Re: R2RML practicability concerns

> I believe that the R2RML mapping language must allow full mapping
> functionality. However, to address the other extreme of the spectrum and
> points in between, R2RML should provide shortcut constructs where
> default/automatic mappings can be specified with very concise mapping
> specification. (Please note, however, that the example we have included
> in the current draft is probably artificially complex because its main
> purpose was to illustrate most if not all functionality allowed by R2RML.)

Yes, I agree with both Souri and Soeren - namely, that the language must
allow "very expressive" mapping (and will, probably get a bit more complex
when Eric gets through various edgecases), but so that people can learn it
and use it, we strongly need to have default mapping standardized to
prevent people from writing too many triples.

Since I imagine the editors are quite busy, would it be possible  that
Soeren and the default mapping people combine forces with them to see what
sensible default mapping can be done and write the details of how that
would look like in the R2RML draft?

It's a very sensible suggestion since I think Marcelo, Juan, and Eric
agree on 90 percent of the default mapping behavior.

> We will add constructs that will allow minimal mapping specification
> that can be used and also that can be incrementally refined, if necessary.

One neat practice idea might be, one idea to test how it looks would be to
make mapping files for each of the use-cases in the use-case note.

> Thanks,
> - Souri.
> On 10/5/2010 7:15 PM, Sören Auer wrote:
>> Dear all,
>> unfortunately there was not time today during the telco to raise this
>> concern, that is why now by email:
>> When looking at the example I notice, that the relational tables
>> definition would be very concise (~15 lines). The R2RML mapping,
>> however, is very verbose and takes probably 5 times more space.
>> I'm really afraid, that R2RML will be very impractical and has a quite
>> steep learning curve. Even if you have user interfaces which
>> automatize the generation of R2RML, these will have to be understood
>> and modified manually as soon as the DB schema changes. From that
>> perspective, the current draft appears to be quite impractical.
>> Suggestion: do you think it would be possible to follow a convention
>> over configuration approach and only require the user to configure
>> something in case he wants to alter the default behaviour. For
>> example, an rr:Table2TriplesMap based on an rr:logicalTable could be
>> mapped based on reasonable assumptions and maybe a default mapping of
>> DB datatypes to XML-Schema datatypes, instead of having to configure
>> every rr:propertyObjectMaps in addition for every column.
>> I think simplifying things is really crucial, if we want the standard
>> to be quickly and widely adopted.
>> Best,
>> Sören

Received on Wednesday, 6 October 2010 07:12:38 UTC