和搜索服務的主機開始回答用戶請求，例如： Archie, Gopher, Veronica 和  WAIS，它們經過基於菜單的接口提供服務。 */

In contrast, the web uses hypertext to allow browsing, and a number of Web-based search engines were created, such as Google, Yahoo!, and MSN. 
/*相比之下，Web使用超文本容許瀏覽，許多基於Web的搜索引擎被創做，例如谷歌，雅虎，和MSN.*/

　　From initially connecting a handful of nods with APPANET, the Internet was estimated to have over 100 million users in Junuary 1997. 

@ a handful of =  幾個，很少；@

@estimate/'əstimət/ vt. 估計；估算；@

/*從最初幾個和APPANET連接的爲數很少的結點，Internet 被估計有超出1億用戶在1997 年1月份。*/

One year later, the estimate had risen to over 270 million users in over 100 countries, and by the end of 2000 the revised estimate was over 418 million users with z further rise to 945 million users by the end of 2004. 

@40. revise estimate = a calculation that has been changed to make it more accurate. 修正的估計@

/*一年後，估計值已經超過了2億7仟萬用戶在100多個國家，而且截止2000年末，修證估計值已超過4億1仟8佰萬用戶，更有可能上升到9億4仟5佰萬用戶到2004年末。*/

One projection for expected growth predicts 2billion users by 2010 (at end of 2008, there were approximately 1.5 billion online users)

/*針對一項指望增加值預言截止2010年將有20億用戶（在2008年末，存在大約有15億在線用戶。）*/

In addition, there are currently about 3.5 billion documents in the Internet, growth at 7.5 million a day. 

/*另外， 在Internet 上， 存在35億個文檔， 天天新增7.5億個文檔。*/

If we include intranets and extranets ( explained next), the number of documents rises to an incredible 550 billion.

@incredibly/in'krediəbli/ adv. in a way that is hard to believe. 難以置信的。@

/* 若是咱們包括intranets 和 extranets （如下做解釋）， 文檔數可能上升難以置信的爲5仟5佰億。*/

 

30.1.1  Intranets  and Extranets

intranet      A web site or group of sites belonging to an organization, accessible only by the members of the organization. 

/* intranet     屬於一個公同的一個網址或一組網址，數據只能被本公司內部員工讀取。*/

　　Internet standards for exchanging email and publishing Web pages are becoming  increasingly popular for business use within closed networks called intranets.

/*Internet 標準對於交換電子郵件和發佈web頁面，是逐漸變的流行對於商業使用在封閉網絡內部，被稱爲 intranet.*/

 

Typically, an intranet is connected to the wider public Internet through a firewall ( see section 20.5.2)， with restriction imposed on the types of information that can pass into and out of the intranet.

@42. impose /'impəuz/ vt. to force someone to have the same ideas or beliefs as you. （將想法，信仰）強加於某人@

/*  經典的， 一個intranet被連接到一個比較寬廣的Internet上經過一個防火牆，將限制條件強加於進入intranet或走出intranet 的信息類型 。* /

For example, staff may be allowed to use external email and access any  external Web site, but people external to the organization may be limited to sending email into the organization and forbidden to see any published Web pages within the intranet. 

@43. external /ik'stænl/ adj. connected with the outside of a surface or body. 外面的，外部的；@

@44. forbidden/fə'bidn/ adj. not allowed, especially because of an official rule. (尤指因官方規定而)被禁止的@

/*例如， 員工可能被使用外部的電子郵件而且讀取任何外部的網址，可是對於公司外部的員工，可能被限止發送電子郵件到公司而且被禁止去瀏覽的發佈的網頁在intranet內部。*/

Secure intranets are now the fastest-growing segment of the Internet, because they are much less expensive to build and manage than private networks based on proprietary protocols. 

@secure /si:'kjuə/ adj. permance / certain 永久的/肯定的；a situation that is secure is one that you can depend on because it is not likely to change 穩定的；可靠的；穩定的；@

@propriety /prə'praiət/ n. formal (正式) !(singlar u) correctness of social moral behaviour especially between men and women or between people of different social ranks, age etc. (尤指男女之間或不一樣社會等級或年齡之間的)禮貌；規矩@

/*安全的Intranet 如今是Internet 發展最快的部分，由於他們是比較便宜的去建設和管也理比起基於條條框框協議的私有網絡。*/

Extranet      An intranet that is partially accessible to authorized outsiders.

/* EXTRANET    被外部受權者部分讀取的Intranet.*/

　　Whereas an intranet resides behind a firewall and is accessible only to people who are members of the same organization, an extranet provides various levels of accessibility to outsiders.

@47. partially /'pa:ʃəli/ adv. formal (正式) not completely partly 不徹底的；部分的；@

@48. whereas /'wear'æs/ adj. used to say that although something is true of one thing, it is not true of another. 可是，卻（用於說某事不適用於全部狀況）@

/*可是， 在防火牆背後的Intranet，只有同一個公司的員工僅僅有讀取信息的可能性，然而， entranet 對於外部人員提供了各類級別去讀取信息。*/

Typically, an extranet can be accessed only if the outsider has a vaild user-name and password, and this identity determines which parts of the externet can be viewed.

/* 典型的， 若是一個外部人員當且僅當有一個有效的用戶名和密碼時，才能讀取extranet, 而且這個標識符，決定了externet的哪一部可以被瀏覽。*/

Extranets have become a very popular means for business partners to exchange information. 

/*Extranet 已經變成了企業合做夥伴之間交換信息的流行的方式。 */

　　other approaches that provide this facility have been used for a number of years. 

/*提供這種功能的其它方式已經被使用許多年了。*/

For example, Electronic Data Inter-change (EDC) allows organizations to link systems such as inventory and puchase-order. 

@49. inventory /'invətri/ n. a list of all the things in a place (一個地方全部東西的)詳細目錄；清單；@

@50. purchase /'pætʃiəs/ n. formal the act of buying something (正式)購買；採購；@

/*例如， 電子數據交互容許公司去連接系統諸如庫存清單和採購清單。*/

These links foster applications such as just-in-time (JIT) inventory and manufacturing, in which products are manufactured and shipped to a retailer on an "as-needed" basis. 

@51.foster/'fɔstə/ vt. to help a skill, feeling, idea etc develop over a period time. 促進，培養；滋長； @

@52. retail /ri'teil/ v. technical to sell goods in a shop (術語)零售；零賣； @

 /*這些連接促進了倉庫清單和產品製造的即時應用程序， 產品被手工生產，而且被針對所需運輸到零售商。*/

However, EDI requires an expensive infrastructrue. 

@infrastructure/ˈɪnfrəstrʌktʃə(r)/ n. 基礎設施 @

/*不管如何， EDI 須要一個昂貴的基礎疫施。*/

Some organizations use costly leased lines; most outsource the infrastructure to value-added netwoks(VANs), which are still far more expensive than using the Internet. 

/*一些公司使用昂貴的租用線路，最大的外源對於外源增值網絡的基礎設施，比起使用Internet仍然比較貴。*/

EDI also necessitates expensive integration among applications.

@54. necessitate /niə'sesiəteit/ vt. formal to make it necessary for you to do something. (正式)使成爲必需；須要；@

/*EDI也是在應用程序之間成爲必要昂貴的集成。*/

Consequently, EDI  has been slow to spread outside its key markets, which include transportation, manufacturing, and retail. 

 所以，EDI 已經緩慢向外蔓延自已的市場，它包括：運輸業，製造業，和零售業。

In constrast, implementing  an extranet is relatively simple. 

/*偏偏相反，實現一個extranet是相對簡單的；*/

It used standard Internet componenet: a Web server, a brower- or applet-based application, and the Internet itself as a communications infructure. 

/*它使用標準的因特網組件： 一個網頁服務器， 一個是基於瀏覽器一個是基於applet的應用程序，而且Interent自己是一個通訊架構。*/

In addtion, the extranet allows  organizations to provides information about themselves as a product  for their  customs. 

/*另外， 一個extranet容許組織去提供與本身相關的信息，做爲一個對於客戶的產品。 */

For example, Federal Express provides an extranet that allows customs to track their own packages.

@55. federal /'fedərəl/ adj. (聯幫)制@

/*例如，聯邦快遞公司，提供一個Internet 容許顧客去跟蹤他們本身的包裹。*/

Organizations can also save money using extranets: moving parpaer-based  information to Web, where user access the data they need when they need it, and can potentially save organizations significant amounts of money and resources that would otherwise have been spent on priting, assembing packets of information, and mailing. 

/*使用extranets 也能夠節約金錢： 從以紙爲本的的信息到網站頁面， 當用戶須要時，他們能夠讀取數據，這樣就潛意識中節約了公司極大的金錢和資源---它們相反可能被用於印刷，彙編信息包和郵遞。*/

In this chapter , generally we use thw more inclusive term "Internet" to incorprate both intranets and extranets. 

@56. inclusive / in'klu: siv /n. an inclusive price or cost include everything. (價錢、費用)包括一切的；、@

/*在這章中，通長咱們使用單詞「Internet「 去包括價格和每一件事情 */

 

30.1. 2 e-commerce and e-Business 

There is consideral discussion currently about the opportunities the Internet provides for electronic commerce (e-commerce) and electronic bsiness (e-business).  

/*如今關於Interent 所提供的e-commerce 和e-business有一個值得深思的討論.*/

As with many emerging developments of this nature, there is some debate over the actual definitions of these two terms.

@57. mebate/di'beit/ n. discussion or argument on a subject that people have different  opinions about. 討論； @

/*因爲這種性質滋生的發展，在精肯定義這兩個詞彙上存在許多討論*/

Cisco systems, now one of the largest organizations in the world, defined five incremental stages to the Internet evolution of a business, which include definitions of these terms. 

@58. increment / 'iŋkriəmənt/ n. an amount that is regularly added to the amount that someone is paid each year. （每一年薪金的按期）增長；增額；@

/*Cisco 系統，如今全球最大的公司之一， 描述了Internet商業革命的五個促進階段，包括定義這些詞彙。*/

 

Stage 1 : Email   As well as communicating and exchanging files across an internal network, businesses at this stage are beginning to communicate with supplier and customers by using the Internet as an external communication medium. 

/*第一階段：  e-mail (電子郵件)   正如在Internet上進行通訊和文件交互同樣，商業中的供應商和顧客使用Internet做爲外部通信媒介在這個階段開始去通信*/

This delivers an immediate boost to the business's efficiency and simplifies global communication. 

@59. deliver /di'livə/ vt. 給予： @

@60. boost /bu:st/ n. something that helps someone be more successful and confident, or that helps something increase or improve. 激勵；鼓勵；增長，改進；@

/*對於商業的效率和簡化全球通信這給予了一次瞬時增長。*/

stage 2. web site 

Business at this stage have developed a web site, which acts as a shop window to the world for their business products. 

/*在這一階段，商業已經開發了網址，它們扮演了廚窗對於商業產品。*/

  The Web site also allows customs to communicate with the business at any time, from any where, which gives even the smallest business a global presence. 

@61. presene // n. 出席；到場；存在；@

/*網址，容許顧客在商業上不管什麼時候何地進行交流，給予了一個全球現場最小的商業。*/

 

stage 3 :  e-commerce 

 

e-commerce  customers can place and pay for orders via the business's web site.

@62. place an order = make an order 定貨；下訂單；@

/*顧客經過電子商務平臺訂單和付款*/

Business at this stage are not using their Web site as a dynamic brochure but also allowing  customers to make procurements from the Web site, and even be providing service and support online as well. 

@63. brochure /'brəuʃə/n. a thin book giving information or advertising something. 小冊子@

@64. procure /'prəkjuə/ v. to obtain something, especially something that is difficult to get. 得到；取得（尤指難以獲得的事物）。  @

/*這一階段的商業不只使用他們的網站地址做爲動態手冊，並且還容許顧客從網站上下載，甚至還提供再線服務。*/

This would involve some form of secure transaction using one of the technologies discussed in Section 20.5.7. 

/*這也涉及了一些安全事務的格式使用在20.5.7所討論的技術之一。*/

This allows the business to trade 24 hours a day, every day of the year, thereby increasing sales opportunities, reducing the cost of sale and service, and achieving improved customer stasifaction.

/*這也容許商業一個24小時進行交易，所以，增長了銷售機會，減小了服務成本，得到提升客戶溫馨度。*/

 

stage 4 e-Business 

 

e-Business  complete integration of Internet technology into the economic infrastruction of the business.

/* 電子商業   整合Internet 技術進入電子商業的基礎設施。*/

 

Business at this stage have  embraced Internet technology through many parts of their business. 

@embrace /im'breis/ v. formal  to include something as part of a subject, discusion etc. (正式)包括；涉及； @

/*這一階段在電子商業中的許多部分已經涉及Internet技術*/

Internal and extenal processes are managed through intranets and extranets: sales， service, and promotion are all based around the web. 

/*內在和外在的程序都被intranet和extranet管理： 銷售，服務，促銷都基於網頁。*/

Among the potential advantages are that the business  achieves faster communication, streamlined and more efficient processes, and improved producitivity.

@66. streamlined /'stri:mlaid/ adj. to form something into a smooth shape so that it moves easily through the air or water. 使...成爲流線型； @

/*集合這些潛在的優勢，商業得到了更快的交流， 被流水線化，並且更高效，提升了產量。*/

 

Stage 5. Ecosystem 

 

In this stage, the entrie business process is automated via the Internet.

/*在這個階段，全部的商業程序都經過Internet。*/

Customers, suppliers, key alliance partners, and the corporate infrastructure are integrated into a seamless systems.

@67. seamless /'si:mləs/ adj. something seamless is done or happens so sommthly that  you can not tell where one thing stops and anther begins 平滑的；渾然一體的；@

@68. alliance /ə'laiəns/ n. the arrangment in which two or more countries, groups etc agree to work together in order to try to change or achieve something.(國家、團體之間的)聯盟、同盟 ；@

/*顧客，供應商，關鍵合做夥伴，和公司基礎設施被集成爲一個渾然一體的系統。*/

It is argued that this provides lower costs, higher productivity, and significant competive advantage.

/*那也是被討論的，這提供了更低的成本，更多的生產量，和核心競爭優點。*/

 

According to the Forrester Research GROUP and eMarketer, U.S. online sales reached US$175 billion in 2007 and are projected to grow to US $335 billion by 2012, while in Europe online sales have grown to   106  billion (US  $ 133Billion) and will reach 323 billion (US $ 407  billion ) by 2011.

Forrester  also suggests that the business-to-business (B2B) market segment grew from  US$ 2.8 trillion in 2004 to US $ 4.1 trillion in 2005 and US$ 6.8 trillion in 2007.

By 2012 it has been predicted by IDC that there will be more than 1billion online buyers worldwide, making business-to-consumer (B2C) transaction worth US$1.2 trillion and B2B transaction worth US$ 12.4 trillion.

30.2 The Web 

The Web   A Hyper-media-based  system that provides a means of browsing information on the Internet in non-sequential way using hyperlinks.

@70. hype /haip/ n. attempts to make the public interested in a product, film etc. by saying how good it is on television, radio etc. (傳媒的)大肆宣傳，炒做；@

/*網頁，以媒體爲本的炒做系統提供了一種在Internet上使用超鏈 以無序的方式瀏覽網頁。 */

The world wide web  (the web for short) provides  a simple "point and click" means of exploring the immense volume of pages of information residing on the Internet (Berners-Lee, 1992; Berners-Lee et al., 1994). 

@immense /imens/ adj. extremely large  巨大的；@

/*萬維網（簡稱WEB）提供了一個簡單的「點擊」方式探索Internet內部巨大容量的信息頁面。 */

 

Information on the web is presented on Web pages, which appear as a collection of text, graphics, pictures, sound, and video. 

/*網頁中的信息，在網頁頁面上的體現，以文本、圖像、聲音和視頻的集合形式出現。*/

In addition,  a Web page can contain hyperlinks to other Web pages, which allow users to navigate in a non-sequential way through information. 

/*另外， 一個網頁能夠包含與其它網頁的超連接，容許用戶以一種無序的方法瀏覽信息。*/

 

Much of the web's success is due to the simplicity with which it allows users to provide, use, and refer to information distributed geographically around the world. 

/*多數網頁的成功取決於自己的簡單性，它容許用戶提供、使用和參考世界上不一樣地理分佈的信息。*/

 

Furthermore, it provides users with the ability to browse  multi-media  documents independently of the computer hardware being used.

/*更進一步，它提供用戶去獨立使用計算機硬件去瀏覽多媒體。*/

It is also compatible with other existing data communication protocols, such as Gopher, FTP (File Transfer Protocol), NNTP (Network News Transfer Protocol), and Telnet (for remote login session).

/*它也 是和其它已經存地的通訊協議相兼容，例如as Gopher, FTP (File Transfer Protocol), NNTP , and Telnet.*/

The Web consists of a network of computers that can act in two roles: as servers, providing information;  and as clients, usually referred to as browsers, requesting information. 

/*網頁存在許多網絡計算機，它們可以扮演兩個角色： 做爲服務器，提供信息；做爲客戶端， 一般參考瀏覽器，請求信息。*/

Examples of Web servers are Apache HTTP server, Microsoft Internet Information Serve （IIS), and Google web server (GWS) , and examples of web browsers are Microsoft Internet Explorer, Firefox, Opera, and Safari. 

/*網頁服務器是 Apache HTTP server, Microsoft Internet Information Serve （IIS), and Google web server (GWS) ,網頁瀏覽器的例子是 Microsoft Internet Explorer, Firefox, Opera, and Safari. */

 

Much of the information on the web is stored in documents uising a language called HTML (HyperText Markeup Language), and browsers must understand and interpret HTML to display  these documents. 

/*網頁上的信息大多數是儲存在文檔中使用一種被稱爲HTML（超文本標記語言），而且瀏覽器必須理解和闡釋HTMML 去顯示這些文檔。*/

 

The protocol that govern the exchange of information between the web server and the brower is called HTTP (HyperText Transfer Protocol).

/*管理服務器和瀏覽器信息之間交換的協議被稱爲超文本傳輸協議。*/

Documents and locations within documents are identified by an address, defined as  a uniform Resource Locator (URL).

/*文檔和文檔地址被用一個地址標識，定義爲一個統一資源定位器。*/

Figure 30.1 illustrates the basic components of the web enviroment, we now discuss HTTP, HTML, and URLs in some more detail.

/*圖30.1中，列舉了網頁環境的必要組成部分，如今，咱們討論HTTP,HTML, 和URL在一些更細的方面。*/

 

 

30.2.1 HyperText Transfer Protocol 

HTTP :  the protocol used to transfer web pages through the Internet. 

/* HTTP   被用來在Internet上傳輸網頁的協議。*/

The HyperText Transfer Protocol (HTTP) defines how clients and servers communicate.

/*超文本傳輸協議定義了客戶端和服務器端怎樣進行通訊。*/

HTTP is a generic object-oriented, stateless protocol to transmit information between servers and clients (Berners-Lee, 1992).

@77. stateless /'steitləs/ adj. not officially being a citizen of any country 無國籍的@

@generic /dʒiə'nerik / adj. generic name/term/label etc. a word that describe a whole class of things. 屬名、通稱等（用於描述一類事物的詞）@

/*HTTP 是一個面象對象的，無國籍的協議通稱，進行服務器和客戶端之間信息的傳輸。*/

 

HTTP /0.9 was used during the early development of the web. 

/*HTTP/0.9 被使用早期WEB開發時。*/

HTTP/ 1.0 which was released in 1995 as information RFC 1945， reflected common usage of the protocol (Berners--Lee et al., 1996)

/*HTTP/ 1.0 是被出版 在1995年， 做爲RFC 1945文檔，反映本協議的一般用法（Berners--Lee et al.,1996）*/

 

The  most recent release, HTTP/1.1, provides more functionality and support for allowing multiple transcations to occur between client and  server over the same time. 

/*最新發布， HTTP/1.1,提供了更多的功能和容許在同一時段多事務同時發生。*/

 

HTTP is based on a request-respone paradigm. 

@76.paradigm/'pærədaim/ n. formal a very clear or typical example of something (正式)示例；範例；樣式；technical a model or example pof something works or is produced (術語)（展現工做或製做方式的）模型@

/HTTP，是基於一個請求應答的模式。/

An HTTP transaction consists of the following stages: 

/*一個Http事務包括如下幾個階段。*/

! connection: the client establishes a connection with the web server.

/*聯結： 客戶端和服務器創建聯結;*/

!Request: the client  sends a request message to the web server.

/*請求：客戶端發送一個請求信息到WEB服務器。*/

!response: the web server sends a response (for example, an HTML document) to the client.

/*響應： WEB服務器發送一個響應給客戶端。*/

！close: The connection is closed by the web server. 

/*關閉：聯結被WEB服務器關閉。*/

HTTP is currently a stateless protocol-- the server retains no information between request.

@77. stateless /'steitləs/ adj. not officially being a citizen of any country. 無國籍的； @

@78. retain /ri'tein/ v. to keep something or continue to have something. 保留；保有；@

/*目前，HTTP是一個無國籍協議， 相互發求出請求的服務器不保留信息。 */

Thus, a web server has no memory of previous requests.

/*所以，一個web服務器對於先前的請求，沒有記憶。*/

This means that the information a user enters on one page (through a form, for example) is not automatically available on the next page requested,

unless the web server takes steps to make that happen, in which case the server must somehow identify which requests, out of the thousands of requests it receives, come from the same time. 

/*這意味着，一個用戶在網頁中錄入的信息（經過一個表格，例如）再下一次頁面請求時不會自動生效，除非服務器採起措施，使它 們發生， 服務器自己必須標識這些請求， 接收成千上萬的請求，在同一時間裏。*/

For most applications, this stateless property of HTTP is benefit that permits clients and servers to be written with a logic and run "lean" with no extra memory or disk space taken up with information from old request.

/*對於大多數應用程序，HTTP的這種無國籍的特性，它的發好處是：容許客戶和服務被寫用了一種邏輯；而且，對於來原有請求的信息採起「瘦身」經過刪除多餘的內存和磁盤空間。 */

Unfortunately, the stateless property of HTTP  makes it difficult to support the concept of a session that is essential to basic DBMS transactions. 

@session /'seʃən/ n. a meeting or period of time used for a particular purpose, especially by a group of people. 會期；（某團體從事某項活動的）一段時間；@

/*不幸的， HTTP的無國界性，使它去支持階段時概念（對於DBMS事務是必要的）是困難的。*/

 

Various schemes have proposed to compensate for the stateless nature of HTTP, such as returing web pages with hidden fields containing transaction identifiers, and using web page forms where all the information is entered locally and then submitted as a single transaction.

@80. compensate /'kɔmpənseit/ vt. to replace or balance something good that has been lost or is lackin, by providing or doing something equally good. 彌補；抵消；@

/*已經被聲明各類主題 去彌補HTTP無國界性的缺點， 一些回訪類網頁內部含有隱藏的字段包含事務標識符，而且使用WEB網頁表格（在本地被輸入全部信息，接着提交做爲一個單個事務。）*/

All these schemes are limited in the types of application that they support and require special extensions to the web servers, as we discuss later in this chapter. 

/*全部這些方法都是有限的；它們所支持的應用程序的類型， 對於web服務器所申請的專用擴展，咱們將在本章討論。*/

 

 

Multi-purpose Internet Mail Extensions

/*多目的，Internet 郵件擴展*/

The Multipose Internet Mail Extensions (MIME) specifications define a standard for encoding binary data into ASCII， as well as a standard for indicating the type of the data contained inside a message. 

/*MIME說明定義了編碼二進制成爲ASCII碼的標準， 以及對於信息內部所含數據類型的標準。*/

Although originally used by emial client software, the web also makes use of the MIME standard to determine how to handle multiple media types. 

/*雖然起初被郵件客戶端軟件使用， 網頁也使MIME的標準去決定怎樣去處理多媒體類型。*/

MIME  types are identified using a type/sub-type format, where  type classifies the general type of data being sent, and subtype defines  the specific type of format used.

/*MIME 類型被標識爲使用的類格式和分類格式；類分類爲被髮送數據類型；字類被定義爲過去使用的專用類型格式。*/

For example, a GIF image would be formatted as image/gif. 

/*例如： 一個GIF影像可能格式爲image/gif*/

Some other useful types (with default file extensions) are listed in Table 30.1.

/*一些其它有用的類型 （包括默認的文件擴展名）被列在表30.1 中。*/

 

　　　　　　　　　　　　　　　　　　　　　　　　　　　　TABLE 30.1  Some useful MIME type

MIME TYPE	MIME SUBTYPE	DESCRIPTION
TEXT	html	HTML files (*.html, *htm)
	plain (樸素的；簡單的)	Regular ASCII (*.txt)
image	jpeg	Joint Photographic Experts Group files (*.jpg)
	gif	Graphics Interchange Format  files (*.gif)
	x-bitmap	Microsoft bitmap files (*.bmp)
video	x-msvideo	Microsoft Audio Video  Interleave files (*.avi)
	quicktime	Apple QuickTime Movie files (*.mov)
	mpeg	Moving Picture Experts Group files (*.mpeg)
application	postscript	postscript files (*.ps)
	pdf	Adobe Acrobat files(*.pdf)
	java	Java class file (*.class )

 

HTTP request 

/*HTTP 請求*/

An HTTP request consists of a header indicating the type of request, the name of a resource,  and the HTTP version, followed by an optional body.

/*一個HTTP 請求， 包括一個暗含請求類型的頭部， 資源名，HTTP的版本號，後加一個可選的主體。*/ 

 

The header is separated from the body by a blank line.

/*頭部和主體部分分離經過一個空行。*/

 

The main HTTP request types are:

/*主要的HTTP 請求類型是： */

 

1. GET   This is one of the most common types of request, which retrieves (gets) the resource the user has requested.

/*1. Get  這是最普通請求類型之一， 它檢索用戶所需的資源。*/

2. POST Another common type of request, which transfers (posts) data to the specified resource.

/*2. post    另一個通用請求類型， 傳輸數據到達專用源。*/

 

Usually the data sent comes from an HTML from that the users had filled in, and the server may use this data  to search  the Internet or query a database.

/*一般被髮送的數據來自一個已經被用戶填好的HTML表格， 服務器一般使用這個數據去搜索Internet 和查詢數據庫。*/

3. HEAD Similar to Get but forces the servers to return only an HTTP header instead of respone data.

/*HEAD    與GET 類似，可是強制服務器僅僅返回一個HTTP頭部代替響應數據。 */

 

4. PUT (HTTP /1.1) Uploads th resource from the server.

/*  PUT (HTTP / 1.1 ) 從服務器上上傳資源。*/

5. DELETE (HTTP/1.1) .Deletes the source from the server.

/* DELETE (HTTP/1.1) 刪除資源從服務器上*/

 

6. OPTIONS (HTTP/1.1) Requests the server's configuration options.

/*可先項（HTTP/1.1） 請求服務器的配置選項。*/

 

 

HTTP response

/*HTTP 響應*/

An HTTP response has a header containing the HTTP  version ,  the status of the response, and header information to control the reponse behavior, as well as any requested data in a response body.

/*一個HTTP 響應有一個含有HTTP 版本信息的頭部，響應狀態，和頭部信息去控制響應行爲。 同時還有全部被請求的數據在一個響應主體內。*/

Again, the header is separated from the body by a blank line.

/*另外， 頭部和主體分離，經過一條空行。*/

 

30.2.2  HyperText  Markup language 

/*30.2.2  超文本標記語言*/

HTML   The  document fomatting language used to design most Web pages. 

/*HTML  文檔格式語言應用於設計絕大多數的WEB頁面。*/

The HyperText Markup Language (HTML) is a system for marking up, or tagging, a document so that it can be published on the Web.

@81. tag /tæg/ n. a small piece of paper, plastic etc. fixed to something to show what it is, who owns it, what it costs, etc. 標籤；標牌 @

/*HTML 是一個標記，或者打標籤一個文 檔，以致於它可以在網頁上出版。*/

HTML defines what is generally transmitted between nodes in the network.

/*HTML 定義了在一個網絡中結點之間一般什麼被傳輸。*/

It is a simple, yet powerful, platform-independent document language (Berner-Lee and Connolly, 1993).

/*它是一個簡單的，仍是功能強大的、獨立平臺的文檔語言（Berner-Lee and Connolly, 1993）*/

HTML was originally developed by Tim Berner-Lee while  he was at CERN but was standardized in Novermber 1995 as the IETF(Internet Engineering Task Force) RFC1866, commonly referred to as HTML version 2.

/*當Berner- Lee 在CERN時，HTML 被初步開發， 而不是衩IETF在1995年11月做爲標準的RFC1866, 一般被參考爲HTML 第2套版本。*/

The language has evolved and the World Wild Web Consortium(W3C) currently recommendeds use of HTML 4.0.1, which has mechanisms for frames, stylesheets, scripting, and embedded objects (W3C, 1999a).

@82. evolve /i'vɔlv/ v. to develp or make something develop by gradually changing (使)逐步發展。 @

?W3C is an international joint effort with the goal of overseeing the development of the web.? /*W3 C 是一個國際聯合致力於WEB發展監控。*/

/*語言逐步發展，如今，W3C 推薦使用HTML 4.0.1, 它含有框架、表格式、腳本語言、和嵌入式對象機制。 */

In early 2000, W3C  producted XHTML 1.0 (exetensible HyperText Markup Language) as a reformulation of HTML 4 in XML (extensible Markup Language) (W3C, 2000a).

/*在2000年初， W3C 產生了XHTML 1.0 (擴展性超文本標記語言)做爲HTML4 的更正。*/

We disccuss XML in the next chapter. 

/*咱們討論XML 在下一章。*/

HTML has been developed with the intention that various types of devices should be able to use information on the Web : PCs with graphics displays of varying resolution and color depths, mobile telephones, handheld devices, devices for speech for input or output, and so on. 

@83. resolution /,rezə'lu:ʃən/ n. =clearness 清晰 the power of a television, camera, Micro-scope etc to give a clear picture of things, or a measure of this. (電視、照相機、顯微鏡的)清晰度；分辨率@

/*HTML已經被開發，打算各類類型的設備都應該去使用網頁資源： 從分辨率到色彩深度的不一樣的圖形顯示器的PC， 移動電話，手持設備，對於演講的輸入和輸出設備，等等。*/

HTML is an application of the standardized Gerneralized Markup language (SGML), a system for defining structured document types and markup language to represent instance of those document types (ISO, 1986). 

/*HTML 是一個標準通用標記語言應用程序，定義結構化文檔類型，和標記語言去體現這些文檔類型的實例的系統。*/

HTML is one such markup language.

/*HTML 就是這樣的一種標記語言*/

Figure 30.2 shows a portion of an HTML page （a） and the corresponding page viewed through a Web browser (b).

/*圖30.2 顯示了一個HTML文檔的一部分和經過瀏覽器對應的網頁。*/

 

 

Links are specified in the HTML file using an HREF tag and the resulting display highlights the linked text by underlining them. 

/*在HTML 文件中， 使用一個HREF標籤說明連接；以突出強調連接文本，結果晃示高亮。*/

 

In many browsers, moving the mouse over the link changes the cursor to indicate that the text is a hypelink to another document. 

@ 84.cursor/'kæʃə/ n. a mark or a small light which can be moved around a computer screen to show where you are working.電腦的光標@

/*在許多瀏覽器中，移動光標在連接上方改變光標去暗示那個文本是一個超連接相對於另外一個文本。*/

 

30.2.3  Uniform Resource Locators

 URL  A string of alpha-numeric character that represents the location or address of a resource on the Internet and how that resource should be accessed. 

@85. alpha-numeric/,ælfənju:'merik/ adj. using letters and numbers 字母；數字（混合的）；文數式的；@

@86. location /ləu'keiʃən/ n. the act of finding the position of something 定位；@

/*URL   一串文數式的字符， 表明着將資源的定位和資源地址，怎樣在Internet上取資源；  */

 

URLs define uniquely where documents (resources ) can be found on the Internet.

/*URLs 惟必定義了可以在Internet上被找到的文檔（資源）。*/

Other related terms that may be encounted are URIs and URNs.

@87. encounter/in'kauntə/ vt. to experience problems, difficulties, or opposition when you are trying to do something 遇到；@

/*可能會遇到其它相關的詞彙是URIs 和URNs.*/

Uniform Resource Identifiers （URIs）are the generic set of all names/ address that refer to Internet resources.

/*統一資源標識符是全部名稱/地址的通用集， 那參考Internet 資源。*/

Uniform Resource Names (URN) also designate a resource on the Internet, but do so using a persistent, location-independence name.

@88.persistent /pə'sistənt/ adj. continuing to exist or happen, especially for longer than is usual or desirable. 持續存在（發生）的@

/*URN 在Internet上也設計了一個資源，可是作這些，使用了一個永久的，可依賴地址的名字*/

URNs  are very general and rely on name lookup services and therefore dependent on additional services that are not always generally available (Sollins and Masinter, 1994)

/*URN 是很是 普通的，而且依賴名字檢索服務， 所以依賴額外服務，那些服務並不一直一般使用（Sollins and Masinter, 1994）*/

URLs,  on the other hand, identify a resource on the Internet using a scheme based on the resource's location.

/*URLs, 另外一方面，在Internet上標識一個資源， 使用一個基於資源定位的框架。*/

URLs are the most commonly used identification scheme and are the basic for HTTP and the Web.

/*URLs 是最普通的標識符框架，是HTTP和WEB的基礎。*/

 

The syntax of a URL is quite simple and consists of three basic parts: the protocol used for connection, the host name, and the path name on that host where the resource can be found.

/*URL 的語法是至關簡單而且存在三個基本部分： 鏈接協議，主機名， 可以在那臺主機上的找到資源的路徑。*/

In addition, the URL can optionally specify the port through which the connection to the host should be made (default 80 HTTP), and a query string,

which is one of the primary methods for passing data from the client to the server (for example, to a CGI  script).

/*另外， URL 可以選擇性說明端口，經過*/

The syntax of a URL is as follows: 

<protocol>://<host>[:<port>]/absolute_path [? arguments]

The <protocol> specifies the mechanism to be used by the browser to communicate with the resource.

Common access methods are HTTP, S-HTTP (secure HTTP), file(load file from a local disk), FTP, mailto (send mail to specified mail address), Gopher, NNTP, and Telnet. 

 

For example:   http:// www.w3.org/MarkUp.html

 is a URL that identifies the general home page for HTML information at W3C.

The protocol is HTTP, the host is www.3.org, and the virtual path of the HTML file is /MarkUp/MarkUp.html.

 

We will see an example of passing a query string as an optional set of arguments as part of the URL in Section 30.4.