Re: DAML and Dublin Core: incompatibility?

From: Dan Connolly (
Date: 03/03/01

Dan Brickley wrote:
> This is a followup to some hallway and lunchtable conversations about
> DAML datatyping and the work of the Dublin Core Metadata Initiative.
> My understanding of the forthcoming revision of DAML+OIL+DT(*) is that
> we say all properties are either of the kind that point to resources, or
> of the kind that point to concrete datatypes, strings structured as per
> XML Schema part 2.

I don't think that's quite right; I'm not confident I know where
the latest draft is, but my understanding is: DAML+OIL+DT doesn't
say that all properties are either black or white; it just doesn't
tell you the semantics of the grey ones.

> If this means previous deployed apps such as Dublin Core, RSS, Mozilla
> (Netscape 6), Open Directory and others will be broken because they
> allow some properties to point both to resources and literals,

Regardless of what DAML+OIL+DT does, I consider that practice
broken. Based on the experience I have building tools and apps,
I recommend folks get used to making clear distinctions between
things and names for things.

> I'm
> worried.

Yes, well, the world is a scary place. ;-)

I agree there's a tension between the things that DAML+OIL+DT
facilitates and some existing practice, but my mind is clear
on which should give: the broken practice. Are you suggesting that
the tension should be resolved some other way? If so, how?

I started scribbling
an RDF modelling best-practices outline the other day:

A) use rdf:type to model unary predicates:
   P(x)  becomes rdf:type(x, P)

B) URIs only go in about/resource attributes; don't put
 them in propAttrs nor propElement content; e.g.
no: <Book title="alice..." authorHome="../xyz/homePage"/>
yes: <Book title="alice..."><authorHome resource="../xyz/homePage"/></>

C) choosing a namespace: use #, not / nor ? [not 100% sure about this one,
but seems wisest at this point]

D) things versus their names.

Dublin core is at-risk because of C) as well as D), IMO.

Dan Connolly, W3C

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