Try push notifications with the Android example XMTP app

This guide describes how to set up push notifications for the XMTP Android example app built with the xmtp-android SDK using Firebase Cloud Messaging (FCM) and a custom notification server.

Perform this setup to understand how you can enable push notifications for your own app built with the xmtp-android SDK.

Set up a Firebase Cloud Messaging server

For this tutorial, we'll use Firebase Cloud Messaging (FCM) as a convenient way to set up a messaging server.

1. Create an FCM project.

2. Add the example app to the FCM project. This generates a google-services.json file that you need in subsequent steps.

3. Add the google-services.json file to the example app's project as described in the FCM project creation process.

4. Generate FCM credentials, which you need to run the example notification server. To do this, from the FCM dashboard, click the gear icon next to Project Overview and select Project settings. Select Service accounts. Select Go and click Generate new private key.

Run an example notification server

Now that you have an FCM server set up, take a look at the kotlin folder in the example-notifications-server-go repo.

These files can serve as the basis for what you might want to provide for your own notification server. This proto code from the example notification server has already been generated and added to the xmtp-android example app if you use the example notification server as-is.

1. Clone the example-notification-server-go repo.

2. Complete the steps in Local Setup.

3. Get the FCM project ID and the FCM credentials you created in step 4 of setting up FCM and run:

   Bash

   YOURFCMJSON=$(cat /path/to/FCMCredentials.json)

   Bash

   dev/run \
   --xmtp-listener-tls \
   --xmtp-listener \
   --api \
   -x "grpc.production.xmtp.network:443" \
   -d "postgres://postgres:xmtp@localhost:25432/postgres?sslmode=disable" \
   --fcm-enabled \
   --fcm-credentials-json=$YOURFCMJSON \
   --fcm-project-id="YOURFCMPROJECTID"

4. You should now be able to see push notifications coming across the local network.

Update the example app to send push notifications

1. Add your google-services.json file to the example folder, if you haven't already done it as a part of the FCM project creation process.

2. Uncomment id 'com.google.gms.google-services' in the example app's build.gradle file.

3. Uncomment the following code in the top level of the example app's build.gradle file:

   Groovy

   buildscript {
       repositories {
           google()
           mavenCentral()
       }
       dependencies {
           classpath 'com.google.gms:google-services:4.3.15'
       }
   }

4. Sync the gradle project.

5. Add the example notification server address to the example app's MainActivity. In this case, it should be PushNotificationTokenManager.init(this, "10.0.2.2:8080").

6. Change the example app's environment to XMTPEnvironment.PRODUCTION in ClientManager.kt.

7. Set up the example app to register the FCM token with the network and then subscribe each conversation to push notifications. For example:

   Kotlin

   XMTPPush(context, "10.0.2.2:8080").register(token)

   Kotlin

   val hmacKeysResult = ClientManager.client.conversations.getHmacKeys()
   val subscriptions = conversations.map {
       val hmacKeys = hmacKeysResult.hmacKeysMap
       val result = hmacKeys[it.topic]?.valuesList?.map { hmacKey ->
           Service.Subscription.HmacKey.newBuilder().also { sub_key ->
               sub_key.key = hmacKey.hmacKey
               sub_key.thirtyDayPeriodsSinceEpoch = hmacKey.thirtyDayPeriodsSinceEpoch
           }.build()
       }
    
       Service.Subscription.newBuilder().also { sub ->
           sub.addAllHmacKeys(result)
           sub.topic = it.topic
           sub.isSilent = it.version == Conversation.Version.V1
       }.build()
   }
    
   XMTPPush(context, "10.0.2.2:8080").subscribeWithMetadata(subscriptions)

   Kotlin

   XMTPPush(context, "10.0.2.2:8080").unsubscribe(conversations.map { it.topic })

Decode a notification envelope

You can decode a single Envelope from XMTP using the decode method:

val conversation =
    client.conversations.newConversation("0x3F11b27F323b62B159D2642964fa27C46C841897")
 
// Assume this function returns an Envelope that contains a message for the above conversation
val envelope = getEnvelopeFromXMTP()
 
val decodedMessage = conversation.decode(envelope)