- From: Patrick Stickler <patrick.stickler@nokia.com>
- Date: Mon, 03 Jun 2002 13:13:37 +0300
- To: ext Arnold deVos <adv@langdale.com.au>, Danny Ayers <danny666@virgilio.it>, Uche Ogbuji <uche.ogbuji@fourthought.com>
- CC: "Seaborne, Andy" <Andy_Seaborne@hplb.hpl.hp.com>, "ext Thomas B. Passin" <tpassin@comcast.net>, RDF Interest <www-rdf-interest@w3.org>
On 2002-06-01 9:25, "ext Arnold deVos" <adv@langdale.com.au> wrote: > If anyone is interested in some fairly complete draft proposals for RDF > query languages that are expressed.in RDF I have two: Thanks for the pointers. Some comments... > [1] http://www.langdale.com.au/RDF/NexusQueryLanguage.pdf This seems more like query in XML than in RDF. Perhaps I missed something. The template priority looks interesting. Examples of its use in practice would be nice to see. > [2] http://www.langdale.com.au/RDF/DAML-Query.html This is clearly RDF query in RDF (well DAML ;-) I find the partitioning of the query into the select and from portions a bit cumbersome -- in the same way that trying to view an XML instance stored in an RDBMS is cumbersome. You have to kinda keep track of the target description on several levels -- first specify the properties of relevance in the select statements and then describe, be means of a class no less, the actual value constraints for those properties. And don't the property restrictions make the property select statements redundant? I think that the average RDF user (or even the average advanced RDF but not DAML user) will not warm too much to such a representation. Still, DAML die-hards may feel right at home with it ;-) > [3] http://uche.ogbuji.net/tech/rdf/versa This last link is broken, unfortunately. Cheers, Patrick > > - Arnold > > Arnold deVos > Langdale Consultants > http://www.langdale.com.au > > > > > ----- Original Message ----- > From: "Danny Ayers" <danny666@virgilio.it> > To: "Uche Ogbuji" <uche.ogbuji@fourthought.com> > Cc: "Seaborne, Andy" <Andy_Seaborne@hplb.hpl.hp.com>; "'Patrick Stickler'" > <patrick.stickler@nokia.com>; "ext Thomas B. Passin" <tpassin@comcast.net>; > "RDF Interest" <www-rdf-interest@w3.org> > Sent: Saturday, June 01, 2002 8:57 AM > Subject: RE: Innovation, community and queries > > >> >> >>>>> properties(@"x:spam") >>>>> @"x:spam" - properties() -> * >>>> >>>> Another good reason for an RDF QL in RDF! >>> >>> Possibly. It's hard to judge without seeing your proposal for >>> expressing it >>> in RDF instead. >> >> Fair response, and no, as you probably guessed, I don't have a proposal at >> hand. >> >>> Of course, I must warn you I'm a sceptic. >> >> Me too, which is partly why I have a knee-jerk reaction to new syntaxes. >> >>>> Seriously though, I do think such a QL would be extremely >>> useful, not only >>>> because it would generally help interop. It would also mean that a > whole >>>> range of common expressions could become easier in RDF (without having > to >>>> drop into DAML-land), >>> >>> Examples? >> >> Essentially the kind of stuff like that which SQL scores on (almost >> irrespective of the relational model) - e.g. forall kind of things. >> >>>> and also make things like XSLT-ish transformations a >>>> lot more straightforward. >>> >>> We do this in 4Suite by using Versa to query and using XSLT itself >>> to generate >>> transformed RDF/XML. Works well, but we plan to come up with an >>> XUpdate-like >>> syntax as well. >> >> Hmm - I've experimented in the RDF+XSLT area myself, but have serious > doubts >> on its potential - ok, it can probably solve a lot of specific problems, > but >> having to think in trees is a bit ugly for the general case. >> >>> I'm not sure how Query in RDF would help make this more palatable >>> than me. >>> After all, the analog of RDF query in XSLT, XPath, is not in XML >>> syntax. It >>> still works quite well. >> >> Very true, but might it just be that with the DOM model doesn't need to be >> good at metamodelling, which is something I would hope RDF languages would >> be good at. >> >>>> Not unrelated to the interop point, the ability to >>>> save sets of queries in a common format like RDF/XML has to be a >>> plus - same >>>> parser etc etc. >>> >>> This is a trivial matter of writing an RDF binding for whatever >>> data model a >>> QL uses. >> >> Writing a binding is trivial, writing a good binding is another matter. >> >> Cheers, >> Danny. >> >> > > > > -- Patrick Stickler Phone: +358 50 483 9453 Senior Research Scientist Fax: +358 7180 35409 Nokia Research Center Email: patrick.stickler@nokia.com
Received on Monday, 3 June 2002 06:14:41 UTC