Re: Direct Mapping

On 7 Sep 2010, at 04:43, Juan Sequeda wrote:
> On Mon, Sep 6, 2010 at 10:31 PM, Richard Cyganiak  
> <richard@cyganiak.de>wrote:
>> So there are at least TWO DISTINCT AUDIENCES for the direct mapping  
>> spec:
>>
>> 1. RDB2RDF vendors who implement R2RML engines and want to equip  
>> their
>> systems with functionality similar to D2R's "generate-mapping"  
>> script, which
>> generates a simple canonical R2RML file for a given database, with  
>> the
>> intent of allowing further customization of the R2RML file by the  
>> user.
>>
>> 2. RDB2RDF vendors who implement RIF-based engines (or engines  
>> based on any
>> other RDF-to-RDF transformation language). Users of these engines  
>> will write
>> RIF rules that transform the direct graph into a custom graph.  
>> Users and
>> vendors of these systems don't need the R2RML language.
>
> Great clarification and +1 on everything.
>
> Given that we are clear that there are two audience, the only thing  
> I'm
> saying is that if we are going to write a document on the Direct  
> Mapping,
> which one of the audiences is expecting to see a R2RML file... we  
> need to
> have a R2RML syntax before we have a Direct Mapping document ready.

Again, the “RIF-friendly audience” in 2. doesn't want to see R2RML,  
and is better served by a spec that simply describes the shape of the  
resulting direct graph.

The “R2RML-friendly audience” in 1. would be reasonably well served by  
either approach -- describing the shape of the direct graph, or  
describing a canonical “direct R2RML file”.

My preference would be to normatively specify the direct mapping as a  
direct graph. And have an informative appendix that describes an  
algorithm for creating the canonical direct R2RML file that produces  
the direct graph.

> Hence my suggestion to put priority on syntax right now.

I sort of agree. But I don't see a dependency of the direct mapping on  
R2RML.

Richard

Received on Tuesday, 7 September 2010 04:01:14 UTC