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Re: new W3C CDF specs (XHTML +SVG + SMIL +XForms) --- RDF/XML opportunity?

From: Dave Beckett <Dave.Beckett@bristol.ac.uk>
Date: Sun, 11 Sep 2005 21:14:47 +0100
To: Bjoern Hoehrmann <derhoermi@gmx.net>
Cc: Mark Birbeck <mark.birbeck@x-port.net>, public-rdf-in-xhtml-tf@w3.org, dean@w3.org
Message-Id: <1126469687.8681.11.camel@hedwig.dajobe.org>

On Sat, 2005-09-10 at 17:52 +0200, Bjoern Hoehrmann wrote:
> * Mark Birbeck wrote:
> >Just because you can use any language you like, doesn't make it extensible.
> >Since you have no way to know what language is being used, then I don't see
> >how it could really be called 'extensible'?
> >
> >Perhaps if there was an attribute to indicate the type of the metadata, you
> >could say it was extensible. Something like:
> >
> >  <svg>
> >    <metadata type="application/rdf+xml">
> >      <rdf:RDF...
> >    </metadata>
> >  </svg>
> 
> Excellent remark, indeed, how could we possibly find the RDF fragment in
> a SVG fragment like
> 
>   <svg:metadata>
>     <rdf:RDF
>          xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>          xmlns:rdfs = "http://www.w3.org/2000/01/rdf-schema#"
>          xmlns:dc = "http://purl.org/dc/elements/1.1/">
>       <rdf:Description about="http://example.org/myfoo"
>            dc:title="MyFoo Financial Report"
>            dc:description="$three $bar $thousands $dollars $from
>                            1998 $through 2000"
>            dc:publisher="Example Organization"
>            dc:date="2000-04-11"
>            dc:format="image/svg+xml"
>            dc:language="en">
>         <dc:creator>
>           <rdf:Bag>
>             <rdf:li>Irving Bird</rdf:li>
>             <rdf:li>Mary Lambert</rdf:li>
>           </rdf:Bag>
>         </dc:creator>
>       </rdf:Description>
>     </rdf:RDF>
>   </svg:metadata>

by looking for the rdf:RDF qname.  A mime type attribute would be better
(see below).  Informative examples of RDF/XML in SVG and SVG in RDF/XML
are given in both specifications as far as I recall which are hints at
least what could be expected.

> it does not seem possible! It would be great if you could raise this
> issue with the TAG or the successor of the RDF Core WG. Thankfully, I
> think we already have a solution for this problem, Jeremy Carroll
> pointed out that we could easily obsolete RDF/XML if only we could solve
> the important issue of finding the right XHTML syntax for BNodes, so we
> can make http://www.w3.org/mid/41408F15.4090602@hplb.hpl.hp.com XHTML
> 2.0 documents "with no HTML content whatsoever!" which strikes me as a
> very good idea!

It's an amusing idea for this to obsolete RDF/XML, but incomplete and
non-optimal compared to RDF/XML, for writing some RDF triples (XML
literals for example) and a solution for XHTML2 only.  Other very likely
extensions to RDF such as literal subjects would also cause problems.
There are more issues in this area.  A replacement RDF/XML syntax should
be a different task than something that makes putting RDF in XHTML
possible

> In fact, it's a bit sad, but considering that RDF/XML "is difficult or
> impossible to validate documents that contain RDF/XML using XML Schemas
> or DTD's" and "the syntax of RDF/XML is too unwieldy for use", I think
> replacing it with a superior solution like XHTML-free RDF/A-only XHTML2
> documents is the only way forward. Would you be available to write the
> RFC that moves RFC 3870 to Historic?

People are very recently creating new formats that are difficult or
impossible to validate with XML schemas or DTDs.  For example, Atom 1.0
which only has a RELAXNG schema.   Just like the RDF/XML REC has
(informative) and for very similar reasons - flexibility in inclusion of
XML and allowing validation specified by namespaces; which is
trickier/impossible in WXS.

Using the two mechanisms that atom 1.0 provides - 1) flexible schema,
allowing namespaced XML to be inserted and 2) specification of the mime
type of the XML content, RDF/XML can be embedded and transported in atom
in a way that's quite similar MarkB's idea above:
> >    <metadata type="application/rdf+xml">
> >      <rdf:RDF...
> >    </metadata>

Here's an example of RDF/XML (DOAP) in Atom:
http://www.codezoo.com/about/doap_over_atom.csp

Dave
Received on Sunday, 11 September 2005 20:15:22 GMT

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