In this chapter, you've been shown how you can use MQTT to publish sensor data and interact with actuators on the internet. You've learned the basic principles behind the MQTT protocol, how to connect and maintain a connection with an MQTT broker, how to publish data on topics as well as how to subscribe to topics to receive published data. You've also learned how to test and troubleshot your interfaces. In the end, you were introduced to the basic vulnerabilities inherent in the protocol, and what you must do to protect your solutions. In the next chapter, you'll learn how you can use the HTTP protocol to include your things into the Web of Things.