Re: [xml-dev] Wikipedia on XML

[Michael Ludwig <milu71@gmx.de>]

Elliotte Rusty Harold schrieb am 07.08.2009 um 09:54:34 (-0700):

> However I'm not sure what to say [XML] *is*. A language? A grammar? A
> document format? Perhaps we should just follow the XML spec spec: "The
> Extensible Markup Language (XML) is a subset of SGML that is
> completely described in this document." Thus the first couple of
> paragraphs should be something like this:
> 
> XML (Extensible Markup Language) is a subset of SGML that is described
> in a W3C Recommendation and used to create custom markup languages.
> Markup languages that adhere to the lexical grammar and parsing
> requirements in the XML specification are called XML applications.
> Within the constraints of the specification, a markup-language
> designer has significant freedom in naming and defining markup
> elements.
> 
> XML has been used as the basis for a large number of custom-designed
> languages. Some of these, for example RSS, Atom, SVG, XSLT, and XHTML,
> have become widely used on the Internet. XML is also widely used as a
> file format for office-productivity software packages, including
> Microsoft Office, OpenOffice.org, AbiWord, and Apple's iWork. Many
> configuration languages are based on XML including Ant, Java Servlets,
> and ????. It is also commonly used to transfer machine readable data
> between partners with heterogeneous systems; for instance, Federal
> Express exchanges XML documents to coordinate shipments with
> customers.
> 
> What do folks think?

My voice certainly has very limited weight, but to me, it makes a lot of
sense to make the relationship to SGML clear in the very first sentence,
so things are stated in their natural and historical order.

On the other hand, giving the novice a reference to SGML is not very
likely to help much in shaping his view of what the article is dealing
with. So I'd add Ken Holman's definition of XML as a "labeled
hierarchy". Labels and hierarchies are rather well-known concepts.

Also, the concept of "markup" might require some clarification. Why
would one need markup? For example, to add information to information:
meta-information, or meta-data.

I find the very general, simple and *textual* definition of "XML
applications" as such by virtue of their conformance to grammar and
parsing very useful. Of course, a simple XML config file and a program
that just reads in its values is not on the same level as XSD or XSLT,
but both are XML applications as both require the parser; whereas the
DPH throwing regular expressions into the battle to grok the angle
brackets may do so as much as he can - his process won't be an XML
application. Unless, that is, he implements a conformant parser using
regular expressions.

The second paragraph makes it clear to the newcomer that XML is not some
fringe or niche creature, but right on the scene where the music plays
and the cash flows. That's also very good.

-- 
Michael Ludwig