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[Fwd: flexible SPARQL reification construct instead of hard-wired SOURCE keyword]

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Mon, 17 Jan 2005 12:15:21 +0000
Message-ID: <41EBAC59.7020200@hp.com>
To: RDF Data Access Working Group <public-rdf-dawg@w3.org>

This comment includes a suggestion for syntax support for reification.  This has 
come up before.

Any suggestions for the syntax?

This would be good to do: syntactic support would mean the same as writing out 
the reification long-hand.  A parser can rewrite this and the query engine never 
see it - or a system that wants reification hints can chosoe to pass with through.

	Andy

-------- Original Message --------
Subject: flexible SPARQL reification construct instead of hard-wired SOURCE 	keyword
Resent-Date: Fri, 14 Jan 2005 18:39:57 +0000
Resent-From: public-rdf-dawg-comments@w3.org
Date: Fri, 14 Jan 2005 19:39:16 +0100
From: Benjamin Nowack <bnowack@appmosphere.com>
Organization: appmosphere web applications
To: public-rdf-dawg-comments@w3.org



hi again,

an adjusted version of my comment from yesterday[1] as
just some extended food for thought. The idea is to
introduce a reification shortcut that could be used for
the SOURCE use cases and also for any other custom rdf
store extension:

[[[
...
SELECT ?s  ?p  ?o
WHERE ( ?s rdf:type foaf:Person )
       ( ?s ex:ppd ?ppd )
       ( ?ppd rdf:type foaf:PersonalProfileDocument )
       ( ?ppd foaf:primaryTopic ?s )
REIF  (?s ex:ppd ?ppd) sparql:source <http://trustMe.com/ppdDump>
       (?s ?p ?o) sparql:source ?ppd
       (?s ?p ?o) ex:addedDate "2004-01-13"
]]]

The reification constraint pattern
  ([s] [p] [o]) [prop] [value]
would mean that there had to be an rdf:Statement with [s],[p],[o]
as rdf:subject,rdf:predicate,rdf:object, and that there's also
a matching ([statement] [prop] [value]) triple. store developers
could freely decide how to implement this extended functionality
(explicit reification or with quads etc.) but the query syntax
could be generic. and using URIrefs for the [prop]s instead of
a single built-in SOURCE keyword for n-tuple stores would
keep SPARQL extensible.


regards and apologies for the (probably too) late comments,
benjamin

[1]
http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2005Jan/0002.html

--
Benjamin Nowack

appmosphere web applications
Kruppstr. 100
45145 Essen, Germany

http://www.appmosphere.com/
Received on Monday, 17 January 2005 12:15:49 GMT

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