Re: Non-Turtle mapping documents (ISSUE-57)


> Oracle objects to reopening of ISSUE-57 for the following reason:


> 	• Making support for Turtle a prerequisite to support for R2RML  
> seems inappropriate.

May I ask why? As of today Turtle is available as a FPWD 
  and will be a REC soon. I mean, I would understand this in case of,  
say, JSON-LD, but why is Turtle 'inappropriate'?

Dr. Michael Hausenblas, Research Fellow
LiDRC - Linked Data Research Centre
DERI - Digital Enterprise Research Institute
NUIG - National University of Ireland, Galway
Ireland, Europe
Tel. +353 91 495730

On 9 Aug 2011, at 16:36, Souripriya Das wrote:

> Oracle objects to reopening of ISSUE-57 for the following reason:
> 	• Making support for Turtle a prerequisite to support for R2RML  
> seems inappropriate.
> 	• A conforming implementation for R2RML should be free to support  
> one or more of the available syntaxes for RDF and expect that R2RML  
> mapping specifications will be presented to it using such a syntax.  
> (User may use available tools to do the translation to the  
> appropriate syntax, if necessary. In practice, conforming  
> implementations will provide support for popular syntaxes for RDF --  
> not necessarily limited to Turtle.)
> 	• For tests specified in Turtle, an implementation should have the  
> option of using available translators to translate the tests to a  
> different syntax (e.g., N-Triple) and then run the tests. As long as  
> the output of (say {?S ?P ?O}) query is as expected, the  
> implementation is conformant to R2RML.
> Thanks,
> - Souri.
> Richard Cyganiak wrote:
>> Hi Sören,
>> On 25 Jul 2011, at 14:31, Sören Auer wrote:
>>>> You can encode an R2RML mapping graph in any syntax you like, and  
>>>> it's still a conforming R2RML mapping graph. (It may just not be  
>>>> a conforming R2RML mapping *document*, which is a different  
>>>> concept and a stronger claim.)
>> ...
>>> Ok, with the distinction between mapping document and mapping  
>>> graphs it
>>> might not be a contradiction, but this is quite confusing to the  
>>> reader.
>>> I would omit this distinction (and remove the term mapping document
>>> altogether) and just write "A conforming R2RML processor MUST  
>>> accept an
>>> R2RML mapping graph serialized in Turtle syntax."
>> Dropping the definition of R2RML mapping document and adding this  
>> requirement would work in principle.
>> Another option would be to define R2RML mapping document as *any*  
>> document in *any* RDF syntax that can be parsed to an R2RML mapping  
>> graph; and requiring that processors MUST be able to process any  
>> such document that uses the Turtle syntax.
>> However, I'm not so happy with either of these options. Factors to  
>> consider here:
>> First, in everyday work, people will have to deal with actual R2RML  
>> documents (which would probably be Turtle). So from my POV it makes  
>> sense to define a term that corresponds to this intuitive notion in  
>> the spec.
>> Second, given that Turtle support is required to ensure  
>> interoperability, and given that our test suite consists of R2RML  
>> mapping documents (in Turtle), I feel that it's important to  
>> actually have a well-defined term that corresponds to this set of  
>> interoperable exchange artefacts.
>> How about the following compromise:
>> 1. Rename "R2RML mapping document" to "R2RML mapping document in  
>> Turtle" to reduce the confusion with the similar-looking term  
>> "R2RML mapping graph"
>> 2. Add a Note in an appropriate place that points out the  
>> difference between "R2RML mapping document in Turtle" and "R2RML  
>> mapping graph", perhaps along these lines:
>> [[
>> Note: The main exchange format for R2RML recommended in this  
>> specification is the "R2RML mapping document in Turtle", and any  
>> conforming R2RML processor MUST support it.
>> However, some implementations may require exchange of R2RML  
>> mappings in other ways, such as RDF/XML or through the SPARQL  
>> protocol or through an RDF API. R2RML mappings are expressed in RDF  
>> to enable this flexibility.
>> This specification defines the notion of an abstract "R2RML mapping  
>> graph" to enable other modes of exchanging RDF graphs beside Turtle.
>> ]]
>> Would that solve the confusion that you pointed out?
>> Best,
>> Richard

Received on Tuesday, 9 August 2011 15:47:47 UTC