Lab 03 — Watch visibility timeout

Goal

See a message go invisible and come back, and watch the timer decide.

Setup

To be written — CLI commands and an IaC equivalent for every resource, all prefixed sqs-course-.

Steps

1. Set the queue visibility timeout to 30 seconds
2. Send one message
3. Receive it and do not delete
4. Poll GetQueueAttributes every 5 s and watch NotVisible go 0→1→0 and Visible go 1→0→1
5. Repeat, calling ChangeMessageVisibility(60) at t=20 — observe the extension
6. Repeat, calling ChangeMessageVisibility(0) — observe immediate return

What you should observe

• The message never left the queue; only its visibility changed
• Extension resets the timer from now, not from the original receive
• Visibility 0 is the fail-fast retry

Why it happened

To be written — ties each observation back to the mechanism in 08 — Visibility Timeout.

Experiments to try

To be written — deliberate variations that change the outcome.

Teardown

To be written — every resource created above, in dependency order.

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