Making the Web fit for mobile

While it's already possible to tailor Web pages to mobile devices using CSS (Cascading Style Sheet), there's no way of taking account of the differing capabilities of different handhelds, such as screen size, color or resolution. DIAL allows people to specify different layouts for various devices. The draft standard is part of the W3C's Mobile Web Initiative, an effort to make the Web as accessible on the move as it is at people's desks.

DIAL is based on existing World Wide Web Consortium (W3C) recommendations such as XHTML and CSS, but lets people specify what parts of a document are included according to various criteria, using Media Queries, a previously published W3C recommendation. While Media Queries can already be used to specify different style sheets based on capabilities, DIAL takes the concept a stage further and lets people omit entire parts of a document according to device capabilities.

DIAL may be most useful when it's used before transmission of a document to a mobile device to minimize bandwidth. By processing a DIAL document at the server or in a proxy, parts of the document that aren't going to be displayed never get sent to the client.

"The DIAL suite makes the most of existing, established Web technologies and principles, and extends their reach with new features that better serve the needs of diverse devices," Rhys Lewis, chair of the device independence Working Group--which manages DIAL's development--said in a statement. "Born of expertise from device manufacturers, software vendors, mobile operators, content companies and the accessibility community, DIAL has potential to improve the quality of mobile life."

A dissenting view
However, there are those who feel that there are other ways of making content accessible to mobile users. Hakon Wium Lie, chief technical officer for Opera Software and editor of the Media Queries candidate Recommendation, told Builder UK that which language becomes the standard depends on how easy content providers find them to use.

"The popularity of these languages will depend on whether authors accept them or not. That's what ultimately defines whether a W3C specification succeeds or not. Personally I don't find the syntax intuitive. Maybe other people do, but I don't. The success or failure of this doesn't depend on me," said Lie.

Despite his skepticism over the DIAL language, Lie rejects the idea that a separate set of content should be provided for mobile users. "I strongly believe there will be one Web. We're going to base the work on the specifications we already know: HTML, CSS, JavaScript and DOM."

The W3C's Device Independence working group said it welcomes comments from interested parties on DIAL via its mailing list.

Jonathan Bennett of Builder UK reported from London.