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Re: about, rdf:ID and anonymous resources

From: Arnold deVos <adv@langdale.com.au>
Date: Thu, 5 Oct 2000 19:19:52 +1100
Message-ID: <001101c02ea5$0f50a9c0$fa2d18cb@cockatoo>
To: "McBride, Brian" <bwm@hplb.hpl.hp.com>, "'Pierre-Antoine CHAMPIN'" <pachampi@caramail.com>, <www-rdf-interest@w3.org>
Hi,

As it happens, this issue came up for a group of us in the utility industry.
We are proposing to use RDF to exchange models of power systems.  To do this
more easily we have defined a subset of RDF syntax.

When defining this subset I felt obliged to preserve both rdf:id and
rdf:about.  But perhaps rdf:id is unnecessary because rdf:id="foo" gets
treated as rdf:about="#foo" except that you are only allowed one of the
former but many of the latter for a resource.  That feature of rdf:id is
actually an annoyance sometimes.

Anyway, as far as I can see, there is no such thing as "defining" a
resource.  They just "are".

- Arnold

PS If anyone is interested in how we subset RDF syntax or why we would want
to do that, or what a power system looks like in RDF form, see

http://www.langdale.com.au/XMLCIM.html

There is actually quite a large schema and sample population to play with...


----- Original Message -----
From: "McBride, Brian" <bwm@hplb.hpl.hp.com>
To: "'Pierre-Antoine CHAMPIN'" <pachampi@caramail.com>; "McBride, Brian"
<bwm@hplb.hpl.hp.com>; <www-rdf-interest@w3.org>
Sent: Thursday, October 05, 2000 12:55 AM
Subject: RE: about, rdf:ID and anonymous resources


> > I still have some problem with that ID thing.
>
> Me too.  I guess this another one for the issues list if
> its not there already.
>
> I didn't pick up anything explicit in trawl through the
> archives, though I'm sure there has been previous
> discussion.  The closest thing is the "what does
> for.bar#x identify".
>
> I'll add it to my working list of issues and pointers.
>
> Brian
>
>
> >
> > What exactly is the point of writing, in a file foo.rdf
> >  <rdf:Description ID="bar">
> > As I understand it, it "defines" the resource
> >  foo.rdf#rdf
> > So, why not simply write
> >  <rdf:Description about="#bar">
> > Again, as I understand it, this is because the fragment
> > id "bar" does not exist in the file foo.rdf,
> > so rdf:ID allows to define AND describe it.
> >
> > Well, the fragment id "bar" does not exist in foo.rdf. So
> > what ? Most of the time, rdf:ID is used (as far as I know)
> > for classes or properties: resources that are abstract by
> > essence, that can not be retrieved anyway ! Naming them
> > foo.rdf#bar or whatever is nothing but a convention.
> >
> > Defining a fragment id allows the URI of the resource to
> > return the description of the resource ; but the
> > description is a PROPERTY of the resource, not the resource
> > itself. The metaporperty rdfs:isDefinedBy is intended for
> > that, and XPointer allows to point to any rdf;Description
> > tag in a more standard way.
> >
> >  T(rdfs:isDefinedBy, my_resource, foo.rdf#xpointer(...))
> >
> > So, did I miss something about rdf:ID ?
> >
> >  Pierre-Antoine
> > ______________________________________________________
> > Bote aux lettres - Caramail - http://www.caramail.com
> >
> >
Received on Thursday, 5 October 2000 04:33:51 GMT

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