Datatyping: new medium-range proposal from HP

Summary: use file scope syntactic datatyping mechanism.

After the recent wg fracas about datatyping I have been consulting with my
colleagues.

No one in the WG will be surprised to hear that the HP team is split down
the middle on the tidy/untidy issue.

However, you may be surprise that we have reached a consensus about our
preferred solution, with no dissent (within the HP Jena team).

The first step towards it was to rename "tidy" as "short range" datatyping,
and "untidy" as "long range" datatyping.
Having done that, a compromise of "medium range" datatyping seems thinkable.

Moreover, on further consideration, we determined that our preference for
this new proposal was sufficiently great that we wanted the WG to consider
it, despite its lack of timeliness.

So here goes ...

=========

On the datatyping issue we have two camps:

   camp T want connolly's entailement and an easier life for implementors
and developers

   camp U don't want to repeat the rdf:datatype on every instance

Both of these needs can be met if an rdf/xml parser fully resolves the type
of literals.  When the triples come out of the parser, they have their
datatype attached.

In programming languages we do not write:

   <int>i = <int> i + 1;
   if (<int>i < <int>j) then {
     <int>i = <int>j + <int> i;
   ...

We write:

   int i,j;
   i = i + 1;
   ...

Following that model, add to RDF the ability to make datatype declarations:

   <rdf:RDF>
     <rdf:Datatyping>
       <foo:prop1 rdf:datatypeRange="&xsd;decimal"/>
       <foo:prop2 rdf:datatypeRange="&xsd;string"/>
     </rdf:Datatyping>

      <rdf:Description>
        <foo:prop1>10</foo:prop1>
        <foo:prop2>10</foo:prop2>
        <foo:prop3>10</foo:prop3>
      </...

produces:

   _:a foo:prop1 xsd:decimal"10" .
   _:a foo:prop2 xsd:string"10" .
   _:a foo:prop3 "10" .

The object of the last triple is a literal classic which has tidy semantics.

Moreover we could combine this with Sergey's suggestion of two new types for
tradional RDF String Literals, and traditional RDF XML Literals.

http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Sep/0196.html

Range constraints in a schema are understood as constraints not as long
range datatyping. Thus with the previous data

foo:prop3 rdfs:range xsd:decimal .

simply fails (is contradictory); as would be:

foo:prop3 rdfs:range xsd:string .


====

This proposal is intended as a sketch, but enough of one to allow active
consideration. I understand that the WG will soon reconsider the tidy/untidy
decision, and I ask that this be included as a third possibility.
As with any of the options, I imagine that once a choice is made further
refinements will occur.

I note that DanC has some wizzy multiple choice web voting software (single
transferrable vote?) that would support a three way choice.


Jeremy

Received on Wednesday, 2 October 2002 12:18:10 UTC