An acknowledgment confirms that a Kafka broker has accepted a producer’s message or batch. A producer can wait for that confirmation rather than treating transmission alone as successful delivery. If no acknowledgment arrives before the timeout, it treats the send as failed and retries. section 1.4.2 section 3.1.1
Acknowledgments matter at two points in the delivery path:
- On production, the broker’s confirmation gives the producer a basis for deciding whether to retry. Client settings balance reliability against performance. section 1.4.2 section 3.0
- On consumption, Kafka tracks messages read and acknowledged by consumers so a disconnected consumer can resume processing undelivered messages. section 1.4.2
A customer address update
A service publishes an address-change event for independent subscribers. It can await broker acknowledgment of its send; if confirmation never arrives, retrying protects against loss. A retry can also create a duplicate, so critical event designs must consider consumer idempotence alongside producer acknowledgment settings. section 1.4.1 section 1.4.2 section 10.1.3
Figure 1.6 Acknowledgments: once the cluster accepts a message, it sends an acknowledgment to the service. If no acknowledgment arrives within the timeout, the service treats the send as failed and retries.
The diagram shows the acceptance, acknowledgment, timeout, and retry path. section 1.4.2
