Sending Periodic Acknowledgment

Servers use periodic acknowledgment to reduce the likelihood of duplicate notifications, and to reduce resource usage.

When redundancy is enabled for high availability and redundancy-level is set to 1 or higher, clients send (and servers expect) periodic acknowledgment messages at configurable intervals for notifications they have received. A periodic ack is not sent by the client if there are no unacknowledged notifications at the time.

Use the following system properties in the file to configure periodic ack.


Minimum period between two consecutive acknowledgment messages sent from the client to the server. The default setting (in seconds) is 10.


Minimum time a client continues to track a notification source for duplicates when no new notifications arrive before expiring it. The default setting (in seconds) is 300.

The Pool API also provides attributes to configure periodic ack and duplicate message tracking timeout. See subscription-message-tracking-timeout and subscription-ack-interval in the list of pool attributes under Configuring Pools for Servers or Locators.