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Re: named graphs

From: Phil Dawes <pdawes@users.sf.net>
Date: Mon, 3 May 2004 14:58:19 +0100
Message-ID: <16534.20475.169581.700761@gargle.gargle.HOWL>
To: Patrick Stickler <patrick.stickler@nokia.com>
Cc: "ext Chris Bizer" <chris@bizer.de>, <www-rdf-interest@w3.org>

Hi Patrick,

Patrick Stickler writes:
 > RDFQ has been a useful "thought experiment" that I would like to have
 > seen reach a higher stage of maturity in the implementation, but further
 > development is at the moment, and probably for the summer, "on ice".

That's a shame - for me it represents the most promising query
language for cross-store querying. I suspect querying across multiple
sources will start to become an important requirement for applications
in the near future, especially if tools like Chris's D2R mapping
software open up existing relational databases to RDF query languages.

RDFQ is compelling for this sort of thing because of the following

1) supports adding RDF knowledge to be considered in addition to the
contents of the knowledge base being queried.

  - important when carrying out a query across multiple sources since
  passing existing results between stores facilitates additional
  results to be found.

2) supports multiple queries in one dispatch

  - useful when trying to augument existing knowledge with extra
  descriptive triples - e.g. labels, comments, types. Also I often
  find myself needing to do a number of un-related queries to obtain
  enough information to carry out an action.

3) supports named graphs 

  - important when results are syndicated from multiple sources.

The only thing that puzzled me about the RDFQ spec[1] is the result
format. It's currently constrained to being either a set of
consise-bounded-descriptions or in the rdf format from the
recording-query-results[2] document.

For me, the most useful result format for server-side querying is a
single rdf graph containing all the matched triples. 
This is because usually (in software I've written) query results are
required to be used in tandem with other knowledge to carry out the
required functionality. Getting the results as a graph enables the
client to merge the information with its existing internal store.




[1] http://sw.nokia.com/rdfq/RDFQ.html
[2] http://www.w3.org/2003/03/rdfqr-tests/recording-query-results.html
Received on Monday, 3 May 2004 11:02:40 UTC

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