[OT] OODBs and schema, was Re: [linux-audio-user] Re: sound & midi applications page

[Steve Harris]

On Mon, Feb 02, 2004 at 01:46:31 -0500, Paul Winkler wrote:
> On Mon, Feb 02, 2004 at 06:42:47PM +0000, Steve Harris wrote:
> > > Splitting and joining classes? You lost me there.
> > > Refactoring?
> > 
> > Yeah, I guess. Eg. if you had Green Things and Red Things and you wanted
> > to replace them with Coloured Things.
> 
> How is this done in the RDF world?

You create a mapping schema which says

GreenThings rdfs:subClassOf ColouredThings .
RedThings   rdfs:subClassOf ColouredThings .
(and the same for the properties that need translating.

So any queries you have on GreenThings will be satisfied by instances of
ColouredThings - not a perfect match as you can see, but better than
nothing.

A better example is if someone gives you a load of data in Dublin Core you
can say

dc:title      rdfs:subPropertyOf my:name .
dc:identifier rdfs:subPropertyOf my:url .
...

So you will get eqivalents in your schema for all the DC properties. If
you reverse it as well you will get mapping in both directions so people
who use DC can understand your data.

> sorry to be a pest, it's just new concepts to me and I'm slow 
> to grasp the benefits.

Not at all, its a bit of an odd concept to get your head round. Someone
desciribed ontologies (things like RDFS) as an equivalent of an API for
data - which is close enough.

- Steve