XML Basics (part 1) - A Little History (
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XML, or Extensible Markup Language, is
not new. In fact, it's a subset of SGML, the Standardized General Markup Language,
modified for use on the Web. SGML was originally developed by Goldfarb, Mosher,
and Lorie at IBM in 1969, as a way to structure legal documents; it has evolved
over time into an international standard for representing textual data in system-independent
format. Since SGML is overly complex for the requirements of the Web, XML has
evolved as a modified (read: simpler) version of SGML, adapted specifically for
use on the Web.
You might be thinking to yourself: isn't there already a universal language for
the Web called HTML? And you'd be right to wonder...
While HTML is great for putting together Web pages, it doesn't offer any way
to describe the data contained within those pages. As a formatting language, it
doesn't offer any mechanism to define data structures within the document, thereby
limiting its usefulness. The fact that it understands a limited set of tags -
and even that frequently depends on which browser you're using - reduces its flexibility
and makes it difficult to extend its usefulness to other applications.
XML was designed to avoid these disadvantages by creating a markup language which
would be simple yet flexible, easy to use yet powerful enough to offer a variety
of different applications. Briefly, the original design goals for XML (as stated
in the W3C's XML 1.0 Recommendation) were: XML should be simple and easy to use.
XML should support a variety of different applications, by allowing users to
develop their own markup.
XML documents should precisely follow certain formally-defined rules and principles.
XML documents should be human-legible and reasonably clear.
This article copyright Melonfire 2001. All rights reserved.
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