SQS queue concept in AWS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new SQS queue using AWS CLI.

AWS

aws sqs create-queue --queue-name [1]

Drag options to blanks, or click blank then click option'

AQueueUrl

BMyQueue

CReceiveMessage

DDeleteMessage

Attempts:

3 left

💡 Hint

Common Mistakes

Using AWS CLI commands that are not related to queue creation.

Confusing queue URL with queue name.

The --queue-name option requires the name of the queue to create. Here, MyQueue is a valid queue name.

2fill in blank

medium

Complete the code to send a message to an SQS queue using AWS CLI.

AWS

aws sqs send-message --queue-url [1] --message-body "Hello World"

Drag options to blanks, or click blank then click option'

AReceiveMessage

BDeleteMessage

Chttps://sqs.us-east-1.amazonaws.com/123456789012/MyQueue

DMyQueue

Attempts:

3 left

💡 Hint

Common Mistakes

Using the queue name instead of the full queue URL.

Omitting the message body.

The --queue-url option requires the full URL of the queue, not just the name.

3fill in blank

hard

Fix the error in the code to receive messages from an SQS queue.

AWS

aws sqs [1] --queue-url https://sqs.us-east-1.amazonaws.com/123456789012/MyQueue

Drag options to blanks, or click blank then click option'

Areceive-message

Bdelete-message

CReceiveMessage

Dsend-message

Attempts:

3 left

💡 Hint

Common Mistakes

Using camel case or incorrect capitalization.

Using send-message instead of receive-message.

The correct AWS CLI command to receive messages is receive-message all lowercase and hyphenated.

4fill in blank

hard

Fill both blanks to configure a dead-letter queue for an SQS queue using AWS CLI.

AWS

aws sqs set-queue-attributes --queue-url [1] --attributes RedrivePolicy='{"deadLetterTargetArn":"[2]","maxReceiveCount":"5"}'

Drag options to blanks, or click blank then click option'

Ahttps://sqs.us-east-1.amazonaws.com/123456789012/MainQueue

Bhttps://sqs.us-east-1.amazonaws.com/123456789012/DeadLetterQueue

Carn:aws:sqs:us-east-1:123456789012:DeadLetterQueue

Darn:aws:sqs:us-east-1:123456789012:MainQueue

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up queue URLs and ARNs.

Using the main queue ARN instead of the dead-letter queue ARN.

The --queue-url is the main queue URL, and the deadLetterTargetArn is the ARN of the dead-letter queue.

5fill in blank

hard

Fill all three blanks to create an SQS queue with a visibility timeout of 45 seconds using AWS CLI.

AWS

aws sqs create-queue --queue-name [1] --attributes [2]=[3]

Drag options to blanks, or click blank then click option'

AMyVisibilityQueue

BVisibilityTimeout

C45

DDelaySeconds

Attempts:

3 left

💡 Hint

Common Mistakes

Using DelaySeconds instead of VisibilityTimeout.

Setting the timeout value as a string with quotes.

The queue name is MyVisibilityQueue. The attribute VisibilityTimeout is set to 45 seconds to control how long a message stays invisible after being received.

Practice

1. What is the main purpose of an AWS SQS queue?

easy

A. To store messages safely between different parts of a system

B. To run code automatically when triggered

C. To host websites and web applications

D. To store large files like videos and images

Solution

1. Step 1: Understand what SQS does

   AWS SQS is designed to hold messages so different parts of a system can communicate safely without losing data.

2. Step 2: Compare options with SQS purpose

   Running code automatically is Lambda's job, hosting websites is for services like S3 or EC2, and storing large files is for S3. Only storing messages fits SQS.

3. Final Answer:

   To store messages safely between different parts of a system -> Option A

4. Quick Check:

   SQS = message storage between system parts [OK]

Hint: SQS holds messages, not code or files [OK]

Common Mistakes:

• Confusing SQS with Lambda or S3
• Thinking SQS runs code
• Assuming SQS stores large files

2. Which of the following is the correct way to create a standard SQS queue using AWS CLI?

easy

A. aws sqs create-queue --queue-name MyQueue --attributes DelaySeconds=0

B. aws sqs create-queue MyQueue --delay 0

C. aws sqs new-queue --name MyQueue

D. aws sqs make-queue --queue MyQueue --delay 0

Solution

1. Step 1: Recall AWS CLI syntax for creating SQS queue

   The correct command uses 'aws sqs create-queue' with '--queue-name' and optional '--attributes'.

2. Step 2: Check each option's syntax

   aws sqs create-queue --queue-name MyQueue --attributes DelaySeconds=0 matches the correct syntax. Options B, C, and D use incorrect commands or flags.

3. Final Answer:

   aws sqs create-queue --queue-name MyQueue --attributes DelaySeconds=0 -> Option A

4. Quick Check:

   Correct CLI syntax = aws sqs create-queue --queue-name MyQueue --attributes DelaySeconds=0 [OK]

Hint: Use 'aws sqs create-queue --queue-name' to create queues [OK]

Common Mistakes:

• Using wrong command verbs like 'new-queue' or 'make-queue'
• Missing '--queue-name' flag
• Incorrect attribute syntax

3. Given this code snippet using AWS SDK to receive messages from an SQS queue, what will be the output if the queue is empty?

const params = { QueueUrl: 'https://sqs.us-east-1.amazonaws.com/123456789012/MyQueue', MaxNumberOfMessages: 1 };
const data = await sqs.receiveMessage(params).promise();
console.log(data.Messages);

medium

A. []

B. null

C. undefined

D. An error is thrown

Solution

1. Step 1: Understand SQS receiveMessage behavior when empty

   If no messages are available, the 'Messages' property is not included in the response, so data.Messages is undefined.

2. Step 2: Check what console.log prints

   Logging undefined prints 'undefined' in JavaScript, not null or empty array. No error is thrown.

3. Final Answer:

   undefined -> Option C

4. Quick Check:

   Empty queue means data.Messages = undefined [OK]

Hint: Empty queue returns undefined Messages, not empty array [OK]

Common Mistakes:

• Assuming empty array is returned
• Expecting null instead of undefined
• Thinking an error occurs on empty queue

4. You set the VisibilityTimeout of an SQS queue to 30 seconds. A message is received and not deleted. What happens after 30 seconds?

medium

A. The message is deleted automatically

B. The message becomes visible again and can be received again

C. The message is moved to a dead-letter queue

D. The queue stops delivering messages

Solution

1. Step 1: Understand VisibilityTimeout effect

   VisibilityTimeout hides a message from other consumers for the set time after being received.

2. Step 2: What happens if message is not deleted after timeout?

   If not deleted, after 30 seconds the message becomes visible again for processing by others.

3. Final Answer:

   The message becomes visible again and can be received again -> Option B

4. Quick Check:

   VisibilityTimeout expiry = message visible again [OK]

Hint: VisibilityTimeout hides message temporarily, then shows it again [OK]

Common Mistakes:

• Thinking message deletes automatically after timeout
• Confusing dead-letter queue behavior
• Assuming queue stops working

5. You want to delay processing of messages by 10 minutes after they are sent to an SQS queue. Which configuration should you use?

hard

A. Set the VisibilityTimeout to 600 seconds

B. Set the ReceiveMessageWaitTimeSeconds to 600 seconds

C. Set the MessageRetentionPeriod to 600 seconds

D. Set the DelaySeconds attribute to 600 on the queue or per message

Solution

1. Step 1: Identify delay setting for message delivery

   DelaySeconds controls how long a message waits before becoming visible after sending.

2. Step 2: Compare other attributes

   VisibilityTimeout controls message invisibility after receipt, MessageRetentionPeriod controls how long messages stay in queue, ReceiveMessageWaitTimeSeconds controls long polling wait time.

3. Final Answer:

   Set the DelaySeconds attribute to 600 on the queue or per message -> Option D

4. Quick Check:

   DelaySeconds = message delivery delay [OK]

Hint: Use DelaySeconds to delay message visibility after sending [OK]

Common Mistakes:

• Confusing VisibilityTimeout with DelaySeconds
• Using MessageRetentionPeriod for delay
• Mistaking ReceiveMessageWaitTimeSeconds for delay