Mikael,
Thanx to you, and others for suggestions/corrections to our pilot RDF schema. Since I'm only using RDF to the XML level and trying not to delve too deep into the tuples arena maybe it's a case of "a little knowledge is dangerous"...
>>> [log in to unmask] 26/07/02 20:49:57 >>>
> > 2. Confusingly, DCMIType is handled differently to other encoding schemes in the DCMI proposal. In Roland Schwaenzl's version it is treated the same as others, so we have used that version (previously we had re-defined the DCMIType encoding scheme within our nlnzdl namespace to make it consistent).
> Can you clarify the difference? I'm interested...
The RDF schema sample that appears in the DCMI proposal appendix [1] declares the class dcterms:TypeScheme then declares DCMIType using an rdf:about link to the DCMIType RDF schema:
<dcterms:TypeScheme rdf:about="&dctypens;DCMIType"/>
In the DCMIType RDF schema DCMIType is a class and so is each code:
<rdfs:Class rdf:about="&dctypens;DCMIType">
<rdfs:label>DCMI Type Vocabulary</rdfs:label>
<rdfs:comment>
The DCMI Type Vocabulary provides a general, cross-domain list of approved
terms that may be used as values for the Resource Type element to identify
the genre of a resource.
</rdfs:comment>
<rdf:type rdf:resource = "&dctermsns;TypeScheme" />
<rdfs:seeAlso
rdf:resource="http://dublincore.org/documents/dcmi-type-vocabulary/"/>
<rdfs:isDefinedBy rdf:resource="&dctypens;"/>
</rdfs:Class>
<rdfs:Class rdf:about="&dctypens;Image">
<rdfs:label>Image</rdfs:label>
<rdfs:isDefinedBy rdf:resource="&dctypens;"/>
<rdfs:seeAlso
rdf:resource="http://dublincore.org/documents/dcmi-type-vocabulary/"/>
<rdfs:comment>
An image is a primarily symbolic visual representation other than text.
For example - images and photographs of physical objects, paintings,
prints, drawings, other images and graphics, animations and moving
pictures, film, diagrams, maps, musical notation. Note that image may
include both electronic and physical representations.
</rdfs:comment>
<rdf:type rdf:resource="&dctypens;DCMIType"/>
</rdfs:Class>
In Roland Schwaenzl's version [2] DCMIType appears inline like all other dcterms encoding schemes:
<dcterms:TypeScheme rdf:about="&dctermsns;DCMIType">
<rdf:type rdf:resource="&rdfsns;Class"/>
<rdfs:label xml:lang="en-US">DCMI Type Vocabulary</rdfs:label>
<rdfs:comment xml:lang="en-US">A list of types used to categorize the nature or genre of the content of the resource</rdfs:comment>
<rdfs:isDefinedBy rdf:resource="&dctermsns;"/>
<rdfs:seeAlso rdf:resource="&dctypens;"/>
<rdfs:seeAlso
rdf:resource="http://dublincore.org/documents/dcmi-type-vocabulary/"/>
<dcterms:issued>2000-07-11</dcterms:issued>
</dcterms:TypeScheme>
Now maybe both the above are equivalent, but I don't know enough to know. The second version appears easier to follow for our situation...
The first version defines DCMITypes as URIs, eg. http://purl.org/dc/dcmitype/Image whereas the second version looks like it allows you to just place the text version of the code (eg "Image") in as content, like any other encoding scheme. This is a lot better for us as we are interested in the RDF as pure XML rather than a set of tuples.
> > We're following Roland Schwaenzl's version for incorporating version dating in our RDF schema.
> Can you clarify on that as well: how, precisely are you incorporating
dates?
Roland Schwaenzl's version adds dcterms:issued and dcterms:modified against each property/class. Though I'm not sure how tracking which version of each property/class is OK at different points of time would be implemented beyond that. Perhaps dcterms:valid with a date range??
<dcterms:IdentifierScheme rdf:about="&dctermsns;URI">
<rdf:type rdf:resource="&rdfsns;Class"/>
<rdf:type rdf:resource="&dctermsns;RelationScheme"/>
<rdf:type rdf:resource="&dctermsns;SourceScheme"/>
<rdfs:label xml:lang="en-US">URI</rdfs:label>
<rdfs:comment xml:lang="en-US">A URI Uniform Resource Identifier</rdfs:comment>
<rdfs:isDefinedBy rdf:resource="&dctermsns;"/>
<rdfs:seeAlso rdf:resource="http://www.ietf.org/rfc/rfc2396.txt"/>
<rdfs:seeAlso
rdf:resource="http://www.dublincore.org/usage/decisions/#2001.04"/>
<dcterms:issued>2000-07-11</dcterms:issued>
<dcterms:modified>2001-05-21</dcterms:modified>
</dcterms:IdentifierScheme>
Thanx,
Douglas Campbell
National Library of New Zealand
[1] http://dublincore.org/documents/2002/04/14/dcq-rdf-xml/
[2] http://www.mathematik.uni-osnabrueck.de/projects/dcqual/qual21.3.1/Schema/A/dcterms
|