W3C home > Mailing lists > Public > www-rdf-interest@w3.org > February 2000

Re: A certain difficulty

From: David Megginson <david@megginson.com>
Date: Fri, 25 Feb 2000 06:06:05 -0500 (EST)
Message-ID: <14518.25117.609557.332649@localhost.localdomain>
To: xml-dev@xml.org, www-rdf-interest@w3.org
Pierre-Antoine CHAMPIN writes:

 > I would not say that either !
 > I find the RDF model very simple and uniform (it's all about triples)
 > which makes its elegance... and for some people its weakness !

Unfortunately, it's not about triples.  The only way to discover the
true RDF data model is to reverse-engineer it from the XML, and it
turns out that there are at least six components (not three) in each

  subjectType (global id, local id, URI pattern)
  objectType (literal text, literal XML markup, reference)

These are not simply syntactic artifacts -- it's information that
*must* be exposed through any RDF API, and thus, part of the core
model, independent of the peculiarities of the XML markup (note that
I'm assuming that bagID, etc. are predigested).  The URI patterns
(aboutEachPrefix), especially, make it much trickier to do any
relational database implementation of RDF, since you the set of
possible subjects is open.

 > In the contrary, the XML syntax is a bit confuse, true.

Yes, it is also unnecessarily confusing.

 > In my point of view, the problem comes from the recommandation
 > mixing modeling and syntaxic aspects (I won't mention semantic
 > aspects !)  in a way it's hard to differentiate them without some
 > RDF experience.

The problem is that the model as presented is naively simple, and the
WG failed to notice that the XML syntax is not based directly on that
simple model.

All the best,


David Megginson                 david@megginson.com
Received on Friday, 25 February 2000 06:07:18 UTC

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