How to implement the notification system

Now we are ready to implement the last part of this project: the notification system. In the next paragraphs, we will describe how to send a notification to the user smartphone when motion is detected. As the messaging system, this IoT project uses Google Firebase. This is a cloud platform developed by Google providing several interesting services. We will use the Notification service.

There are several ways we can send a notification from the Android Things app to a user smartphone. To keep things simple, we will use topic. You can imagine a topic like a channel. After a device subscribes to a topic, it will receive all the messages published to this channel. In our project, the user smartphone behaves like a subscriber receiving messages from the channel, while the Android Things app behaves like a publisher publishing the messages.

Now it is clear the roles these two apps play in this project.

Before implementing it, we have to configure the Firebase...