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Re: Multiple GRDDL results in a single transform??? GRDDL and Named Graphs

From: Phil Archer <parcher@icra.org>
Date: Thu, 24 Jan 2008 11:14:11 +0000
Message-ID: <47987303.8070601@icra.org>
To: Jeremy Carroll <jjc@hpl.hp.com>
CC: "Booth, David (HP Software - Boston)" <dbooth@hp.com>, "public-grddl-wg@w3.org" <public-grddl-wg@w3.org>

I think I finally get it... (about time too).

Sorry, you've said this repeatedly, Jeremy, but it's only just sinking in.

Rather than a document of the form

<rdf:RDF ...>
   <wdr:DR>
     ...
   </wdr:DR>
</rdf:RDF>

There could be no <rdf:RDF> root element and therefore POWDER-unaware 
RDF tools would skip it. But, we could retain all the flexibility and 
extensibility of RDF/XML.

Let's just test that...

http://www.fosi.org/projects/powder/dr-o1TN.rdf is example 1 from [1] 
reformatted without the rdf:RDF root node as below. The RDF Validator 
gives the helpful reply "Error: Your document does not contain any RDF 
statement." and yet of course my browser parses the XML just fine.

Thus we just might buck the trend of history by being able to have our 
cake and eat it.

<wdr:TBD
   xmlns:owl ="http://www.w3.org/2002/07/owl#"
   xmlns:rdf ="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
   xmlns:wdr = "http://www.w3.org/2007/05/powder#"
   xmlns:foaf = "http://xmlns.com/foaf/0.1/"
   xmlns:dcterms = "http://purl.org/dcterms/0.1/"
   xmlns:dc="http://purl.org/dc/elements/1.1/"
   xmlns:ex="http://example.org/vocab#">

   <rdf:Description rdf:about="">
     <foaf:maker rdf:resource="http://authority.example.org/foaf.rdf#me" />
     <dcterms:issued>2007-12-14</dcterms:issued>
     <wdr:validFrom>2008-01-01</wdr:validFrom>
     <wdr:validUntil>2008-12-31</wdr:validUntil>
   </rdf:Description>

   <wdr:DR rdf:ID="DR_1">
     <wdr:hasScope rdf:parseType="Resource">
       <wdr:includeHosts>example.org</wdr:includeHosts>
       <wdr:hasDescriptors rdf:parseType="Resource">
         <ex:colour>red</ex:colour>
         <ex:shape>square</ex:shape>
       </wdr:hasDescriptors>
     </wdr:hasScope>
     <dc:description>Everything on example.org is red and 
square</dc:description>
   </wdr:DR>

</wdr:TBD>


[1] http://lists.w3.org/Archives/Public/public-powderwg/2008Jan/0021.html

Jeremy Carroll wrote:
> Phil Archer wrote:
> 
>> I tried to think of a strong reason or use case for using RDF/XML as 
>> the serialisation for a DR-O and couldn't do so. That doesn't mean 
>> there aren't any, just that I can't think of one.
> 
> My reason is (c) in my previous message:
> 
> c) it should be fairly easy to add additional metadata in an open ended
> fashion - this metadata can be: about the powder document and its
> assertions etc. or about the resources described in that document
> 
> 
> I think this is a reasonable objective, which is most easily met by 
> re-using RDF/XML.
> 
> I think the worth of this objective is disputable, and can see that it 
> is arguable that it is clearer to have a single formal meaning via 
> GRDDL, rather than two related formal meanings (one via RDF/XML and one 
> via GRDDL).
> 
> OTOH the GRDDL formal meaning of a POWDER document is likely to be 
> esoteric, in the sense that you need to run XSLT and then understand 
> some fairly complex OWL; whereas the direct formal meaning in RDF/XML of 
> my proposed format or a variant, will be more easily intelligible to 
> people with some knowledge of RDF. However, it won't say everything.
> 
> Personally I would see this is a legitimate design choice for the POWDER 
> WG, and would be surprised if anyone would strongly object either way.
> 
> A possible compromise would be:
> 
> POWDER syntax is defined as the typed-node construct from RDF/XML, with 
> one or two possible alternatives for that typed-node (e.g. wdr:DR 
> wdr:Package) - but the content is not served as RDF/XML, but the GRDDL 
> result includes the file as is, as well as the more complex format.
> 
> This would then avoid the potential confusion of this being mistaken for 
> RDF/XML, while retaining the advantages of actually being RDF/XML (but 
> when I can seriously write such a self-contradictory sentence, perhaps I 
> am being too clever)
> 
> Jeremy
> 
> 

-- 
Phil Archer
Chief Technical Officer,
Family Online Safety Institute
w. http://www.fosi.org/people/philarcher/
Received on Thursday, 24 January 2008 11:14:26 UTC

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