Next-generation XHTML stripped down for handhelds
With a keen eye on small Web access devices, a major standards organization recommends a stripped-down version of its replacement for HTML.
The World Wide Web Consortium (W3C) gave its seal of approval to Extensible Hypertext Markup Language (XHTML) Basic, a subset of XHTML that backers hope will impose some discipline on a proliferation of new Web lingos for small computing devices.
Based on Extensible Markup Language (XML), the full XHTML version is ultimately meant to replace HTML, long known as the lingua franca of the Web. XML, also a W3C recommendation, allows for the creation of new Web languages and the tagging of digital documents to make them easier for computers to read and manipulate.
First issued nearly a year ago, the full-featured XHTML recommendation so far has failed to make a significant mark on the Web. By supporting XML, new browsers can read XHTML pages, and some groups such as the W3C have begun writing their pages in the markup language.
But backers say the markup language's biggest opportunity is to shape the way Web pages are written for non-PC Web browsing devices.
"In terms of desktop browsers, little has changed since XHTML's recommendation," said David Raggett, senior architect of Openwave Systems and a W3C fellow. "Most public attention has been on the wireless stuff and television. As we start wanting to access the Web from other devices from anywhere at any time, we're using devices with limited memory and processing power. So it's important to distill HTML down."
With the XHTML Basic subset, the W3C is in one sense returning to HTML's less complex roots. Early versions of the markup language were extremely simple. But as demand forced browser makers to add bells and whistles, the language and the browsers designed to render it became bigger and demanded more computing power.
From its first public statements about full-featured XHTML, the W3C has heralded the language as a valuable tool for making the Web more digestible by small devices. With Tuesday's subset release, the standards body is trying to make it even easier to design Web pages that can be read by cell phones, set-top boxes and the like.
XHTML Basic joins a growing crowd of HTML variations designed for non-desktop Web access devices. Among these are Compact HTML (CHTML), the Wireless Markup Language (WML) and the W3C's own "HTML 4.0 Guidelines for Mobile Access."
The W3C hopes to reconcile competing markup languages using XHTML Basic as a common reference.
"The basic idea here is to provide a common basis for mobile applications," Raggett said. "I think we'll see a convergence of the mobile markup languages around it. And you'll see there will be extensions, for instance the next version of WAP (Wireless Application Protocol) next year, which will add style and scripting."
Developers working on Web content for use with digital television have also expressed interest in XHTML and XHTML Basic, Raggett said.
HTML features missing from XHTML Basic include style sheets, which separately delineate stylistic elements on a Web page; script and events, which can demand more computing power than typically found on a handheld device; and presentation features including fonts and other text elements. The new recommendation supports forms and tables--with strict limitations--but does not support frames.
The W3C concedes that its new bare-bones markup language may seem unimpressive compared with the souped-up evolutions of HTML people are used to.
"Compared to the rich functionality of HTML 4, XHTML Basic may look like one step back," the W3C acknowledged in its recommendation. "But in fact, it is two steps forward for clients that do not need what is in HTML 4 and for content developers who get one XHTML subset instead of many."
Some say XHTML's greatest asset in slimming down browser applications for potential use by small devices is the strictness it aims to impose on Web authors. While HTML has evolved to tolerate minor coding errors, XHTML has been designed to require strict conformance with the rules.
However, the whole idea of pushing a stripped-down subset for smaller computing devices has its critics, including some within W3C ranks, who argue that the average Web author is unlikely to create a special version of a site for such devices.
"I firmly believe that in order for small devices to survive on the Web they will need to display full HTML," said Hakon Lie, chief technology officer of browser maker Opera Software and a founding member of the W3C. "You may be able to use XHTML Basic to get to your favorite portal, but to get to your grandmother's Web page you're going to need HTML. In other words, it will be hard to convince the world to use just this basic module."