diff options
Diffstat (limited to 'oslo_messaging/notify/messaging.py')
| -rw-r--r-- | oslo_messaging/notify/messaging.py | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/oslo_messaging/notify/messaging.py b/oslo_messaging/notify/messaging.py index 61c7357..da633d8 100644 --- a/oslo_messaging/notify/messaging.py +++ b/oslo_messaging/notify/messaging.py @@ -21,19 +21,30 @@ Notification drivers for sending notifications via messaging. The messaging drivers publish notification messages to notification listeners. -The driver will block the notifier's thread until the notification message has -been passed to the messaging transport. There is no guarantee that the -notification message will be consumed by a notification listener. +In case of the rabbit backend the driver will block the notifier's thread +until the notification message has been passed to the messaging transport. +There is no guarantee that the notification message will be consumed by a +notification listener. + +In case of the kafka backend the driver will not block the notifier's thread +but return immediately. The driver will try to deliver the message in the +background. Notification messages are sent 'at-most-once' - ensuring that they are not duplicated. If the connection to the messaging service is not active when a notification is -sent this driver will block waiting for the connection to complete. If the -connection fails to complete, the driver will try to re-establish that +sent the rabbit backend will block waiting for the connection to complete. +If the connection fails to complete, the driver will try to re-establish that connection. By default this will continue indefinitely until the connection completes. However, the retry parameter can be used to have the notification -send fail with a MessageDeliveryFailure after the given number of retries. +send fail. In this case an error is logged and the notifier's thread is resumed +without any error. + +If the connection to the messaging service is not active when a notification is +sent the kafka backend will return immediately and the backend tries to +establish the connection and deliver the messages in the background. + """ import logging |