[Zope-Moz] Design discussion (was RDF Use cases)

[Shalabh Chaturvedi]

Hi Martijn,

> SC> ----- Original Message -----
<snipped>
> SC> Are we mixing up 'metadata' and 'data' here?
>
> There are other advantages to using RDF, such as aggregation. You can
> mix and match RDF datasources. Also, the RDF APIs that exist now, like
> Mozilla, allow you to query and manipulate RDF in a very specific way.
>
> These issues were also discussed by the people designing things like
> the Mozilla sidebar. It's an interisting discussion you might want to
> have a look at, as it discusses the why and how of RDF:
>
>   http://www.mozilla.org/xpfe/xulrdf.htm

Now that was enlightening.
I suggest another link for the benifit of others:-
http://www.mozilla.org/rdf/doc/api.html

> Then again, we would be running ahead of the game if we were to decide
> on an implementation now. Again, I am only speculating about a
> possible use for RDF in Zope.

> SC> One question: Will a 'Zope Studio mozilla' be distributed with
Zope or
<snipped>
> SC> With this architecture too, a nicer SQL Method would be possible.
>
> This could be another scenario for Zope Studio. One point: XML Schema
> is still very much a moving target. Also, an XML Schema cannot
> represent the contents of a ZODB, only the class definitions that were
> used to create the instances in the ZODB. You would need:
>
> 1. An XML Schema that defines the classes, and therefor also the
>    operations permitted on them. These are all also callable through
>    XML-RPC.
> 2. An XML Document describing the actual contents of the ZODB, or at
>    least of the object that we're manipulating.

Yes, my original idea was that there be an XML Schema (or DTD) for each
of the classes in the ZODB. And, there be an XML Document for each
_instance_ of the class. Obviously, the document for an object will
conform to the Schema (or DTD) for the
corresponding class. I had mixed up schema and document in what I had
said (being too impatient to send it across :-P). Also, these documents
don't exist as such but come into existance when Zope creates them from
the data in the ZODB.

> There is a parallel specification for RDF Schemas:
>
>   http://www.w3c.org/TR/PR-rdf-schema

I've seen this. In fact the architecture above is more or less parallel
to what you suggested earlier (replace XML with RDF in the text above).

I defer my initial suggestion for a (non-RDF) XML based model in favour
of an RDF-based model. I'm not saying that we ought to use RDF in the
said way. I'm saying that if we have to choose between RDF and a new
zope XML schema for representing the data in an ZODB, RDF is the way to
go. RDF Schemas will still have to be designed, but the immense support
for RDF in mozilla will be very useful.

So, where do we go from here?

Cheers,
~Shalabh