- From: Harry Halpin <hhalpin@ibiblio.org>
- Date: Fri, 16 May 2008 17:08:12 +0100
- To: Bijan Parsia <bparsia@cs.man.ac.uk>
- Cc: Jeremy Carroll <jjc@hpl.hp.com>, public-grddl-comments@w3.org, public-grddl-wg@w3.org, alanruttenberg@gmail.com
Bijan (cc'ing Alan over this issue), After waiting a few days, it appears this discussion has come to some sort of end - so I'll summarize what I think the message to the OWL2 WG over this debate is from the remaining active members of the GRDDL WG on this list. In effect, while it appears active GRDDL WG members on the list recognize the dangers posed by someone thinking an conformant GRDDL transformation in XSLT for OWL2/XML to RDF is more "normative" than some other transformation, it appears to be the feeling of the majority of the people from the GRDDL Working Group that the benefits of having such a GRDDL transformation accessible from the namespace document of OWL2's XML syntax outweigh the costs. This is in particular *if* the OWL2 Working Group believes that RDF-aware agents may want to access information in OWL2 in RDF and may not have their own locally installed OWL2 XML to RDF transformer. So: 1) It seems general opinion in the GRDDL WG that having a GRDDL Transformation Property point to a non-executable list of implementations is not a useful use of GRDDL, and the GRDDL WG did not explicitly discuss this possibility when creating the GRDDL Specification or test-cases. A GRDDL transformation, while not necessarily XSLT, is usually executable, and currently all examples are in XSLT. 2) However, while the "cost" of alienating developers of other non-GRDDL transformations may exist, this is a misunderstanding about the "normative" nature of GRDDL transformations. In particular, a list of other conformant implementations could be accessible at the namespace document. Also, a few sentences explaining GRDDL and the fact that it is no more "normative" than other implementations could be included in the namespace document. If this does actually cause problems, these problems could be dealt with re the usual feedback channels of the W3C. The advantage of having a GRDDL from OWL 2 to RDF is that it is to a larger audience (RDF users without an explicit OWL 2 to RDF transform), who might otherwise be unable to have what benefits OWL 2. in RDF, can have these benefits with a minimal of work. 3) Re the possibility of the OWL namespace document being overloaded by requests for the transform, we do in the specification encourage caching of GRDDL transformations. Regards the possibility of GRDDL transformations being "automatically" run, this is a matter of local policy. Current libraries such as Redland and Jena do allow GRDDL to be turned on explicitly by the local client. Although this is not the solution that Bijan wants per se, think this is the general opinion of the GRDDL WG members who have responded so far on this list, except for possibly Jeremy Carroll. Thanks for the provocative and intelligent critiques and comments re GRDDL and OWL 2. The choice of whether or not to include a GRDDL transformation that is an XSLT from OWL2 XML to RDF is, of course, in the competent hands of the OWL 2 WG. However, I do hope this feedback helps clarify things. -harry Bijan Parsia wrote: > > On May 13, 2008, at 5:09 PM, Jeremy Carroll wrote: >> Dan Connolly wrote: >> >>>> People are reading the SHOULD as a MUST. >>> Really? I am not. I just haven't seen a good reason to make >>> an exception in this case. >> >> +1 >> >> (the definition of SHOULD is very good in my view, see RFC 2119, >> which I am sure Bijan knows ...) > > Sure. > > It would help me if I could see a hypothetical circumstances what you > think the case is successfully made to go against the SHOULD. > > In the OWL/XML case we have: > 1) an existing specification (at the W3C) for a format closely > identified with semweb > 2) widely available (in multiple ways) implementations > 3) a culture of manually invoked translation (e.g., between Turtle > versions and OWL/RDF, etc.) > 4) no clear use case for other sorts of user programs wherein they > would have grddl but not be able to manage other ways of getting > translation > And no clamor from users of those tools who are also OWL > users. Alan Ruttenberg *is* an OWL user, but my understanding is that > he's concerned more with legacy OWL oriented tools that only consume > RDF/XML. > 5) a somewhat complex transformation > > (And let us presume there is an existing, seemingly decent, XSLT to > hand. Or two!) > > I think without a thumb on the scale (i.e., that we have a default to > override via a SHOULD) that the case is clear. (Do we agree?) With the > thumb on the scale, I also think it's clear, but evidently you and Dan > don't agree. (i.e., there are problems, and no clear upsides, and the > downsides of not doing it are easily mitigated.) What other facts (or > sorts of fact) would tip the scale for you? If there are none, or they > are outlandish (e.g., space aliens say we shouldn't), then you and dan > are treat this SHOULD as a de facto MUST. Or, at least, I cannot > discern the actual difference. > > If it's a de facto should, you should make it an actual should. It's > really misleading and confusing otherwise. > > Cheers, > Bijan. > >
Received on Friday, 16 May 2008 16:08:48 UTC