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Re: URI for abstract concepts (domain, host, origin, site, etc.)

From: Martin J. Dürst <duerst@it.aoyama.ac.jp>
Date: Mon, 29 Jun 2009 16:35:34 +0900
Message-ID: <4A486EC6.8080101@it.aoyama.ac.jp>
To: Xiaoshu Wang <wangxiao@musc.edu>
CC: Dan Brickley <danbri@danbri.org>, Larry Masinter <LMM@acm.org>, "'Pat Hayes'" <phayes@ihmc.us>, "'Eran Hammer-Lahav'" <eran@hueniverse.com>, "'Dan Connolly'" <connolly@w3.org>, "apps-discuss@ietf.org" <apps-discuss@ietf.org>, "www-tag@w3.org" <www-tag@w3.org>, "'URI'" <uri@w3.org>
On 2009/06/29 0:02, Xiaoshu Wang wrote:
> Martin J. Dürst wrote:
>> On 2009/06/27 3:36, Xiaoshu Wang wrote:
>>> Thus,
>>> "http://danbri.org/foaf.rdf#danbri" denotes a person.
>>> "http://danbri.org/foaf.rdf#(application/rdf+xml)danbri" denotes an RDF
>>> node.
>>> "http://danbri.org/foaf.rdf#(application/xhtml+xml)danbri" denotes an
>>> HTML element ided "danbri
>> I don't understand this. Why wouldn't I just use
>> http://danbri.org/foo.html#danbri
>> or anything similar for HTML fragments? (I'm assuming that foaf.rdf
>> returns an application/rdf+xml documend, and foo.html returns an
>> application/xhtml+xml document; the extensions may be meaningless to
>> the protocol but help to keep things apart for humans and computers.)

> Well, then it just doesn't work for extending the referential range of
> URI to denote things beyond engineering entities. If you take a URI
> (fragment or not) to denote document (or its sub-structure), then the
> Web is not much useful to our daily use. If you take a URI to denote
> other things, like a human or person, then you cannot describe a
> document structure. And there is one URI, then you have to make a
> decision which one it denotes, right?

Yes, each URI better denotes only one thing. But that doesn't mean that 
all URIs (with fragment identifiers) denote subdocuments, and it doesn't 
mean that all URIs (with fragment identifiers) denote 'other things'. It 
means that each individual URI denotes either one or the other, and that 
you find out which one (if you need to) by getting more information 
about it.

>> Also, I don't see much of a need to denote an RDF node per se. I'm
>> sure there are special applications one can come up with where
>> reasoning about RDF nodes per se is helpful/necessary/whatever, but
>> for such cases, there are other techniques available already. A single
>> special property and blank nodes would do the job.
> Sure, we can use special property and blank nodes, but don't we need to
> know a URI does first before applying a property to that right?

People who 'apply properties' to URIs (which I assume you mean to add 
properties about an URI) will know an URI from other information or 
because they created the URI and decided what they want to use it for. 
People who see an URI for the first time have to find out what it stands 
for either from context or from dereferencing (or probably from both).

Regards,   Martin.
#-# Martin J. Dürst, Professor, Aoyama Gakuin University
#-# http://www.sw.it.aoyama.ac.jp   mailto:duerst@it.aoyama.ac.jp
Received on Monday, 29 June 2009 07:36:47 UTC

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