Re: Requirements: tooling & named graphs

Hello Lee,

> Cambridge Semantics plans to implement the RDB2RDF standards in our Anzo 
> software... we've identified 2.5 requirements for the 
> RDB2RDF mapping language:
>
> 1/ Tooling
> 
> It must be straightforward to create tooling that generates mappings. 
> Most of the candidate designs I've seen have no problem here, but I 
> wanted to include it anyway. Declarative XML- or RDF-based mappings are 
> very easy to target. Mappings based on less structured query forms (SQL 
> views or SPARQL CONSTRUCT queries) are less desirable but are doable. 
>  From our perspective with respect to tooling, a SPARQL CONSTRUCT-based 
> approach is are preferable to a SQL DDL-based approach.

CONSTRUCT approach does not provide enough information about mapping to
SPARQL-to-SQL optimizing compiler. Efficient mapping requires much more
details than CONSTRUCT may fit. It would be nice to use CONSTRUCT but
we've made much more complicated language to not kill the performance.

> 2/ Named Graphs
> 
> The mapping language should be capable of mapping a relational schema 
> into SPARQL's named graph model. The granularity of the graphs should be 
> tweakable within the mapping -- for example, we sometimes will map an 
> entire table into a single graph, and other times we will map specific 
> rows/resources into their own graphs.

We've found that mapping of graph does not differ much from mapping of
other items of a quad. So I absolutely support this requirement.



> ...and a half/ Update
> 
> I realize that updating the relational database is beyond the scope of 
> our charter. That said, we would like to consider the potential 
> extensibility of the mapping approach chosen to handle (some cases of) 
> writing data back to a relational schema. (Either via SPARQL Update or 
> via triple/quad removes & adds.
> 
> (As we begin to compare and contrast design candidates, these are some 
> of the criteria that we'd like to use to evaluate the possibilities.)

I've written http://esw.w3.org/topic/UpdatingRelationalDataViaSPARUL
as a seed for a discussion but it did not cause any reaction so I
postponed the implementation. I'd like to hear any comments/wishes, even
strong reject is better than nothing.

Best Regards,

Ivan Mikhailov
OpenLink Software
http://virtuoso.openlinksw.com

P.S. This is my personal opinion, not a formal reply from any W3C
working group.

Received on Friday, 12 March 2010 10:34:18 UTC