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Re: Fragment identifiers and intermediaries

From: Christopher B Ferris <chrisfer@us.ibm.com>
Date: Fri, 26 Jul 2002 16:04:18 -0400
To: www-tag@w3.org
Message-ID: <OFA4572E7A.F544EF31-ON85256C02.0063F08A@rchland.ibm.com>


Mark Baker wrote:

> On Fri, Jul 26, 2002 at 09:48:00AM -0700, Joshua Allen wrote:
> > Can you please elaborate on how you believe RDF to be related to
> > *accessing* a resource?

> Well, RDF is what you get when you access a resource.

No, it is not.

It might be, but only if the origin server decides that "RDF" is the
representational form that will be returned for the resource identified.
Of course, there are a number of *different* representations of RDF
(RDF/XML, N3, NTriples). Given that there appear to be no registered
media types (and their formal specification) for any of these, it isn't
at all clear to me that the fragment identifier has any meaning at all,
given that its interpretation is based on the rules defined for the
media type of the representation retrieved (RFC2396).

If the "RDF" is returned as text/plain, then the fragment identifier
is meaningless. If it is returned as 'application/xml', it is equally
meaningless since RFC3023 doesn't specify any fragment id mechanism,
but defers to the WD of XPointer which doesn't seem to have any
rules for naked fragment identifiers. These seem only to have conventional
interpretation as meaning, "some element that has an attribute that is
of type ID that has the same value as the fragment identifier". Of course,
RDF doesn't have a DTD, and hence it isn't at all clear to me that
even if expressed as:
      http://mumble/#xpointer(id("foo"))
or
      http://mumble/#id("foo")
That it would have any meaning that an XML parser could infer on its
own because absent any DTD processing, there's nothing to tell the
parser that rdf:ID is supposed to be an XML ID.

      http://mumble/#xpointer(/decendent::*/[@rdf:ID="foo"])
might be meaningful if the namespace qualifier of the RDF namespace
happened to be 'rdf', so in truth, the only possible meaningful
fragment identifier would be something like:
      http://mumble/#xmlns(rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns#)
xpointer(/decendent::*/[@rdf:ID="foo"])

And then, there's the issue of getting the same fragment identifier rules
to apply to all possible representations of the identified resource, which
would seem to exclude using XPointer since that's XML specific and RDF
is not exclusively represented as RDF/XML.

But, I digress:)

Cheers,

Christopher Ferris
Architect, Emerging e-business Industry Architecture
email: chrisfer@us.ibm.com
phone: +1 508 234 3624
Received on Friday, 26 July 2002 16:09:14 GMT

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