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Re: Q: Is rdf:about compatable with xlink?

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Tue, 22 Apr 2003 11:37:30 +0100
To: jimbobbs <jimbobbs@hotmail.com>
cc: www-rdf-interest <www-rdf-interest@w3.org>
Message-ID: <18586.1051007850@hoth.ilrt.bris.ac.uk>

>>>Jimmy Cerra said:
> I've been experimenting with mixing RDF with concepts from Topic Maps
> and XLink to help with "link overload" [1].  Well, it seems that the
> attribute, rdf:about, can be used to define (a reference to) a topic.
> What if I want to link to this reference with an XLink?  Usually, one
> uses the attribute, xlink:label, to define a resource and, "xlink:href",
> [2] to link to it.  It seems redundant to label a resource with a uri in
> the attribute rdf:about and then add the XLink property xlink:label
> pointing to the same uri, as in:
> <rdf:Description rdf:about="#salad"
>                  xlink:type="resource"
>                  xlink:label="salad" />
> <rdf:Description rdf:about="#bar"
>                  xlink:type="resource"
>                  xlink:label="bar" />
> <rdf:Description rdf:about="#foo">
>    <q:link parsetype="Resource"
>            xlink:type="arc"
>            xlink:from="#salad"
>            xlink:to="#bar" />
> </rdf:Description>
> Note that the xlink:type property can be automatically added with
> additions to the DOCTYPE.  Is there a less verbose way of doing this?

This is pretty unwise for several reasons :)

RDF/XML isn't defined in terms of DTDs (or XML Schema, another longer
story) so although you can make things appear by adding internal DTD
subsets to the XML, it's probably not going to work.

RDF/XML isn't defined to use XLink (which has a long history before
and after RDF was made a recommendation) so won't recognise the
vocabulary as special.  Since it isn't special, RDF/XML uses these
terms as more RDF properties so that you will get more triples in
this case with properties xlink:type etc.  (This might be what you
want in some cases, but not  here).

Connecting the RDF graph - a set of triples - to another data model
is not best done at the XML level which is the transfer syntax for
formats usually.  Think in terms of how the triples map and then try
connecting them up.  XML Topic Maps uses XLink in it's XML syntax -
encoding the TM model - but you can't just expect that syntax to map
directly to the transfer syntax for another format.  In this case, it
has some unfixable issues with respect to compatibility with the RDF
transfer syntax RDF/XML.

That being said, see these XML, RDF and XLink ideas:

  XPackage - http://www.xpackage.org/

  Harvesting RDF Statements from XLinks - http://www.w3.org/TR/xlink2rdf/

I think there might be some more nearby RDDL http://www.rddl.org/
plus I'm sure the lurking topic map experts can dig out some more ;)


Received on Tuesday, 22 April 2003 06:38:22 UTC

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