Sending and receiving messages in AWS - Step-by-Step Execution

Process Flow - Sending and receiving messages

Create Queue

↓

Send Message to Queue

↓

Message Stored in Queue

↓

Receive Message from Queue

↓

Process Message

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Delete Message from Queue

This flow shows how a message is sent to a queue, stored, received, processed, and then deleted.

Execution Sample

AWS

aws sqs create-queue --queue-name MyQueue
aws sqs send-message --queue-url <url> --message-body "Hello"
aws sqs receive-message --queue-url <url>
aws sqs delete-message --queue-url <url> --receipt-handle <handle>

This sequence creates a queue, sends a message, receives it, and deletes it from the queue.

Process Table

Step	Action	Queue State	Message Content	Result
1	Create Queue 'MyQueue'	Empty	-	Queue created successfully
2	Send Message 'Hello'	Contains 1 message	Hello	Message sent and stored
3	Receive Message	Contains 1 message (invisible)	Hello	Message received for processing
4	Process Message	Contains 1 message (invisible)	Hello	Message processed
5	Delete Message	Empty	-	Message deleted from queue

💡 Message deleted, queue is empty, process complete

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 5
Queue Messages	0	1 (Hello)	1 (invisible Hello)	0
Message Visibility	N/A	Visible	Invisible (received)	Deleted

Key Moments - 2 Insights

Why does the message remain in the queue after receiving it?

When a message is received, it becomes invisible temporarily but is not deleted until explicitly removed (see Step 3 and Step 5 in execution_table).

What happens if the message is not deleted after processing?

If not deleted, the message becomes visible again after a timeout and can be received again, causing duplicate processing.

Visual Quiz - 3 Questions

Look at the execution_table, what is the queue state immediately after sending the message?

A Empty

B Contains 1 message

C Contains 1 invisible message

D Deleted

💡 Hint

Check Step 2 in the execution_table under 'Queue State'

At which step does the message become invisible to other receivers?

A Step 3

B Step 2

C Step 4

D Step 5

💡 Hint

Look at Step 3 in execution_table where message visibility changes

If the delete message step is skipped, what happens to the message?

A It is permanently removed

B It stays invisible forever

C It becomes visible again after timeout

D It duplicates automatically

💡 Hint

Refer to key_moments about message deletion and visibility timeout

Concept Snapshot

AWS SQS message flow:
1. Create a queue
2. Send message to queue (stored and visible)
3. Receive message (becomes invisible)
4. Process message
5. Delete message (removes from queue)
Message must be deleted to avoid reprocessing.

Full Transcript

This visual execution shows how AWS SQS handles sending and receiving messages. First, a queue is created. Then a message is sent and stored in the queue. When a receiver gets the message, it becomes invisible to others but remains in the queue until deleted. Processing happens while the message is invisible. Finally, deleting the message removes it permanently. If deletion is skipped, the message reappears after a timeout, risking duplicate processing.