How does firebase receive push notifications?

Question

Push technologies

I'm trying to set up push notifications through firebase but it doesn't work.

At the front:

import { initializeApp } from "firebase/app";
import { getMessaging, getToken, onMessage  } from "firebase/messaging";

const firebaseConfig = {
    apiKey: "xxxxxx,
    authDomain: "xxxxx",
    databaseURL: 'xxxxx',
    projectId: "xxxx",
    storageBucket: "xxxxxx",
    messagingSenderId: "xxxxx",
    appId: "xxxx",
    measurementId: "xxxxx"
};

const app = initializeApp(firebaseConfig);
const messaging = getMessaging();

getToken(messaging).then((currentToken) => {
    if (currentToken) {
        console.log(currentToken)
    } else {
        console.log('No registration token available. Request permission to generate one.');
    }
}).catch((err) => {
    console.log('An error occurred while retrieving token. ', err);
});

onMessage(messaging, (payload) => {
    console.log('Message received. ', payload);
});

I go to the page, take the client's token - and send him a push from the back, in the firebase admin panel you can see that the message counter is increasing, but they are not in the received status. onMessage is also silent.

And here I don’t quite understand through what channel he should have received them at all?

firebase does not poll any api, does not connect to the socket - where do they come from?

To send, I use the https://github.com/laravel-notification-channels/fcm package - everything seems to be fine here - the request goes away, the response is null As a token, I hardcoded the key for tests:
User::first()->notify(new PushNotification)

public function routeNotificationForFcm() {
        return 'xxxxxx'; // Ключ взял из выхлопа console.log на фронте
}

It's about the browser on the desktop. On android / ios, this apparently works differently by internal means of ios - I haven’t gotten there yet - just to get a web push for the test.

Answer 1

the problem was that I didn't pass vapidKey to getToken() which can be obtained in cloud messagind certificates - they just weren't generated.
But the question through which channel the data comes is still relevant. I don't see any xhr or ws messages when push comes in

Answer 2

And here I don’t quite understand through what channel he should have received them at all?

Are you sure you did everything according to the instructions? https://firebase.google.com/docs/cloud-messaging/j...
For at the very beginning it says

Add and initialize the FCM SDK
1. If you haven't already, install the Firebase JS SDK and initialize Firebase.

And the link is given: https://firebase.google.com/docs/web/setup#add-sdk...