OK, Werner: you asked for it ;-)
It may also be for my benefit: I hope someone can suggest how to
improve
this.
As a solution, all that speaks for it is that it works. Elegant,
it is
not. What I *wanted*
to do was define the RDF schema and only have references from the
the DC
schema
to the RDF one. The way it worked out, each references the other.
Eugh.
OK. First of all the DC schema, because it's alright in itself.
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema";
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
xmlns:dc="http://purl.org/dc/elements/1.1/";
targetNamespace="http://purl.org/dc/elements/1.1/";>
<xsd:annotation>
<xsd:documentation xml:lang="en"
source="http://xml.vimia.com/cms/sitetree/meta-dc.xsd";>
Based on dcmes-dc.xsd from www.dublincore.org and
modified
to allow processing with
Castor. </xsd:documentation>
</xsd:annotation>
<!-- note this reference to the RDF schema: it's a backward
reference, so I would regard it
as kosher. -->
<!-- Import the RDF namespace schema for rdf:resource -->
<xsd:import namespace="http://www.w3.org/1999/02/22-rdf-syntax-
ns#"
schemaLocation="meta-rdf.xsd" />
<!-- this is not necessary: all the following complexTypes
could extend
rdf:commonType directly, but it gives me an abstract class
in Java
which will be useful as a supertype of all the other DC
classes -->
<xsd:complexType name="abstractRoot" abstract="true">
<xsd:complexContent>
<xsd:extension base="rdf:commonType"> </xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<!-- I define different types for each kind of element -->
<xsd:complexType name="titleType">
<xsd:complexContent>
<xsd:extension base="dc:abstractRoot"> </xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<xsd:complexType name="creatorType">
<xsd:complexContent>
<xsd:extension base="dc:abstractRoot"> </xsd:extension>
</xsd:complexContent>
</xsd:complexType>
<!-- and as many further types as are needed to support the DC
types
-->
<!-- define an element for each kind of DC tag -->
<xsd:element name="title" type="dc:titleType" />
<xsd:element name="creator" type="dc:creatorType" />
<!-- and as many further element definitions as are needed ...
-->
</xsd:schema>
Now for the nasty RDF schema, which unfortunately references the
DC schema:
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema";
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
xmlns:dc="http://purl.org/dc/elements/1.1/";
targetNamespace="http://www.w3.org/1999/02/22-rdf-syntax-ns#";>
<xsd:annotation>
<xsd:documentation xml:lang="en"
source="http://xml.vimia.com/cms/sitetree/meta-rdf.xsd";>
Based on dcmes-rdf.xsd from www.dublincore.org and
modified
to allow processing
with Castor.
</xsd:documentation>
</xsd:annotation>
<!-- Import the XML namespace schema for xml:lang -->
<xsd:import namespace="http://www.w3.org/XML/1998/namespace";
schemaLocation="http://www.w3.org/2001/xml.xsd"; />
<!-- this is a forward reference to the DC schema, which
contains a
backward reference to
here. If this were the only inelegant bit, it would be OK.
But
see below for worst stuff... -->
<!-- Import the namespace schema for dc:* -->
<xsd:import namespace="http://purl.org/dc/elements/1.1/";
schemaLocation="meta-dc.xsd" />
<xsd:element name="RDF">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="rdf:Description" minOccurs="0"
maxOccurs="unbounded"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<!-- this is horrible. Description belongs to the RDF
namespace, so
that element is in the right
place here. But the references to stuff from the DC
namespace is
awful. If substitutionGroups
worked, the DC stuff could be encapsulated in the DC
schema -->
<xsd:element name="Description">
<xsd:complexType>
<xsd:choice minOccurs="0" maxOccurs="unbounded">
<xsd:element ref="dc:title" />
<xsd:element ref="dc:creator" />
<!-- etc --->
</xsd:choice>
<xsd:attribute ref="rdf:about" use="optional" />
</xsd:complexType>
</xsd:element>
<xsd:complexType name="commonType">
<xsd:attribute ref="xml:lang" use="optional" />
<xsd:attribute ref="rdf:resource" use="optional" />
</xsd:complexType>
<xsd:attribute name="about" type="xsd:anyURI" />
<xsd:attribute name="resource" type="xsd:anyURI" />
</xsd:schema>
There are other permutations which are valid XML, but this is the
only
solution I have found which
Castor's source generator works with. If there are any XSD wizards
out
there who would like to
comment, I'd be very grateful for the feedback.
If there's any way that the source generator could be made to handle
substitutionGroups, the above
would be a lot cleaner.
Regards
Steve
On 8 May 2006, at 20:50, Werner Guttmann wrote:
Yes, please .. ;-). For the benefit of everybody else, please do so
... ;-).
Werner
Stephen Winnall wrote:
I've found a solution to this problem. It's not pretty, but it
seems to
work. If anyone is interested in the details, I'll
post the two schemas.
Steve
On 7 May 2006, at 18:16, Stephen Winnall wrote:
When you have documents which contain multiple namespaces, is
there a
way to define XML Schemas so that Castor can handle those
documents? I
want to be able to read documents like the following:
<?xml version="1.0"?>
<!DOCTYPE rdf:RDF PUBLIC "-//DUBLIN CORE//DCMES DTD 2002/07/31//
EN"
"http://dublincore.org/documents/2002/07/31/dcmes-xml/dcmes-xml-
dtd.dtd">
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
xmlns:dc="http://purl.org/dc/elements/1.1/";>
<rdf:Description
rdf:about="http://www.ilrt.bristol.ac.uk/people/cmdjb/";>
<dc:title>Dave Beckett's Home Page</dc:title>
<dc:creator>Dave Beckett</dc:creator>
<dc:publisher>ILRT, University of Bristol</dc:publisher>
<dc:date>2002-07-31</dc:date>
</rdf:Description>
</rdf:RDF>
Yup, it's Dublin Core again ;-) Clearly two schemas are
needed, one
for the RDF (rdf:) and one for the DC (dc:) namespace. The schemas
from the Dublin Core website for handling this stuff work
perfectly in
Oxygen when I compose example files, but since they make
extensive use
of substitution groups, the Castor source generator cannot
handle them.
I've spent some time trying to produce Castor-friendly schemas
equivalent to the official ones, but I don't seem to be getting
anywhere. This is due on the one hand to my limited knowledge
of XML
Schema, but I am beginning to wonder whether there is a way to
do this
with Castor.
Can anyone give me some guidance on this, please?
Steve
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