The oslo.messaging session at the summit [1] resulted in some plans to evolve 
how oslo.messaging works, but probably not during this cycle.

First, we talked about what to do about the various drivers like ZeroMQ and the 
new AMQP 1.0 driver. We decided that rather than moving those out of the main 
tree and packaging them separately, we would keep them all in the main 
repository to encourage the driver authors to help out with the core library 
(oslo.messaging is a critical component of OpenStack, and we’ve lost several of 
our core reviewers for the library to other priorities recently).

There is a new set of contributors interested in maintaining the ZeroMQ driver, 
and they are going to work together to review each other’s patches. We will 
re-evaluate keeping ZeroMQ at the end of Kilo, based on how things go this 
cycle.

We also talked about the fact that the new version of Kombu includes some of 
the features we have implemented in our own driver, like heartbeats and 
connection management. Kombu does not include the calling patterns 
(cast/call/notifications) that we have in oslo.messaging, but we may be able to 
remove some code from our driver and consolidate the qpid and rabbit driver 
code to let Kombu do more of the work for us.

Python 3 support is coming slowly. There are a couple of patches up for review 
to provide a different sort of executor based on greenio and trollius. Adopting 
that would require some application-level changes to use co-routines, so it may 
not be an optimal solution even though it would get us off of eventlet. (During 
the Python 3 session later in the week we talked about the possibility of 
fixing eventlet’s monkey-patching to allow us to use the new eventlet under 
python 3.)

We also talked about the way the oslo.messaging API uses URLs to get some 
settings and configuration options for others. I thought I remembered this 
being a conscious decision to pass connection-specific parameters in the URL, 
and “global” parameters via configuration settings. It sounds like that split 
may not have been implemented as cleanly as originally intended, though. We 
identified documenting URL parameters as an issue for removing the 
configuration object, as well as backwards-compatibility. I don’t think we 
agreed on any specific changes to the API based on this part of the discussion, 
but please correct me if your recollection is different.

We also learned that there is a critical bug [2] related to heartbeats for 
RabbitMQ, and we have a few patches up to propose fixes in different ways (see 
the bottom of [1]). This highlighted again the fact that we have a shortage of 
reviewers for oslo.messaging.

Doug

[1] https://etherpad.openstack.org/p/kilo-oslo-oslo.messaging
[2] https://bugs.launchpad.net/nova/+bug/856764


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