Back-End Development Message Queues and Event-Driven Architecture 3

Question 1

What is CQRS (Command Query Responsibility Segregation)?

Accepted Answer

A pattern that separates the model for writing data (commands) from reading data (queries)

Answer

CQRS splits an application into a write side (commands that change state) and a read side (queries that return data), allowing each to be optimized independently.

Question 2

What problem does 'backpressure' address in event-driven systems?

Accepted Answer

Preventing a fast producer from overwhelming a slow consumer

Answer

Backpressure signals producers to slow down or pause when consumers cannot keep up, preventing buffer overflow and message loss.

Question 3

What is the 'Saga pattern' used for in event-driven microservices?

Accepted Answer

Managing distributed transactions across multiple services without a global lock

Answer

The Saga pattern coordinates long-running distributed transactions using a chain of local transactions and compensating events to roll back on failure.

Question 4

What is the primary advantage of event-driven architecture over synchronous direct service-to-service calls?

Accepted Answer

It reduces coupling between services, improving resilience and independent scalability

Answer

Event-driven architecture decouples services so they don't depend on each other's availability, enabling each to scale and fail independently.

Question 5

What does 'idempotency' mean in the context of a message consumer?

Accepted Answer

Processing the same message multiple times produces the same result as processing it once

Answer

An idempotent consumer produces the same outcome no matter how many times it receives and processes the same message, which is essential under at-least-once delivery.

Back-End Development Practice Test

Back-End Development Practice Test

Back-End Development Message Queues and Event-Driven Architecture 3