Re: Direct Mapping

On 6 Sep 2010, at 20:33, Juan Sequeda wrote:
> A RDB2RDF system with a R2RML file will always define a RDF graph.
>
> So what makes the direct mapping different?
>
> They way I see it, is that the R2RML file is generated  
> automatically, and
> with this file, given a RDB2RDF system, you will have a RDF graph.  
> If other
> see it different (I can tell that Eric does), then please shout out.


The goal of the direct mapping is to have a simple, canonical RDF  
graph representation of every possible database (let's call it the  
“direct graph”).

There are two ways how you could define the direct mapping:

1. As a mapping from a database to a direct graph

2. As a mapping from a database to an R2RML file that maps the  
database to the direct graph

I would prefer the first option, because it better supports the  
specification of RDB2RDF mappings using generic RDF-to-RDF  
transformation technologies such as RIF, SPARQL CONSTRUCT, R2R, and so  
on. If the direct mapping is specified as the first option, then  
RDB2RDF mappings can be written using these technologies as a mapping  
from the direct graph to the desired target RDF schema/vocabulary.

Hence I'm with Eric here.

> The automatic mapping file that is generated in D2R is equivalent to  
> the
> Direct Mapping (right Richard?).

Well I'd say the *graph* produced by an auto-generated D2R mapping  
file is equivalent to the direct mapping.

Best,
Richard

Received on Monday, 6 September 2010 20:03:06 UTC