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Re: Datatypes (ISSUE-48)

From: Ivan Herman <ivan@w3.org>
Date: Wed, 10 Aug 2011 12:59:40 +0200
Cc: Richard Cyganiak <richard@cyganiak.de>, W3C RDB2RDF <public-rdb2rdf-wg@w3.org>
Message-Id: <087D9F37-F99A-4E17-9D4C-29B8BFB7A403@w3.org>
To: Nuno Lopes <nuno.lopes@deri.org>
So here is the question: should we use XML schema based datatypes as the 'target' datatype, or rather OWL 2 based datatypes?

I believe the type you described below would be:

<newType> a rdfs:Datatype ;
   owl:onDatatype xsd:string ;
   owl:withRestrictions (
     [ xsd:pattern "\p{Nd}{4}-\p{Nd}{2}-\p{Nd}{2}" ]
   ) .

It is not overly pretty either (neither is the XML Schema based) but the question is which one could be used more efficiently in practice. I may be mistaken, but I do not know of any RDF environment that would interpret derived datatypes defined with XML Schemas. At least there are OWL environments that do, however (eg, they can check range restrictions based on literal values, stuff like that).

Ivan


On Aug 10, 2011, at 12:35 , Nuno Lopes wrote:

> Hi Richard,
> 
> I added to the Wiki an explanation for the "or" mapping, most of them are left up to the implementation. Regarding the boolean type there is no mention and it seems to be mapped directly.  As for the dates and durations, the lexical values are restricted by the "xs:pattern" facet as I mentioned. For example the DATE SQL type is mapped to the XSD type:
> 
> <xs:simpleType>
>  ANN
>  <xs:restriction base="xs:date">
>    <xs:pattern value="\p{Nd}{4}-\p{Nd}{2}-\p{Nd}{2}"/>
>  </xs:restriction>
> </xs:simpleType>
> 
> where ANN may indicate the original SQL datatype (implementation defined).  I'll add this example to the wiki.
> 
> Did I miss some other question?
> 
> Cheers,
> --
> Nuno Lopes
> 
> 
> 
> On 9 Aug 2011, at 19:03, Richard Cyganiak wrote:
> 
>> Hi Nuno,
>> 
>> I had another look at the wiki page:
>> http://www.w3.org/2001/sw/rdb2rdf/wiki/Mapping_SQL_datatypes_to_XML_Schema_datatypes
>> 
>> Ok, this answers what we ought to do with user-defined and constructed types.
>> 
>> There are still a couple of questions open from here:
>> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2011Aug/0017.html
>> 
>> Maybe you could comment on these?
>> 
>> Cheers,
>> Richard
> 
> 


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Received on Wednesday, 10 August 2011 10:57:40 UTC

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