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   Re: [xml-dev] The XML 500 word Challenge

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AndrewWatt2000@aol.com wrote:
> Picking up Mike Champion's question about how to communicate that XML is, so 
> it is suggested, "simple" let's have a challenge for list members to explain 
> XML in 500 words to someone who is a Web developer but has no formal CS 
> training.


XML is a common alphabet and grammar ("syntax") for newer Web 
development standards like SVG (a common vector graphics format for the 
Web), XForms (the next generation of Web forms) and RSS (a way to 
summarize the information on your site so that "subscribers" can find 
out about documents added to the site).

Before XML was popular, it was common to invent new syntaxes from 
scratch. Learning, implementing and using new syntaxes can be quite 
challenging so this process was very inefficient.

For instance before SVG, it was common to do vector graphics in 
PostScript. If you compare these SVG and Postscript examples you'll see 
that the SVG example has much more in common with the HTML you already 
know than the Postscript:

Postscript: http://www.strubi.ox.ac.uk/bobscript/ps-01.html


Tools for working with HTML (especially its XHTML variant) can more 
easily be adapted for working with SVG than with something totally 
different like Postscript.

XML goes well beyond web interface development standards. It is also 
used under the covers for many machine to machine communications such as 
automated purchasing. The benefits there are similar.

Compare a purchase order in the older EDI syntax:

  * http://www.lecrc.com/busops2000/sld056.htm

to the markup-based one in XML:

  * http://www.networkcomputing.com/908/908ws12.html

Similarly, compare the line-based syntax MCF to RSS:

MCF: http://developer.netscape.com/docs/technote/metadata/metadata.html

RSS: http://webreference.com/xml/column13/4.html

Each of these standards (SVG for graphics, RSS for syndication, ebXML 
for electronic business) can be considered a "vocabulary". Just as it is 
more efficient to invent new words for English than to invent a whole 
new language, it is more efficient to invent new vocabularies for XML 
than invent whole new syntaxes.

Vocabularies in English are defined in glossaries or dictionaries. 
Similarly, vocabularies in XML are defined in so-called "schemas". Just 
as there are a variety of formats for glossaries, there are a variety of 
"schema languages" for defining XML vocabularies. The existence of 
schema languages serves to encourage an important best-practice: 
documentation of vocabularies! Before XML, it was common for the syntax 
and vocabulary of data formats to be completely proprietary trade 
secrets (consider the Office document file format). This is no longer 
considered an acceptable practice and Microsoft Office 11 is expected to 
have a fully-documented XML file-format (and perhaps a formal schema).

XML also encourages best practices around internationalization. XML 
builds on a standard for characters known as "Unicode." Using XML (and 
thus Unicode), it is easy to insert characters in anything from Arabic 
to Chinese to Cyrllic and even from ancient dead languages! This is an 
important step forward in an industry that has historically thought of 
English first and then other languages only much later.


  Paul Prescod


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