XDI RDF addressing alternatives? (was RE: Minutes: XDI TC Telecon Thursday 1-2PM PT 2009-04-02)

["Drummond Reed" <drummond.reed@cordance.net>]

Giovanni,

Thanks for making this posting. In reading through "A Different Proposal" at
the end, I am trying but have not yet been able to fully understand the
proposal. It appears that you are proposing that for the same X3 graph
rooted on the one XDI RDF subject, you are proposing that +x/+y addresses
one part of that graph (rooted on the +x subject) and +x+y addresses another
part of the same graph still rooted on the +x subject.

That seems to destroy the extensiblity model of the XDI RDF graph. You can't
actually create a new subject. As I understand the model you have written
up, you can't go beyond three levels, i.e., you can talk about +x, +x+y, and
+x+y+z. But what do you do about +x+y+z+j+k?

The $has verb in the proposed metagraph model in
http://wiki.oasis-open.org/xdi/XdiOne/RdfGraphModel is not limited to 2 or 3
levels deep. You can extend and create new XDI RDF subjects, predicates, or
objects to any depth.

The more I think about this topic, the more I believe that the addressing
capability of the XDI RDF graph is not something that can be expressed in
conventional RDF. It simply can't be done. It's like trying to express a
three-dimensional space in two dimensions. We are adding the dimension of
addressability to RDF graphs. It results in identifiers being combined into
new identifiers. RDF graphs have no such notion. I can't see any way around
it.

Thoughts? (We'll just have to continue the conversation in email this week
since I can't attend the XDI TC call tomorrow.)

=Drummond 

> -----Original Message-----
> From: Giovanni Bartolomeo [mailto:giovanni.bartolomeo@uniroma2.it]
> Sent: Wednesday, April 08, 2009 5:23 AM
> To: xdi@lists.oasis-open.org
> Subject: RE: [xdi] Minutes: XDI TC Telecon Thursday 1-2PM PT 2009-04-02
> 
> Hello,
> 
> After our call of last week, I've updated today the XDIMetamodel page:
> http://wiki.oasis-open.org/xdi/XdiMetamodel
> 
> Kind Regards,
> Giovanni
> 
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