Lab 10 — Spring Boot producer and consumer

Goal

SqsTemplate and @SqsListener end to end — and what Spring is doing underneath.

Setup

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

Steps

1. Create a Spring Boot 3 project with the Spring Cloud AWS SQS starter
2. Send with SqsTemplate
3. Consume with @SqsListener, acknowledgementMode = ON_SUCCESS
4. Throw from the handler; watch the message return via SQS
5. Add @Retryable to the handler; watch ApproximateReceiveCount stay at 1
6. Switch to acknowledgementMode = ALWAYS; watch a failing message vanish
7. Set concurrency and observe parallel invocation

What you should observe

• In-process retry never touches SQS — the receive count does not move and the DLQ never fires
• ALWAYS acknowledgement is silent data loss
• Acknowledgement is just DeleteMessage

Why it happened

To be written — ties each observation back to the mechanism in 23 — SQS with Java and Spring Boot.

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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