Re: [dev-biblio] [Fwd: [RFC] RDF metadata API draft]

["Bruce D'Arcus" <bdarcus@gmail.com>]

On Wed, Mar 19, 2008 at 7:39 AM, Michael Stahl <Michael.Stahl@sun.com> wrote:

...

>   > Am *really* not sure about this, but I wonder if it would make sense to
>   > consider the document itself a graph?
>
>  hmmm, interesting idea.
>  If I understand the RDF model correctly, then a document would have a
>  graph associated, which consists of a set of named graphs (the RDF/XML files).
>  So the whole document is a graph, and every single RDF/XML file is a
>  subset of the document graph, and _also_ its own named graph.

Yes, except I'm suggesting that the content files also have their own graphs.

>  But: we cannot add a RDF statement to the "whole document graph", while
>  not adding it to any named graph; if we allowed a statement that is not
>  part of any named graph, where would we store it in the ODF file
>  (especially in a way that is interoperable with other implementations of
>  the ODF metadata spec)?

Right.

>  So I would claim that it does not make sense to expose in the API a "whole
>   document graph"; you just add your statements to some named graph, and
>  they end up in the "whole document graph" as a side effect.
>  The drawback of this approach is that you cannot enumerate the "whole
>  document graph".

Except as a collection of named graphs, which is fine.

>  But you can still query it with SPARQL, and it seems to me that is good
>  enough.
>
>  oh, and if you think i have misunderstood something, please tell me!
>  i only started reading up on RDF a month ago...
>
>
>  > 2) "executes a SPARQL "SELECT" query."
>  >
>  > Oooh ... nice! Do I thus assume the endpoint can be arbitrary? E.g. if I
>  > have an endpoint setup on a relational database somewhere, I can query
>  > that from the OOo API?
>
>  That was the idea, yes. The XRDFRepository interface can be implemented
>  either by an in-memory repository (as would be done for ODF documents), or
>  by some database, accessed via HTTP or SQL or whatever.
>  However, we want to have one repository per document, and the database
>  repository would be distinct as well, so you would not be able to write a
>  SPARQL query across document metadata and a database; you would have to
>  write two queries.

OK, but I think a single SPARQL query can point to multiple repositories (?).

...

>  So, the graph name must be an URI, and it must represent the file name
>  somehow.

The URI is a name for a graph, which in the context of ODF, gets
seialized as RDf/XML. In that sense, the file name is rather
orthogonal.

Bruce