Publisher confirms in RabbitMQ - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What does enabling publisher confirms in RabbitMQ do?

When a publisher enables publisher confirms in RabbitMQ, what is the main effect?

A Messages are encrypted end-to-end between publisher and consumer.

B The publisher receives acknowledgments from the broker when messages are successfully handled.

C The broker automatically retries sending messages if the consumer is slow.

D The publisher can send messages without waiting for any confirmation.

💡 Hint

Think about how the publisher knows if the broker accepted the message.

Publisher confirms let the publisher know when the broker has safely received and stored the message, improving reliability.

💻 Command Output

intermediate

What is the output when a publisher confirms channel is enabled in RabbitMQ CLI?

After enabling publisher confirms on a channel using RabbitMQ client, what output or state change should you expect?

RabbitMQ

channel.confirmSelect();
System.out.println(channel.waitForConfirms() ? "Confirmed" : "Not Confirmed");

A Confirmed

B Not Confirmed

C SyntaxError

D TimeoutException

💡 Hint

Assuming the broker accepted the message, what does waitForConfirms() return?

waitForConfirms() returns true if all messages were confirmed by the broker, so the output is 'Confirmed'.

❓ Troubleshoot

advanced

Why does waitForConfirms() throw TimeoutException in RabbitMQ?

When using publisher confirms, the method waitForConfirms() sometimes throws a TimeoutException. What is the most likely cause?

A The message payload is too large for the broker to process.

B The consumer has not acknowledged the message yet.

C The publisher did not enable confirm mode on the channel.

D The broker did not send an acknowledgment within the expected time.

💡 Hint

Consider what happens if the broker is slow or unresponsive.

A TimeoutException means the broker did not confirm the message in time, possibly due to network delays or broker overload.

🔀 Workflow

advanced

Correct order of steps to use publisher confirms in RabbitMQ

Put the following steps in the correct order to properly use publisher confirms in RabbitMQ.

A 1,3,2,4

B 2,1,3,4

C 1,2,3,4

D 2,3,1,4

💡 Hint

Think about enabling confirm mode before publishing, then waiting for confirmation.

The correct workflow is to enable confirm mode first, publish the message, wait for confirmation, then handle the result.

✅ Best Practice

expert

Best practice to handle negative acknowledgments (nacks) with publisher confirms

When using publisher confirms, what is the best practice to handle messages that receive a negative acknowledgment (nack) from the broker?

A Log the nack and retry publishing the message after a delay.

B Ignore the nack and assume the message was delivered.

C Immediately close the channel and stop publishing messages.

D Delete the message from the queue to prevent duplicates.

💡 Hint

Consider how to ensure message delivery reliability after a nack.

When a nack is received, the best practice is to log it and retry sending the message to ensure it is delivered.