In this chapter, we started our journey toward understanding the MQTT protocol. We understood convenient scenarios for this protocol, the details of the publish-subscribe pattern, and message filtering. We learned basic concepts related to MQTT and understood the different components: clients, servers or brokers, and connections.
We learned to install a Mosquitto server on Linux, macOS, and Windows. We used the default configuration, as it allowed us to learn how everything works under the hood while using Mosquitto. Then, we will secure the server. This way, it will be easier for us to start using the client libraries in Python to publish MQTT messages and subscribe to MQTT topic filters.
Now that we have our environment ready to start working with a still-unsecured Mosquitto server, we will work with command-line and GUI tools to learn how MQTT works in detail. We will learn MQTT basics, the specific vocabulary for MQTT, and its working modes, which are the topics that we are going to discuss in Chapter 2, Using Command-Line and GUI Tools to Learn How MQTT Works.