- From: Frank Manola <fmanola@mitre.org>
- Date: Tue, 17 Jul 2001 17:54:29 -0400
- To: rdf core WG <w3c-rdfcore-wg@w3.org>
In the July 13 minutes, I took an action to: "Clarify the choices for anonymous resources with some of their ramifications". This is essentially a reprise (with some amplification) of the points I made in http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jul/0124.html (quoted in Graham's response http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2001Jul/0131.html) In my earlier message, I said: "I think the main (and fundamental) argument for anonymous resources in the model/abstract syntax is to support, in the model/abstract syntax, the capability described in the current M&S for talking about resources that don't have URIs (that you know of), e.g.(P41): "The individual whose name is Ora Lassila, email <lassila@w3.org>, is the creator of http://www.w3.org/Home/Lassila." the graph for which shows a resource *without a URI*. That is, the current M&S says we can express this in RDF. I interpret this as meaning that the model/abstract syntax must be capable of expressing this, not just the XML serialization. It seems to me, then, that the choice is whether to (a) explicitly support anonymous resources as something other than resources with generated URIs; (b) clarify this part of the spec by saying we really have to generate a URI in this case (and have the graph show a *generated* URI, not *no* URI); (c) delete this capability from the spec." On going back and reading the issues list (and some other things), I now realize there's a bit more to this than I originally thought (for one thing, both the current RDF container model and reification seem to involve anonymous resources too), but rather than dealing with those cans of worms in this message, I'll stick to trying to clarify the choices I described earlier, and talk about those other issues later. However, one bottom line here is that I agree with everyone who's said that we've got to clarify a lot of issues surrounding URIs as a matter of very high priority. Now to the immediate issue: We need to be clear about how we're interpreting "anonymous resources". The graph pictures show them as having *no URIs*. However, parsers produce generated identifiers for these things, and our triple model seems to require some such interpretation, that is, that these apparently "anonymous" resources have some identifier produceed for them that can be plugged into the appropriate places in the triples). So my original choices for what was happening were (in the same order): a. these resources are "anonymous" in the sense that they don't have URIs. However, they have to have *identifiers* of some kind in order to reflect them in triples. In this case, the M&S should say that another kind of identifier is internally generated to identify "anonymous" resources, and say what the characteristics of those identifiers are (like, they're internal, temporary, not meant for use outside of something like a "session", ...) and how they work compared to ordinary URIs. b. these resources are "anonymous" only in the sense that the writer of the RDF doesn't have to explicitly supply a URI. However, a genuine URI will be generated for the resource, and once generated this URI will behave like any other URI. In this case, the M&S should say explicitly that URIs are generated for "anonymous" resources, the graph diagrams should show *generated* URIs, not *no* URIs, for these resources, and the M&S should say how these generated URIs work (e.g., when different parsers operate on the same XML serialization). c. we don't want to support generated identifiers, either some special kind of non-URI identifier, or generated URIs. Then we should remove "anonymous" resources from the M&S (e.g., require explicit specification of URIs in these cases, hand-wave about how URIs get assigned in a manner outside the scope of the M&S, or some alternative TBD). Note the distinction I'm making in choices (a) and (b). I understand that parsers generate *identifiers* for anonymous resources. What I want to be clear about (if only in my own mind) is *what kind* of identifiers these are expected to be. So, for one thing, in future discussion it would be helpful if we wouldn't use generic terms like "genids" or "generated IDs" for these things if what we mean is "generated *URIs*" (of course, clearing up URI semantics would help clarify the requirements of "generating URIs" in such circumstances). --Frank -- Frank Manola The MITRE Corporation 202 Burlington Road, MS A345 Bedford, MA 01730-1420 mailto:fmanola@mitre.org voice: 781-271-8147 FAX: 781-271-875
Received on Tuesday, 17 July 2001 17:52:42 UTC