Re: R2RML Linked Data Aspects

On 15 Mar 2011, at 12:31, Sören Auer wrote:
> 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.

In D2RQ, we specify that any URIs generated by the mapping (via SQL expressions or URI patterns) can be relative URIs. These are then turned into absolute URIs by resolving them against a system-provided base URI.

If D2RQ is run in a linked data server (D2R Server), then the server pre-configures the base URI of the mapping to the URI where the server itself runs. Thus, if we have a URI pattern "person/@@employee.ID@@", it could create a relative URI <person/23>, which could be resolved against a server location such as <http://localhost:2020/> to become <http://localhost:2020/person/23>. This makes it very easy for the mapping author to ensure that the generated URIs are resolvable.

> 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.

I'm not sure that I understand what you're aiming at with this analogy. Any R2RML document written in Turtle can already use Turtle's support for QNames to abbreviate URIs, so in that sense it has exactly the same capability as SPARQL.

Best,
Richard

Received on Tuesday, 15 March 2011 14:42:39 UTC