How do you send a Firebase Notification to all devices via CURL?

Question

I'm attempting to send out a notification to all app users (on Android), essentially duplicating what happens when a notification is sent via the Firebase admin console. Here is the CURL command I begin with:

curl --insecure --header "Authorization: key=AIzaSyBidmyauthkeyisfineL-6NcJxj-1JUvEM" --header "Content-Type:application/json" -d "{\"notification\":{\"title\":\"note-Title\",\"body\":\"note-Body\"}}" https://fcm.googleapis.com/fcm/send

Here's that JSON parsed out to be easier on your eyes:

{
"notification":{
    "title":"note-Title",
    "body":"note-Body"
    }
}

The response that comes back is just two characters:

to

That's it, the word "to". (Headers report a 400) I suspect this has to do with not having a "to" in my JSON. What would one even put for a "to"? I have no topics defined, and the devices have not registered themselves for anything. Yet, they are still able to receive notifications from the Firebase admin panel.

I'm want to attempt a "data only" JSON package due to the amazing limitation of Firebase notification processing whereby if your app is in the foreground, the notification gets processed by YOUR handler, but if your app is in the background, it gets processed INTERNALLY by the Firebase service and never passed to your notification handler. APPARENTLY this can be worked around if you submit your notification request via the API, but ONLY if you do it with data-only. (Which then breaks the ability to handle iOS and Android with the same message.) Replacing "notification" with "data" in any of my JSON has no effect.

Ok, then I attempted the solution here: Firebase Java Server to send push notification to all devices which seems to me to say "Ok, even though notifications to everyone is possible via the Admin console... it's not really possible via the API." The workaround is to have each client subscribe to a topic, and then push out the notification to that topic. So first the code in onCreate:

FirebaseMessaging.getInstance().subscribeToTopic("allDevices");

then the new JSON I send:

{
"notification":{
    "title":"note-Title",
    "body":"note-Body"
    },
"to":"allDevices"
}

So now I'm getting a real response from the server at least. JSON response:

{
"multicast_id":463numbersnumbers42000,
"success":0,
"failure":1,
"canonical_ids":0,
"results":
    [
    {
    "error":"InvalidRegistration"
    }
    ]
}

And that comes with a HTTP code 200. Ok... according to https://firebase.google.com/docs/cloud-messaging/http-server-ref a 200 code with "InvalidRegistration" means a problem with the registration token. Maybe? Because that part of the documentation is for the messaging server. Is the notification server the same? Unclear. I see elsewhere that the topic might take hours before it's active. It seems like that would make it useless for creating new chat rooms, so that seems off as well.

I was pretty excited when I could code up an app from scratch that got notifications in just a few hours when I had never used Firebase before. It seems like it has a long way to go before it reaches the level of, say, the Stripe.com documentation.

Bottom line: does anyone know what JSON to supply to send a message out to all devices running the app to mirror the Admin console functionality?

Answer 1

Firebase Notifications doesn't have an API to send messages. Luckily it is built on top of Firebase Cloud Messaging, which has precisely such an API.

With Firebase Notifications and Cloud Messaging, you can send so-called downstream messages to devices in three ways:

1. to specific devices, if you know their device IDs
2. to groups of devices, if you know the registration IDs of the groups
3. to topics, which are just keys that devices can subscribe to

You'll note that there is no way to send to all devices explicitly. You can build such functionality with each of these though, for example: by subscribing the app to a topic when it starts (e.g. /topics/all) or by keeping a list of all device IDs, and then sending the message to all of those.

For sending to a topic you have a syntax error in your command. Topics are identified by starting with /topics/. Since you don't have that in your code, the server interprets allDevices as a device id. Since it is an invalid format for a device registration token, it raises an error.

From the documentation on sending messages to topics:

https://fcm.googleapis.com/fcm/send
Content-Type:application/json
Authorization:key=AIzaSyZ-1u...0GBYzPu7Udno5aA

{
  "to": "/topics/foo-bar",
  "data": {
    "message": "This is a Firebase Cloud Messaging Topic Message!",
   }
}

Answer 2

The most easiest way I came up with to send the push notification to all the devices is to subscribe them to a topic "all" and then send notification to this topic. Copy this in your main activity

FirebaseMessaging.getInstance().subscribeToTopic("all");

Now send the request as

{
    "to": "/topics/all",
    "data":
    {
        "title":"Your title",
        "message":"Your message"
        "image-url":"your_image_url"
    }
}

This might be inefficient or non-standard way, but as I mentioned above it's the easiest. Please do post if you have any better way to send a push notification to all the devices.

Just checked the FCM documentation, this is the only way to send notifications to all the devices (as of 8th July 2022).

As mentioned in the comments, the notification is not automatically displayed, you have to define a class that is derived from FirebaseMessagingService and then override the function onMessageReceived.

First register your service in app manifest.

<!-- AndroidManifest.xml -->

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

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

<!-- AndroidManifest.xml -->

<!-- Set custom default icon. This is used when no icon is set 
for incoming notification messages. -->
<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. -->
<meta-data
    android:name="com.google.firebase.messaging.default_notification_color"
    android:resource="@color/colorAccent" />

Now create your service to receive the push notifications.

// MyFirebaseMessagingService.java

package com.google.firebase.example.messaging;

import android.content.Context;
import android.util.Log;

import androidx.annotation.NonNull;
import androidx.work.OneTimeWorkRequest;
import androidx.work.WorkManager;
import androidx.work.Worker;
import androidx.work.WorkerParameters;

import com.google.firebase.messaging.FirebaseMessagingService;
import com.google.firebase.messaging.RemoteMessage;

public class MyFirebaseMessagingService extends FirebaseMessagingService {

    private static final String TAG = "MyFirebaseMsgService";

    // [START receive_message]
    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        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());
        }

    }
    // [END receive_message]

    // [START on_new_token]
    /**
     * There are two scenarios when onNewToken is called:
     * 1) When a new token is generated on initial app startup
     * 2) Whenever an existing token is changed
     * Under #2, there are three scenarios when the existing token is changed:
     * A) App is restored to a new device
     * B) User uninstalls/reinstalls the app
     * C) User clears app data
     */
    @Override
    public void onNewToken(@NonNull String token) {
        Log.d(TAG, "Refreshed token: " + token);

        // If you want to send messages to this application instance or
        // manage this apps subscriptions on the server side, send the
        // FCM registration token to your app server.
        sendRegistrationToServer(token);
    }
    // [END on_new_token]

    private void scheduleJob() {
        // [START dispatch_job]
        OneTimeWorkRequest work = new OneTimeWorkRequest.Builder(MyWorker.class)
                .build();
        WorkManager.getInstance(this).beginWith(work).enqueue();
        // [END dispatch_job]
    }

    private void handleNow() {
        Log.d(TAG, "Short lived task is done.");
    }

    private void sendRegistrationToServer(String token) {
        // TODO: Implement this method to send token to your app server.
    }

    public static class MyWorker extends Worker {

        public MyWorker(@NonNull Context context, @NonNull WorkerParameters workerParams) {
            super(context, workerParams);
        }

        @NonNull
        @Override
        public Result doWork() {
            // TODO(developer): add long running task here.
            return Result.success();
        }
    }
}

_{You can follow this tutorial if you're new to sending push notifications using Firebase Cloud Messaging Tutorial - Push Notifications using FCM and Send messages to multiple devices - Firebase Documentation}

---

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:

{
   "data":
   {
      "title": "Your title",
      "message": "Your message"
      "image-url": "your_image_url"
   },
   "condition": "'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)"
}

Read more about conditions and topics here on FCM documentation

Answer 3

EDIT: It appears that this method is not supported anymore (thx to @FernandoZamperin). Please take a look at the other answers!

Instead of subscribing to a topic you could instead make use of the condition key and send messages to instances, that are not in a group. Your data might look something like this:

{
    "data": {
        "foo": "bar"
    },
    "condition": "!('anytopicyoudontwanttouse' in topics)"
}

See https://firebase.google.com/docs/cloud-messaging/send-message#send_messages_to_topics_2

Answer 4

One way to do that is to make all your users' devices subscribe to a topic. That way when you target a message to a specific topic, all devices will get it. I think this how the Notifications section in the Firebase console does it.

Answer 5

I was looking solution for my Ionic Cordova app push notification.

Thanks to Syed Rafay's answer.

in app.component.ts

const options: PushOptions = {
  android: {
    topics: ['all']
  },

in Server file

"to" => "/topics/all",

Answer 6

Check your topic list on firebase console.

1. Go to firebase console

2. Click Grow from side menu

3. Click Cloud Messaging

4. Click Send your first message

5. In the notification section, type something for Notification title and Notification text

6. Click Next

7. In target section click Topic

8. Click on Message topic textbox, then you can see your topics (I didn't created topic called android or ios, but I can see those two topics.

9. When you send push notification add this as your condition.

   "condition"=> "'all' in topics || 'android' in topics || 'ios' in topics",

Full body

array(
    "notification"=>array(
        "title"=>"Test",
        "body"=>"Test Body",
    ),
    "condition"=> "'all' in topics || 'android' in topics || 'ios' in topics",
);

If you have more topics you can add those with || (or) condition, Then all users will get your notification. Tested and worked for me.

Answer 7

Just make all users who log in subscribe to a specific topic, and then send a notification to that topic.

Answer 8

For anyone wondering how to do it in cordova hybrid app:

• go to index.js -> inside the function onDeviceReady() write :

    subscribe();
  

(It's important to write it at the top of the function!)

• then, in the same file (index.js) find :

  function subscribe(){

   FirebasePlugin.subscribe("write_here_your_topic", function(){
  
   },function(error){
  
       logError("Failed to subscribe to topic", error);
   });
   }
  

and write your own topic here -> "write_here_your_topic"

Answer 9

It is a PHP Admin-SDK example to subscribe an user to a Topic and to send messages to a device by device token or to a Topic. Note that the Topic is created automatically when you subscribe an user.

$testTokens = ['device token 1', 'device token 2', ....]

// CREDENTIALS, YOU HAVE TO DOWNLOAD IT FROM FIREBASE CONSOLE.
$factory = (new Factory())->withServiceAccount('credentials.json');

$messaging = $factory->createMessaging();

// Subscribe a token or a group of tokens to a topic (this topic is created automatically if not exists)
// YOU CAN DO THIS IN THE MOBILE APP BUT IS BETTER DO IT IN THE API.
$result = $messaging->subscribeToTopic('all', $testTokens); // 'all' is the topic name

// Send a message to a specific Topic (Channel) 
$message = CloudMessage::withTarget('topic', 'all')
    ->withNotification(Notification::create('Global message Title', 'Global message Body'))
    ->withData(['key' => 'value']); // optional
$messaging->send($message);

// Send a message to a token or a grup of tokens (ONLY!!!)
 foreach($testTokens as $i=>$token){
     $message = CloudMessage::withTarget('token', $token)
         ->withNotification(Notification::create('This is the message Title', 'This is the message Body'))
         ->withData(['custom_index' => $i]); // optional
     $messaging->send($message);

You can check this repo for more details: firebase-php-admin-sdk

Answer 10

Your can send notification to all devices using "/topics/all"

https://fcm.googleapis.com/fcm/send
Content-Type:application/json
Authorization:key=AIzaSyZ-1u...0GBYzPu7Udno5aA

{
  "to": "/topics/all",
  "notification":{ "title":"Notification title", "body":"Notification body", "sound":"default", "click_action":"FCM_PLUGIN_ACTIVITY", "icon":"fcm_push_icon" },
  "data": {
    "message": "This is a Firebase Cloud Messaging Topic Message!",
   }
}