- From: <charles@w3.org>
- Date: Sun, 24 Oct 2004 06:21:49 -0400 (EDT)
- To: "Graham Klyne" <GK@ninebynine.org>
- Cc: "Stephane Fellah" <fellah@pcigeomatics.com>, www-rdf-interest@w3.org
You could just use rdf:datatypes which are defined as being a length in metres expressed as a "float". See http://www.w3.org/2001/sw/Europe/200409/geox for some examples of how I set about doing this. I asked DanC why he did InterpretationProperties instead and he said it was because cwm had a bug in handling datatypes. I believe Jena, for example, has no such problem. I also think they are useful things... cheers chaals > > Stephane, > > (I'm responding to just the first few lines of your message. I haven't > studied your example. Please ignore if not helpful. Also, trimmed reply > list.) > > See also, "interpretation properties": > http://www.w3.org/DesignIssues/InterpretationProperties.html > > #g > -- > > At 16:23 22/10/04 -0400, Stephane Fellah wrote: > >>Hi, >> >> >> >>I am trying currently to qualified literal with more attributes than >>xml:lang and rdf:datatype. >> >> >> >>In RDF, there are two three types of literal. >> >> >> >>* Plain Literal, which consists of a string with an optional attribute >>xml:lang >> >>* Typed Literal, which is a string with rdf:datatype attribute. >> >>* XML Literal, which is a literal representing an XML literal. >> >> >> >>Sometimes, it is necessary to qualified further a typed Literal without >>creating a resource. For example, a unit of measure or a codespace >>(taxonomy) in which the value belongs to (tree name taxonomy for >> example). >>The only way to describe these attributes in the current RDF >>specification, is to create an anonymous resource having these different >>properties. This makes the serialization of RDF in XML pretty lengthy and >>ugly to read by human. >> >> >> >>Here an example (in a sloppy syntax, I apologize) >> >> >> >><Road> >> >> <length> >> >> <value rdf:datatype="&xsd;float">10</value> >> >> <gml:uom rdf:resource="urn:opengis:uom:meter"> >> >> <length> >> >> <surfaceType> >> >><value>asphalt</value> >> >><gml:codespace rdf:resource= urn:ataxonomyofsurfacetype /> >> >> </surfaceType> >> >><Road> >> >> >> >>A more elegant way to serialize this would be: >> >> >> >><Road> >> >> <length gml:uom="urn:opengis:uom:meter" >> rdf:datatype="&xsd;float">10</length > >> >> <surfaceType gml:codespace= >> urn:ataxonomyofsurfacetype >asphalt</surfaceType> >> >><Road> >> >> >>Please note that this syntax will bridge some gaps with current XML >>document syntax defined in XML schema. >> >> >> >>The problem with this syntax is that RDF parsers such as ARP or Jena, >>would return an error because no other property attribute can be used >> with >>rdf:datatype. >> >> >> >>In RDFS, a literal is a subclass of Resource, however most of RDF API >> does >>not use the same hierarchy. In Jena for example, Literal is subclass of >>RDFNode and not Resource. So it does not provide the ability to add >>additional properties to a literal. However, if we follow the ontology, I >>should be able to add either annotation property to Literal or subclass >>the class Literal with additional properties (probably would be in OWL >>Full in this case). >> >> >> >>If a Literal was a subclass of resource, the former RDF example could be >>represented in a canonical way: >> >> >> >><Road> >> >> <length> >> >> <Literal> >> >> <rdf:datatype rdf:resource="&xsd;float"/> (this is an >> extension of rdf) >> >> <rdf:lexicalform>10</rdf:lexicalform> (this is an extension >> of rdf) >> >> <gml:uom rdf:resource="urn:opengis:uom:meter"/> >> >> <Literal> >> >> <length> >> >><Road> >> >> >> >>Note that rdf:datatype and rdf:lexicalform does not seem to be defined in >>RDFS or RDF, but may be needed to support RDF API. >> >> >> >>This form would be equivalent to the previous compact example. The only >>constraint we would have to the literal interface is to have properties >>with resource URI or string values. May be they should be annotation >>properties. Technically, tuning existing a parser to support this >>extension would not be a big job. The question is whether this is valid >>with RDF semantics or not. >> >>Is there any reason why this could not be done ? Does my reasoning make >>sense ? Is the proposal acceptable to improve RDF specification? Does not >>anyone experiment such an approach ? >> >> >> >>Best regards >> >> >> >>Stephane Fellah >> >>Web Chief Architect >> >>PCI Geomatics, Hull, QC >> >> >> >>Yahoo! Groups Sponsor >>ADVERTISEMENT >> >> >>---------- >>Yahoo! Groups Links >> * To visit your group on the web, go to: >> * >> <http://groups.yahoo.com/group/jena-dev/>http://groups.yahoo.com/group/jena-dev/ >> >> * >> * To unsubscribe from this group, send an email to: >> * >> <mailto:jena-dev-unsubscribe@yahoogroups.com?subject=Unsubscribe>jena-dev-unsubscribe@yahoogroups.com >> >> * >> * Your use of Yahoo! Groups is subject to the >> <http://docs.yahoo.com/info/terms/>Yahoo! Terms of Service. > > ------------ > Graham Klyne > For email: > http://www.ninebynine.org/#Contact > >
Received on Monday, 25 October 2004 08:10:37 UTC