[Nml-wg] Relation mapping XML-RDF (subPropertyOf)

[Freek Dijkstra]

Jeroen van der Ham wrote:

> For example:
> 
>   <nml:Node id="urn:ogf:network:internet2.edu:2011:rtr.atla.net">
>     <nml:Relation type="hasPort"> 
>       <nml:Port idRef="urn:ogf:network:internet2.edu:2011:rtr.atla.net:ge-6-0-0_in" />
>     </nml:Relation>  
>   </nml:Node>
> 
> Would be translated to:
> 
>     nml:hasPort rdfs:subPropertyOf nml:Relation .
> 
>     <urn:ogf:network:internet2.edu:2011:rtr.atal.net> a nml:Node;
>         nml:hasPort <urn:ogf:network:internet2.edu:2011:rtr.atla.net:ge-6-0-0_in> .
> 
>     <urn:ogf:network:internet2.edu:2011:rtr.atla.net:ge-6-0-0_in> a nml:Port .

This seems easy to read, and easy to translate between XML and OWL, so
I'm in favour.

It brings up a question I like workgroup consensus on.

The XML uses a string ("hasPort") to defined the type of relation, while
OWL uses a URI (nml:hasPort) to define the same relation type.

There seem three options here:

1. Use strings in both XML and RDF/OWL.
   Con: this does not work with Jeroen's proposal

2. Use a URI in both XML and RDF/OWL.
   Con: this makes the XML verbose (even if
   Pro: easier to define new relation types (users can define their own
        relation URI, even without involvement of the OGF)

3. Use string in XML and a URI in RDF/OWL, where the URI MUST reside
   in a specific namespace, so it is easy to translate between the
   string and URI.
   Pro: feel more natural in both RDF/OWL and XML.
   Con: requires OGF standards action to define new relation types.

I don't have strong opinion on it, as long as we choose something.

Jeroen's proposal above is option #3, so if there are no objects, I
propose that we pick that.

I'm slightly inclined to use a different namespace for the relation
types than the NML-base namespace, for no reason other than that is is
slightly easier to document the translation between string-form and
URI-form of the type ("for XML, always remove the URI, for RDF/OWL,
always use the URI xyz"). But this is a minor decision that I gladly
leave to Jeroen to decide.

Regards,
Freek