[Acme] Message Type/Version Identifiers

[Anders Rundgren <[e-mail]>]

Hi List,
Back in the olden days when XML was king, we used a top-level element + namespace
(some even added a version attribute) to identify a particular message object.

I have "backported" these things to JSON because I think they were good.  A system like
ACME could also use such a scheme since there will undoubtedly be revisions over time.

A real-world example:
https://openkeystore.googlecode.com/svn/resources/trunk/docs/keygen2.html#Sample.KeyCreationResponse

In my particular take on this, the specific @context and @qualifier objects are registered with a
class-factory making the supporting parsing framework return a properly instantiated object of the
associated class as well as automatically rejecting unknown object types.  The framework is only
about 300 lines of java.

Anders