>In transactional messaging, there can be the
risk of legal consequences if
you don't know exactly which version of a
message Schema applies to an
message instance, since each Schema
version is like a different version of
a contract, and you introduce a
business risk of you decide do something
under the terms of a contract,
without checking which version of the
contract actually
applies.
>The upshot is that each message instance really should
identify which
Schema, and which version of that Schema, applies to
it. The most popular
way to do this is to have a unique namespace
for each version of each
Schema. The way I like to do it,
sometimes in addition to the namespace
technique, is to provide
top-level attributes which have a fixed value
that is required to
appear, and which identify the Schema and version.
Sometimes
people try to use the 'schemaLocation' to provide Schema
version
information, but this is a fragile technique that I don't
recommend in
general.
Remember - ATG is just not using minor
versioning of the namespaces. They continue to use minor versioning of the
schema. The namespaces is only a conceptual holder used to differentiate
conflicting names.