Re: What is Oracle's objection to the use of Turtle as R2RML syntax?

On 12/13/11 11:34 AM, Souripriya Das wrote:
> There are currently two proposed options:
> 1) Turtle-syntax-MUST
> 2) one-w3c-RDF-syntax-MUST
>
> The Turtle-syntax-MUST option does not support any syntax other than 
> Turtle for the R2RML mapping documents
> while the one-w3c-RDF-syntax-MUST option only requires at least one of 
> the (W3C Recommendation) RDF syntaxes be used for R2RML mapping documents
> (while, because of the Turtle-convertibility,  still allowing the test 
> cases, tutorials, books, etc. to be written in Turtle).
>
> Again, here is the one-w3c-RDF-syntax-MUST proposal:
> [[
> An R2RML mapping document is any document that encodes an R2RML 
> mapping graph and
> is written in any RDF syntax that is a W3C Recommendation and that can 
> be converted to Turtle.
> ]]
> (By "Turtle" we mean the future Turtle W3C Recommendation)
>
> The following can be said about the effect of using the above proposal:
>
> ------------------
> Consider an R2RML mapping document written in RDF/XML syntax:
> - Is it a conforming R2RML mapping document?
> YES. (for Turtle-syntax-MUST: NO)
> - Why?
> Because one can convert the document to generate an equivalent 
> document written in Turtle syntax.
>
> ---------------------
> Consider an R2RML mapping processor which ONLY accepts R2RML mapping 
> documents written in RDF/XML syntax:
> - Is it a conforming R2RML mapping processor?
> YES. (for Turtle-syntax-MUST: YES)
> - Why?
> Because it accepts all conforming R2RML mapping documents, written in 
> RDF/XML syntax.
>
> ---------------------
> Testing for conformance of an R2RML mapping processor that ONLY 
> accepts RDF/XML documents:
>
> For each test in "tests for conformance"
> 1) obtain the mapping documents (written in Turtle syntax)
> 2) Convert these Turtle-syntax mapping documents into RDF/XML syntax 
> (assuming this is possible)
> 3) Process the converted documents
> 4) Run the corresponding SPARQL queries from "tests for conformance" 
> and compare the results
> 5) If query results match, then this processor is indeed a conforming 
> R2RML mapping processor
>
> ---------------------
> Sharing of an R2RML mapping document between two non-overlapping 
> syntax accepting processors:
> - MappingProcessor1 accepts ONLY RDF/XML and MappingProcessor2 accepts 
> ONLY N-Triples
> - an R2RML mapping document (written in RDF/XML) and used at 
> MappingProcessor1 is to be shared with MappingProcessor2
> - convert the mapping document into an equivalent N-Triples document 
> (via Turtle, if direct conversion is not possible)
> - present the N-Triples R2RML mapping document to MappingProcessor2

Put differently, should an R2RML processor be expected to support 
content negotiation? I guess that's an implementation specific detail 
rather than one for the spec.

I think we need to be clear about the fact that R2RML is a Language that 
leverages RDF's underlying Data Model which is distinct from the variety 
of syntaxes and serialization formats associated with the RDF model. In 
a nutshell, R2RML is a Domain Specific Language (DSL).

You write R2RML mappings using the R2RML language which happens to be 
Turtle. Thus, this issue really boils down a clear definition of R2ML so 
that it doesn't get intermingled with RDF in general.

Souri: R2RML should only be about mappings using its syntax (which 
happens to be Turtle). Of course, as per comments above, a specific 
processor could decide to do translation in the middle, but from a 
language spec perspective, Richard's position is cleaner.

Kingsley
>
> Thanks,
> - Souri.
>
> ----- Original Message -----
> From: richard@cyganiak.de
> To: souripriya.das@oracle.com
> Cc: public-rdb2rdf-wg@w3.org
> Sent: Wednesday, December 7, 2011 1:52:14 PM GMT -05:00 US/Canada Eastern
> Subject: Re: What is Oracle's objection to the use of Turtle as R2RML 
> syntax?
>
> On 7 Dec 2011, at 18:07, Souripriya Das wrote:
>> Instead of the following definition of the mapping document:
>>
>> [[
>> An R2RML mapping document is any document written in the Turtle 
>> [TURTLE] RDF syntax that encodes an R2RML mapping graph.
>> ]]
>>
>> we propose the following:
>>
>> [[
>> An R2RML mapping document is any document that encodes an R2RML 
>> mapping graph and
>> is written in any RDF syntax that is a W3C Recommendation and can be 
>> converted to Turtle [2].
>> ]]
>
> Why is this better?
>
> Richard
>
>


-- 

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