RE: DAML API usage

From: Hart, Lewis ([email protected])
Date: 06/28/01


-----Original Message-----
From: Marin Dimitrov [mailto:[email protected]]
Sent: Thursday, June 28, 2001 8:22 AM
To: [email protected]; [email protected]
Subject: DAML API usage


>
>Hi,
>
>What is the correct sequence of API calls for creating an ontology from
>scratch and exporting it in RDFS?
>
>The following fragment is not working:
>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
>        DAMLOntology coreOntology = new DAML(new
>DAMLOntologyImp(DAML.DAML_URI));
>        DAMLOntology ewnOntology = new DAMLOntologyImp();
>        ewnOntology.addImport(coreOntology);
>
>        DAMLClass classTop = ewnOntology.createClass("Top");
>        classTop.addSubClassOf(DAML.Class);
>
>        DAMLClass class1 = ewnOntology.createClass("FirstOrderEntity");
>        class1.addSubClassOf(classTop);
>
>        DAMLClass class2 = ewnOntology.createClass("SecondOrderEntity");
>        class2.addSubClassOf(classTop);
>
>        ..........
>
>            Model m = ewnOntology.toRDFModel();
>            RDFUtil.dumpModel(m,
>                                                  System.out,
>
>(RDFSerializer)Class.forName("org.w3c.rdf.implementation.syntax.sirpac.SiRS
"
>).newInstance());
>
>        ..........
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>

The above code is correct. You have found a (rather obvious) bug in the
toRDFModel code, a fix will be posted later today.


>
>
>The output looks like:
>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
><?xml version='1.0' encoding='ISO-8859-1'?>
><!DOCTYPE rdf:RDF [
>  <!ENTITY rdf 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
>  <!ENTITY a 'http://www.daml.org/2001/03/daml+oil#'>
>  <!ENTITY b ''>
>]>
><rdf:RDF xmlns:rdf="&rdf;"
>  xmlns:a="&a;"
>  xmlns:b="&b;">
><a:Class rdf:about="FirstOrderEntity"/>
><a:Class rdf:about="SecondOrderEntity"/>
><a:Class rdf:about="Top"/>
></rdf:RDF>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>
>
>i.e. the subClassOf relations are missing - in fact the RDFS namespace in
>not referenced at all, and additionally there exists a namespace "b" which
>is never used.

The RDFS namespace is not used, because the DAML+OIL resouces are used where
applicable. That is, daml:Class rather than rdfs:class. After all, this is a
DAML ontology.

I don't know where the extra  null namespace, in this case "b", is comming
from. It does no harm so it is a low priority.

>
>The API docs and samples are not that helpful so I'll appreciate any hints

Sorry about that. I know one thing that is missing is that there is no
example of building an ontology programmatically. That is coming shortly. Do
you have any specific comments?


>
>thanx,
>
>    Marin
>
>----
>"When someone is seeking, it happens quite easily that he only sees
>the thing that he is seeking; that he is unable to find anything, unable to
>absorb anything, because he is only thinking of the thing he is seeking,
>because he is obsessed with his goal. Seeking means: to have a goal;
>but finding means: to be free, to be receptive, to have no goal. ..."
>
>
>                                Herman Hesse, "Siddhartha"
>
>
>
>


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