Re: Relationship between EricP's default mapping and Datalog rules approach?

Harry,

On Sun, Jul 18, 2010 at 8:26 AM, Harry Halpin <hhalpin@w3.org> wrote:

> While I enjoyed the talk last week, I was wondering about the relationship
> between Eric's proposed direct mapping [1] and the rules put forward last
> week by Marcelo [2]. This question goes to both, and the entire working
> group.
>
> One of the advantages of Eric's default mapping mechanism [1] is that it
> allows relational data to be expressed in RDF without the author of the
> mapping knowing *any* rules or having any ontology that he or she wants to
> map their relational data to.
>

This is exactly the same as the Database-Instance-Only mapping.

>
>  This is one of the requirements of our charter, although of course we
> want mappings to other vocabularies to be possible. Remember, this can be
> thought of as a two-step process, where the first step is a default
> mapping, and then later mappigs (via Datalog rules, RIF, SQL or whatever)
> could then transform
>

In this simple approach, the predicates are the only things that are going
to be mapped:

ex:name ->foaf:name
....

So you could have a system that can automatically generate:

Triple(s, "ex:name", name) <- student(s_id, name), generateURI(s_id, s)

or the user can write the mapping with the :

Triple(s, "foaf:name", name) <- student(s_id, name), generateURI(s_id, s)


> Could we take the rules given earlier [2] and then use these to produce
> the same effects as Eric's direct mapping proposal? Could someone specify
> this in detail?
>
>
The Database-Instance-Only mapping does that.


> Then the default mapping could be seen as a certain default application of
> rules, an application that *can* be changed.
>

The rules defines the semantics of what needs to be implemented in an
application


>
>            cheers,
>                 harry
>
> [1] http://www.w3.org/2001/sw/rdb2rdf/directGraph/
> [2]http://web.ing.puc.cl/~marenas/W3C/mapping_language.txt
>
>
>
>