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RE: RDF datatyping: retro chic / progress report

From: <Patrick.Stickler@nokia.com>
Date: Fri, 9 Aug 2002 20:01:48 +0300
Message-ID: <A03E60B17132A84F9B4BB5EEDE57957B160B8F@trebe006.NOE.Nokia.com>
To: <danbri@w3.org>, <w3c-rdfcore-wg@w3.org>

Thanks Dan. This was very illumnating. See my next post
that was stimulated by this, as well as todays telecon.


> -----Original Message-----
> From: ext Dan Brickley [mailto:danbri@w3.org]
> Sent: 09 August, 2002 19:56
> To: w3c-rdfcore-wg@w3.org
> Subject: RDF datatyping: retro chic / progress report
> Thought this might be of historical interest. And perhaps 
> motivate some
> closure. It's over four years since we first published a W3C 
> WD discussing
> RDF datatyping. I don't intend to be still doing this in another four
> years. I don't think any of us should. We need to get 
> something simple and
> useful out the door, and worry about elaborations later...
> The amount of telecon time we have left to work on 
> datatype-related issues
> is best counted in minutes not years. I'm encouraged by the 
> recent turn of
> discussions as it holds out some hope for modest but useful 
> progress over
> RDF'98. Time will tell...
> Dan
> From http://www.w3.org/TR/1998/WD-rdf-schema-19980409/
> 	W3C Working Draft 9 April 1998
> 	Editors:
> 	Dan Brickley, University of Bristol
> 	R.V. Guha, Netscape
> 	Andrew Layman,  Microsoft
> [[
> Open Issue C.21. Interactions with External Type Systems
> The RDF Schema mechanism defines a basic type system. It was 
> not developed
> to provide every imaginable capability. Instead, in the interests of
> simplicity and performance, it will be only as expressive as needed to
> meet the requirements of PICS. (Support for PICS generic 
> capability, which
> we expect to be in the next public release of this document, 
> will provide
> enough sophistication for most applications).
> The RDF Schema mechanism will need to interact with many externally
> developed typing systems. There are two broad categories of 
> such systems.
> The first are externally defined "primitive data types", such as IEEE
> floating point numbers, Integers, Boolean values, Dates and 
> Times, etc.
> The second category are external "type systems", which 
> provide features
> such as inheritance, type inferencing, etc.
> At this time we have not even begun to consider the second category.
> Several factors make it difficult to decide on the appropriate
> interactions with the first category. RDF models are exchanged as XML
> document instances. The XML Working group has expressed an interest in
> working on the problem of data typing, to provide the ability 
> to specify
> that element content should be interpreted as an integer, a 
> date, a float,
> left as a string, etc. The interactions between data typing 
> efforts in XML
> and RDF is currently being discussed by the W3 staff, so this document
> does not provide a specification for those interactions that 
> is as firm as
> the specification for elements such as RDFS:Class, 
> RDFS:subClassOf, etc.
> However, it is the rough consensus of the RDF Schema WG that 
> it would be
> useful to show that the current schema system can actually accommodate
> externally defined primitive data types. Therefore, figure 1, and the
> relevant portion of the text of the specification, was 
> modified to give a
> provisional indication of how external types might be 
> handled. The reader
> is advised that those portions of the specification are 
> highly subject to
> change, even more so than the rest of this specification. All of those
> sections have been explicitly marked to refer to this open issue.
> ]]
> From 2.1 The Type System [[
>  We anticipate the development of a set of classes 
> corresponding to a set
>  of "datatypes." This paper does not define datatypes, but 
> does note that
>  datatypes may be used as the value of the RDFS:range property.
> ]]
Received on Friday, 9 August 2002 13:01:57 UTC

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