W3C home > Mailing lists > Public > www-rdf-rules@w3.org > November 2003

RE: RDF query and Rules - my two cents

From: Danny Ayers <danny666@virgilio.it>
Date: Thu, 20 Nov 2003 12:52:44 +0100
To: "Patrick Stickler" <patrick.stickler@nokia.com>
Cc: <www-rdf-interest-request@w3.org>, "Graham Klyne" <GK@ninebynine.org>, "Jim Hendler" <hendler@cs.umd.edu>, "Dan Brickley" <danbri@w3.org>, <www-rdf-rules@w3.org>, <www-rdf-interest@w3.org>
Message-ID: <BKELLDAGKABIOCHDFDBPOEJCEIAA.danny666@virgilio.it>

> > I haven't fully digested your arguments yet, but would be grateful if
> > you
> > could answer one quick question: can't the functionality of MGET be
> > achieved
> > just using mimetypes?
> >
> No. Tried that. It doesn't work. Because you can't differentiate
> between request for a description of a resource, versus a request
> for a representation of a resource that happens to be a description
> of another resource.

request for a description of a resource:

http://example.org/xxx [mimetype:application/rdf+xml-description]

request for a representation of a resource

http://example.org/xxx [mimetype:application/rdf+xml]

The first of these corresponds to MGET, the second to GET. Rather than the
switch being on the verb, it's on the mimetype. If the latter representation
happens to be a description of another resource, how is that significant?
What is the logical difference between these approaches?

> Or if the resource in question has an RDF/XML representation, you
> can't use content negotiation to ask for a description in RDF/XML
> because how then do you differentiate between the RDF/XML representation
> and the RDF/XML description.

Different mime type, recognized at both ends. A request for
"application/rdf+xml-description" means "please return a concise bounded
description of the resource denoted by the request URI", the correct
behaviour of the server is confirmed by the returned Content-Type.

> I even tried defining a distinct MIME type for concise bounded
> descriptions, but as I indicate above, in the case where you want
> a description of a description, it doesn't work

I'd be grateful for an example of how this is different with MGET, it sounds
like there's something I'm not grokking here.

> In short, there are certain "meta" distinctions which the SW needs
> that simply must be kept distinct from the existing web semantics.
> The distinction between requests involving a representation (web)
> and requests involving a description (sw) is one such distinction.

Yes, I think you've made a good case for the distinction, but I don't see
why this distinction couldn't be made through mime type negotiation (or some
other existing mechanism)...

> And IMO the cleanest way to implement that is with distinct methods
> such as MGET, MPUT, and MDELETE.

Still not convinced... ;-)

Received on Thursday, 20 November 2003 07:00:44 UTC

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