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RefPredicateMaps (was: Re: Request for comments: suggesting some minor R2RML changes)

From: Richard Cyganiak <richard@cyganiak.de>
Date: Thu, 7 Jul 2011 13:30:25 +0100
Cc: W3C RDB2RDF <public-rdb2rdf-wg@w3.org>, Souripriya Das <souripriya.das@oracle.com>, David McNeil <dmcneil@revelytix.com>, Ivan Mikhailov <imikhailov@openlinksw.com>
Message-Id: <55B458AE-9E77-412D-883C-73DEAE5BFE42@cyganiak.de>
To: Eric Prud'hommeaux <eric@w3.org>
Thanks for the comments Eric.

On 6 Jul 2011, at 13:20, Eric Prud'hommeaux wrote:
>> ISSUE: Why two classes rr:PredicateMap and rr:RefPredicateMap? They behave exactly the same, we could drop the second
> 
> I thought they had different properties (ref* vs. a smaller set of direct properties) and that the class differentiation was a didactic tool for the spec. There may be better ways to explain this. (ericP)
> 
>> ISSUE: Why two properties for rr:predicateObjectMap and rr:refPredicateObjectMap? Better to have just one, and spot the difference by looking at the (ref)objectMap contained within
> 
> I presume the same motivation and outcome as for the RefPredicateMap.

Ah, you're right; I was confused.

A RefPredicateMap can only be what is now called a “constant-valued term map”. It must have a rr:predicate property that specifies a fixed predicate. It cannot dynamically construct the predicate using rr:template or rr:column like normal PredicateMaps.

I don't remember why we made this restriction, and can't think of a good reason now. So I'm tempted to change it and make PredicateMap and RefPredicateMap the same.

Richard
Received on Thursday, 7 July 2011 12:30:55 GMT

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