1202  MQTT Labs and Implementations

1202.1 Overview

This chapter series provides comprehensive hands-on MQTT implementation guidance, from beginner-friendly browser simulators to production-ready secure deployments. The content has been organized into three focused chapters for easier navigation and learning.

1202.2 Chapter Index

1202.2.1 Getting Started with MQTT Implementation

Difficulty: Beginner | Time: ~45 minutes

Perfect for those new to MQTT development. This chapter covers:

  • Three Core Components: Understanding brokers, publishers, and subscribers
  • Browser Simulators: Try MQTT in Wokwi without any hardware
  • Python Publisher/Subscriber: Complete code examples with paho-mqtt
  • Learning Paths: Choose between simulator-based learning or real hardware
  • Common Questions: FAQ for beginners starting their first MQTT project

Start here if: You’ve learned MQTT theory but haven’t built anything yet.

1202.2.2 Python Patterns and Security

Difficulty: Intermediate | Time: ~30 minutes

Production-ready patterns and critical security knowledge:

  • Callback Architecture: Event-driven MQTT clients with proper error handling
  • Loop Management: loop_forever(), loop_start(), and loop() options
  • Security Pitfalls: Why public brokers are dangerous (with real breach statistics)
  • Connection Limits: Capacity planning and monitoring broker health
  • TLS Timeouts: Configuring ESP32/ESP8266 for reliable secure connections
  • Debugging Workflow: Systematic troubleshooting approach

Start here if: You can write basic MQTT code but need production-ready patterns.

1202.2.3 Hands-On Labs

Difficulty: Intermediate | Time: ~2 hours

Four complete lab exercises with code, circuits, and simulators:

  • Lab 1: ESP32 DHT22 temperature publisher with QoS levels
  • Lab 2: Python multi-sensor dashboard with wildcards
  • Lab 3: Home automation with motion-controlled lights (2 ESP32s)
  • Lab 4: Secure MQTT with TLS certificates and authentication
  • QoS Simulator: Interactive comparison of QoS 0, 1, and 2
  • LWT Patterns: Last Will and Testament for disconnect detection
  • Knowledge Checks: Self-assessment questions with explanations

Start here if: You want hands-on experience building complete IoT systems.

1202.4 Worked Examples

NoteWorked Example: Sizing MQTT Broker for Industrial Monitoring

Scenario: A manufacturing plant deploys an MQTT-based monitoring system for 200 CNC machines. Each machine publishes sensor data (spindle speed, temperature, vibration) and receives occasional control commands.

Key Calculations: - Inbound: 200 machines x 3 topics x 1 msg/sec = 600 messages/second - Fan-out: 600 msg/sec x 6 subscribers = 3,600 messages/second outbound - Bandwidth: ~3 Mbps total (inbound + outbound) - Memory: ~53 MB (connections + topics + subscriptions + buffers)

Result: Single Mosquitto instance on modest hardware (4 CPU cores, 128 MB RAM) handles this with 95%+ headroom. See Hands-On Labs for complete capacity planning formulas.

NoteWorked Example: Implementing Last Will and Testament for Device Health

Scenario: A smart building needs to detect when door lock controllers go offline unexpectedly within 90 seconds.

Solution: - Configure LWT with topic locks/{id}/status, message {"state":"OFFLINE","reason":"unexpected"} - Set keep-alive to 60 seconds (broker timeout = 1.5 x 60 = 90 seconds) - Use QoS 1 and retain=true for LWT - Always publish explicit “online” status after connecting

Result: Dashboard receives automatic offline notification within 90 seconds of any lock failure. See Hands-On Labs for complete LWT implementation patterns.

MQTT Foundations: - MQTT Fundamentals - Core concepts and pub-sub patterns - MQTT QoS and Session - Reliability and message guarantees - MQTT Comprehensive Review - Advanced topics and best practices

Hands-On Comparisons: - CoAP Features and Labs - Compare CoAP implementations - IoT Protocols Overview - Protocol selection guide

Hardware Integration: - Prototyping Hardware - ESP32 and sensor setup - Sensor Labs - Integrating sensors with MQTT

Security Implementation: - Cyber Security Methods - TLS/SSL configuration - Encryption Architecture - Securing MQTT brokers

Learning Tools: - Simulations Hub - Interactive MQTT simulators - Network Design - Testing MQTT systems

1202.5 What’s Next

Choose your path based on your experience level:

After completing this series, continue with MQTT Comprehensive Review to synthesize your knowledge with scenario-based questions and protocol comparisons.