W3C home > Mailing lists > Public > www-rdf-interest@w3.org > December 2001

Re: Namespaces wihtout "#" Was: Few CWM Bugs

From: Jonathan Borden <jborden@mediaone.net>
Date: Sat, 22 Dec 2001 10:39:27 -0500
Message-ID: <004701c18afe$d9282e60$0301a8c0@ne.mediaone.net>
To: "Tim Berners-Lee" <timbl@w3.org>, "Dan Brickley" <danbri@w3.org>
Cc: "Sean B. Palmer" <sean@mysterylights.com>, "Dan Connolly" <connolly@w3.org>, <www-rdf-interest@w3.org>
Tim Berners-Lee wrote:
> >
> > > The second issue is more significant.   In my worldview,
> > > (which I claim to be (a) consistent and (b) useful)
> > > http://example.org/x is a document.  You can't reuse
> > > its URI for an abstract thing without a change to HTTP.
> >
> > In-principle plausible, although _please_ define "document".
>
> I uyse the term "document" because unfortunately "resource" has been
> used differently in URI and RDF specs.   I mean by "document"
> "resource" as in URI.   DAML uses the term "Thing" to mean what RDF
> terms a resource.

This is really helpful, yet when I read the RFC 2396 definition of a
resource I don't see how a resource can be _limited_ to only things which
are documents:

"A resource can be anything that has identity. Familiar examples include an
electronic document, an image, a service (e.g., "today's weather report for
Los Angeles"), and a collection of other resources. Not all resources are
network "retrievable"; e.g., human beings, corporations, and bound books in
a library can also be considered resources. "

This language clearly states, to my very best reading, that a _document_ is
a subClass of a _resource_ and a _human being_ is another subClass of
_resource_. This is why I cannot understand why a plain old URI (i.e.
without fragment identifer)  cannot identify a person. Perhaps you are
saying that the _type_ of resource is indicated by the URI scheme? i.e. that
people would be indicated e.g.

person://smith/joe

>
> When the content-type is RDF or N3, then a document can be used
> to describe people and planes and ideas.  These can be identified
> (in N3) by using the localname of concept within the document
> as a fragment identifier.  (I think the same should be true of RDF/XML).

Ok, I buy this. Here you say that people, places and things can be
identified by URI References. This still does not solve the problem that RFC
2396 says what URIs themselves may identify...
>
> >.The distinction
> > is only useful if it can be defined clearly enough to implement to.
>
> Well,  you certianly can't return a person across the net, so the
> distinction is
> not that fine ;-)

Again, RFC 2396 explicitly does not limit resources to things that are
network retrievable, so I need more guidance here.

Perhaps the problem is that many people treat RFCs as axioms and in trying
to understand how 'logic on the Web' will work in practice, inconsistencies
are problematic.

Jonathan
Received on Sunday, 23 December 2001 07:25:45 GMT

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