Newbie question: Attributes and schema's

[Robert Dunn]

Hi,

I'm interested in creating a schema that enforces a node tree based on
an attribute. For example:

<Invocation type="COM">
<GUID>{63D94CD7-C566-457D-B011-D544483D7862}</GUID>
</Invocation>
<Invocation type="DCOM">
<MachineName>IITWEB-1</MachineName>
<GUID>{63D94CD7-C566-457D-B011-D544483D7862}</GUID>
</Invocation>
<Invocation type="DLL">
<Location>C:\Temp\Product.dll</Location>
</Invocation>

Is this possible? At the moment I've got the schema with a choice
around MachineName, GUID and Location but ultimately it would be nice
to enforce the relationship between the nodes and the attribute.
Current schema:

<xs:element name="Invocation">
<xs:complexType>
<xs:choice>
<xs:element ref="MachineName" minOccurs="0"/>
<xs:element ref="GUID" minOccurs="0"/>
<xs:element ref="Location" minOccurs="0"/>
</xs:choice>
<xs:attribute name="type" use="required">
<xs:simpleType>
<xs:restriction base="xs:NMTOKEN">
<xs:enumeration value="COM"/>
<xs:enumeration value="DCOM"/>
<xs:enumeration value="DLL"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:complexType>
</xs:element>

Thanks,
Rob.

 

[Martin Honnen]

Robert Dunn wrote:

I'm interested in creating a schema that enforces a node tree based on
an attribute. For example:

<Invocation type="COM">
<GUID>{63D94CD7-C566-457D-B011-D544483D7862}</GUID>
</Invocation>
<Invocation type="DCOM">
<MachineName>IITWEB-1</MachineName>
<GUID>{63D94CD7-C566-457D-B011-D544483D7862}</GUID>
</Invocation>
<Invocation type="DLL">
<Location>C:\Temp\Product.dll</Location>
</Invocation>

Is this possible? At the moment I've got the schema with a choice
around MachineName, GUID and Location but ultimately it would be nice
to enforce the relationship between the nodes and the attribute.

There is no way with a W3C XML schema to enforce an element's content
depending on an attribute's value.

There are other schema languages like Schematron for instance which
allow yo to make assertions using the full power of XPath and that way
you are able to check that for a certain attribute value you have a
certain element substructure.
You can find more about Schematron here:
http://xml.ascc.net/schematron/

 

[Robert Dunn]

Robert Dunn wrote:



There is no way with a W3C XML schema to enforce an element's content
depending on an attribute's value.

There are other schema languages like Schematron for instance which
allow yo to make assertions using the full power of XPath and that way
you are able to check that for a certain attribute value you have a
certain element substructure.
You can find more about Schematron here:
http://xml.ascc.net/schematron/

Martin, thanks for your response.

Rob.