The MQTT Protocol

Last week we used HTTP to communicate between applications. HTTP was a request-response protocol. This week, we look at MQTT, which is a publish-subscribe protocol.

Some useful things to Know About MQTT

Read the following articles:
5 Things to Know About MQTT (

MQTT – Frequently Asked Questions (

MQTT V3.1 Protocol Specification – The Message Format

Read pt 2.1 – 2.3:
Fixed header
Variable header

Connecting Internet of Things (IoT) with MQTT (Introduction to MQTT)


In the lecture, we will be using MQTT.fx. As part of the preparation, at least one member of the team need to install this tool on a laptop.

MQTT.fx is an application to send and receive MQTT messages. It is ideal during development, since you can also see which messages are sent in the system and see if everything is okay.

(MQTT.fx will not be part of the RAT)

At HiveMQ you can find the resources you need for the installation:
Introducing MQTT.fx
MQTT.fx – A closer look