Where you have an XSD schema, and want to create a new version of the schema that adds a couple of elements, is changing the schemaLocation hint a sensible way to indicate that an XML document is using a newer version of the schema Or is changing the targetNamespace the way to do this
For example: notice the different value for schemaLocation:
<mt395 xmlns="urn:incident:mt395" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:incident:mt395 mt395-1.xsd">
<mt395 xmlns="urn:incident:mt395" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:incident:mt395 mt395-2.xsd">
Irrespective of SQL Server 2005, is this a sensible approach for XML
I believe SQL Server 2005 requires a new targetNamespace if using typed XML, so I couldn't use this approach in the database. Would this be a sensible enhancment to SQL Server to allow it to store different XML documents against multiple versions of a schema, using the schemaLocation to identify the specific version Or is this generally considered a bad idea in the XML world
Thanks,
Andy Mackie
Schema versioning - change schemaLocation, but keep same namespace ?
Shailesh Patel
SchemaLocations are only hints according to the XML Schema validation semantics and should not be used for versioning.
Using a new namespace may be an option, but is quite heavy weight. Only recommended if everything changes or for new parts.
In SQL Server you can just create a new schema collection for the new data if you don't have to store the data of both versions in the same collection.
Best regards
Michael
Tee40
OK thanks.
Any thoughts on using the version attribute within an XSD to indicate a schema is a new version Downside is it's totally optional, and can be ignored by validating parsers. e.g.
<xsd:schema ... version="1.2" >
Or alternatively, use custom version attributes on the root element This enables validation to be enforced against a specific schema version. e.g.
Schema:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"; targetNamespace="http://www.example.com/doc";>
<xs:element name="doc">
<xs:complexType>
<xs:extension base="xs:string">
<xs:attribute name="version" use="required" fixed="2.3.1" />
</xs:extension>
</xs:complexType>
</xs:element>
</xs:schema>
Instance document
<doc xmlns="http://www.example.com/doc"; xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; xsi:schemaLocation="http://www.example.com/doc http://www.example.com/doc/2.3.1/doc.xsd";
version="2.3.1">Hello World!</doc>
It seems that we need both a targetNamespace, and some form of version number, to uniquely identify a schema, if we don't want XPath statements to be totally re-written everytime a targetNamespace changes.