RE: [xml-dev] XML schema - multiple import of module

["Michael Kay" <mike@saxonica.com>]

Unfortunately the topic of schema composition is one where the spec isn't
all that prescriptive, and where in consequence there are differences
between implementations.

Having said that, I can't see why you have three schema documents or why you
are trying to use xs:redefine.

You should have two schema documents, one for each namespace, and each
should reference the other using an xsl:import. If your chosen tool doesn't
allow that, I can only suggest you try a different tool.

Regards,

Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay  

> -----Original Message-----
> From: DUNN, Mark [mailto:mark.dunn@oup.com] 
> Sent: 04 June 2009 17:35
> To: xml-dev@lists.xml.org
> Subject: [xml-dev] XML schema - multiple import of module
> 
> Hello,
> 
> I'm new to XML Schemas, and investigating conversion of a DTD 
> to an XML Schema. I have a problem describing the Schema 
> version of the following
> structure:
> 
> <doc>
>  <div>
>   <title>Section 1</title>
>   <p>Some text...</p>
>   <p>
>    <law:extraxt>
>     <title>Title of Regulation</title>
>     <p>Text of regulation</p>
>    </law:extract>
>   </p>
>  </div>
> </doc>
> 
> 
> The problem is in the non-namespaced <title> and <p> elements 
> occurring within the namespaced <law:extract> element. They 
> are the same as the ones occurring outside this element, so 
> I'd like to define them only once.
> 
> My attempt at expressing this structure uses three .xsd files:
> 
> main.xsd:
> 
> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";
> xmlns="http://xsd.oup.com/ac-xsd/";
> xmlns:law="http://xsd.oup.com/ac-law/";
> targetNamespace="http://xsd.oup.com/ac-xsd/";
> elementFormDefault="qualified">
> 	<xs:redefine schemaLocation="struct.xsd">
> 		<xs:group name="paragraph-content">
> 			<xs:choice>
> 				<xs:group ref="paragraph-content"/>
> 				<xs:element ref="law:extract"/>
> 			</xs:choice>
> 		</xs:group>
> 	</xs:redefine>
> 	<xs:import namespace="http://xsd.oup.com/ac-law/";
> schemaLocation="law.xsd"></xs:import>
> 	...
> </xs:schema>
> 
> law.xsd:
> 
> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";
> elementFormDefault="qualified"
> targetNamespace="http://xsd.oup.com/ac-law/";
> xmlns:law="http://xsd.oup.com/ac-law/";
> xmlns:struct="http://xsd.oup.com/ac-xsd/";>
> 	<xs:import schemaLocation="struct.xsd"
> namespace="http://xsd.oup.com/ac-xsd/";></xs:import>
> 	<xs:element name="extract">
> 		<xs:complexType>
> 			<xs:sequence>
> 				<xs:element ref="struct:title"
> minOccurs="0"/>
> 				<xs:element ref="struct:p"
> minOccurs="1"/>
> 			</xs:sequence>
> 		</xs:complexType>
> 	</xs:element>
> 	...
> </xs:schema> 
> 
> 
> struct.xsd:
> 
> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema";
> elementFormDefault="qualified" attributeFormDefault="unqualified"
> targetNamespace="http://xsd.oup.com/ac-xsd/";
> xmlns="http://xsd.oup.com/ac-xsd/";>
> 	<xs:group name="general-inline">
> 		<xs:choice>
> 			<xs:element ref="b"/>
> 			<xs:element ref="i"/>
> 		</xs:choice>
> 	</xs:group>
> 	<xs:group name="paragraph-content">
> 		<xs:choice>
> 			<xs:group ref="general-inline"></xs:group>
> 			<!-- ... [plus others] ... --->
> 		</xs:choice>
> 	</xs:group>
> 	<xs:element name="p">
> 		<xs:complexType mixed="true">
> 			<xs:choice minOccurs="0" maxOccurs="unbounded">
> 				<xs:group ref="paragraph-content"/>
> 			</xs:choice>
> 		</xs:complexType>
> 	</xs:element>
> 	...
> </xs:schema>
> 
> 
> When I try saving the schema files in XMLSpy 2009, I get an 
> error saying that <title> is already declared, presumably 
> because the file struct.xsd has ben imported twice.
> 
> The W3C spec says that importing twice is legitimate, but 
> vendors are encouraged to raise it as an error. Fair enough - 
> I don't like the circularity in my description.
> 
> But the structure itself seems reasonable, I just can't see a 
> way of expressing it in XML Schema.
> 
> Can anyone help?
> 
> 
> Kind regards,
> 
> Mark Dunn
> XML Data Engineer
> Oxford University Press
> 
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