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Re: Innovation, community and queries

From: Uche Ogbuji <uche.ogbuji@fourthought.com>
Date: Fri, 31 May 2002 17:15:22 -0600
Message-Id: <200205312315.g4VNFM017879@localhost.localdomain>
To: "Danny Ayers" <danny666@virgilio.it>
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>

> >> >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.

Well, I can offer a similarly theoretic viewpoint:

I cannot imagine an RDF syntax for query that I'd be pleased to use.  And I 
have a pretty fertile imagination.


> >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.

XPath was also a new syntax.  It's not the newness of the syntax that matters, 
but its suitability to the task.


> >> 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.

I'm still not sure what you mean, but guessing you mean stuff like "for all 
resources of type x:spam, give me their author, their date, and any of their 
relays used that are not already in the RBL list".

Versa does this sort of thing quite well.  If you give me some specific 
examples, I'll try to  give you renditions in Versa.


> >> 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.

Well, I and colleagues have built practical applications used in real-world 
projects using this approach, and based on that experience, I claim it works 
well.  I suspect whether you like it would pargely depend on whether you like 
XSLT.


> >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.

XPath is not DOM, and I'm not sure how to interpret your comment on 
metamodeling.


> >> 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.

OK.  Granted.  However, it is not a task that scares me nearly as much as the 
idea of writing a good RDF syntax for query.


-- 
Uche Ogbuji                                    Fourthought, Inc.
http://uche.ogbuji.net    http://4Suite.org    http://fourthought.com
Track chair, XML/Web Services One (San Jose, Boston): 
http://www.xmlconference.com/
DAML Reference - http://www.xml.com/pub/a/2002/05/01/damlref.html
The Languages of the Semantic Web - http://www.newarchitectmag.com/documents/s=
2453/new1020218556549/index.html
XML, The Model Driven Architecture, and RDF @ XML Europe - 
http://www.xmleurope.com/2002/kttrack.asp#themodel
Received on Friday, 31 May 2002 19:31:25 GMT

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