W3C home > Mailing lists > Public > www-rdf-logic@w3.org > August 2001

Re: XML Serialization

From: Dan Brickley <danbri@w3.org>
Date: Fri, 31 Aug 2001 15:11:08 -0400 (EDT)
To: pat hayes <phayes@ai.uwf.edu>
cc: <www-rdf-logic@w3.org>
Message-ID: <Pine.LNX.4.30.0108311501110.17596-100000@tux.w3.org>
On Fri, 31 Aug 2001, pat hayes wrote:

> >On Thu, 30 Aug 2001, pat hayes wrote:
> >
> > > >Now, why did the RDF WG chose XML instead of s-expressions or
> > > >something else elegant?  I wasn't there, but I love rumor mongering
> > > >and wild speculation.  Maybe they figured in the mood of the day, it
> > > >would give RDF a leg up.  And it probably did, with the librarians.
> > > >Perhaps it wasn more of a leg iron to the computer scientists, though.
> > >
> > > Quite, and elegantly put.
> >
> >
> >Some of the work that fed into the RDF design didn't use XML.
> >
> >eg: http://www.w3.org/TR/NOTE-pics-ng-metadata
> >(RDF's origins as a pornography description framework aka PICS-NG)
> >
> >or Guha's MCF stuff, http://www.guha.com/mcf/wp.html which itself went
> >through the XMLization process, http://www.w3.org/TR/NOTE-MCF-XML/
> >
> >Probably the main reason for XMLizing all this is so that RDF could be
> >mixed freely with other content, eg. embedded in SVG graphics, XHTML etc.
> >http://www.w3.org/TR/SVG-access/ and so it could embed fragments of other
> >markup languages (eg. MathML).
> Just as a technical point, I fail to follow the reasoning here. Is
> there an assumption that anything other than XML is inherently
> incapable of being mixed freely with, er, other content? MathML can
> be represented in almost any language capable of rendering labelled
> directed graph structures, surely?

It was a sociological point: in 1997 all the other W3C specs were
migrating towards XML as a common syntax; and XML was designed to allow
multiple namespaces to be mixed together in a single document. Sure, we
could have mixed curly and pointy brackets, but when you have as many
working groups producing Web content formats as W3C, picking a common
live-able-with format starts to look attractive.

BTW the W3C home page still shows an example of the old style PICS labels
embedded in (X)HTML:

	<meta http-equiv="PICS-Label"
	content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true for
	"http://www.w3.org/" r (cz 1 lz 1 nz 1 oz 1 vz 1)
	"http://www.rsac.org/ratingsv01.html" l gen true for "http://www.w3.org/"
	r (n 0 s 0 v 0 l 0))' />

The problem is that all this sub-structure is invisible from XML tools
(the DOM APIs etc).

> >You might ask why those folks use pointy brackets instead of curvy ones,
> >but that's not an argument worth having in 2001...
> The issue isn't the shape of the brackets (though it is kind of
> brain-damaged to choose the 'less-than' symbol as a bracket; it
> strongly suggests that none of the XML designers were mathematicians)
> so much as the gratuitous and wasteful use of four brackets and two
> labels and a slash, where two brackets and one label would do fine
> (not to mention that often, probably most of the time, you don't even
> need the label anyway.) And the fact that this point is so blindingly
> obvious to anyone with a modicum - nay, an infinitesimal grain - of
> experience with formal notations does give the XML hoopla a slightly
> sour note to many of us, I suspect.


Wasn't RDF's fault... ;-)

Received on Friday, 31 August 2001 15:11:08 UTC

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