W3C home > Mailing lists > Public > uri@w3.org > May 2001

Re: Are URI-References bound to resources?

From: Roy T. Fielding <fielding@ebuilt.com>
Date: Fri, 11 May 2001 13:23:24 -0700
To: Dan Connolly <connolly@w3.org>
Cc: Aaron Swartz <aswartz@upclink.com>, uri@w3.org
Message-ID: <20010511132324.C13361@waka.ebuilt.net>
> > This seems to imply that URI references (that is, URIs with fragment
> > identifiers) are not bound to a resource themselves.
> 
> Careful... it does not imply that URI references are
> bound to resources; but nor does it imply that they are *not*
> bound to resources. RFC2396 is silent on what
> a URI reference is bound to.

Eh?  It is a resource identifier. It identifies resources.

> > Instead, the only
> > resource involved is that of the absolute URI itself.
> > 
> > Is this interpretation correct?
> 
> I don't think so; I think you're reading more into RFC2396
> than is there. (you're certainly not the first, and
> I don't expect you'll be the last.)

No, that is correct.  At no time whatsoever is the resource transferred
across the network when doing a GET.  Only a REPRESENTATION of that resource
is transferred, and the fragment refers to a target within the representation
and not within the resource.  That is why fragments are media-type specific.

> > If so, it would have serious consequences
> > for many RDF specifications.
> 
> RDF isn't the only spec that extends the domain
> of the URI->resource mapping; XLink does too--
> er... it did in earlier drafts... I pointed
> that out in a review comment... during last call,
> I think; they seem to have changed their mind since then...
> 
> [[[
> The notion of resources is universal to the World Wide Web. [Definition:
> As
> discussed in [IETF RFC 2396], a resource is any addressable unit of
> information or service.] Examples include files, images, documents,
> programs, and query results. The means used for addressing a resource is
> a URI (Uniform Resource Identifier) reference (described more in 5.4
> Locator Attribute (href)). It is possible to address a portion of a
> resource.
> ]]]

That definition is wrong.  So are the definitions used by RDF.  That's
why they keep having semantic problems with the Web.

> Keep in mind that RDF 1.0 was finished Feb 1999,
> just a few months after RFC2396 in Aug 1998. It would
> seem perfectly reasonable to do an editorial revision
> of RDF to make a new term for what RDF 1.0 calls 'resource',
> and use 'resource' to mean just what RFC2396 defines
> it to mean.

Dude, I finished the definition of resource a long time before RFC 2396
was published -- it was in the November 1997 draft.  And even that was
just a rewording of the "HTTP object model" (now called the REST architectural
style) that I was working on back in 1995 during our whiteboard discussions
at the W3C.

> TimBL went that way in some code he wrote recently;
> he uses 'Thing' for the class of things that includes
> resources *and* things denoted by absolute-uris-with-fragments:

Just shoot me.  Its my fault for not sending you guys a copy of my
dissertation when I was writing it.  I didn't realize that we had diverged
so far from a common model.

....Roy
Received on Friday, 11 May 2001 16:26:51 UTC

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