Каким образом происходит доставка push-уведомлений в Firebase?

Push notification delivery in Firebase occurs through Firebase Cloud Messaging (FCM). The process is as follows:

1. The client application (e.g., iOS) registers with FCM and receives a unique device token.
2. The server or cloud function sends a push notification to FCM, specifying the device token and message content.
3. FCM receives the request and delivers the notification to the device via APNs (Apple Push Notification service) for iOS or directly for Android.

Thus, Firebase acts as an intermediary, providing reliable and scalable delivery of notifications to user devices.

Example of sending a notification from a server in Python using Firebase Admin SDK:

from firebase_admin import messaging

message = messaging.Message(
    notification=messaging.Notification(
        title='Hello!',
        body='This is a test notification.'
    ),
    token='device_registration_token',
)
response = messaging.send(message)
print('Successfully sent message:', response)