Overview

On incoming events such as a new message, or an incoming call, the user often expects to receive a push notification, if the app is not active.

This guide explains how to configure your Android app to receive push notifications from the Nexmo Client SDK.

Set up Firebase project for your app

In order to enable push notifications for your Android app, you should use the Firebase Cloud Messaging (FCM) API. To do that, start by adding Firebase to your Android project.

In case you have not done that already, more details can be found in the official Firebase documentation.

Provision your server key

Obtain a jwt_dev, which is a jwt without a sub claim. More details on how to generate a JWT can be found in the setup guide.

Get your private_key_file from the Firebase console. Navigate to Firebase console, Project settings, Service accounts, Firebase Admin SDK, generate new private key. You will need to ensure the private_key_file is encoded to JSON using a suitable method before you can send it to the push service.

Get your projectId from the Firebase console. Navigate to Firebase console, Project settings, General, projectId.

Get your Nexmo Application ID, app_id. It can be obtained from Nexmo Dashboard.

Run the following Curl command, replacing jwt_dev, private_key_file, projectId, app_id with your values:

curl -v -X PUT \
   -H "Authorization: Bearer $jwt_dev" \
   -H "Content-Type: application/json" \
   -d "{\"token\":\"$private_key_file\", \"projectId\":\"$projectId\"}" \
   https://api.nexmo.com/v1/applications/$app_id/push_tokens/android  

Add Firebase Cloud Messaging to your Android project

In your IDE, in your app level build.gradle file (usually app/build.gradle), add the firebase-messaging dependency:

dependencies{
    implementation 'com.google.firebase:firebase-messaging:x.y.z'
}

You need to replace x.y.z with the latest Cloud Messaging versions number, which can be found on the Firebase website.

Implement a service to receive push notifications

If you do not have one already, create a service that extends FirebaseMessagingService. Make sure your service is declared in your AndroidManifest.xml:

<service android:name=".MyFirebaseMessagingService">
    <intent-filter>
        <action android:name="com.google.firebase.MESSAGING_EVENT" />
    </intent-filter>
</service>

Enable Nexmo server to send push notifications to your device

In order for Nexmo to be able to send push notifications to a device, the Nexmo server has to know the device token, also known as InstanceID.

In your implementation of FirebaseMessagingService, override onNewToken() and update the Nexmo servers with it:

override fun onNewToken(token: String?) {
    token?.let {
        NexmoClient.get().enablePushNotifications(token, requestListener)
    }
}

Receive push notifications

Push notifications are received in your implementation of MyFirebaseMessagingService, on onMessageReceived() method.

You can use NexmoClient.isNexmoPushNotification(message.data)) to determine if the message is sent from Nexmo server.

Use NexmoClient.get().processPushNotification(message.data, listener) to process the data received from Firebase Cloud Messaging (FCM) into an easy to use Nexmo object.

For example, in your MyFirebaseMessagingService:

 val pushEventListener = object : NexmoPushEventListener {
        override fun onIncomingCall(p0: NexmoCall?, p1: MemberEvent?) {
            TODO("not implemented")
        }

        override fun onNewEvent(p0: NexmoEvent?) {
            TODO("not implemented")
        }

        override fun onError(p0: NexmoApiError?) {
            TODO("not implemented")
        }
    }

    override fun onMessageReceived(message: RemoteMessage?) {
        message?.data?.let {
            if (NexmoClient.isCommsPushNotification(message.data)) {
                NexmoClient.get().processPushNotification(message.data, pushEventListener)
            }

        }
    }

Conclusion

In this guide you have seen how to set up push notifications.