Programming the Internet of Things

Chapter 7. MQTT Integration–Java Client

Build a Publish/Subscribe Client in Java Using MQTT

Wash, rinse, and repeat.

What purpose does it now serve?

Practice makes perfect!

Fundamental concepts: Continued work with the MQTT pub/sub protocol; implementation strategies and exercises specific to the Gateway Device App written in Java; integration strategies using MQTT to communicate between the Constrained Device App and the Gateway Device App.

This chapter continues with the patterns established in Chapter 6, but with a focus on building your MQTT client connection logic within the GDA. This will eventually be used to support integration between the CDA and the GDA and will also lay the groundwork for the GDA to communicate with one or more cloud services using MQTT.

What You’ll Learn in This Chapter

You’ll continue digging into MQTT fundamentals, but this time you’ll focus on building out your GDA functionality via integration with an open source MQTT library. Not only will this allow you to test your gateway and eventually integrate with remote cloud services that implement the MQTT protocol via a hosted broker, but it will also enable you to talk to the CDA in a reliable manner.

You’ll see how MQTT can be used to push updates to one or more devices (such as your CDA) via a gateway (your GDA) and learn how to do so using an open source MQTT Java client library.

Programming Exercises

The steps you need to take to integrate MQTT with your GDA are nearly identical to those ...