[openstack-dev] [nova] [rfc] drop XML from v3 API entirely

Sean Dague sean at dague.net
Mon Jan 13 14:38:47 UTC 2014

I know we've been here before, but I want to raise this again while 
there is still time left in icehouse.

I would like to propose that the Nova v3 API removes the XML payload 
entirely. It adds complexity to the Nova code, and it requires 
duplicating all our test resources, because we need to do everything 
onces for JSON and once for XML. Even worse, the dual payload strategy 
that nova employed leaked out to a lot of other projects, so they now 
think maintaining 2 payloads is a good thing (which I would argue it is 

As we started talking about reducing tempest concurrency in the gate, I 
was starting to think a lot about what we could shed that would let us 
keep up a high level of testing, but bring our overall time back down. 
The fact that Nova provides an extremely wide testing surface makes this 

I think it would be a much better situation if the Nova API is a single 
payload type. The work on the jsonschema validation is also something 
where I think we could get to a fully discoverable API, which would be huge.

If we never ship v3 API with XML as stable, we can deprecate it 
entirely, and let it die with v2 ( probably a year out ).


Sean Dague
Samsung Research America
sean at dague.net / sean.dague at samsung.com

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