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XML resources
XML 1.0
The W3C official recommendation.
XML.com
XML.com's mission is to "help you discover XML and learn how this new Internet technology can solve real-world problems in information management and electronic commerce." Includes features, columns, and related standards.
The XML Files
The XML Files include columns and features all devoted to XML and related topics. From WebDeveloper.com.
XMLU.com
XMLU.com offers hands-on training courses in XML and other technologies in connection with Architag University.
Project Cool XML Zone
This site takes you through the basics of XML and what it can do for you. It also includes a mailing list and bulletin board.
XML Finetuning.com
Technical information, updates, and resources about XML.
The XML FAQ
Answers to your frequently asked questions.
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What it is
Extensible Markup Language (XML) is not a markup language per se, but rather a metalanguage that lets Web builders define their own markup languages. Extensible by definition, it specifies the syntax for tags, not the tags themselves.
Not a replacement for HTML, XML is meant to augment HTML. Both are text-based languages derived from SGML, but where HTML is an application of SGML, XML is a subset. In other words, XML is a simplified, offshoot version of SGML.
Why it's important
If XML delivers on expectations, it will change the face of the Web. XML is expected to hurdle HTML's limitations and offer a standard way to exchange data across the Internet, increasing e-commerce dramatically.
While HTML describes how to present a document's data, XML defines the data's actual content. For example, an HTML tag such as <H1> specifies a certain font and size. XML, on the other hand, describes the content that appears within the tags. By separating presentation from content, XML adds structure to documents and allows them to be viewed on various devices without having to be rewritten specifically for each device.
The extensibility of XML is where it really shines. Web builders can create a set of tags specific to their tasks and then share them throughout their industry. Several industries, such as real estate and health care, have already taken advantage of XML.
XML will also improve searching capabilities on the Web. For instance, searching for jaguar on the Web will probably turn up thousands of documents about the car. But what if you're looking for information about the cat? When XML becomes ubiquitous, you'll be able to find only those documents that match your search, because the relevant pages could be marked up like this:
<ANIMAL>Jaguar</ANIMAL>
Where it's at (as of 11/3/98)
The W3C approved XML as an official recommendation in February 1998, making the metalanguage the hot topic in the Web building industry.
Even before the standard was official, though, a number of industries had already implemented XML technology, such as Microsoft with its Channel Definition Format (CDF). And several industries are already sharing XML tag sets to enable the exchange of data. For example, mathematicians can use Math Markup Language (MathML) to display their equations and other mathematical notation.
Even with all of these real-world applications, XML is far from ubiquitous. That may take some time--CNET predicts two to three years. In the meantime, the XML working group has been reorganized into five subgroups, and both major browsers will have at least some support for XML in their next releases.
Netscape considers itself a leader in supporting XML and Resource Description Framework, according to Eric Byunn, group product manager for Communicator. He has recently made it known that Navigator 5.0 will incorporate NGLayout, the XML-compliant HTML layout engine developed by the Mozilla project.
| XML timeline |
| 1986: |
International Standards Organization (ISO) adopts SGML |
| 11/96: |
W3C presents first XML draft |
| 1/97: |
First XML parser developed |
| 3/97: |
First XML applications start to appear |
| 2/98: |
W3C recommends XML as a standard |
Microsoft Internet Explorer 4.0 was the first browser to implement XML with two built-in parsers. However, since this browser was developed before the XML recommendation was official, many of its XML features are experimental. The company recently announced plans to release an enhanced parser, in partnership with DataChannel, that is compliant with the XML 1.0 standard. At this point, IE 5.0 supports rendering XML documents via CSS, called XML+CSS. According to Tim Bray, co-editor of the XML recommendation, IE 5.0's XML support is a step in the right direction, but the current beta is still "shaky."
Finally, even as support for XML is being refined, the W3C and other organizations are continuing to define how XML should work.
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