add oslo.messaging implementation

Blueprint oslo-messaging

Change-Id: If19fcc609c3bc8bad1b8405c7811168568aee4f0

specs/juno/oslo-messaging.rst

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+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+==========================================
+Migrate to oslo-messaging
+==========================================
+
+
+Problem description
+===================
+Neutron currently uses an older version of Oslo's RPC code which is being
+deprecated in favor of oslo.messaging.
+
+Proposed change
+===============
+Neutron will be updated to utilize oslo.messaging and the copied code from
+oslo-incubator will be removed from the tree.
+
+Alternatives
+------------
+None.  oslo.messaging is the only supported RPC framework from the Oslo team.
+
+
+Data model impact
+-----------------
+None
+
+REST API impact
+---------------
+None
+
+Security impact
+---------------
+None
+
+Notifications impact
+--------------------
+The content of the notifications should not change; however, configuration
+options will slightly change.
+
+Other end user impact
+---------------------
+The underlying library uses the compatible wire format, so users upgrading
+should not be impacted.
+
+Performance Impact
+------------------
+This is a code refactor for a new library api, so performance changes will be
+minimal.
+
+Other deployer impact
+---------------------
+Configuration options will change slightly to utilize the standard set from
+oslo.messaging. The options are standard across other OpenStack projects, so
+deployers will benefit from the standardization.
+
+
+Developer impact
+----------------
+None.  Shims will be used to provide compatibility with internal code
+interfaces.
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+ihrachys
+
+
+Work Items
+----------
+- Introduce shims modules for existing RPC classes with Neutron
+- Introduce exception compatibility layer
+- Convert shims to use oslo.messaging constructs
+- Future work could include removal of shims, but this can be done later.
+
+Dependencies
+============
+None
+
+Testing
+=======
+Exisiting Unit, Functional, and Tempest tests will ensure the refactor does
+not introduce any regressions.  Grenade testing should validate that the
+message payload are compatible.
+
+Documentation Impact
+====================
+Messaging configuration will need to be updated to reflect the set of options
+provided by oslo.messaging.
+
+References
+==========
+N/A
+