Cloned from launchpad blueprint https://blueprints.launchpad.net/nova/+spec/versioned-notification-api.

Description:

Versioned notification API

Notification interface of nova is not well defined and the current
notifications define a very inconsistent interface. There is no easy
way to see from the notification consumer point of view what is the format
and the content of the notification nova sends.

Nova developers can add new notifications to the system without specifying
the format and the content of the notification.

Moreover developers can change existing notifications without considering
backward compatibility towards the notification consumers.

Due to this situation maintaining a consumer for nova notifications is really
hard.

Specification URL (additional information):

http://specs.openstack.org/openstack/nova-specs/specs/mitaka/approved/versioned-notification-api.html