Broker

The broker acts as an intermediary between TheengsGateway and your controller. Consider it as a centralized hub at the heart of your home automation system. It carries on messages following a publish/subscribe mechanism.

All the events or commands could pass by the broker.

There are many choices of brokers, here are some of the most popular:

• Mosquitto (opens new window) (open source)
• Moquette (opens new window) (open source)
• HiveMQ (opens new window)
• Embedded MQTT brokers (Home Assistant and openHAB)

This comparison of MQTT implementations (opens new window) on Wikipedia gives you more details about the different choices you have. This list of brokers (opens new window) on GitHub seems to be the most exhaustive ones. Here is also a list of criteria for selecting a MQTT broker (opens new window) from HiveMQ.

Once you've installed your broker, it can be interesting to see the traffic passing to it and to publish data. There are several tools available to do this:

• MQTT Explorer (opens new window)
• HiveMQ MQTT web client (opens new window)
• MQTT FX (opens new window)