XHTML

Computerworld - The days in which you could learn HTML in a short time and craft your own Web page using a text editor are numbered. On the bright side, handling any Web site that's bigger than 10 or 20 pages is about to get a lot easier.

"The big win is that you no longer have to force data structures in HTML," says Steven Pemberton, chairman of the World Wide Web Consortium's (W3C) HTML Working Group.

W3C works with businesses and governments to create Web standards. But browser makers historically haven't waited for W3C specifications and have either implemented standards before they're fully defined or implemented them incorrectly. XHTML is the W3C's attempt to redraw lines blurred by browser makers.

HTML was created to be a structural language - nothing more. But browser makers quickly began pushing the envelope, adding presentation capabilities. That often involved nonstandard tags or tricky shortcuts such as using tables to lay out a page, which could slow page-loading times drastically and complicate Web site content management.

In the XHTML specification, the language is once again only structural. Tags are used to mark up headings, paragraphs, lists, hypertext links and other structural parts of the document. Style sheets, on the other hand, handle issues of presentation: fonts, colors and margins. The intent is to simplify sites, decrease download times and more easily present the same content to multiple types of devices.

Easy Does It

XHTML works by separating content from style. Content creators craft HTML; designers create style sheets. This simplifies the Web server's job, since site visitors need to download a style sheet only once. Every subsequent page that refers to that style sheet downloads much more quickly. Changing the look of the site is simplified because you have to change only a few style sheets, not thousands of HTML pages. Web server processing power is saved and less material is transmitted, since HTML documents are free of font tags and color specifications.

A future version of XHTML will introduce modules. Many devices, such as cell phones, would need only a subset of XHTML because modules would automatically filter the XHTML to include only what the device needs.

XHTML will ultimately replace proprietary Web file formats such as Portable Document Format files and Flash and other multimedia formats. For example, the Synchronized Multimedia Integration Language (SMIL Version 1.0, pronounced "smile") allows designers to describe the temporal behavior and layout of a Web page as well as associate hyperlinks with objects. Along with the Scalable Vector Graphics XML standard, designers could create animations or even augment television feeds using XML.