- From: Ron Daniel <rdaniel@interwoven.com>
- Date: Thu, 28 Jun 2001 09:22:35 -0700
- To: "Brian McBride" <bwm@hplb.hpl.hp.com>, "Aaron Swartz" <me@aaronsw.com>
- Cc: "rdf core" <w3c-rdfcore-wg@w3.org>
Aaron Swartz started a thread by saying: >rdfms-literals-as-resources and rdfms-literalsubjects: > A large body of implementation and user experience shows the > need for these issues to be clarified. I think that there is > certainly room for clarification of this within the charter of > the Working Group. and later he said: > I'm suggesting that we make Literals a subset of > Resources. [...] I'd suggest something like: > > <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" > xmlns="http://rdf.example.org/#"> > <rdf:Description rdf:about="data:text/plain;Chicago"> > <startsWith>C</startsWith> > </rdf:Description> > </rdf:RDF> > >become: > > <data:text/plain;Chicago> <http://rdf.example.org/#startsWith> > <data:text/plain;C> . Since no-one else from the original M&S and Schema groups has spoken up, I guess I will. My recollection is that we considered "strings", later called "literals", as being clearly (although unfortunately) distinct from Resources. That distinction is called out in the M&S document in the part of section 2.1 Brian cited earlier: > The object of a statement (i.e., the property value) can > be another resource or it can be a literal; i.e., a > resource (specified by a URI) or a simple string or > other primitive datatype defined by XML. While I would prefer that we have a way to make literals the subject of statements, it seems completely clear that such a feature is NOT part of the 1.0 M&S. Since we are chartered to clear up misunderstandings, any changes we make to the model need implementation experience as a justification (such as the essentially universal lack of support for aboutEachPrefix). All the RDF parsers I am familiar with treat literals as distinct from strings. None of them convert literals into data URLs. (However, I have not made any sort of broad study of RDF parsers, so perhaps someone else can comment?) I simply don't see sufficient implementation experience to justify this kind of change to the 1.0 M&S. I would suggest that we should do two things to clarify the M&S on this point. The first is to strengthen the section in 2.1 that was cited above, so that it says something like: The object of a statement (i.e., the property value) must be a resource or a literal. Resources are specified by URIs(or URI references - this depends on how we resolve the whole mess around identifiers.) Literals are strings or other primitive datatypes, which may contain XML markup. For version 1 of the RDF Model and Syntax, the set of Resources is distinct from the set of Literals. Second, we should go on to clarify the case of data: URLs, which was not treated in the original M&S. For that clarification, I suggest that implementations treat them as URLs, not as literals. But Aaron's suggestion that we convert literals into occurances of data: URLs is CLEARLY a change to the model. I am not at all convinced this is a real simplification. We already have an incredible mess around URIs to clean up. I don't see adding something like such an automagic conversion as any sort of real simplification, I'm afraid it is just going to make things worse. This is particularly the case since I don't see any real evidence that the current model is in doubt (as opposed to having a different model with different properties). I am, of course, willing to abide by the rule of the majority if the group decides such a change is in-scope. But before this group spends its resources on this issue, postponing other issues we must consider, may I request a straw poll on the level of support? Regards, Ron
Received on Thursday, 28 June 2001 12:24:32 UTC