W3C home > Mailing lists > Public > www-rdf-interest@w3.org > December 1999

Re: RDF API 1.0 Draft / signing RDF content

From: Dan Brickley <danbri@w3.org>
Date: Mon, 6 Dec 1999 18:38:25 -0500 (EST)
To: Sergey Melnik <melnik@DB.Stanford.EDU>
cc: Gabe Beged-Dov <begeddov@jfinity.com>, RDF Interest Group <www-rdf-interest@w3.org>
Message-ID: <Pine.LNX.4.20.9912061809540.22044-100000@tux.w3.org>


On Mon, 6 Dec 1999, Sergey Melnik wrote:
[...]
> That's another tough issue, you are absolutely right. First, on the
> model level there no "proper" noname resources, since every resource
> must have a URI.

Just a brief side-comment for now; longer response another time.

Regarding anonymous (ie. 'noname' resources)...

I see nothing in RDF model that justifies the claim that we must _know_
the URI string that names each and every resource in a model. We can pass
around graphlets that have intermediate anonymous nodes that stand for
resources which in other contexts have known URIs. While every resource
has to be the 'kind of thing' that might have a URI, ie. an object for
which the notion of identity makes sense, my reading of the RDF model is
that it remains agnostic on whether implementations must know the URI for all
resources in a given graph. 

Knowing a URI is just knowing some more information about a resource. For
example, sometimes we'll know that there is a resource that was the
creator of some page, and that the creator had such'n'so age, such'n'so
gender, surname etc. But we won't have a URI. If we find out (possibly
years later) the URI for the creator of that page, we're still talking
about the same resource (entity, object, whatever...). Since a URI is a
(particularly intimate) piece of information about a resource, I can well
imaging software components knowing facts about some resource without
hnowing it's URI. I don't believe RDF model forces us to pretend we know
the URI, although I can see how the spec might be read that way.

Obviously an implementation will need some way of internally assigning an
identifier for such resources, or it would get confused. The only way I
can think to deal with this is to reflect URIs themselves into the RDF
graph as attributes of resources; sometimes we know these, sometimes we
don't. 

This all boils down to the fact that there are some unresolved issues of
Web architecture concerning the relationship between resources and
URIs. If a resource can be known by multiple URIs, we get one solution for
RDF APIs; if a Web resource has exactly one URI, we get another. In either
case it's really a URI and Web architecture issue (though that doesn't
mean we can't talk about it here...)

Dan
Received on Monday, 6 December 1999 18:38:35 GMT

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