W3C home > Mailing lists > Public > public-sparql-dev@w3.org > April to June 2006

RE: Implementations using "compositional semantics"

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Fri, 23 Jun 2006 15:07:16 +0100
Message-ID: <DF5E364A470421429AE6DC96979A4F6FAFFB99@sdcexc04.emea.cpqcorp.net>
To: "Olaf Hartig" <OleBowle@gmx.de>
Cc: <public-sparql-dev@w3.org>, "Richard Cyganiak" <richard@cyganiak.de>




-------- Original Message --------
> From: Richard Cyganiak <>
> Date: 23 June 2006 14:06
> 
> Olaf,
> 
> On 22 Jun 2006, at 11:15, Olaf Hartig wrote:
> > In a recent paper about "Semantics and Complexity in SPARQL"
> > (http://www.dcc.uchile.cl/~cgutierr/ftp/sparql-ext.pdf)
> > Perez et.al.
> > mention two approaches to compute solutions for graph patterns - one
> > using a procedural semantics and another using a compositional
> > semantics. As a real
> > implementation for the first they name Jena's ARQ. I'm interested in
> > an implementation following the second approach. Does someone,
> > familiar with the paper, know of any?
> 
> sparql2sql [1] implements only a subset of SPARQL, but that subset is
> evaluated using compositional semantics. 


I don't see the distinction made in the paper as so black and white in
ARQ - for example, the output from the parser turns into the abstract
SPARQL operators, which in turn is turned into a concrete execution plan
and that is executed.  Naively, it's possible to directly implement the
SPARQL operators but when converting to SQL (in the new query engine),
it gets turned into something closer to relational algrebra (based on
Richard's work) which reflects the particular database schema being
used, which is turned into SQL and sent to the database engine.

	Andy

> 
> Best,
> Richard
> 
> [1] http://jena.sourceforge.net/sparql2sql/
> 
> 
> > --
> > Bye,
> > Ole
> > ----------
> > GnuPG key: http://www.informatik.hu-berlin.de/~hartig/hartig.asc
Received on Friday, 23 June 2006 14:07:31 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 8 January 2008 14:17:05 GMT