W3C home > Mailing lists > Public > www-rdf-interest@w3.org > February 2004

Re: URI: Name or Network Location?

From: Benja Fallenstein <b.fallenstein@gmx.de>
Date: Wed, 18 Feb 2004 20:53:34 +0200
Message-ID: <4033B4AE.4060304@gmx.de>
To: "Rhoads, Stephen" <SRhoads@ThruPoint.net>
Cc: "'www-rdf-interest@w3.org'" <www-rdf-interest@w3.org>

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Rhoads, Stephen wrote:
| Supposed I define an ex:TelevisionSeries called Sopranos and assign it a
| URI:
|
| <ex:TelevisionSeries rdf:about="http://www.hbo.com/Sopranos">
|    <ex:Title>The Sopranos</ex:Title>
| </ex:TelevisionSeries>
|
| But then when you dereference the URI, you get back a webpage.  So
what does
| the URI refer to, the Sopranos, or a webpage *about* the Sopranos?

Supposing that you own www.hbo.com and thus have the authority to say
what the URI means, it referes to the television series, not the web
page, because you have just said so. (Providing that ex:TelevisionSeries
is not defined in a really strange way, of course.)

| Maybe I want to make statements about the webpage:
|
| <ex:Webpage rdf:about="http://www.hbo.com/Sopranos">
|    <ex:homepageOf rdf:resource="http://www.hbo.com/Sopranos"/>
|    <ada:accessibilityRating>Good</ada:accessibilityRating>
| </ex:Webpage>
|
| So "http://www.hbo.com/Sopranos" is both an ex:TelevisionSeries and an
| ex:Webpage about itself.  That doesn't seem right.

You have to assign a different URI to the webpage.
http://www.hbo.com/Sopranos/home, say. This can solve to the same
representation as the URI for the series; you can use an HTTP
Content-Location header when serving http://www.hbo.com/Sopranos
(causing relative URIs to work right).

For the benefit of your human readers, you may want to include a
statement in small print at the bottom of your page, stating which URI
refers to which thing.

| OK, so maybe I change my URI so that it does not resolve:
|
| "http://www.hbo.com/names/Sopranos"
|
| And when you try to dereference it you get back 404.  That I can live
with.
| But, per the below, you are suggesting that the server fall back to
| providing an RDF description of the URI.  So we are back to original
problem
| -- what is described, the TelevisionSeries or the information resource
which
| is returned.

As an HTML description can in human terms, an RDF description can say in
triples which URI refers to which. E.g.,

<ex:TelevisionSeries rdf:about="http://www.hbo.com/names/Sopranos">
~    <hopp:describedBy
~        rdf:resource="http://www.hbo.com/metadata/Sopranos"/>
</ex:TelevisionSeries>

You can then serve the same RDF data at both of these URIs.

| So maybe we *don't* fall back to returning an RDF description and all
I get
| is 404.  And so I go ahead and issue an MGET to the server for the URI and
| get back an RDF description.  That I *do* like, because I am essentially
| saying "give me the metadata you have for this URI" rather than "give me a
| representation of this URI".

That's also fine, of course.

- - Benja
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Received on Wednesday, 18 February 2004 13:53:49 UTC

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