Lab 31. Crash-course on MQTT

MQTT is a publish/subscribe solution which is built for IoT applications. As shown below, in consists of a broker (an MQTT server typically running on the Internet) to which entities (typically other computers connected to the Internet) connect. Once connected, these entities can publish messages and subscribe to messages.

Each message consists of a topic and payload. When you publish a message, you specify a topic (a string). When subscribing to messages, you subscribe to a specific topic. An entity can subscribe to multiple topics at the same time. When multiple entities subscribe to the same topic, they all receive a notification with a copy of each message which is published with that topic. 

While you can install your own broker, we are going to use the demo broker run by HiveMQ, a company that delivers high-performance MQTT brokers. The demo broker is meant for evaluation only; it is free to use, but anyone can see any of the data you publish. That's perfectly acceptable for this lab.

Here are the details about the broker to use:

What company invented MQTT?

What is the name of the most popular open-source MQTT broker?