1183  MQTT: Message Queuing Telemetry Transport

1183.1 MQTT Protocol Overview

Time: ~60 min (full guide) | Intermediate | P09.C23

MQTT (Message Queuing Telemetry Transport) is a lightweight publish-subscribe messaging protocol designed for constrained devices and unreliable networks. It is the de facto standard for IoT communication, powering systems from Amazon Alexa to industrial automation.

1183.2 Quick Start

New to MQTT? Start with MQTT Introduction for fundamentals, terminology, and prerequisites.

1183.3 MQTT Chapter Guide

This comprehensive MQTT guide is organized into seven focused chapters:

Chapter Focus Estimated Time
MQTT Introduction Fundamentals, terminology, when to use MQTT 10 min
MQTT Architecture Broker architecture, pub-sub pattern, components 15 min
MQTT Topics & Wildcards Topic design, wildcards, naming best practices 10 min
MQTT QoS Levels QoS 0/1/2, battery considerations, delivery guarantees 15 min
MQTT Security TLS encryption, authentication, ACLs 15 min
MQTT Labs ESP32 labs, Python examples, interactive simulators 30 min
MQTT Advanced Topics Clustering, HA, performance, troubleshooting 20 min

1183.4 Key Concepts at a Glance

TipMQTT in 60 Seconds

What it is: Lightweight publish-subscribe protocol for IoT

How it works: Devices publish messages to topics on a broker; subscribers receive messages from topics they’re interested in

Why it matters: 2-byte minimum overhead, works over unreliable networks, perfect for battery-powered devices

Key features: - Publish-Subscribe: Decouples message producers from consumers - Quality of Service: Three levels (0, 1, 2) for reliability trade-offs - Retained Messages: Last value stored for new subscribers - Last Will: Automatic notification on unexpected disconnect - Topics: Hierarchical message routing with wildcards

1183.5 MQTT vs Other Protocols

Feature MQTT CoAP HTTP
Pattern Publish-Subscribe Request-Response Request-Response
Transport TCP UDP TCP
Min Overhead 2 bytes 4 bytes ~200 bytes
Best For Frequent updates, many subscribers Direct queries, RESTful APIs Web integration

1183.6 Learning Path

Beginner Path (45 min): 1. Introduction - Start here 2. Architecture - Understand the broker 3. Topics & Wildcards - Design your topics

Intermediate Path (add 30 min): 4. QoS Levels - Master reliability trade-offs 5. Security - Secure your deployment

Advanced Path (add 50 min): 6. Labs - Hands-on implementation 7. Advanced Topics - Production deployment

1183.7 Video Overview

NoteMQTT Protocol Tutorial
MQTT Protocol Overview
Overview of MQTT publish/subscribe model, QoS, retained messages, and LWT.

1183.8 Quick Reference

1183.8.1 MQTT Ports

Port Purpose
1883 Unencrypted MQTT (development only)
8883 MQTT over TLS (production)
443 MQTT over WebSocket with TLS

1183.8.2 QoS Levels

Level Name Guarantee Use Case
0 At most once Fire and forget Frequent sensor readings
1 At least once Acknowledged Important alerts
2 Exactly once Guaranteed once Critical commands

1183.8.3 Topic Wildcards

Wildcard Matches Example
+ Single level home/+/temp matches home/bedroom/temp
# Multi-level home/# matches home/bedroom/sensor/temp

1183.9 See Also