Learning/AWS SQS/29 — Hands-on Labs/Lab 06 — FIFO ordering and message groups
Advanced outline
This chapter is an outline. The curriculum, learning objectives and structure are settled; the prose, diagrams and code are still being written. What is below is the plan for the chapter, not the chapter.

Lab 06 — FIFO ordering and message groups

Goal

Ordering inside a group, parallelism across groups, and head-of-line blocking.

Setup

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

Steps

  1. Create a .fifo queue with content-based deduplication
  2. Send 10 messages with one MessageGroupId; consume and confirm strict order
  3. Send the same message twice within 5 minutes; confirm only one is enqueued
  4. Send the same body with different message attributes; observe it is also deduplicated
  5. Send 10 messages across 5 groups; run 5 consumers; observe parallelism
  6. Make one message fail repeatedly; observe its whole group stall while others proceed

What you should observe

  • Ordering holds within a group and not across groups
  • Content-based dedup hashes the body only — attributes do not make a message unique
  • One bad message blocks exactly one group

Why it happened

To be written — ties each observation back to the mechanism in 07 — FIFO Queues.

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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