SQS queue concept in AWS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an Amazon SQS queue?

An Amazon SQS queue is a service that stores messages temporarily so that different parts of an application can communicate by sending and receiving messages asynchronously.

beginner

What are the two types of SQS queues?

The two types of SQS queues are Standard queues, which offer high throughput and at-least-once delivery, and FIFO queues, which guarantee exactly-once processing and preserve message order.

beginner

How does SQS help in decoupling application components?

SQS acts like a mailbox where one part of the app puts messages and another part picks them up later, so they don't need to work at the same time or know about each other directly.

intermediate

What is the visibility timeout in SQS?

Visibility timeout is the time period after a message is received during which it is hidden from other consumers, preventing multiple processing of the same message.

intermediate

Why would you use a FIFO queue instead of a Standard queue?

Use a FIFO queue when the order of messages matters and you want to make sure each message is processed exactly once without duplicates.

What does SQS stand for?

A Simple Query Service

B Secure Query System

C Standard Queue Setup

D Simple Queue Service

SQS stands for Simple Queue Service, which is AWS's message queuing service.

Which SQS queue type guarantees message order?

A Standard queue

B Both Standard and FIFO

C FIFO queue

D Neither

FIFO queues guarantee that messages are processed in the exact order they are sent.

What happens to a message during the visibility timeout?

A It is hidden from other consumers

B It is visible to all consumers

C It is deleted immediately

D It is moved to a dead-letter queue

During visibility timeout, the message is hidden from other consumers to avoid duplicate processing.

Which feature of SQS helps different parts of an app work independently?

A Decoupling

B Encryption

C Auto-scaling

D Load balancing

Decoupling allows parts of an app to communicate without depending on each other’s timing or availability.

What is a common use case for SQS?

A Storing large files

B Passing messages between microservices

C Hosting websites

D Sending emails directly

SQS is commonly used to pass messages between microservices or components asynchronously.

Explain how SQS helps improve application reliability and scalability.

Think about how messages wait safely and how components don’t need to be active at the same time.

Describe the differences between Standard and FIFO SQS queues and when to use each.

Consider message order and duplicate handling.