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Re: Linking an RDF instance to its RDF Schema

From: <MDaconta@aol.com>
Date: Sun, 17 Nov 2002 18:55:05 EST
Message-ID: <137.178fb775.2b098659@aol.com>
To: fmanola@mitre.org, www-rdf-interest@w3.org
Hi Frank,

Unfortunately, the protege editor is not following the conventions
you discuss ... more responses below...

In a message dated 11/17/2002 3:39:57 PM US Mountain Standard Time, 
fmanola@mitre.org writes:
>>>
Mike--

If you have rdf:type properties in your instances, their values should 
be URIs that identify Class resources in your schema.  User-defined 
properties in the instance data should be (after QName resolution) URIs 
that identify Property resources in your schema.  Are you looking for 
some other kind of explicit link?
<<<

The good news in that is that it provides a link to the RDF Schema
which is what I was looking for.  The bad news is that it does not seem 
to agree with the treatment of namespaces in XML Documents.
I thought namespaces did not have to refer to a document which is why
you have either the DOCTYPE declaration or the schemaLocation attribute.
Also, I thought this is what prompted the RDDL to be proposed.  In other 
words,
should we assume that RDF uses namespaces differently than XML documents?
This doesn't seem like it would bode well for embedding RDF in XML (like
XHTML).

>>>
MDaconta@aol.com wrote:
>Hi All,
>
>Working with protege recently, It can generate both an RDF
>Schema and separate instance documents conforming to the
>schema; however, there is no direct, explicit link between the RDF 
>Schema and
>its instance document.  Why not? 
>
>I notice that the RDF Schema spec and the Primer are both silent on
>this issue.  As this is different than the process for XML documents,
>I would think an explanation or justification is in order.
>

fmanola@mitre.org writes:
The Primer isn't silent on the issue.  At least there's an example of 
instance data at the end of Section 5.2 that illustrates the points I 
made above.  Perhaps it could be elaborated (suggestions are welcome, 
although people are always complaining about how long the Primer has 
gotten in trying to follow all the other suggestions.. :-) ...
<<<

Sorry.  You are correct that you do address it in the Primer.  I missed it
as your instance example is separated from the discussion of using
the namespace as the link to the Schema.  In your example of an 
RDF instance you have:

  <?xml version="1.0"?>
  <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
              xmlns:xyz="http://example.org/schemas/vehicles#>

    <rdf:Description rdf:ID="johnSmithsCar">
         <rdf:type rdf:resource="#PassengerVehicle"/>
         <xyz:registeredTo 
rdf:resource="http://www.example.org/staffid/85740"/>
         <xyz:rearSeatLegRoom 
             rdf:datatype="http://www.w3.org/2001/XMLSchema#integer">127<
/xyz:rearSeatLegRoom>
    </rdf:Description>
  </rdf:RDF>
            
Doesn't the <rdf:type rdf:resource="#PassengerVehicle"> mean
that the definition of PassengerVehicle is an ID in the current document?

A note on the length of the Primer ... I don't think you can put a 
limit on a good tutorial.  I think you have done an excellent job on
the document.  It is a 1000% better than the previous version and a
superb document.

Best wishes,

 - Mike
----------------------------------------------------
Michael C. Daconta
Director, Web & Technology Services
www.mcbrad.com
Received on Sunday, 17 November 2002 18:55:54 GMT

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