Where to add a version to an XSD schema?

Question

The application I work on has XML output that conforms to an XSD schema. As features are added to the application, the XSD changes and I would like to note the version of the schema in the XSD file.

Perhaps I'm missing something, but I haven't found a built-in way to mark the version of the schema.

How do you do it?

Solution 1

You can use the namespace of your xsd document

<xs:schema targetNamespace="http://yourcompany/yourapp/1.0" ... >
  ...
</xs:schema>

As an example look at the xsd's defined by w3.org, this is how they do it. Do note that changing the version number here would usually by definition be a breaking change for any consumers of your xsd (no matter how small the actual change was, or which part of the version number you changed).

For less impacting versioning, there seems to be an agreement about putting a version attribute at your root element:

<xs:schema version="1.0.0" ...>
  ...
</xs:schema>

Solution 2

According to the schema element itself has a version attribute:

<schema
  attributeFormDefault = (qualified | unqualified) : unqualified
  blockDefault = (#all | List of (extension | restriction | substitution))  : ''
  elementFormDefault = (qualified | unqualified) : unqualified
  finalDefault = (#all | List of (extension | restriction | list | union))  : ''
  id = ID
  targetNamespace = anyURI
  version = token
  xml:lang = language
  {any attributes with non-schema namespace . . .}>
  Content: ((include | import | redefine | annotation)*, (((simpleType | complexType | group | attributeGroup) | element | attribute | notation), annotation*)*) 
</schema>

See http://www.w3.org/TR/xmlschema-1/#key-schema, "3.15.2 XML Representations of Schemas"

However, if you published the schema, then I think the best way to deal with it would be to use the target namespace. This would enforce the right version being used (but break compatibility)

Comments

[Karussell]

Why not specify the version into the xsd file name? e.g. myschema1.0.xsd

[elifiner]

This is a great idea actually.

[DanSkeel]

Duplicate of What are the best practices for versioning XML schemas?

[Roland Bouman]

I think this is an appropriate solution when changing major version. However, its not so good if you want to do a correction or new development iteration, because al XML documents would have to be migrated to a new namespace. The version attribute of the schema element like I point out in my seems more appropriate for those cases IMO.

[DanSkeel]

Bad answer. See recommendations. Also you can try this

[DanSkeel]

From xml-google-styleguide: Namespaces MUST NOT be changed unless the semantics of particular elements or attributes has changed in drastically incompatible ways. [Rationale: Changing the namespace requires changing all client code.]

[CMPE]

Is there a way to get the version from the root? ie <xs:schema... version="1.0"/>