Learning/AWS SQS/Chapter template

Chapter Template

Every module README.md follows this exact structure. Consistency matters more than per-chapter flourish — a reader should be able to jump to "§9 Common mistakes" in any module without hunting.

Sections marked (omit if N/A) may be dropped when genuinely irrelevant; everything else is mandatory.

# NN — <Title>

> <Difficulty emoji> <Difficulty>  ·  **Reading time:** ~N min  ·  **Prerequisites:** [Module X](../X/), [Module Y](../Y/)

<One-paragraph statement of what this chapter is about, in plain English.>

---

## 1. What you will learn

- Bulleted, concrete, testable objectives.
- "You will be able to X" — not "we will discuss X".

## 2. Why this concept exists

Start with the **engineering problem**, before the AWS feature.
What breaks without it? Show the broken system first.

## 3. Beginner explanation

Plain language. Assume the reader has never met the concept.
Analogy allowed here — but it must be immediately followed by §4.

## 4. How it actually works

The real AWS behaviour. Precise terminology. No hand-waving.
This is where the analogy gets cashed out into mechanism.

## 5. Diagram

One or more Mermaid diagrams — **always followed by prose explaining the diagram.**
A diagram that isn't explained does not count.

## 6. Step-by-step flow

Numbered walkthrough of exactly what happens, in order, naming the component acting at each step.

## 7. Configuration

The knobs, their ranges and defaults. **Link to [`_reference/aws-facts.md`](../_reference/aws-facts.md)
rather than restating numbers.**

## 8. Production considerations

What goes wrong at scale, under failure, during deploys.
🔴 **Level 3 depth** — this is the section that separates this course from a tutorial.

## 9. Common mistakes

Each as: **Mistake → why it's wrong → what to do instead.**

## 10. Real-world example

A concrete corporate scenario with realistic numbers.

## 11. Interview questions

### 🟢 Beginner
### 🟡 Intermediate
### 🔴 Advanced
### ⚫ System design

Advanced and system-design questions get **reasoning**, not one-line answers.

## 12. Summary

Compact bullets. Should be re-readable in 60 seconds.

---

**Next:** [NN+1 — <Title>](../NN+1-.../)

Cross-cutting authoring rules

Terminology rule

The first time an AWS term appears anywhere in the course:

Term — Simple: one sentence a beginner understands. Technical: the precise behaviour. Example: a concrete instance.

Defined once, in its owning module. Later modules link, never redefine.

Depth rule

For hard topics, explicitly mark the three levels:

  • 🟢 Level 1 — What is it?
  • 🟡 Level 2 — How does it work?
  • 🔴 Level 3 — What goes wrong and how do I design around it?

The "Why?" rule

Whenever a beginner could reasonably ask "but why?", answer it inline in a callout:

Why? …

Mandatory for at least: why deletion is explicit, why visibility timeout exists, why duplicates happen, why metrics are "Approximate", why FIFO needs MessageGroupId, why more consumers stops helping, why a queue can grow while consumers look healthy.

Numbers rule

All quotas, limits and pricing live in _reference/aws-facts.md. Chapters link to it. Never hard-code a limit in chapter prose.

Code rule

  • Java 21+, AWS SDK for Java 2.x.
  • Spring Boot chapters use a currently supported version, and must state clearly which behaviour is SQS and which is Spring.
  • Never credentials in source. Show DefaultCredentialsProvider, profiles, env vars, IAM roles.
  • Explain the important lines; skip the boilerplate.

Diagram rule

Mermaid only. Simple beats clever. Every diagram gets explanatory prose. Verify diagrams render before marking a chapter done.

Callout boxes

📌 Remember this — the one thing to retain.

⚠️ Common mistake — the trap.

🎯 Interview point — what an interviewer is listening for.

Why? — the pedagogical answer.