W3C home > Mailing lists > Public > www-tag@w3.org > August 2003

RE: resources and URIs

From: <Patrick.Stickler@nokia.com>
Date: Mon, 4 Aug 2003 12:46:51 +0300
Message-ID: <A03E60B17132A84F9B4BB5EEDE57957B5FBC1A@trebe006.europe.nokia.com>
To: <timbl@w3.org>, <Norman.Walsh@Sun.COM>
Cc: <www-tag@w3.org>


	-----Original Message----- 
	From: ext Tim Berners-Lee [mailto:timbl@w3.org] 
	Sent: Fri 8/1/2003 12:38 AM 
	To: Norman Walsh 
	Cc: www-tag@w3.org 
	Subject: Re: resources and URIs

	> If I used "#" instead of "/" it would be practically impossible to get
	> the RDF that described each word (it would mean downloading the
	> *entire* Word Net database as a single document and extracting the
	> relevant bit). Technically better, perhaps, but practically impossible
	> given the size of Word Net.
	I would suggest for this corner case downloading a file which
	gives instructions in some rule language as to where to find
	the word in question.


Sigh... hacks upon hacks. So much for simple, consistent, portable behavior.

So when each web site uses a different rule language to tell how to obtain a representation of a resource that one could simply GET if not mis-using a fragment identifier an agent must support every such language to interact with arbitrary sources of knowledge.

No thanks.

	I wonder what Cyc does.
	Other good things to do include responding with something which says
	that the is a service available for querying for things of this form.

Value added interfaces, tools, functionality, etc. is great, but should be optional and not the only means of obtaining representations of resources. The same is true for obtaining descriptions of resources. Having a powerful, general RDF query interface provided by some web server to execute complex queries about resources relevant to that server is great, but should not be necessary for obtaining basic descriptions of particular resources.

	I would note that word net is a set of words but does not see, to be a
	RDF ontology like cyc.  It is more a set of english words.

What does it matter *what* the resources are. They are resources for which it is useful to provide representations which are available via the web. And therefore, there should be nothing wrong with using http: URIs without fragment identifiers to denote them, even if they are abstract concepts or terms.

	I agree it is nice to have URIs for them, though.


Ahhh, a glimmer of hope...  ;-)

	It is not a normal case at all.

What is not a normal case? That abstract resources be denoted by URIs without fragment identifiers? I'd say that is both a very common and a very normal case.

	The document is a bit weird:
	    <Aarhus>     a :Class;
	          :description "port city of Denmark in eastern Jutland";
	          :label "Aarhus";
	          :subClassOf <> .
	Aarhus is a class, says the RDF, and  city, says the description.
	Apart from their weird use of class and subClass, though....
	Aahus is a subclass of the document.
	The empty URIref <> always refers to the current document.
	It is actually defined that way in the URI spec.
	So the problem of doing it this way is apparent immediately.

The quality of the representation provided is completely irrelevant to the issue at hand, about whether a URI without fragment identifier could/should be used to denote arbitrary resources.

If the WordNet RDF is broken, they should fix it. That doesn't mean that their use of URIs without fragment identifiers to denote their terms is in any way "problemmatic".

	> The fact that I can GET http://xmlns.com/wordnet/1.6/City and retrieve
	> RDF that defines "City" is so valuable, I'm quite willing to live with
	> the contradiction that if you choose to assert axiomatically that
	> http://xmlns.com/wordnet/1.6/City must be a document, you're saying
	> that the URI is both a city and a document.
	We have different priorities.  You are happy to make the whole system
	inconsistent because something is convenient in a corner case.
	I am not.  I'd prefer to do though more hoops in the wordnet case.

I see nothing inconsistent in Norman's view, nor any need to introduce a contradiction by axiomatically presuming that all resources denoted by http: URIs without fragment identifiers denote "information resources".

http://xmlns.com/wordnet/1.6/City  denotes a resource. One may obtain representations of that resource using HTTP. One should ideally be able to obtain a description of that resource using URIQA. There is no inconsistency. So long as you don't try to impose some artificial constraint on the nature of resources denoted by certain types of URIs.


Received on Monday, 4 August 2003 05:47:16 UTC

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