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    Send messages to multiple devices

    To target a message to multiple devices, use Topic messaging . This feature allows you to send a message to multiple devices that have opted in to a particular topic.

    This tutorial focuses on sending topic messages from your app server using the Admin SDK or REST API for FCM , and receiving and handling them in an android app. We'll cover message handling for both backgrounded and foregrounded apps. All the steps to achieve this are covered, from setup to verification.

    Set up the SDK

    This section may cover steps you already completed if you have set up an Android client app for FCM or worked through the steps to Send your First Message .

    Before you begin

    • Install or update Android Studio to its latest version.

    • Make sure that your project meets these requirements (note that some products might have stricter requirements):

      • Targets API level 21 (Lollipop) or higher
      • Uses Android 5.0 or higher
      • Uses Jetpack (AndroidX) , which includes meeting these version requirements:
        • com.android.tools.build:gradle v7.3.0 or later
        • compileSdkVersion 28 or later

    • Set up a physical device or use an emulator to run your app.Note that Firebase SDKs with a dependency on Google Play services require the device or emulator to have Google Play services installed.

    • Sign into Firebase using your Google account.

    If you don't already have an Android project and just want to try out a Firebase product, you can download one of our quickstart samples .

    Create a Firebase project

    Before you can add Firebase to your Android app, you need to create a Firebase project to connect to your Android app. Visit Understand Firebase Projects to learn more about Firebase projects.

    Register your app with Firebase

    To use Firebase in your Android app, you need to register your app with your Firebase project. Registering your app is often called "adding" your app to your project.

    1. Go to the Firebase console .

    2. In the center of the project overview page, click the Androidicon ( ) or Add appto launch the setup workflow.

    3. Enter your app's package name in the Android package namefield.

      What's a package name, and where do you find it?

      • A package name uniquely identifies your app on the device and in the Google Play Store.

      • A package name is often referred to as an application ID .

      • Find your app's package name in your module (app-level) Gradle file, usually app/build.gradle (example package name: com.yourcompany.yourproject ).

      • Be aware that the package name value is case-sensitive, and it cannot be changed for this Firebase Android app after it's registered with your Firebase project.

  • (Optional) Enter other app information: App nicknameand Debug signing certificate SHA-1.

    How are the App nickname and the Debug signing certificate SHA-1 used within Firebase?

  • Click Register app.

    • Add a Firebase configuration file

    1. Download and then add your app's Firebase config file ( google-services.json ) to your codebase:

      1. Click Download google-services.jsonto obtain your app's Firebase config file.

      2. Move your config file into the module (app-level)root directory of your app.

      What do you need to know about this config file?

      • The Firebase config file contains unique, but non-secret identifiers for your project and app. To learn more about this config file, visit Understand Firebase Projects .

      • You can download your Firebase config file again at any time.

      • Make sure the config file name is not appended with additional characters, like (2) .

    2. To make the values in your google-services.json config file accessible to Firebase SDKs, you need the Google services Gradle plugin ( google-services ).

      1. In your root-level (project-level)Gradle file ( <project>/build.gradle.kts or <project>/build.gradle ), add the Google services plugin as a dependency:

        Kotlin 

         plugins 
  
 { 
  
 id 
 ( 
 "com.android.application" 
 ) 
  
 version 
  
 "7.3.0" 
  
 apply 
  
 false 
  
 // ... 
  
  // Add the dependency for the Google services Gradle plugin 
  
 id 
 ( 
 "com.google.gms.google-services" 
 ) 
  
 version 
  
 "4.4.3" 
  
 apply 
  
 false 
 }

        Groovy 

         plugins 
  
 { 
  
 id 
  
 'com.android.application' 
  
 version 
  
 '7.3.0' 
  
 apply 
  
 false 
  
 // ... 
  
  // Add the dependency for the Google services Gradle plugin 
  
 id 
  
 'com.google.gms.google-services' 
  
 version 
  
 '4.4.3' 
  
 apply 
  
 false 
 }

      2. In your module (app-level)Gradle file (usually <project>/<app-module>/build.gradle.kts or <project>/<app-module>/build.gradle ), add the Google services plugin:

        Kotlin 

         plugins 
  
 { 
  
 id 
 ( 
 "com.android.application" 
 ) 
  
  // Add the Google services Gradle plugin 
  
 id 
 ( 
 "com.google.gms.google-services" 
 ) 
  
 // ... 
 }

        Groovy 

         plugins 
  
 { 
  
 id 
  
 'com.android.application' 
  
  // Add the Google services Gradle plugin 
  
 id 
  
 'com.google.gms.google-services' 
  
 // ... 
 }

    Add Firebase SDKs to your app

    1. In your module (app-level) Gradle file (usually <project>/<app-module>/build.gradle.kts or <project>/<app-module>/build.gradle ), add the dependency for the Firebase Cloud Messaging library for Android. We recommend using the Firebase Android BoM to control library versioning.

      For an optimal experience with Firebase Cloud Messaging , we recommend enabling Google Analytics in your Firebase project and adding the Firebase SDK for Google Analytics to your app.

       dependencies 
  
 { 
  
  // Import the BoM 
for the Firebase platform 
  
 implementation 
 ( 
 platform 
 ( 
 "com.google.firebase:firebase-bom:34.2.0" 
 )) 
  
  // Add the dependencies for the Firebase Cloud Messaging 
and Analytics 
libraries 
  
 // When using the BoM 
, you don't specify versions in Firebase library dependencies 
  
  implementation 
 ( 
 "com.google.firebase:firebase-messaging" 
 ) 
  
 implementation 
 ( 
 "com.google.firebase:firebase-analytics" 
 ) 
 }

      By using the Firebase Android BoM , your app will always use compatible versions of Firebase Android libraries.

      (Alternative)   Add Firebase library dependencies  without  using the BoM

      If you choose not to use the Firebase BoM , you must specify each Firebase library version in its dependency line.

      Note that if you use multiple Firebase libraries in your app, we strongly recommend using the BoM to manage library versions, which ensures that all versions are compatible.

       dependencies 
  
 { 
  
  // Add the dependencies for the Firebase Cloud Messaging 
and Analytics 
libraries 
  
 // When NOT using the BoM 
, you must specify versions in Firebase library dependencies 
  
  implementation 
 ( 
 "com.google.firebase:firebase-messaging:25.0.0" 
 ) 
  
 implementation 
 ( 
 "com.google.firebase:firebase-analytics:23.0.0" 
 ) 
 }

    2. Sync your Android project with Gradle files.

      Are you getting a build failure about invoke-custom support and enabling desugaring? Here's how to fix it.

      Gradle builds that use Android Gradle plugin (AGP) v4.2 or earlier need to enable Java 8 support. Otherwise, these Android projects get a build failure when adding a Firebase SDK.

      To fix this build failure, you can follow one of two options:

      • Add the listed compileOptions from the error message to your app-level build.gradle.kts or build.gradle file.
      • Increase the minSdk for your Android project to 26 or above.

      Learn more about this build failure in this FAQ .

    Client apps can subscribe to any existing topic, or they can create a new topic. When a client app subscribes to a new topic name (one that does not already exist for your Firebase project), a new topic of that name is created in FCM and any client can subsequently subscribe to it.

    To subscribe to a topic, the client app calls Firebase Cloud Messaging subscribeToTopic() with the FCM topic name. This method returns a Task , which can be used by a completion listener to determine whether the subscription succeeded:

    Kotlin 

     Firebase 
 . 
 messaging 
 . 
 subscribeToTopic 
 ( 
 "weather" 
 ) 
  
 . 
 addOnCompleteListener 
  
 { 
  
 task 
  
 - 
>  
 var 
  
 msg 
  
 = 
  
 "Subscribed" 
  
 if 
  
 ( 
 ! 
 task 
 . 
 isSuccessful 
 ) 
  
 { 
  
 msg 
  
 = 
  
 "Subscribe failed" 
  
 } 
  
 Log 
 . 
 d 
 ( 
 TAG 
 , 
  
 msg 
 ) 
  
 Toast 
 . 
 makeText 
 ( 
 baseContext 
 , 
  
 msg 
 , 
  
 Toast 
 . 
 LENGTH_SHORT 
 ). 
 show 
 () 
  
 } 
 
      MainActivity 
 . 
 kt

    Java 

     FirebaseMessaging 
 . 
 getInstance 
 (). 
 subscribeToTopic 
 ( 
 "weather" 
 ) 
  
 . 
 addOnCompleteListener 
 ( 
 new 
  
 OnCompleteListener<Void> 
 () 
  
 { 
  
 @Override 
  
 public 
  
 void 
  
 onComplete 
 ( 
 @NonNull 
  
 Task<Void> 
  
 task 
 ) 
  
 { 
  
 String 
  
 msg 
  
 = 
  
 "Subscribed" 
 ; 
  
 if 
  
 ( 
 ! 
 task 
 . 
 isSuccessful 
 ()) 
  
 { 
  
 msg 
  
 = 
  
 "Subscribe failed" 
 ; 
  
 } 
  
 Log 
 . 
 d 
 ( 
 TAG 
 , 
  
 msg 
 ); 
  
 Toast 
 . 
 makeText 
 ( 
 MainActivity 
 . 
 this 
 , 
  
 msg 
 , 
  
 Toast 
 . 
 LENGTH_SHORT 
 ). 
 show 
 (); 
  
 } 
  
 }); 
 
      MainActivity 
 . 
 java

    To unsubscribe, the client app calls Firebase Cloud Messaging unsubscribeFromTopic() with the topic name.

    Receive and handle topic messages

    FCM delivers topic messages in the same way as other downstream messages.

    To receive messages, use a service that extends FirebaseMessagingService . Your service should override the onMessageReceived and onDeletedMessages callbacks.

    onMessageReceived is provided for most message types, with the following exceptions:

    • Notification messages delivered when your app is in the background. In this case, the notification is delivered to the device's system tray. A user tap on a notification opens the app launcher by default.

    • Messages with both notification and data payload, when received in the background. In this case, the notification is delivered to the device's system tray, and the data payload is delivered in the extras of the intent of your launcher Activity.

    In summary:

    App state Notification Data Both
    Foreground
    		 onMessageReceived onMessageReceived onMessageReceived
    Background
    		 System tray onMessageReceived Notification: system tray
    Data: in extras of the intent.
    For more information about message types, see Notifications and data messages .

    The onMessageReceived callback is given timeouts that enable you to simply post a notification but the timers are not designed to allow the app to access the network or to do additional work. As such, if your app does anything more complicated, you need to do additional work to ensure the app can complete its work.

    If you expect your app could require close to 10 seconds to handle a message, you should schedule a WorkManager job or follow the WakeLock guidance below . In some cases, the time window for handling a message may be shorter than 10 seconds depending on delays incurred ahead of calling onMessageReceived , including OS delays, app startup time, the main thread being blocked by other operations, or previous onMessageReceived calls taking too long. After that timer expires, your app may be subject to process killing or background execution limits . Keep in mind, latencies for network transactions and app startup can be significant, so when in doubt, plan for your message processing to run long if there are any asynchronous dependencies such as network access or intensive data loading requirements.

    Edit the app manifest

    To use FirebaseMessagingService , you need to add the following in your app manifest:

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

     
     
 . 
 xml

    Also, you're recommended to set default values to customize the appearance of notifications. You can specify a custom default icon and a custom default color that are applied whenever equivalent values are not set in the notification payload.

    Add these lines inside the application tag to set the custom default icon and custom color:

    < ! 
 -- Set custom default icon. This is used when no icon is set for incoming notification messages. 
  
 See 
  
 README 
 ( 
 https 
 : 
 // 
 goo 
 . 
 gl 
 / 
 l4GJaQ 
 ) 
  
 for 
  
 more 
 . 
  
 -- 
>
< meta 
 - 
 data 
  
 android 
 : 
 name 
 = 
 "com.google.firebase.messaging.default_notification_icon" 
  
 android 
 : 
 resource 
 = 
 "@drawable/ic_stat_ic_notification" 
  
 / 
>
< ! 
 -- Set color used with incoming notification messages. This is used when no color is set for the incoming 
  
 notification 
  
 message 
 . 
  
 See 
  
 README 
 ( 
 https 
 : 
 // 
 goo 
 . 
 gl 
 / 
 6 
 BKBk7 
 ) 
  
 for 
  
 more 
 . 
  
 -- 
>
< meta 
 - 
 data 
  
 android 
 : 
 name 
 = 
 "com.google.firebase.messaging.default_notification_color" 
  
 android 
 : 
 resource 
 = 
 "@color/colorAccent" 
  
 / 
> 
      AndroidManifest 
 . 
 xml

    Android displays the custom default icon for

    • All notification messages sent from the Notifications composer .
    • Any notification message that does not explicitly set the icon in the notification payload.

    Android uses the custom default color for

    • All notification messages sent from the Notifications composer .
    • Any notification message that does not explicitly set the color in the notification payload.

    If no custom default icon is set and no icon is set in the notification payload, Android displays the application icon rendered in white.

    Override onMessageReceived

    By overriding the method FirebaseMessagingService.onMessageReceived , you can perform actions based on the received RemoteMessage object and get the message data:

    Kotlin 

     override 
  
 fun 
  
 onMessageReceived 
 ( 
 remoteMessage 
 : 
  
 RemoteMessage 
 ) 
  
 { 
  
 // TODO(developer): Handle FCM messages here. 
  
 // Not getting messages here? See why this may be: https://goo.gl/39bRNJ 
  
 Log 
 . 
 d 
 ( 
 TAG 
 , 
  
 "From: 
 ${ 
 remoteMessage 
 . 
 from 
 } 
 " 
 ) 
  
 // Check if message contains a data payload. 
  
 if 
  
 ( 
 remoteMessage 
 . 
 data 
 . 
 isNotEmpty 
 ()) 
  
 { 
  
 Log 
 . 
 d 
 ( 
 TAG 
 , 
  
 "Message data payload: 
 ${ 
 remoteMessage 
 . 
 data 
 } 
 " 
 ) 
  
 // Check if data needs to be processed by long running job 
  
 if 
  
 ( 
 needsToBeScheduled 
 ()) 
  
 { 
  
 // For long-running tasks (10 seconds or more) use WorkManager. 
  
 scheduleJob 
 () 
  
 } 
  
 else 
  
 { 
  
 // Handle message within 10 seconds 
  
 handleNow 
 () 
  
 } 
  
 } 
  
 // Check if message contains a notification payload. 
  
 remoteMessage 
 . 
 notification 
 ?. 
 let 
  
 { 
  
 Log 
 . 
 d 
 ( 
 TAG 
 , 
  
 "Message Notification Body: 
 ${ 
 it 
 . 
 body 
 } 
 " 
 ) 
  
 } 
  
 // Also if you intend on generating your own notifications as a result of a received FCM 
  
 // message, here is where that should be initiated. See sendNotification method below. 
 } 
 
      MyFirebaseMessagingService 
 . 
 kt

    Java 

     @Override 
 public 
  
 void 
  
 onMessageReceived 
 ( 
 RemoteMessage 
  
 remoteMessage 
 ) 
  
 { 
  
 // TODO(developer): Handle FCM messages here. 
  
 // Not getting messages here? See why this may be: https://goo.gl/39bRNJ 
  
 Log 
 . 
 d 
 ( 
 TAG 
 , 
  
 "From: " 
  
 + 
  
 remoteMessage 
 . 
 getFrom 
 ()); 
  
 // Check if message contains a data payload. 
  
 if 
  
 ( 
 remoteMessage 
 . 
 getData 
 (). 
 size 
 () 
 > 
 0 
 ) 
  
 { 
  
 Log 
 . 
 d 
 ( 
 TAG 
 , 
  
 "Message data payload: " 
  
 + 
  
 remoteMessage 
 . 
 getData 
 ()); 
  
 if 
  
 ( 
 /* Check if data needs to be processed by long running job */ 
  
 true 
 ) 
  
 { 
  
 // For long-running tasks (10 seconds or more) use WorkManager. 
  
 scheduleJob 
 (); 
  
 } 
  
 else 
  
 { 
  
 // Handle message within 10 seconds 
  
 handleNow 
 (); 
  
 } 
  
 } 
  
 // Check if message contains a notification payload. 
  
 if 
  
 ( 
 remoteMessage 
 . 
 getNotification 
 () 
  
 != 
  
 null 
 ) 
  
 { 
  
 Log 
 . 
 d 
 ( 
 TAG 
 , 
  
 "Message Notification Body: " 
  
 + 
  
 remoteMessage 
 . 
 getNotification 
 (). 
 getBody 
 ()); 
  
 } 
  
 // Also if you intend on generating your own notifications as a result of a received FCM 
  
 // message, here is where that should be initiated. See sendNotification method below. 
 } 
 
      MyFirebaseMessagingService 
 . 
 java

    Keep the device awake while handling FCM messages

    If your app needs to keep the device awake while processing an FCM message, then it will need to hold a WakeLock during this time or it will need to create a WorkManager job. WakeLocks work well for short processing activities that might exceed the onMessageReceived default timeouts. For extended workflows, such as sending multiple serial RPCs to your servers, using a WorkManager job is more appropriate than a WakeLock. In this section we focus on how to use WakeLocks. A WakeLock prevents the device from sleeping while your app is running, which can result in increased battery use, so use of WakeLocks should be reserved for cases where your app should not be paused while handling the message such as:

    • Notifications to the user that are time sensitive.
    • Interactions with something off device that shouldn't be interrupted (such as network transfers or communications with another device, like a paired watch).

    First you'll need to make sure that your app requests the WakeLock permission (the FCM SDK includes this by default, so normally nothing needs to be added).

    <uses-permission android:name="android.permission.WAKE_LOCK" />

    Then your app will need to acquire a WakeLock at the start of the FirebaseMessagingService.onMessageReceived() callback and release it at the end of the callback.

    App's custom FirebaseMessagingService :

    @Override
public void onMessageReceived(final RemoteMessage message) {
  // If this is a message that is time sensitive or shouldn't be interrupted
  WakeLock wakeLock = getSystemService(PowerManager.class).newWakeLock(PARTIAL_WAKE_LOCK, "myApp:messageReceived");
  try {
    wakeLock.acquire(TIMEOUT_MS);
    // handle message
    ...
  finally {
    wakeLock.release();
  }
}

    Override onDeletedMessages

    In some situations, FCM may not deliver a message. This occurs when there are too many messages (>100) pending for your app on a particular device at the time it connects or if the device hasn't connected to FCM in more than one month. In these cases, you may receive a callback to FirebaseMessagingService.onDeletedMessages() When the app instance receives this callback, it should perform a full sync with your app server. If you haven't sent a message to the app on that device within the last 4 weeks, FCM won't call onDeletedMessages() .

    Handle notification messages in a backgrounded app

    When your app is in the background, Android directs notification messages to the system tray. A user tap on the notification opens the app launcher by default.

    This includes messages that contain both notification and data payload (and all messages sent from the Notifications console). In these cases, the notification is delivered to the device's system tray, and the data payload is delivered in the extras of the intent of your launcher Activity.

    For insight into message delivery to your app, see the FCM reporting dashboard , which records the number of messages sent and opened on Apple and Android devices, along with data for "impressions" (notifications seen by users) for Android apps.

    Build send requests

    After you have created a topic, either by subscribing client app instances to the topic on the client side or via the server API , you can send messages to the topic. If this is your first time building send requests for FCM , see the guide to your server environment and FCM for important background and setup information.

    In your sending logic on the backend, specify the desired topic name as shown:

    Node.js

      // The topic name can be optionally prefixed with "/topics/". 
 const 
  
 topic 
  
 = 
  
 'highScores' 
 ; 
 const 
  
 message 
  
 = 
  
 { 
  
 data 
 : 
  
 { 
  
 score 
 : 
  
 '850' 
 , 
  
 time 
 : 
  
 '2:45' 
  
 }, 
  
 topic 
 : 
  
 topic 
 }; 
 // Send a message to devices subscribed to the provided topic. 
 getMessaging 
 (). 
 send 
 ( 
 message 
 ) 
  
 . 
 then 
 (( 
 response 
 ) 
  
 = 
>  
 { 
  
 // Response is a message ID string. 
  
 console 
 . 
 log 
 ( 
 'Successfully sent message:' 
 , 
  
 response 
 ); 
  
 }) 
  
 . 
 catch 
 (( 
 error 
 ) 
  
 = 
>  
 { 
  
 console 
 . 
 log 
 ( 
 'Error sending message:' 
 , 
  
 error 
 ); 
  
 });

    Java

      // The topic name can be optionally prefixed with "/topics/". 
 String 
  
 topic 
  
 = 
  
 "highScores" 
 ; 
 // See documentation on defining a message payload. 
 Message 
  
 message 
  
 = 
  
 Message 
 . 
 builder 
 () 
  
 . 
 putData 
 ( 
 "score" 
 , 
  
 "850" 
 ) 
  
 . 
 putData 
 ( 
 "time" 
 , 
  
 "2:45" 
 ) 
  
 . 
 setTopic 
 ( 
 topic 
 ) 
  
 . 
 build 
 (); 
 // Send a message to the devices subscribed to the provided topic. 
 String 
  
 response 
  
 = 
  
 FirebaseMessaging 
 . 
 getInstance 
 (). 
 send 
 ( 
 message 
 ); 
 // Response is a message ID string. 
 System 
 . 
 out 
 . 
 println 
 ( 
 "Successfully sent message: " 
  
 + 
  
 response 
 ); 
 
      FirebaseMessagingSnippets 
 . 
 java

    Python

      # The topic name can be optionally prefixed with "/topics/". 
 topic 
 = 
 'highScores' 
 # See documentation on defining a message payload. 
 message 
 = 
 messaging 
 . 
 Message 
 ( 
 data 
 = 
 { 
 'score' 
 : 
 '850' 
 , 
 'time' 
 : 
 '2:45' 
 , 
 }, 
 topic 
 = 
 topic 
 , 
 ) 
 # Send a message to the devices subscribed to the provided topic. 
 response 
 = 
 messaging 
 . 
 send 
 ( 
 message 
 ) 
 # Response is a message ID string. 
 print 
 ( 
 'Successfully sent message:' 
 , 
 response 
 ) 
 
      cloud_messaging 
 . 
 py

    Go

      // The topic name can be optionally prefixed with "/topics/". 
 topic 
  
 := 
  
 "highScores" 
 // See documentation on defining a message payload. 
 message 
  
 := 
  
& messaging 
 . 
 Message 
 { 
  
 Data 
 : 
  
 map 
 [ 
 string 
 ] 
 string 
 { 
  
 "score" 
 : 
  
 "850" 
 , 
  
 "time" 
 : 
  
 "2:45" 
 , 
  
 }, 
  
 Topic 
 : 
  
 topic 
 , 
 } 
 // Send a message to the devices subscribed to the provided topic. 
 response 
 , 
  
 err 
  
 := 
  
 client 
 . 
 Send 
 ( 
 ctx 
 , 
  
 message 
 ) 
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 log 
 . 
 Fatalln 
 ( 
 err 
 ) 
 } 
 // Response is a message ID string. 
 fmt 
 . 
 Println 
 ( 
 "Successfully sent message:" 
 , 
  
 response 
 ) 
 
      messaging 
 . 
 go

    C#

      // The topic name can be optionally prefixed with "/topics/". 
 var 
  
 topic 
  
 = 
  
 "highScores" 
 ; 
 // See documentation on defining a message payload. 
 var 
  
 message 
  
 = 
  
 new 
  
 Message 
 () 
 { 
  
 Data 
  
 = 
  
 new 
  
 Dictionary<string 
 , 
  
 string 
> () 
  
 { 
  
 { 
  
 "score" 
 , 
  
 "850" 
  
 }, 
  
 { 
  
 "time" 
 , 
  
 "2:45" 
  
 }, 
  
 }, 
  
 Topic 
  
 = 
  
 topic 
 , 
 }; 
 // Send a message to the devices subscribed to the provided topic. 
 string 
  
 response 
  
 = 
  
 await 
  
 FirebaseMessaging 
 . 
 DefaultInstance 
 . 
 SendAsync 
 ( 
 message 
 ); 
 // Response is a message ID string. 
 Console 
 . 
 WriteLine 
 ( 
 "Successfully sent message: " 
  
 + 
  
 response 
 );

    REST

     POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
  "message":{
    "topic" : "foo-bar",
    "notification" : {
      "body" : "This is a Firebase Cloud Messaging Topic Message!",
      "title" : "FCM Message"
      }
   }
}

    cURL command:

     curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
  "message": {
    "topic" : "foo-bar",
    "notification": {
      "body": "This is a Firebase Cloud Messaging Topic Message!",
      "title": "FCM Message"
    }
  }
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

    To send a message to a combination of topics, specify a condition , which is a boolean expression that specifies the target topics. For example, the following condition will send messages to devices that are subscribed to TopicA and either TopicB or TopicC :

     "'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)"

    FCM first evaluates any conditions in parentheses, and then evaluates the expression from left to right. In the above expression, a user subscribed to any single topic does not receive the message. Likewise, a user who does not subscribe to TopicA does not receive the message. These combinations do receive it:

    • TopicA and TopicB
    • TopicA and TopicC

    You can include up to five topics in your conditional expression.

    To send to a condition:

    Node.js

      // Define a condition which will send to devices which are subscribed 
 // to either the Google stock or the tech industry topics. 
 const 
  
 condition 
  
 = 
  
 '\'stock-GOOG\' in topics || \'industry-tech\' in topics' 
 ; 
 // See documentation on defining a message payload. 
 const 
  
 message 
  
 = 
  
 { 
  
 notification 
 : 
  
 { 
  
 title 
 : 
  
 '$FooCorp up 1.43% on the day' 
 , 
  
 body 
 : 
  
 '$FooCorp gained 11.80 points to close at 835.67, up 1.43% on the day.' 
  
 }, 
  
 condition 
 : 
  
 condition 
 }; 
 // Send a message to devices subscribed to the combination of topics 
 // specified by the provided condition. 
 getMessaging 
 (). 
 send 
 ( 
 message 
 ) 
  
 . 
 then 
 (( 
 response 
 ) 
  
 = 
>  
 { 
  
 // Response is a message ID string. 
  
 console 
 . 
 log 
 ( 
 'Successfully sent message:' 
 , 
  
 response 
 ); 
  
 }) 
  
 . 
 catch 
 (( 
 error 
 ) 
  
 = 
>  
 { 
  
 console 
 . 
 log 
 ( 
 'Error sending message:' 
 , 
  
 error 
 ); 
  
 });

    Java

      // Define a condition which will send to devices which are subscribed 
 // to either the Google stock or the tech industry topics. 
 String 
  
 condition 
  
 = 
  
 "'stock-GOOG' in topics || 'industry-tech' in topics" 
 ; 
 // See documentation on defining a message payload. 
 Message 
  
 message 
  
 = 
  
 Message 
 . 
 builder 
 () 
  
 . 
 setNotification 
 ( 
 Notification 
 . 
 builder 
 () 
  
 . 
 setTitle 
 ( 
 "$GOOG up 1.43% on the day" 
 ) 
  
 . 
 setBody 
 ( 
 "$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day." 
 ) 
  
 . 
 build 
 ()) 
  
 . 
 setCondition 
 ( 
 condition 
 ) 
  
 . 
 build 
 (); 
 // Send a message to devices subscribed to the combination of topics 
 // specified by the provided condition. 
 String 
  
 response 
  
 = 
  
 FirebaseMessaging 
 . 
 getInstance 
 (). 
 send 
 ( 
 message 
 ); 
 // Response is a message ID string. 
 System 
 . 
 out 
 . 
 println 
 ( 
 "Successfully sent message: " 
  
 + 
  
 response 
 ); 
 
      FirebaseMessagingSnippets 
 . 
 java

    Python

      # Define a condition which will send to devices which are subscribed 
 # to either the Google stock or the tech industry topics. 
 condition 
 = 
 "'stock-GOOG' in topics || 'industry-tech' in topics" 
 # See documentation on defining a message payload. 
 message 
 = 
 messaging 
 . 
 Message 
 ( 
 notification 
 = 
 messaging 
 . 
 Notification 
 ( 
 title 
 = 
 '$GOOG up 1.43 
 % o 
 n the day' 
 , 
 body 
 = 
 '$GOOG gained 11.80 points to close at 835.67, up 1.43 
 % o 
 n the day.' 
 , 
 ), 
 condition 
 = 
 condition 
 , 
 ) 
 # Send a message to devices subscribed to the combination of topics 
 # specified by the provided condition. 
 response 
 = 
 messaging 
 . 
 send 
 ( 
 message 
 ) 
 # Response is a message ID string. 
 print 
 ( 
 'Successfully sent message:' 
 , 
 response 
 ) 
 
      cloud_messaging 
 . 
 py

    Go

      // Define a condition which will send to devices which are subscribed 
 // to either the Google stock or the tech industry topics. 
 condition 
  
 := 
  
 "'stock-GOOG' in topics || 'industry-tech' in topics" 
 // See documentation on defining a message payload. 
 message 
  
 := 
  
& messaging 
 . 
 Message 
 { 
  
 Data 
 : 
  
 map 
 [ 
 string 
 ] 
 string 
 { 
  
 "score" 
 : 
  
 "850" 
 , 
  
 "time" 
 : 
  
 "2:45" 
 , 
  
 }, 
  
 Condition 
 : 
  
 condition 
 , 
 } 
 // Send a message to devices subscribed to the combination of topics 
 // specified by the provided condition. 
 response 
 , 
  
 err 
  
 := 
  
 client 
 . 
 Send 
 ( 
 ctx 
 , 
  
 message 
 ) 
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 log 
 . 
 Fatalln 
 ( 
 err 
 ) 
 } 
 // Response is a message ID string. 
 fmt 
 . 
 Println 
 ( 
 "Successfully sent message:" 
 , 
  
 response 
 ) 
 
      messaging 
 . 
 go

    C#

      // Define a condition which will send to devices which are subscribed 
 // to either the Google stock or the tech industry topics. 
 var 
  
 condition 
  
 = 
  
 "'stock-GOOG' in topics || 'industry-tech' in topics" 
 ; 
 // See documentation on defining a message payload. 
 var 
  
 message 
  
 = 
  
 new 
  
 Message 
 () 
 { 
  
 Notification 
  
 = 
  
 new 
  
 Notification 
 () 
  
 { 
  
 Title 
  
 = 
  
 "$GOOG up 1.43% on the day" 
 , 
  
 Body 
  
 = 
  
 "$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day." 
 , 
  
 }, 
  
 Condition 
  
 = 
  
 condition 
 , 
 }; 
 // Send a message to devices subscribed to the combination of topics 
 // specified by the provided condition. 
 string 
  
 response 
  
 = 
  
 await 
  
 FirebaseMessaging 
 . 
 DefaultInstance 
 . 
 SendAsync 
 ( 
 message 
 ); 
 // Response is a message ID string. 
 Console 
 . 
 WriteLine 
 ( 
 "Successfully sent message: " 
  
 + 
  
 response 
 );

    REST

     POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
   "message":{
    "condition": "'dogs' in topics || 'cats' in topics",
    "notification" : {
      "body" : "This is a Firebase Cloud Messaging Topic Message!",
      "title" : "FCM Message",
    }
  }
}

    cURL command:

     curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
  "notification": {
    "title": "FCM Message",
    "body": "This is a Firebase Cloud Messaging Topic Message!",
  },
  "condition": "'dogs' in topics || 'cats' in topics"
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

    Next steps

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