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Re: Clarifying what a URL identifies (Four Uses of a URL)

From: Michael Mealling <michael@neonym.net>
Date: 21 Jan 2003 14:44:19 -0500
To: Sandro Hawke <sandro@w3.org>
Cc: Tim Bray <tbray@textuality.com>, David Booth <dbooth@w3.org>, www-tag@w3.org, "Roy T. Fielding" <fielding@apache.org>, Dan Connolly <connolly@w3.org>
Message-Id: <1043178259.23504.127.camel@blackdell.neonym.net>

On Tue, 2003-01-21 at 14:37, Sandro Hawke wrote:
> > On Tue, 2003-01-21 at 13:59, Tim Bray wrote:
> > > David Booth wrote:
> > > >   Quoting from the abstract:
> > > > 
> > > > [[
> > > > URLs can be used to identify abstract concepts or other things that do 
> > > > not exist directly on the Web. This is sensible, but it means that the 
> > > > same URL might be used in conjunction with four different (but related) 
> > > > things: a name, a concept, a Web location or a document instance. 
> > > > Somehow, we need conventions for denoting these four different uses. Two 
> > > > approaches are available: different names or different context. 
> > > 
> > > I remain unconvinced.  One of the strengths of the Web architecture is 
> > > its uniform naming framework where URIs identify resources and yield 
> > > representations of them, and resources can be anything ranging  web 
> > > pages to schools of philosophy.  The Web Architecture has no built-in 
> > > way to talk about what a Resource "is", and seems to get by just fine. 
> > > RDF is all about talking about what a resource is.  If you need to know 
> > > what kind of thing a resource is, publish some RDF assertions to that 
> > > effect.  What am I missing?
> > > 
> > > Now, I think that a nice pre-cooked RDF vocabulary of general categories 
> > > of things that resources can be - your note being a first step to that - 
> > > is quite likely worth investing in.  But Web Architecture in the large 
> > > doesn't depend on it at all.  -Tim
> > 
> > I'd like to recommend that what Tim just said be in the architecture
> > somewhere. Its succinct, clear and unambiguous....
> 
> And misleading to the point of being incorrect, IMHO.   :-)   

Awe come on, say how you truly feel! ;-)

> URIs are strings which are used for different things in different
> situations, in a manner controlled by the semantics of the situation.

That's very true, but completely orthogonal to what Tim said above.

> There is no single thing identified by a URI in all situations.  The
> notion that there is or should be exactly one conceptual thing
> corresponding in all situations in some standand way to each URI (that
> the URI is a logical symbol with a single denotation) is a fallacy
> which causes the httpRange-14 rat-hole.  And it's not necessary to
> understand URIs, HTTP, REST, etc, as pointed out by Joshua Allen [1].

Its not a fallacy. Its merely insufficient when you are within some
system's set of semantics that requires that function. URIs exist
outside any set of semantics you may require for the time being. Since
they do and the only information that exists across contexts is that a
URI identifies a Resource and two URIs identify two Resources, etc then
your statement and Tim's is still orthogonal. The httpRange-14 problem
is not a problem with URIs, its a problem with the context that contains
"the HTTP protocol, the 'http:' URI scheme, XML, HTML and web browsers".
If you're not in that particular context then there isn't a problem.
Thus the problem isn't with URIs but how they're being used in that
context. Not everyone is using the same context....

-MM
Received on Tuesday, 21 January 2003 14:47:03 GMT

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