RE: Range of URI+fragment dereference function (new issue?)

Dan,

> If the question is
> 	What do URI references refer to?
> the answer is:
> 	They're abbreviations for URIs,
> 	which refer to resources.

What URI is the URI reference http://example.com#myCar an abbreviation of?

Thanks

Stuart
--

> -----Original Message-----
> From: Dan Connolly [mailto:connolly@w3.org]
> Sent: 15 August 2002 19:56
> To: Paul Prescod
> Cc: www-tag@w3.org
> Subject: Re: Range of URI+fragment dereference function (new issue?)
> 
> 
> 
> On Thu, 2002-08-15 at 13:10, Paul Prescod wrote:
> > Dan Connolly wrote:
> > > 
> > > ...
> > > 
> > > But there is, I think, a fairly simple and appealing
> > > architectural view in which http://example#foo
> > > is in the same class as http://example, but
> > > ../foo is in a very different class from
> > > http://example#foo . Does this rendition of it appeal to you?
> > 
> > What is the range of the URI REF dereference function?
> 
> 'URI REF'? I'm not sure what you mean by that.
> 
> If the question is
> 	What to URIs refer to?
> 
> the answer is:
> 	resources. Uniform Resource Identifiers identify resources.
> 
> If the question is
> 	What do URI references refer to?
> the answer is:
> 	They're abbreviations for URIs,
> 	which refer to resources.
> 
> 
> > For example, the document says "In the case of a graphics 
> format, a URI
> > reference might designate a circle or spline.". Does it designate a
> > "circle or spline" or circle _element_ or spline _element_.
> 
> Uh... it said 'circle or spline'; if it meant circle element,
> it should have said so. Or at least it should have made
> a disclaimer ala:
> 
>   "It is convenient to adopt a familiar abuse of terminology
>   and identify a single triple with the graph consisting of
>   the singleton set containing that triple."
> 	-- http://www.w3.org/TR/rdf-mt/
> 
> Part 1 of the XML Schema spec is extremely explicit about
> when it means a schema component versus when it means
> an element describing a schema component. Some readers
> hate this, but I'm not sure we could have been sufficiently clear
> otherwise.
> 
> > For
> > instance, given two different elements I know that they are really
> > different. I can infer distinctness just by virtue of the 
> fact that XML
> > elements have unique identity.
> 
> Really? Where is XML element identity defined?
> Not from the XML 1.0 spec, and not from the infoset spec.
> 
> The XML Query specs almost specified identity
> for XML elements, but then the weasled out:
> 
>   Message-ID: <3AD5C1F9.B042A733@w3.org>
>   Date: Thu, 12 Apr 2001 09:55:53 -0500
>   From: Dan Connolly <connolly@w3.org>
>   To: www-xml-query-comments@w3.org
>   Subject: XML query constructors: not well-defined
>  
> http://lists.w3.org/Archives/Public/www-xml-query-comments/200
> 1Apr/0014.html
> 
> WG reply:
> http://lists.w3.org/Archives/Public/www-xml-query-comments/200
> 1May/0003.html
> 
> You can tell that XML elements are distinct by looking at their
> infoset properties, meanwhile, which is perhaps sufficient
> for the point you were making...
> 
> > But two splines might be "the same" in
> > some SVG sense. Perhaps that is inferrable from the rules of SVG or
> > perhaps it needs to be explicitly asserted. Either way, 
> identity for an
> > SVG abstraction is different than identity for an XML abstraction.
> 
> Yup.
> 
> > Similarly, I would expect an SVG circle to have a "radius" property
> > whereas an XML "circle element" could at best have an "attributes"
> > property with a "radius" attribute information item in there.
> > 
> > I think that it is dangerous to declare that the referent is the SVG
> > abstraction and not the XML abstraction because how then do 
> I talk about
> > the XML element?
> 
> This doesn't generalize to formats that aren't XML based. You'd
> agree we want to talk about postscript pages, PNG pixels
> and regions, MPEG frames, etc, no?
> 
> I agree this is an important issue, though.
> In my most recent writing-and-noodling on all this,
>   http://www.w3.org/2001/tag/doc/ures14
> I didn't get around to elaborating "pointing to elements
> vs. pointing to things." It has come up before
> in discussions of mapping XLink <-> RDF.
> 
> Hm... I wonder if TimBL touched on it in...
>   http://www.w3.org/DesignIssues/XLink
> ... no, not really...
> 
> I think this belongs on the TAG issue list.
> It's been suggested that there are two kinds of dereferencing:
> xlink:href-style, for pointing at parts of documents,
> and rdf:resource-style, for pointing at things described
> by or mentioned in documents. A new tdb: URI scheme
> (thing-described-by) has been suggested.
> I'm not comfortable with either of those solutions, yet,
> but I agree it merits investigation.
> 
> I keep thinking
> I should capture the RDF/XLink issue in a test case, but
> I haven't gotten around to it yet.
> 
> > The grove view is that by default we address elements and 
> explicitly ASK
> > to address beyond elements into other layers of abstractions.
> 
> Hmm... the grove view assumes everything has element structure?
> 
> > I think
> > the Web needs to formalize its view.
> 
> Maybe, but maybe not. Maybe we don't need any more constraints
> here.
> 
> > >...
> > > > and if I have a resource identified
> > > > by the URIRef 
http://example.com/someResource#otherResource, how do I
> > > reference a fragment of that resource (assuming it has one)?
> > 
> > OK, assuming it has one, I can coin a new URI
> > 
> >   mid:2002-08-14.thismessage@w3.org#abc
> >         (pretend that's the MID for this message)
> > 
> > to refer to it.
> 
> But we've lost the benefits of the HTTP URI scheme.

How so?

> If resources can
> have resources as fragments then it only makes sense that the syntax
> should have first-class support for it:
> 
> http://example.com/someResource#otherResource#anotherResource
> 
> Historically, fragments pointed at things that were NOT resources

Really? Where is that documented?
The documentation I'm aware of says that everything with identity
is a resource, so of course the things fragments point to
are resources.

> so
> there was no issue of recursion.

I don't think that changing the words used to describe a concept
makes issues go away. Either first-class syntax support for
fragment composition is and issue or it's not. I think
it is an issue, but it's acceptable, at least so far,
that the Web doesn't have it.

I think COM Monikers have complex composition; I'm not sure if
every COM Moniker is composable with every other or if
there are limits.




> -- 
> "When I walk on the floor for the final execution, I'll wear a denim 
> suit. I'll walk in there like Willie Nelson, John Wayne, Will Smith 
> -- Men in Black -- James Brown. Maybe do a Michael Jackson moonwalk."
> Congressman James Traficant.
-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/

Received on Friday, 16 August 2002 11:19:12 UTC