Hope is finally at hand for developers weary of hypertext headaches.
While most developers have adopted Cascading Style Sheets, or CSS, as a better way of handling presentation of Web documents, HTML5 codifies this by eliminating most presentational attributes. To earn its Web Applications 1.0 moniker, HTML5 also adds APIs that include direct provisions for audio and video content; client-side persistent storage with both key/value and SQL database support; offline-application, editing, drag-and-drop, and network APIs; and cross-document messaging. While much of this is possible today through browser plug-ins, standardizing on these features and building them into browsers will make it much easier for developers to add advanced functionality that will work across platforms.
In contrast to XHTML2, supporting existing content is a key HTML5 design principle. Other design goals center on compatibility, utility, interoperability, and universal access. Compatibility means not only that existing Web pages should still render properly, but that new functionality introduced with HTML5 should degrade gracefully when an older browser is used.
Another key conviction: Browser implementers should do their best to render pages that may have incorrect markup, and do so in a consistent manner. In stark contrast, XML is supposed to "error out" when a fault is reached, so a single mistake on a developer's part may create an unreadable Web page. Considering the number of pages that don't properly validate, that's a real burden to put on Web developers. "The HTML5 specification is a good step because it's a fairly realistic one," says Charles McCathieNevile, chief standards officer for Opera Software. "It doesn't aim to change the world in a radical way."
Internet Explorer doesn't support XHTML, and at press time Microsoft hadn't released plans to support it in future versions, instead saying it's concentrating on fixing more pressing issues, such as CSS and rendering errors in versions through IE7 and IE8 betas.
Fortunately, HTML5 makes concessions for phased adoption.
The W3C predicts that the full HTML5 recommendation will be ratified in the third quarter of 2010. You won't have to wait that long to take advantage, however; among the four most popular browsers--Internet Explorer, Firefox, Safari, and Opera--bits of support for HTML5 already are available. For example, all but Internet Explorer have implemented the Canvas element, and Opera includes Web Forms.
THE ACID TEST
At the same time, however, developers of the two most popular browsers, Internet Explorer and Firefox, are still struggling to come closer to full compliance with existing standards. The Acid2 test, developed by the Web Standards Project in 2005, was created to cajole browser developers into complying with current CSS specs, for example. On Dec. 19, Microsoft said its latest IE8 beta passed the Acid2 test, and on Dec. 7, changes to Firefox's Gecko layout engine that make this version pass as well were submitted. Both IE8 and Firefox 3 are expected to pass the Acid2 test.
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