W3C home > Mailing lists > Public > www-rdf-rules@w3.org > November 2001

Re: Scope

From: Wolfgang Nejdl <nejdl@kbs.uni-hannover.de>
Date: Sun, 18 Nov 2001 16:03:13 +0100
Message-Id: <200111181503.fAIF3DP01558@mahler.kbs.uni-hannover.de>
To: "Geoff Chappell" <geoff@sover.net>
cc: "Libby Miller" <Libby.Miller@bristol.ac.uk>, "Seaborne, Andy" <Andy_Seaborne@hplb.hpl.hp.com>, www-rdf-rules@w3.org
> 
> ----- Original Message -----
> From: "Libby Miller" <Libby.Miller@bristol.ac.uk>
> To: "Seaborne, Andy" <Andy_Seaborne@hplb.hpl.hp.com>
> Cc: <www-rdf-rules@w3.org>
> Sent: Thursday, November 08, 2001 10:26 AM
> Subject: Re: Scope
> 
> 
> [..]
> > > Above all, what I would like to see is a common core query language so
> that
> > > tool sets can choose to provide the same basic query and application
> > > programmers don't have to learn a new language for each tool set.  This
> > > would also be good so queries can be shipped over SOAP to different RDF
> > > stores.
> >
> > This is a great idea, and Dan Brickley already has some demos using Eric
> > Prud'hommeax's Algae and also SquishQL servers, showing that
> > SquishQL and Algae can more or less be mapped to each other. A common
> > syntax would be very useful, but syntactic differences might be less
> > significant if there is a common model of what a query is.
> 
> What would be the context of such an effort (finding a common query
> language)? what capabilities would be assumed for the server? for example,
> the KIF spec describes various conformance dimensions/categories (logical
> form, term complxity, etc.) -- would a common query language seek to
> encompass a variety of conformance profiles? or would it pick just a small
> subset (or a single profile) and define the client/server interactions for
> it?

A useful approach might be to include several complexity levels for
such a query language, the lowest one being conjunctive queries
(basically equivalent in expressive power to RDF itself), then AND/OR
tree queries, then basic SQL queries (non-recursive Datalog), then
full Datalog. We have taken that approach in the Edutella project (see
http://edutella.jxta.org/ and
http://edutella.jxta.org/reports/edutella-whitepaper.pdf).

Wolfgang

> 
> Rgds,
> 
> Geoff Chappell
> 
> 
Received on Sunday, 18 November 2001 10:02:58 UTC

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