Back-End Development Message Queues and Event-Driven Architecture

Question 1

What is a message queue primarily used for in back-end systems?

Accepted Answer

Decoupling services and enabling asynchronous communication

Answer

Message queues decouple producers and consumers, allowing services to communicate asynchronously without direct dependencies.

Question 2

In a publish-subscribe (pub/sub) pattern, what is a 'subscriber'?

Accepted Answer

A service that receives and processes messages from a topic

Answer

In pub/sub, subscribers listen to topics and receive every message published to those topics.

Question 3

What is the key difference between a point-to-point queue and a pub/sub topic?

Accepted Answer

A queue delivers each message to one consumer; a topic delivers to all subscribers

Answer

In point-to-point queues each message is consumed by exactly one consumer, while topics broadcast messages to all active subscribers.

Question 4

What does a message acknowledgment (ACK) tell the broker in a queue system?

Accepted Answer

The consumer signals it has successfully processed the message

Answer

An ACK tells the broker the consumer finished processing the message, allowing the broker to safely remove it from the queue.

Question 5

What is a Dead Letter Queue (DLQ) used for?

Accepted Answer

Holding messages that failed processing after the maximum retry limit

Answer

A DLQ captures messages that could not be successfully processed after exhausting retries, enabling investigation and reprocessing.

Back-End Development Practice Test