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HTML5 Leads a Web Revolution


New York City geolocation map on mobile screen

Thanks to HTML5, developers can now enable transparent access to geolocation information without having to write separate code for each browser and device.

Credit: mobile-patterns.com

Developers of software for the World Wide Web say the new HTML5 standard is revolutionizing the way the Web evolves, 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 them 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 HTML5 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 and 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 (APIs), 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 Consortium's (W3C's) Open Web Platform, an umbrella term that changes over time and that refers to the markup language and various technologies 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 W3C's HTML4 recommendations and other standards. "The Web over 20 years has developed from a Web of more-or-less static 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 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.

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A Developer-Friendly Standard

Ocupop, a graphics and Web design and marketing firm, has begun using HTML5 for all its 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 made them into stuff that's 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 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 presentation language, allows a developer to produce certain looks natively in the browser, without constructing them externally—say, in Photoshop—and 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 McVickar. "It's a huge timesaver."

McVickar notes the new standards are providing a useful catalyst for vendors eager to take advantage of the Web's 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 feature 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 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.

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Tighter Specs

The new specifications are a big help to the vendors, agrees Ian Hickson, a software engineer at Google and the company's 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 Mozilla Foundation, and Opera Software. "One of the most important strides we've 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 honestly 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 it's critically important stuff."


The newly updated presentation language CSS3 allows a developer to produce certain looks natively in the browser without constructing them externally and then importing them.


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 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 Apple's own collection of Web technologies, including HTML5. Meanwhile, Microsoft and Google have their own not entirely compatible approaches 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 "HTML5 has tremendous momentum, but it's not 100% supported across all browsers because it's 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 they 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 information and that vendors' technologies for codecs, streaming protocols, and DRM will be "the slowest to converge" to standards.

Officially, HTML5, when narrowly defined as the hypertext markup language specification, is on track to become a full specification and an official recommendation by the W3C in 2014. "But the individual specifications are at different maturity levels and will become standards at different times," the W3C's Jacobs says.

Philippe Le Hégaret, interaction domain lead at the W3C, says, "It is not a product where we say, 'OK, now we are done.' The scope keeps increasing." It includes about 60 APIs now, and requests for additions keep coming in, he says. For example, the W3C recently received a request to include support for conversion between speech and text inside the Web browser, a request that is under consideration.

"There's a near-infinite volume of things that the Web doesn't support yet," says Google's Hickson. Asked about HTML6, he says, "HTML is just HTML, we [WHATWG] dropped the number early last year. It's just continuously developed, like the browsers. Development of HTML will just proceed until HTML is dead."

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Further Reading

Bidelman, E., et al.
HTML5 Rocks, http://www.html5rocks.com.

Khan, S.
HTML5 unleashed: tips, tricks and techniques, http://www.w3avenue.com, May 7, 2010.

Lawson, B. and Sharp, R.
Introducing HTML5, 2nd Edition, New Riders Press, Berkeley, CA, 2011.

Web Hypertext Application Technology Working Group
HTML–Living Standard, http://www.whatwg.org/specs/web-apps/current-work/multipage.

World Wide Web Consortium
HTML5—A vocabulary and associated APIs for HTML and XHTML, Editor's Draft, May 8, 2012, http://dev.w3.org/html5/spec/Overview.html.

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Author

Gary Anthes is a technology writer and editor based in Arlington, VA.

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Figures

UF1Figure. Thanks to HTML5, developers can now enable transparent access to geolocation information without having to write separate code for each browser and device.

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©2012 ACM  0001-0782/12/0700  $10.00

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