外文翻譯5理解可擴(kuò)展性標(biāo)記語(yǔ)言XML

1、大連交通大學(xué)2012屆本科生畢業(yè)設(shè)計(jì) （論文） 外文翻譯understanding the extensible markup language (xml) this appendix takes a look at the extensible markup language (xml)a superb structured document format standard that businesses are using to exchange business data. xml complements ejb nicely as well; in fact, the ejb 1.1

2、specification uses xml as a document format for deployment descriptors. by reading this appendix, you will learn the following: why businesses need xml the core concepts behind xml programming how ejb and xml are related (which well expand upon in appendix d, covering ejb 1.1) xml is an extremely im

3、portant technology for the internet, and it is destined to become the de-facto standard for structuring document content. if you already know xml, feel free to skip to the second half of this appendix, where we discuss how xml and ejb are related. otherwise, read on, and we will explain xml from the

4、 ground-up. this appendix explains enough xml for you to begin programming with ejb 1.1. for a full tour of xml, see the books accompanying web site for links to external resources. business needs for xml we begin by studying the needs of the business community that make xml such a useful standard.

5、why is xml important? what business problems does it solve? why did we need to create xml rather than use existing technology? those are the questions we will answer in this section. electronic commerce the business need for a standard such as xml has arisen with the advent of electronic commerce (a

6、lso called e-commerce, e-business, or your favorite buzzword). when most people hear the word “electronic commerce”, they usually think of web storefronts that you can visit to purchase goods electronically. this is called business-to-consumer e-commerce because a business is conducting a transactio

7、n with a consumer. examples of business-to-consumer web sites are a (), b (), and caro (www.caro). but e-commerce extends beyond simply the business-to-consumer model. for instance, an online auction house such as ebay () facilitates trans- actions between consumers by hosting auctions. this is call

8、ed consumer-to- consumer e-commerce because goods are exchanging hands between consumers. a business may also sell goods to other businesses and take consumers out of the picture altogether. this economic model is called business-to-business e-commerce, and is where most of the money changes hands b

9、y far, because every business needs to conduct inter-business transactions to survive. manufacturers need to buy parts from suppliers. resellers need to buy products from manufacturers. and all corporations need to buy office supplies and furniture. geographically distributed companies, conglomerate

10、s and even whole industries (such as aerospace) rely on communication, and the ability to distribute manufacturing activities gives some companies an essential economic advantage. business-to-business e-commerce is the single largest financial impact the internet is making on the world economy, and

11、has been estimated to be 20 times as large as the other internet economic models. as we will see, business-to- business e-commerce is where xml has the largest impact as well. inadequacies with existing technology the challenge for businesses to conduct affairs electronically is for businesses to un

12、derstand each others data, such as products, customers, and financial data. with a paper-based system, a human being always intervened and could make go back to the first page for a quick link to buy this book online! logical guesses about ambiguous data. with electronic business, however, computer

13、programs need to receive accurate, structured data, or millions of dollars could be lost due to incorrect transactions. thus, a structured data document standard is needed that businesses can use to share information. this document standard should be simple enough for anyone to use elegantly, yet be

14、 powerful enough to represent any business data. a computer program should be able to read an electronic document structured in this language and figure out the semantic details of the document based on its structure. for example, an application should be able to query a digital purchase order docum

15、ent and determine what product and quantity the purchase order is for. lets take a look at the existing technology standards and examine why they are inadequate for our needs. vans and edi electronic business is not a new concept. companies have already been doing it for years in a very proprietary

16、way. before the internet hit mainstream, two corporations would conduct business electronically using a third-party vendors value-added network (van), or private network that links companies together. the largest four van vendors are general electric information services, ibm global information netw

17、ork, sterling commerce, inc., and harbinger corporation. the standard for conducting business over vans is called electronic data ex- change (edi), a standard for facilitating the electronic exchange of data. edi has traditionally been used over vans although it is been extended to run over the inte

18、rnet as well. edi has widespread use in multiple vertical industries, from the business sector (transferring business documents) to the educational sector (transferring student records, transcripts, and test scores). the problems with vans and edi are as follows: vans using edi are a very expensive

19、subscription service, and charge businesses outrageous per transaction fees. vans are a challenge to link to other businesses that are already on the internet. vans are designed for batch-mode processing (rather than just-in-time processing, which is necessary for efficient transactions). within ind

20、ustries, large companies typically define a set of edi templates that lock other companies into proprietary standards for data exchange. edi is an outdated, cumbersome, and non-extensible format for transferring data. note that there is definitely a lot to be said about vans and edi. many businesses

21、 run quite smoothly on these technologies today, as vans using edi are quite reliable and secure. many corporations are also very concerned about gambling their businesses on anything new. due to these factors, plus the slow rate of technology adoption, the edi market is growing rapidly as we speak.

22、 in the long run, though, vans and edi are likely to die off in favor of newer technology evolutions. what would you do to replace vans and edi with an internet-based model? first you would need to replace the proprietary van networks with an internet link. thats simply a hardware problem. the large

23、r issue is replacing or enhancing edi with an efficient, modern, structured data document standard that business can use to exchange information. as we will see, xml is that standard, and it is what early adopting businesses are tackling as an integration method, even as we speak. sgml the standard

24、generalized markup language (sgml) is a meta-markup languageyou can use a meta-markup language to design your own markup language (such as xml or html). sgml provides a mechanism to add structure to your documents, and has a great track record of successful deployments of applications, especially in

25、 the publishing realm. but, unfortunately, sgml has never become mainstream, largely because of its complexity. sgml is quite powerful, and it could easily be used to represent business data. its power comes at the cost of ease of use, as sgml is a bit too powerful for everyday business applications

26、. the ramp-up curve for programming with sgml is particularly steep, and the high cost of leveraging sgml is very prohibitive. few people use sgml in its raw form, but everyone uses implementations of sgml, such as html and xml. html the hypertext markup language (html) is the predominant standard f

27、or web documents. html is an application of sgml that is intended for multimedia presentation of information over the internet. html is an inappropriate markup language for electronic data, primarily because html was designed around the use of gui tags, rather than business data content. html is gre

28、at for displaying documents to end users, but it is very poor for defining other structure in a document. for example, consider the following html snippet: john doe the doe corporation here, the and tags tell the client-side browser to represent the associated text in bold and italics, respectively.

29、 however, the structure ends there. the browser has no way of structuring the semantic meaning of the text within the document. for example, by glancing at this code, theres no way we can automatically identify that the string “john doe” is the name of a person. nor can a computer program discern th

30、at “the doe corporation” is the name of a company. note that there are clunky ways around this (for example, you could add id attributes). similary, html is not extensible. if a business needs to add new tags to accommodate its needs, that business will run into a wall with html. this is because htm

31、l is a markup language, but is not a meta-markup language. xml the extensible markup language (xml) is a universal standard for structuring content in electronic documents. xml is extensible, enabling businesses to add new structure to their documents as needed. the xml standard does not suffer the

32、version control problems of other markup languages such as html because it has no predefined tags. rather, with xml you define your own tags for your business needs. xml is a meta-markup language because you can define your own markup language which is self-describing. this makes xml the ideal docum

33、ent format for transferring business data electronically, and it has a wide variety of other applications as well. benefits of xml from a business perspective, xml is compelling because it allows businesses to structure data in an elegant, extensible way. but xml has other benefits as well: xml is s

34、imple and easy to use. the raw xml language does not contain specific tags for vertical markets. learning to use xml is straightforward and does not require much ramp-up time. xml is an open, internet-standard. the worldwide web consortium (w3c) recommended the xml 1.0 standard in february 1998. no

35、single commercial company controls the standard, which means that everyones interests are taken into account. xml is human-readable. an xml document can be stored as a simple text file, yet it can represent complex business data. if you want to inspect or modify an xml document, you can simply edit

36、the text file. this is a huge benefit over binary data formats that cannot be easily viewed or modified, such as serialized java objects (see appendix a for more on java object serialization). xml compresses very well.because an xml document can be stored as a flat text file, it gains the advantage

37、of very high compression rates. this makes xml well suited for massive document storage, and it also makes xml useful as an on-the-wire data format. xml has massive industry support behind it. microsoft, ibm, sun microsystems, oracle corporation, webmethods, sap, and many others are jumping on the x

38、ml bandwagon. xml has great tools available. there are already numerous xml tools and other xml applications available for download or purchase. these include xml viewers, high-performance xml parsers, xml javabean toolkits, xml- based databases, xml browsers, xml search engines, xml file utilities,

39、 and much more. see the books accompanying web site for links to xml resources. xml is the basis for other standards. already there are companies using xml as a foundation for standards in other technologies and industries. for example, webmethods has defined an interface definition language for the

40、 web using xml. sun microsystems has used xml within its ejb and jsp specifications. by learning xml, you will be prepared to understand these new topics as well. xml brings new power to content searches. once you add structure to your data using xml, it is quite straightforward to search your docum

41、ents for specific information. for example, lets say youre building a repository of historical information. using xml, you can specify that the string george washington represents a united states president. once youve built up your historical information repository, you can search that repository fo

42、r all documents that contain information about united states presidents. note that this is unlikely to happen on a large-scale (such as searching the internet for xml tags) because of schema differences between companies. xml is self-describing. an xml document can contain all the information needed

43、 for a program to interpret it. this makes xml highly useful for communicating data between applications because an application can discover information about a document at runtime, without preconceived knowledge of the documents format. xml uses unicode, rather than ascii. this makes xml highly sui

44、table for international electronic commerce. xml allows for the use of urls. this makes xml ideal for internet usage (sgml does not support urls). xml compared to edi while edi is a useful format for structuring business data, it is also a fixed format. edi does not have the flexibility that xml off

45、ers because it does not let you define rules for your business data. xml is a language that can be used to define message formats, whereas edi defines a bunch of message formats that are used to conduct specific business-to-business transactions. just as html has limited success as a web markup lang

46、uage because it isnt extensible, edi has limited success in conducting business-to-business transactions because the predefined transactions arent extensible. xmls extensibility is its big win over edi. it should also be noted that endeavors are underway to unite xml and edi. for instance, the xml/e

47、di group is working on xml/edi, a standard that allows xml to express edi, and also allows for edi to be transported across the internet rather than through traditional vans. this opens up new potential for edi, as xml brings widespread industry support with it. see the books accompanying web site f

48、or links to xml/edi resources. xml compared to sgml xml is an application profile of sgml, meaning xml is a subset of sgml. the advantage that xml has over sgml is simplicityit will not take you long at all to understand how xml works, yet xml is powerful enough to format any businesss data. xml pac

49、kages the most important aspects of sgml into an easy- to-use document format that you can use to format data transferred over the internet, using conventional internet protocols such as http. xml compared to html html is also an application profile of sgml. whereas html serves as a markup language

50、that defines static tags such as and , xml is a meta-markup language that you can use to define your own markup language. you can invent your own tags that represent business data in xml, and you can use the tags to represent semantic information about your business data. the power that xml has over

51、 html is xml documents can contain tags that relate business semantics, and not just format semantics. xml concepts now that youve seen the xml value proposition, lets take a quick technical tour of xml concepts. the best way to learn xml is by example, and so that is how we will begin. source c.1 s

52、hows a sample xml document. lets dissect this document and reveal how xml works. 1984 george orwell 268 essential com don box 440 microsoft com explained for developers. the catcher in the rye j. d. salinger 214 library source c.1 an xml document. prolog every xml document begins with a prolog, or a

53、 header statement introducing the document. the prolog in our example above is: this identifies that our document uses version 1.0 of xml (which is the only version of xml right now). there are some other interesting things you can put in the prolog as well, such as your text encoding type or whethe

54、r the document is a stand-alone document that does not have any dependencies on external markup declarations. - 8 -大連交通大學(xué)2012屆本科生畢業(yè)設(shè)計(jì) （論文） 外文翻譯理解可擴(kuò)展性標(biāo)記語(yǔ)言xml此附錄描述的是可擴(kuò)展性標(biāo)記語(yǔ)言（xml）-一種極好的用于事務(wù)之間交換數(shù)據(jù)的架構(gòu)文檔格式標(biāo)準(zhǔn)。xml同時(shí)完善了ejb；事實(shí)上，ejb 1.1規(guī)格說(shuō)明書使用xml作為一種文檔格式的配置描述符。通過(guò)閱讀此附錄，您將學(xué)習(xí)到一下內(nèi)容：為何事務(wù)需要xmlxml編程背后的核心觀念ejb與xml之間的聯(lián)

55、系（我們將在附錄d里對(duì)其進(jìn)行擴(kuò)展）xml是一種因特網(wǎng)上極其重要的技術(shù)，它注定要成為構(gòu)造文檔內(nèi)容的實(shí)際標(biāo)準(zhǔn)。假如你已經(jīng)了解xml，可以跳過(guò)這個(gè)附錄的第二個(gè)部分，我們將在那部分討論xml和ejb是如何關(guān)聯(lián)的。否則，繼續(xù)閱讀，我們講從基礎(chǔ)上解釋xml。xml所需要的事務(wù)我們通過(guò)學(xué)習(xí)使xml作為如此重要標(biāo)準(zhǔn)所需要的事務(wù)共同體。為什么xml如此重要呢？它包含著什么樣的事務(wù)問(wèn)題呢？為什我們需要去創(chuàng)建xml而不是用已經(jīng)存在的技術(shù)？以上是我們將在此部分將要回答的問(wèn)題。電子商務(wù)隨著電子商務(wù)的到來(lái)，事務(wù)需要一種像xml一樣的標(biāo)準(zhǔn)。當(dāng)大多數(shù)人聽(tīng)到“電子商務(wù)”這個(gè)詞的時(shí)候，通常會(huì)聯(lián)想到一種能夠通過(guò)訪問(wèn)網(wǎng)絡(luò)店面來(lái)訂購(gòu)物

56、品的電子方式。這就是所謂的“商務(wù)-消費(fèi)者”的電子商務(wù)。這種消費(fèi)者商務(wù)的網(wǎng)站例如, , 和www.caro.但是電子商務(wù)提供的不僅僅是簡(jiǎn)單的商業(yè)-消費(fèi)者的模式。例如，一個(gè)在線拍賣機(jī)構(gòu)易趣(), 通過(guò)集合拍賣，方便了消費(fèi)者之間的交易。這就是所謂的“消費(fèi)者-消費(fèi)者”之間的電子商務(wù)因?yàn)榛蛟S是通過(guò)消費(fèi)者手中進(jìn)行交換的。一次交易也可以是將貨物賣給另外一次交易同時(shí)這期中不包括消費(fèi)者。這種經(jīng)濟(jì)模式叫做“商務(wù)商務(wù)”電子商務(wù)，是目前為止金錢流通最廣泛的方式。因?yàn)槊總€(gè)商業(yè)需要通過(guò)管理內(nèi)部商業(yè)交易來(lái)生存。制造商需要從供應(yīng)商那里買原料。銷售商需要從制造商手里買產(chǎn)品。而且所有的公司需要買辦公用品和設(shè)備。地理分布型公司，聯(lián)

57、合企業(yè)甚至是整個(gè)工業(yè)（例如航空宇宙）都依賴于信息交流，這種分散加工的能力給予許多公司一種本質(zhì)的商業(yè)好處?！吧虅?wù)商務(wù)”電子商務(wù)是影響因特網(wǎng)的唯一的最大的世界金融模式。估計(jì)至少將是因特網(wǎng)上其他金融模式的二十倍。正如我們所看到的，xml對(duì)“商務(wù)商務(wù)”電子商務(wù)的影響最大。存在的技術(shù)不合適對(duì)商務(wù)的挑戰(zhàn)是電子化的控制事務(wù)，正如事務(wù)之間理解彼此的數(shù)據(jù)，例如產(chǎn)品，顧客和金融數(shù)據(jù)。在一個(gè)紙質(zhì)系統(tǒng)上，人們總是介入同時(shí)對(duì)不明確的數(shù)據(jù)做出合理的猜測(cè)。然而對(duì)電子商務(wù)來(lái)說(shuō)，電腦程序需要接收精確的，有組織邏輯的數(shù)據(jù)，否者數(shù)百萬(wàn)美元將會(huì)由于不正確的交互而丟失。vans和edi電子商務(wù)并不是一種新的觀念。很多公司已經(jīng)用非常合適的方式坐了很多年。在因特網(wǎng)成為主流之前，已經(jīng)有兩個(gè)企業(yè)能夠通過(guò)第三方賣主的附加價(jià)值網(wǎng)絡(luò)（van）來(lái)電子化的控制商務(wù)，或者是講許多公司連接在一起的私人網(wǎng)絡(luò)。最大的四個(gè)van賣主是通用電子信息服務(wù)，ibm全球信息網(wǎng)絡(luò)，sterling商業(yè)有限公司和harbinger公司。通過(guò)van來(lái)管理商務(wù)的標(biāo)準(zhǔn)叫做電子數(shù)據(jù)交換（edi），一種是交換電子數(shù)據(jù)更