Android Things is the new operating system developed by Google to build IoT projects. This helps you to develop professional applications using trusted platforms and Android. Yes Android, because Android Things is a modified version of Android and we can reuse our Android knowledge to implement smart Internet of things projects. This OS has great potential because Android developers can smoothly move to IoT and start developing and building projects in a few days. Before diving into Android Things, it is important to have an overview. Android Things OS has the layer structure shown in the following diagram:
This structure is slightly different from Android OS because it is much more compact so that apps for Android Things have fewer layers beneath and they are closer to drivers and peripherals than normal Android apps. Even if Android Things derives from Android, there are some APIs available in Android not supported in Android Things. We will now briefly describe the similarities and the differences.
Let us start with the content providers, widely used in Android, and not present in Android Things SDK. Therefore, we should pay attention when we develop an Android Things app. To have more information about these content providers not supported, please refer to the Official Android Things website at https://developer.android.com/things/sdk/index.html.
Moreover, like a normal Android app, an Android Things app can have a User Interface (UI), even if this is optional, and it depends on the type of application we are developing. A user can interact with the UI to trigger events as they happen in an Android app. From this point of view, as we will see later, the developing process of a UI is the same as used in Android. This is an interesting feature because we can develop an IoT UI easily and fast, re- using our Android knowledge.
It is worth noting that Android Things fits perfectly in the Google services. Almost all cloud services implemented by Google are available in Android Things with some exceptions. Android Things does not support Google services strictly connected to the mobile world and those that require user input or authentication. Do not forget that user interface for an Android Things app is optional. To have a detailed list of Google services available in Android Things refer to the official page at https://developer.android.com/things/sdk/index.html.
An important Android aspect is the permission management. An Android app runs in a sandbox with limited access to the resources. When an app needs to access a specific resource outside the sandbox it has to request permission. In an Android app, this happens in the
Manifest.xml file. This is still true in Android Things and all the permissions requested by the app are granted at installation time. Android 6 (API level 23) has introduced a new way to request a permission. An app can request a permission not only at installation time (using the
Manifest.xml file), but at run-time too. Android Things does not support this new feature, so we have to request all the permissions in the Manifest file.
The last thing to notice is the notifications. As we will see later, Android Things UI does not support the notification status bar, so we cannot trigger notifications from our Android Things apps.