Message queue
~~~~~~~~~~~~~

OpenStack uses a :term:`message queue` to coordinate operations and
status information among services. The message queue service typically
runs on the controller node. OpenStack supports several message queue
services including `RabbitMQ <https://www.rabbitmq.com>`__,
`Qpid <https://qpid.apache.org>`__, and `ZeroMQ <http://zeromq.org>`__.
However, most distributions that package OpenStack support a particular
message queue service. This guide implements the RabbitMQ message queue
service because most distributions support it. If you prefer to
implement a different message queue service, consult the documentation
associated with it.

The message queue runs on the controller node.

.. toctree::
   :glob:

   environment-messaging-*