W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > February 2002

Re: URIs vs. URIviews (Pat's questions)

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Tue, 19 Feb 2002 14:10:00 -0600
Message-Id: <p05101408b8985e371987@[65.212.118.219]>
To: Aaron Swartz <me@aaronsw.com>
Cc: w3c-rdfcore-wg@w3.org
>Hope you don't mind if I consolidate your questions into one message...
>
>On 2002-02-18 4:19 PM, "Pat Hayes" <phayes@ai.uwf.edu> wrote:
>
>>  I fear to tread in these waters, but could this be resolved by
>>  regarding RDF as being like a media type? That is, RDF applications
>>  will treat fragment IDs in a particular RDF-ish way, as far as the
>>  rest of the Web is concerned (so the view from RFC 2369 is that RDF
>>  is a media type) but in fact are treated uniformly by RDF in the
>>  privacy of its own application environments (thus satisfying the RDF
>>  feeling of freedom expressed in the first quote.)
>
>This seems to me like just continuing RDF's charade of living in its own
>little world.

No, the point is to allow RDF to live in a much bigger world. RDF 
graphs can be about *anything*, even things that are not remotely 
like documents, and cannot possibly be 'on' any kind of web (things 
like unicorns and galaxies.) But that means that RDF (and other) 
ontologies must be able to *use* (not refer to) names inside other 
ontologies. Just pointing to a document is far too coarse-grained an 
access mechanism to support the conceptual precision that an ontology 
language needs.

>I thought the idea was to have RDF describe the Resources in
>the rest of the Web,

and the resources in distant galaxies, or inside possible worlds (as 
in action planning and counterfactual reasoning), or in a moving Army 
vehicle in Afghanistan, or in the past or future. NOT (just) the 
things that are whisked around on the current web and used to make 
colored patterns on screens.

>not to create it's own sense of Web Resources and
>describe that. If we're going to create our own little world, why not go the
>whole way?

I want to go the whole way, but to describe the entire universe, not 
just documents and GIF images.

>
>>  What is an abstract resource?
>
>I meant a Resource in the general RFC2396 sense of the word. I know you have
>problems with this definition, but "anything with identity."

IE anything whatsoever, right? (Name me something that doesn't have 
an identity.) OK, Im taking that idea at its face value, to mean 
*anything*. I want to be able to name *anything* that is named in any 
other ontology, for sure. I want to say more in my ontology about 
some thing that is named in another RDF ontology, and that ontology 
is in a document with a URI.  How do I get to that one name, without 
somehow adding something to the URI to tell the RDF ontology which 
name Im using?

>I believe
>fragments are restricted, because they are based on a retrieval action
>(getting back some bits).

Thats a use/mention confusion. The fragment isn't the thing, its a 
NAME FOR the thing. Its the names that we need to be able to identify.

>
>>  RFC2396 seems to be pretty clear that frags, while not technically
>>  part of the URI, are expected to be used with URIs
>
>Of course, as it states:
>"""
>    The term "URI-reference" is used here to denote the common usage of a
>    resource identifier.  A URI reference may be absolute or relative,
>    and may have additional information attached in the form of a
>    fragment identifier.  However, "the URI" that results from such a
>    reference includes only the absolute URI after the fragment
>    identifier (if any) is removed and after any relative URI is resolved
>    to its absolute form.  Although it is possible to limit the
>    discussion of URI syntax and semantics to that of the absolute
>    result, most usage of URI is within general URI references, and it is
>    impossible to obtain the URI from such a reference without also
>    parsing the fragment and resolving the relative form.
>"""
>  - RFC 2396, section 4

Right, another passage that seems to make my point rather than yours, 
in its last sentence.

Pat

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Received on Tuesday, 19 February 2002 15:10:08 EST

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