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Re: PS-8: Query with Datatype Value Comparison & Support for Arbitrary Datatypes in Query

From: Janne Saarela <janne.saarela@profium.com>
Date: Fri, 02 Apr 2004 10:49:00 +0300
Message-ID: <406D1AEC.50900@profium.com>
To: public-rdf-dawg@w3.org
Cc: Patrick Stickler <patrick.stickler@nokia.com>

Following yesterday's teleconference I would like to continue
discussion on this support for arbitrary datatypes in a query.

I suggested that if the support is really for any arbitrary
datatype, for a DAWG recommendation compatible RDF query
processor we need to lay a set of minimal datatypes it needs
to support. This would enable us to lay a minimal set of
operators that operate on these datatypes.

I suggest the minimal set of datatypes would be a
subset of all XML Schema datatypes. I leave it up to
further discussion to see which ones are truly necessary.


> A client wishes to discover all resources which are of rdf:type
> ex:Person, and have an ex:ageInYears which is between "16"^^ex:count
> and "18"^^ex:count, inclusive.
> The client is aware of a knowledge source from which such
> resources might be discovered.
> Following the DAWG recommendation, the client formulates a query
> which expresses the desired characteristics to match and submits
> the query to the knowledge source.
> The knowledge source returns zero or more resource descriptions
> describing the matched resources.
> -- 
> I deliberately used unknown datatypes in this example to illustrate
> the need to be able to allow arbitrary datatypes in input queries,
> regardless of what datatypes a particular query resolution engine
> may be able to handle.
> Note that if the client is able to include auxiliary knowledge
> which may be relevant to resolution of the query along with
> the query itself (e.g. in a single input RDF graph) this would allow
> the client to provide information about the terminology used
> in the query, such as about the nature of particular datatypes,
> their relationship to other datatypes, and even references to
> formal definitions of the datatypes which could be used by the
> knowledge source to evaluate typed literals and perform comparisons.
> E.g. the auxiliary knowledge could indicate an XML Schema which
> defines the datatype in question, and if the knowledge source is
> able to understand XML Schemas, could load and utilize to deal
> with values of that datatype.
> -- 
> Patrick Stickler
> Nokia, Finland
> patrick.stickler@nokia.com

Janne Saarela <janne.saarela at profium.com>
Profium, Lars Sonckin kaari 12, 02600 Espoo, Finland
Received on Friday, 2 April 2004 02:49:40 UTC

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