Re: R2RML Linked Data Aspects

On Mar 15, 2011, at 13:31 , Sören Auer wrote:

[snip]
>> 
>> Well, that is what I am questioning, in fact. *RDF* does not have a concept of namespaces, only serializations do. And the different serializations (RDF/XML, Turtle, RDFa, soon JSON) may have different approaches. R2RML does not define which serialization is used at the end of the process...
> 
> I understand that, but this was not the issue. The issue is:
> 
> We have to generate IRIs manually sometimes with R2RML, e.g. in
> SQL-based logical table definitions. The IRIs are created by using a
> namespace and adding a local name component. Currently, if I look at the
> examples, this is done by writing and concatenating the namespace always
> in full. Also, if we want to generate various types of IRIs from
> database columns it would be good to be able to use CURIEs. For both the
> definition of namespaces which can be used would be beneficial.
> 
> The issue is in a way similar to that of SPARQL also there you declare
> prefixes as shortcuts within the query although the resulting RDF
> serialization (e.g. of a DESCRIBE query) might do that differently.
> 

Ah! Now I understand. Sorry to be a bit slow...

I agree this is good to have. What misled me was that, in fact, I do not regard that as being and issue related to Linked Data per se, just as a useful feature for R2RML. And that is of course enough of an argument to think about it!

In practice, what I am a little bit concerned is that in a R2RML file there are two level of prefix mechanisms

1. Prefixes used for the R2RML language itself: R2RML is a set of RDF triples and if Turtle is used for their serialization then there are prefixes on that lefvel
2. Prefixes used for the _content_ of those triples, ie, in the way the literals in those RDF triples are interpreted by an R2RML processor.

I am just afraid that it will be easy to mix those two levels... But it may be worth brainstorming about it. 

I would not consider that as a showstopper for the next publication round, however. Let us leave that for the next round (at least imho)

Ivan


> 
> Sören
> 


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Ivan Herman, W3C Semantic Web Activity Lead
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