Publisher confirms in RabbitMQ - Step-by-Step Execution

Process Flow - Publisher confirms

Start Publisher

↓

Enable Publisher Confirms

↓

Send Message to Exchange

↓

Wait for Broker Ack/Nack

↓

Confirm Success

↓

Continue or Retry

The publisher sends a message and waits for the broker to confirm if it was received successfully (ack) or not (nack).

Execution Sample

RabbitMQ

channel.confirmSelect()
channel.basicPublish(exchange, routingKey, props, message)
channel.waitForConfirms()

Enable confirms, publish a message, then wait for confirmation from RabbitMQ.

Process Table

Step	Action	Message Sent?	Broker Response	Publisher State
1	Enable publisher confirms	No	N/A	Waiting to send
2	Publish message to exchange	Yes	Waiting for ack/nack	Waiting for confirmation
3	Broker sends ack	Yes	Ack received	Message confirmed
4	Publish next message or finish	Depends	N/A	Ready for next message

💡 Publisher confirms received ack, message delivery confirmed.

Status Tracker

Variable	Start	After Step 2	After Step 3	Final
message_sent	false	true	true	true
broker_response	none	waiting	ack	ack
publisher_state	idle	waiting_confirm	confirmed	confirmed

Key Moments - 3 Insights

Why does the publisher wait after sending the message?

The publisher waits to receive an ack or nack from the broker to know if the message was successfully received, as shown in step 2 and 3 of the execution table.

What happens if the broker sends a nack?

If a nack is received, the publisher knows the message was not confirmed and can retry or handle failure. This is the alternative path after step 3 in the concept flow.

Can the publisher send multiple messages before waiting for confirms?

Yes, but each message will be confirmed in order. The example shows waiting after one message for simplicity, but confirms can be handled asynchronously.

Visual Quiz - 3 Questions

Look at the execution table, what is the publisher state after step 2?

A Idle

B Message confirmed

C Waiting for confirmation

D Finished

💡 Hint

Check the 'Publisher State' column at step 2 in the execution table.

At which step does the broker send an ack?

A Step 3

B Step 1

C Step 2

D Step 4

💡 Hint

Look at the 'Broker Response' column in the execution table.

If the broker sends a nack instead of an ack, what should the publisher do?

A Ignore and continue

B Retry or handle failure

C Shutdown immediately

D Send a duplicate message without waiting

💡 Hint

Refer to the concept flow where nack leads to 'Handle Failure'.

Concept Snapshot

Publisher confirms in RabbitMQ:
- Enable confirms with channel.confirmSelect()
- Publish message with basicPublish()
- Wait for ack/nack with waitForConfirms()
- Ack means message received, nack means failure
- Use confirms to ensure reliable delivery

Full Transcript

Publisher confirms in RabbitMQ allow the publisher to know if a message was successfully received by the broker. The publisher first enables confirms, then sends a message. After sending, it waits for the broker to send an acknowledgement (ack) or negative acknowledgement (nack). If ack is received, the publisher knows the message was delivered successfully. If nack is received, the publisher can retry or handle the failure. This process helps ensure reliable message delivery in RabbitMQ.