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RE: Summary: URIs : How to find the ontologies behind them

From: <Patrick.Stickler@nokia.com>
Date: Thu, 10 Apr 2003 13:29:50 +0300
Message-ID: <A03E60B17132A84F9B4BB5EEDE57957B01B90CB7@trebe006.europe.nokia.com>
To: <www-rdf-interest@w3.org>



> -----Original Message-----
> From: ext Eli Israel [mailto:Eli@semanticworld.org]
> Sent: 10 April, 2003 11:59
> To: Stickler Patrick (NMP/Tampere)
> Subject: Summary: URIs : How to find the ontologies behind them
> 
> 
> Patrick,
> 
>    I'm intrigued by what you've written, but I want to make 
> sure that I
> understand it fully.  What do you mean by the term "web 
> authority of the
> URIref"?

Many (probably most) URI schemes define a web authority portion
in order to ground the URI in the well managed DNS space.

E.g. for http: URIs, the portion immediately following 'http://'
and preceeding the next '/' (if any) is the web authority. It
can be a domain name, an IP address, and have an optional port.

The web authority of http://sw.nokia.com/URIQA.html is 'sw.nokia.com'
which is a domain name that has a determinable owner.

Since there are clear social/legal mechanisms in place to determine
ownership/authority for such a web authority, one can presume that
ownership/authority is the same for any URI grounded in such a
web authority.

Of course, this is not written in stone in any spec, and unfortunately
falls into the domain of legal resolution (i.e. litigation). I.e.
some folks may disagree who owns a given URI (e.g. a server owner
may feel he owns any URI on the server, yet someone with a personal
web space (e.g. http://.../~joe) may feel he owns URIs in his personal
web space, etc. These issues are not (yet) crystal clear.

Nevertheless, for URIs which have a web authority, that web authority
clearly has the right to control interaction with that URI, namely,
which representations or descriptions can be accessed via that URI.
And control of the nature of and access to representations goes a long 
way towards proof of ownership of a given URI.

Cheers,

Patrick


> Eli
> 
> ----- Original Message -----
> From: <Patrick.Stickler@nokia.com>
> To: <pfps@research.bell-labs.com>; <Eli@semanticworld.org>
> Cc: <www-rdf-interest@w3.org>
> Sent: Thursday, April 10, 2003 9:40 AM
> Subject: RE: URIs : How to find the ontologies behind them
> 
> 
> 
> > > I'm primarily interested in the 'when the SW gets going'
> > case (it's about
> > > time we get it going, no? ;).  You seem to be saying that a
> > best practice
> > > would be to put the OWL describing the resource in the
> > place that the URI of
> > > the resource refers to.
> >
> > Not necessarily in that exact place.  However, most RDF URI
> > references have
> > fragment identifiers, so it would be possible for example to place
> > information about http://foo.ex/bar#bax in a document located at
> > http://foo.ex/bar.
> 
> Sorry. Unfortunately, no.
> 
> RDF fragment IDs do not work in exactly the same way as XML ID's.
> 
> You can describe the resource http://foo.ex/bar#bax in a dozen
> different RDF/XML instances, none of which are http://foo.ex/bar.
> And in all cases, you need not use rdf:ID ever. So even if
> http://foo.ex/bar#bax is defined by http://foo.ex/bar, that
> doesn't guaruntee that rdf:ID="bax" occurs anywhere in that
> RDF/XML instance.
> 
> And there is no assertion that http://foo.ex/bar#bax relates to
> a particular XML *element* in an RDF/XML instance having an
> rdf:ID="bax" even if the parser will map such an rdf:ID value
> to a URI based on an xml:base separated by '#'. rdf:ID is
> not defined as an XML ID attribute.
> 
> And in fact, though there should only be one occurrence of a given
> rdf:ID value for an xml:base scope, one can have descriptions using
> both rdf:ID and rdf:about about the very same resource in the same
> RDF/XML instance.
> 
> One should not think of URIrefs as working in RDF the same way
> as they do in an HTML browser. They don't.
> 
> Thus, just as one cannot reliably get to a namespace document
> from a URI, one cannot get to a definitive RDF/XML instance from
> a URIref.
> 
> *** TAKE NOTE: URIrefs are *fully opaque* in an RDF graph and SW
> *** agents operating on RDF expressed knowledge should not attempt
> *** to parse URIrefs to infer any relationships between the resource
> *** denoted by the URIref and any other resource that might share
> *** some intersection of some character sequence with the URIref.
> 
> The SW deals with RDF graphs, not RDF/XML instances, so
> one should not be concerned with aspects of the XML serialization
> when requesting knowledge from a knowledge base. And looking
> at URI vs. URIref or URI vs. namespace relations (neither of
> which can be reliably utilized) is the wrong way to go.
> 
> The SW architecture should provide for a standardized means by
> which, given a URIref, one can inquire from the web authority
> of the URIref (presuming there is one) for a description of
> the resource denoted by the URIref.
> 
> One can also inquire from various registries or other sources
> for non-web-authoritative descriptions of the resource, allowing
> for one to syndicate various views and opinions of the resource.
> 
> URIQA will provide for both.
> 
> > ... I think that the
> > relationship between ontologies and URI references is many to
> > many (and
> > many to many in interesting ways).
> 
> Agreed.
> 
> Patrick
> 
> --
> Patrick Stickler, Nokia/Finland, (+358 40) 801 9690,
> patrick.stickler@nokia.com
> 
> 
Received on Thursday, 10 April 2003 06:29:53 GMT

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