Ryan
fb30e8e884
Move lesson source into the teaching structure, align the course path with the learner's Go and DevOps experience, and add the interactive lesson guides. Add advanced DevOps lifecycle study as a separate section. Bound MQTT message work and drain accepted jobs during shutdown; align the backend implementation with the revised course through Section 6.
46 lines
2.6 KiB
HTML
46 lines
2.6 KiB
HTML
<!doctype html>
|
|
<html lang="en">
|
|
<head>
|
|
<meta charset="utf-8">
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
<title>HTTP and MQTT Evidence — Quick Reference</title>
|
|
<link rel="stylesheet" href="../assets/lesson.css">
|
|
</head>
|
|
<body>
|
|
<main class="page">
|
|
<p class="eyebrow">Robot Market · Quick reference</p>
|
|
<h1>Three acknowledgements, three meanings</h1>
|
|
<p class="dek">When a backend tells a caller that a device command is progressing, name the component that produced each piece of evidence.</p>
|
|
|
|
<section class="card">
|
|
<h2>Evidence map</h2>
|
|
<table>
|
|
<thead><tr><th>Evidence</th><th>Who produced it?</th><th>What it supports</th><th>What it does not prove</th></tr></thead>
|
|
<tbody>
|
|
<tr><th>HTTP 202</th><td>Go HTTP server</td><td>The request was accepted for processing.</td><td>Broker publication or device execution.</td></tr>
|
|
<tr><th>QoS 1 PUBACK</th><td>MQTT receiver on this hop</td><td>The corresponding QoS 1 PUBLISH exchange was acknowledged, subject to the reason code.</td><td>That a device accepted or completed the business action.</td></tr>
|
|
<tr><th>Command result</th><td>Device application, delivered back through MQTT</td><td>The result contract reports accepted, completed, or rejected work.</td><td>That the report is authentic without identity and authorization checks.</td></tr>
|
|
</tbody>
|
|
</table>
|
|
</section>
|
|
|
|
<div class="flow" aria-label="Evidence sequence">
|
|
<div class="step">API admission<br><strong>HTTP 202</strong></div><span class="arrow">→</span>
|
|
<div class="step">Broker hop<br><strong>PUBACK</strong></div><span class="arrow">→</span>
|
|
<div class="step">Device application<br><strong>Command result</strong></div>
|
|
</div>
|
|
|
|
<section class="card callout">
|
|
<h2>Use this sentence</h2>
|
|
<p>“The API accepted command <code>C</code>. The broker acknowledged the publish. The device result is still pending.”</p>
|
|
<p class="small">If the API process keeps command state only in memory, an HTTP 202 is not a promise that the record survives a process restart.</p>
|
|
</section>
|
|
|
|
<footer>
|
|
<p><a href="../lessons/0008-http-acceptance-vs-completion.html">Open Lesson 8</a> · <a href="../course-source/07-command-response.md">Section 7 source lesson</a></p>
|
|
<p>Primary sources: <a href="https://datatracker.ietf.org/doc/rfc9110/">RFC 9110 §15.3.3</a> and the <a href="https://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html#_Toc3901120">OASIS MQTT 5.0 specification</a>.</p>
|
|
</footer>
|
|
</main>
|
|
</body>
|
|
</html>
|