Article
XML - An Introduction
The XML Vision
The vision for XML, in the words of its creators, is as follows:
"XML shall be easily usable over the Internet."
It's designed to use proven methods, and to require little retooling to make it a vital part of the Web. Adoption should be as painless as possible.
"XML shall support a wide variety of applications."
HTML's reach is widespread. It's independent of hardware and software. People with different platforms can access the same HTML using hundreds of different programs. XML must support a similar, or greater, range of uses and programs to be successful.
"It should be easy to write programs that process XML documents."
If you don't build it, they won't come. The test of a computer's usefulness is how much you can do with it, and this rule applies to XML too. If no one uses a language, it dies. Making it as easy as possible for programs to use XML is essential for its success.
"XML documents should be human-legible."
You should be able to read over a raw XML document and understand it. It may even be easier to understand than normal English. "Jack and Jill went up the hill" marked up as <NAME>Jack</NAME> and <NAME>Jill</NAME> went <DIRECTION>up</DIRECTION> the <GEOLOGIC_FORMATION>hill</GEOLOGIC_FORMATION> may be even more self-explanatory than its unmarked form.
"The XML design should be prepared quickly."
The XML 1.0 specification was released in February 1998, with the second edition appearing in October 2000.
"The design of XML shall be formal and concise."
Instead of often-obscure markup like <P>, <BODY VLINK="#0000ff">, or <TR>, XML is spelled out:
<P> would be <PARAGRAPH>
<BODY VLINK="#0000ff"> would be <BODY VISITEDLINK="#0000ff">
<TR> would be <TABLEROW>
This makes XML easier to understand and compose.
"XML documents shall be easy to create."
XML documents are easy. If you can type <, >, and /, and you can remember that for every opening <MARKUP> there needs to be a closing </MARKUP> you can write "well-formed" XML. Complex or "valid" XML is more difficult, but it's still not overwhelming.
"Terseness in XML markup is of minimal importance."
HTML has a lot of shortened markup. The meaning of <IMG SRC> may be recognizable, but if it's spelled out as <IMAGE SOURCE> it's even clearer. XML seeks to make its markup clear, as opposed to short, across the board.
This is the vision for XML. But XML won't just supplement the Web: it will be the Web. Visions often fail when they try to be all things to all people, but the vision for XML won't. Its job is allowing visions to be all things to all people.