1、畢業(yè)設(shè)計外文資料翻譯學(xué) 院： 專業(yè)班級： 學(xué)生姓名： 學(xué) 號： 指導(dǎo)教師： 外文出處：(外文) HTML5 Leads a Web Revolution.pdf 附 件：1.外文資料翻譯譯文； 2.外文原文 指導(dǎo)教師評語： 簽名： 2015年 10月 14日1外文資料翻譯譯文HTML5將會帶來一場Web革命面向萬維網(wǎng)（WWW）的軟件開發(fā)人員認(rèn)為新的 HTML5 規(guī)范正在革新現(xiàn)有 Web 系統(tǒng)的呈現(xiàn)、工作、使用方式。他們說 HTML5 簡化了程序員的工作，使訪問多種多樣的設(shè)備和應(yīng)用程序更加方便，并且提供了很多迷人的新特性。雖然目前，HTML（HyperText Markup Language）僅

2、僅是提供一種對文檔不同部分的標(biāo)記，使得瀏覽器能夠智能的處理（顯示）。一個不起眼的對網(wǎng)頁的標(biāo)記機(jī)制為何有這么大的影響？ HTML5 引起的廣泛關(guān)注是否僅僅是一時的科技狂熱？ 總之，為什么計算機(jī)專家需要關(guān)心這個呢？ （HTML5 引起的）廣泛關(guān)注是合理的，其解釋的難點在于 HTML5 可以看作是一個單獨的規(guī)范，也可以看作是一系列技術(shù)的集合。雖然標(biāo)記語言從二十年多前開始就已經(jīng)是網(wǎng)頁應(yīng)用（Web Software）的核心， HTML5 的概念（比之前的 HTML ）要寬泛，包括一個新版本的標(biāo)記語言及其附屬的標(biāo)準(zhǔn)，包括訪問和操作 HTML 文檔結(jié)構(gòu)（DOM）的標(biāo)準(zhǔn)；（新的）級聯(lián)樣式表（CSS）標(biāo)準(zhǔn)，用于

3、定義 HTML 文檔的外觀和呈現(xiàn)方式；以及 JavaScript 腳本語言。“HTML5” 這個術(shù)語甚至包含了特定的應(yīng)用程序結(jié)構(gòu)（API），例如基于瀏覽器支持的圖形 API 、地理信息 API 、本地存儲 API 和視頻播放相關(guān)的 API 等。同時，HTML5 還是 W3C 開放網(wǎng)頁平臺（Open Web Platfrom）的核心。開放網(wǎng)頁平臺是 W3C 針對標(biāo)記語言和一系列相關(guān)技術(shù)的統(tǒng)稱，其內(nèi)容隨著時間的發(fā)展而變化。參與了HTML4 等標(biāo)準(zhǔn)制定的 W3C 編委 Ian Jacobs 表示，隨著互聯(lián)網(wǎng)的增長和強(qiáng)大， 術(shù)語“HTML”包含的內(nèi)容比以前更多，大家對其定義的認(rèn)識也日趨成熟，而它的涉及

4、范圍也在增加。經(jīng)過二十多年的發(fā)展，Web 已經(jīng)從一個差不多靜態(tài)的文檔顯示功能過度到了應(yīng)用程序的平臺。在這場革命的背后有兩股力量， Jacobs 說。第一股力量是設(shè)備及瀏覽器的多樣化，使得開發(fā)人員所需的工作日益復(fù)雜，而他們希望能夠“一次編寫，到處部署”。第二股力量是現(xiàn)在的 Web 與社交網(wǎng)絡(luò)模型的結(jié)合，當(dāng)你進(jìn)入（Web）時，你能夠接觸到更多的客戶數(shù)量甚至可以達(dá)到千萬規(guī)模。1 “開發(fā)人員友好”的標(biāo)準(zhǔn)志圖形及網(wǎng)頁設(shè)計營銷企業(yè) Ocupop 已經(jīng)將其所有工作使用 HTML5 實現(xiàn)?！安皇敲總€新標(biāo)準(zhǔn)下的特性都是新的”，Ocupop 網(wǎng)頁開發(fā)及可用性設(shè)計人員 Matthew McVickar 說?！埃ㄐ聵?biāo)

5、準(zhǔn)）是過去使用的技術(shù)的典范化。它將過去開發(fā)人員嘗試做到或希望擁有的東西放在瀏覽器中原生支持”。例如 HTML5 中提供的地理位置信息的 JavaScript 接口（API），使得開發(fā)人員可以直接通過瀏覽器獲得所需信息，不需要調(diào)用一個自定義的 API 訪問相關(guān)的硬件設(shè)備。這些特點對于最終用戶來說可能沒啥大不了的，但是對碼農(nóng)來說太重要了。通過 HTML5 ，開發(fā)人員可以不再需要針對每個不同的瀏覽器和硬件設(shè)備編寫不同的代碼，這點恰恰是一個標(biāo)準(zhǔn)要做的。類似的，最近更新的 CSS3 標(biāo)準(zhǔn)允許開發(fā)人員在瀏覽器中就實現(xiàn)以前需要借助如 Photoshop 之類的外部工具才能實現(xiàn)的效果。例如在新的標(biāo)準(zhǔn)下很容易在

6、瀏覽器中實現(xiàn)標(biāo)題的陰影效果，并且能夠動態(tài)的修改，這節(jié)省了很多時間。McVicker 說。McVicker 說新的標(biāo)準(zhǔn)對急于利用網(wǎng)頁技術(shù)能力的進(jìn)步的廠商來說提供了一個很好的分析手段。瀏覽器廠商的產(chǎn)品目前都跟不上（標(biāo)準(zhǔn)的）發(fā)展。HTML5 的“本地化存儲”特性使得結(jié)構(gòu)化的會話數(shù)據(jù)可以保存在客戶端。與僅能保存少量數(shù)據(jù)的 Cookie 不同，本地化存儲的能力能夠保存大量的數(shù)據(jù)，使得在網(wǎng)絡(luò)中斷或不穩(wěn)定的情況下繼續(xù)服務(wù)。同時 HTML5 支持的圖形格式更加豐富，例如對嵌入式 SVG 圖像格式的支持，新的畫布（Canvas）使得用戶能夠在網(wǎng)頁中用 JavaScript 畫 2D 或 3D 圖形。2 Tigh

7、er Spces新的規(guī)范對于廠商而言是一個很大的幫助，來自 Google 的工程師 Ian Hickson 對此表示同意。Ian Hickson 同時還參與了 W3C 以及 網(wǎng)頁超文本應(yīng)用技術(shù)工作組（WHATWG）。WHATWG 是 Hickson 在2004年建立的一個補(bǔ)充性的標(biāo)準(zhǔn)化組織，包含的成員來自蘋果公司、Mozilla 基金會、以及 Opera Software?！拔覀冊?HTML （標(biāo)準(zhǔn)化） 的進(jìn)程中最大的貢獻(xiàn)是顯著的提高了我們規(guī)范的質(zhì)量。”，Hickson 說?！斑^去的標(biāo)準(zhǔn)有很多模棱兩可的地方，兩個瀏覽器廠商可能都覺得自己實現(xiàn)了標(biāo)準(zhǔn)，但是兩者之間是不兼容的?，F(xiàn)在，新規(guī)范規(guī)定的非常

8、詳盡，只要瀏覽器廠商按照規(guī)范來實現(xiàn)，那么瀏覽器之間必然是兼容的。這需要做大量的工作，同時也是非常重要的。”另一方面，雖然 HTML5 已經(jīng)投入使用，但是其標(biāo)準(zhǔn)化的過程還沒有結(jié)束，不同的公司和廠商的實現(xiàn)還存在差異。它沒有指定一個單獨的視頻壓縮標(biāo)準(zhǔn)、流媒體協(xié)議、數(shù)字版權(quán)保護(hù)（DRM）。產(chǎn)業(yè)界曾經(jīng)打算將業(yè)界事實標(biāo)準(zhǔn) Adobe Flash 作為 HTML5 的視頻標(biāo)準(zhǔn)，但是 2010 年蘋果公司在 iPhone 和 iPad 中拋棄了 Flash 技術(shù)轉(zhuǎn)而采用自己的包括 HTML5 在內(nèi)的網(wǎng)頁技術(shù)（導(dǎo)致此項標(biāo)準(zhǔn)化努力失?。?。與此同時，微軟和谷歌都有自己的網(wǎng)頁視頻技術(shù)，相互之間不是完全兼容的，不同來的

9、瀏覽器支持的音頻和視頻格式也不同。所以目前軟件開發(fā)人員為了（自己的產(chǎn)品）有更廣泛的用戶覆蓋面，還是需要采用多種不同的技術(shù)。對此，CMU 大學(xué)計算機(jī)系教授及網(wǎng)絡(luò)專家 Hui Zhang 解釋道，“HTML5 具有強(qiáng)大的發(fā)展勢頭，但是還沒有被所有的瀏覽器百分之一百的支持，因為它還沒有定型位一個標(biāo)準(zhǔn)。許多廠商在標(biāo)準(zhǔn)化過程中均有貢獻(xiàn)。不是只有視頻編解碼的標(biāo)準(zhǔn)化存在挑戰(zhàn)。廠商知曉標(biāo)準(zhǔn)化對于自己和客戶帶來的好處，與此同時廠商有需要跟競爭對手有所區(qū)別來體現(xiàn)自己的優(yōu)勢?！?他比喻道，“每個人都希望分到最大的一塊蛋糕，但是如果每個人都太貪婪，蛋糕就沒了。”Zhang 敏銳的看到網(wǎng)絡(luò)視頻的機(jī)會，合作成立了 Con

10、viva 公司，從事改進(jìn)互聯(lián)網(wǎng)視頻畫面質(zhì)量的產(chǎn)品開發(fā)。他說視頻是網(wǎng)絡(luò)上最復(fù)雜的信息載體，有關(guān)編解碼技術(shù)、流媒體技術(shù)以及DRM技術(shù)將成為“最慢標(biāo)準(zhǔn)化的一部分”。正式的說，如果將 HTML5 限定為超文本標(biāo)記語言規(guī)范，那么其將在 2014 年被 W3C 采納為推薦標(biāo)準(zhǔn)?！暗瞧渌鼏为毜囊?guī)范各自成熟程度不同，標(biāo)準(zhǔn)化的時間也不同?！?來自 W3C 的 Jacobs 表示。W3C 交互領(lǐng)域?qū)＜?Philippe Le Hgaret 說，“（HTML5）不是一個產(chǎn)品，可以讓我們說我們完成了。 其覆蓋的范圍在不斷增長?！?目前包括了約 60 個API，還在不斷增加中。例如不久前一份在瀏覽器中進(jìn)行語音和文本交

11、流的建議被提出，目前正在考慮中?！斑€有近乎無窮的功能目前 Web 無法支持，” 來自骨骼的 Hickson 說。在被問到 HTML6 時他說， “HTML 就是 HTML ，我們（WHATWG）早在去年就放棄了后綴數(shù)字的命名方法了。HTML 是在不斷發(fā)展的，就像瀏覽器一樣。只要 HTML 不死，就會一直發(fā)展下去?！?外文原文HTML5 Leads a Web RevolutionDevelopers of software for the World Wide Web say the new HTML5 standard is revolutionizing the way the Web e

12、volves, works, and is used. It is simplifying the work of programmers, harmonizing access to diverse devices and applications, and giving users amazing new capabilities, they say. Yet, HTML, the HyperText Markup Language, is just a way to tag parts of a document so that Web browsers can deal with th

13、em intelligently.How could a humble mechanism for tagging Web pages have such a big impact? Is the hype surrounding the fifth version of HTML just a lot of geeky noise? And why should computer professionals care about it, anyway? The hype is justified; the difficulty lies in the definition because H

14、TML5 is both a single specification and a whole set of technologies. While the markup language has for more than two decades remained at the core of Web software, HTML5 is most often thought of broadly to include new versions of the markup language itself and its associated standard for accessing an

15、d manipulating HTML documents, the Document Object Model; Cascading Style Sheets (CSS), a language to define the presentation and appearance of an HTML document; and the JavaScript scripting language. The term is often used even more broadly to include specific application programming interfaces (AP

16、Is), such as those that enable new browser-based graphics, geolocation, local storage, and video capabilities.And HTML5 is at the heart of the World Wide Web Consortiums (W3Cs) Open Web Platform, an umbrella term that changes over time and that refers to the markup language and various technologies

17、that pertain to it.Indeed, the popular definition of HTML has expanded and matured as the Internet has grown more powerful and its reach has increased, says Ian Jacobs, editor of the W3Cs HTML4 recommendations and other standards. The Web over 20 years has developed from a Web of more-or-less static

18、 documents to, now, a platform for applications.There are two driving forces behind this evolution, Jacobs says. First is the proliferation of diverse devices that, coupled with the variety of browsers, greatly complicate life for developers, who want to write once and deploy everywhere. Second, he

19、says, the Web has now embraced the social networking model, and when you can tap into that, you can reach many more customers. In some cases, hundreds of millions of more customers.1 A Developer-Friendly StandardOcupop, a graphics and Web design and marketing firm, has begun using HTML5 for all its

20、Web work. Not all of the highly touted features in the umbrella standard are strictly speaking new, says Matthew McVickar, a Web developer and usability designer at Ocupop. They are codifications of techniques used in the past. It takes stuff that developers were trying to do, or wanted to do, and m

21、ade them into stuff thats natively supported in the browser. For example, he says, HTML5 has a standard JavaScript interface for geolocation, so that a Web browser on a mobile device can access GPS data without invoking a custom-written API to a GPS device or application.That may not be apparent to

22、the end user, but it is a big deal for software developers. Developers can, by writing to HTML5, enable transparent access to geolocation information without having to write separate code for each browser and device. It is exactly what a standard is intended to do.Similarly, CSS3, the newly updated

23、presentation language, allows a developer to produce certain looks natively in the browser, without constructing them externallysay, in Photoshopand then importing them. For example, a heading can be given a text shadow quickly and easily in the browser, and it can be changed on the fly, says McVick

24、ar. Its a huge timesaver.McVickar notes the new standards are providing a useful catalyst for vendors eager to take advantage of the Webs latest capabilities. The browser vendors are falling all over themselves to develop their browsers as quickly and as cutting edge as they can, he says.In a featur

25、e referred to as local storage, HTML5 allows persistent storage of structured session data on the Web client. Unlike cookies, which can only efficiently store data in small amounts and have other technical limitations, this capability allows the storage of large amounts of data for access later when

26、 a connection to a Web server may not be possible or desirable. And HTML5 supports richer graphics, such as native support for embedded Scalable Vector Graphics, and the raster-based Canvas that enables users to draw 2D and 3D graphics in a Web page using JavaScript.2 Tigher SpcesThe new specificati

27、ons are a big help to the vendors, agrees Ian Hickson, a software engineer at Google and the companys liaison with W3C and the Web Hypertext Application Technology Working Group (WHATWG). WHATWG is a complementary standards body founded in 2004 by Hickson, then at Apple, and others from Apple, the M

28、ozilla Foundation, and Opera Software. One of the most important strides weve made with the HTML effort has been the significant increase in the quality of our specifications, says Hickson. It used to be that the specs were pretty vague; two browser vendors could implement the same specs and honestl

29、y claim compliance without those browsers truly being compatible. Now, the specs are so detailed that if you implement the spec as written you really will be compatible with all the other browsers and with all the content that already exists. This has been a huge amount of work, but its critically i

30、mportant stuff.Still, although it is being deployed now, HTML5 is not a finished standard, and its adoption varies by company and industry. For example, it does not specify a single standard for video compression (codec), streaming protocol, or digital rights management (DRM). The industry was well

31、on the way toward adopting Adobe Flash as a de facto standard for video until Apple in 2010 declared its iPhone and iPad would not support Flash but would employ Apples own collection of Web technologies, including HTML5. Meanwhile, Microsoft and Google have their own not entirely compatible approac

32、hes to video, and different browsers support different audio and video codecs. So, software developers still must accommodate multiple methods if they want to have comprehensive coverage.Hui Zhang, an Internet specialist and computer science professor at Carnegie Mellon University, explains that HTM

33、L5 has tremendous momentum, but its not 100% supported across all browsers because its not a standard yet. Many vendors are contributing to the process. The challenge is not unique to video, he notes. Vendors see the advantages of standards for themselves and their customers, but at the same time th

34、ey strive to differentiate their products for competitive advantage. You want to get a bigger share of the pie, he warns. But if you are too greedy, the pie is destroyed.Zhang is keenly interested in video as a cofounder of Conviva Inc., a firm developing products to improve the visual quality of Internet video. He says video is the most complex of Internetborne