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Re: Embedding RDF metadata within an XML document

• From: Dave Beckett <dave.beckett@b...>
• To: xml-dev@l...
• Date: Thu, 22 Feb 2001 17:37:46 +0000

>>>Warren Hedley said:
> Hi folks,
> 
> We are developing an XML-based langauge for defining the structure
> of mathematical models of biological systems called CellML. We want to
> use RDF for metadata in CellML documents, but are not 100% sure about
> the correct way to do so. We want to get this right, to make it feasible
> for RDF-savvy search engines, etc. to make use of our metadata even if they
> have no knowledge of CellML.
> 
> Here are our specific questions:
> 
> 1. Is it OK to leave off the <rdf:RDF> element and simply
> use the <rdf:Description> element as the container for
> a block of metadata?

It is optional however ...

> 
> 2. If we are embedding the metadata inside the resource to
> which it refers, is it appropriate to omit the @about attribute
> on the <rdf:Description> element?
> Does omitting the @about attribute imply that the RDF block
> refers to the resource in which it is contained? (This is the
> behaviour that we are after.)

... best practice IMHO is that the block:
   <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
      ... RDF stuff ..
   </rdf:RDF>

is useful for RDF processors to use to indicate what part of the XML
should be interpreted as RDF.  Inside rdf:RDF there may be many
<rdf:Description> blocks.  

The rdf:about="" should be retained so that you mean this document,
rather than some anonymous resource i.e. use

   <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
     <rdf:Description rdf:about="">
        ... properties  ..
     </rdf:Description>
   </rdf:RDF>


> 
> Here is what we think our metadata block will look like (where
> "cmeta" is the prefix for our RDF schema's namespace):
> 
> <cellml:some_cellml_element>
> 
>   <rdf:Description>
>     <cmeta:some_metadata_element>
>       Some metadata content
>     </cmeta:some_metadata_element>
>   </rdf:Description>
> 
>   Some CellML content
> 
> </cellml:some_cellml_element>
> 
> <cellml:another_cellml_element>
> 
>   <rdf:Description>
>     <cmeta:some_metadata_element>
>       Different metadata content
>     </cmeta:some_metadata_element>
>   </rdf:Description>
> 
>   Some CellML content
> 
> </cellml:another_cellml_element>
> 
> Is this correct use of RDF? Are processors likely to be able to
> make use of it? Are processors going to be able to determine
> which metadata applies to <some_cellml_element> and which
> applies to <another_cellml_element>?
> 
> Thanks in advance for any help.

The above is still correct, but I think you require the rdf:about=""

Hope this helps.

There are various online RDF demos such as the SiRPAC one at
  http://www.w3.org/RDF/Implementations/SiRPAC/
and mine at
  http://www.redland.opensource.ac.uk/demo

and you can even visualize the metadata at the SiRPAC demo.

Dave

• References:
  • Embedding RDF metadata within an XML document
    • From: Warren Hedley <w.hedley@a...>

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