Push notifications operate through services like Apple's APNs, Google's FCM, and Windows Notification Service. The implementation involves three primary steps: adding client-side logic for user registration, sending a push message via an API call, and handling the push event on the device for notification display. The push service manages message validation and delivery, ensuring messages reach online devices or expire if undelivered.

1. How Push Notifications
Works?
By: - Pushmaze

2. The core of push notifications is run through services like Apple’s APNS,
Google’s Firebase Cloud Messaging (FCM) and Windows Notification
service.

3. Let us take the case of FCM which makes it possible for both web and
mobile applications to send notifications to subscribers. The three key
steps to implementing push messages are as follows:

4. 1. Adding the client-side logic with your app’s
JavaScript and UI that registers a user to
Popup messages.

5. First step involves two things; receiving permission from the user to
send push messages, and getting a “Push Subscription” from the
browser.

6. 2. Sending a push message to the user’s
device via an API call to your application’s
back-end.

7. An API call is to be made to the push service, which would include what
data to send, whom to send and how to send the message. Usually, the API
call is made from your server’s end.

8. What is push message service and
what does it do?
A push service validates the push message and sends it to the respective
browser. Each browser can use any push service they want, as every push
service expects the same API call.

9. 3. When push arrives on the device, an
event-driven JavaScript worker file will
receive a “push event”, enabling you to
show the notification.

10. Once you have sent a push message, the push service will keep your
message on its server until:
• -The device comes online and the message is delivered by the push
service.
• -If the message expires, the push service removes it from the queue
and will be no longer valid.

11. Once a push service delivers the message, the browser receives it,
decrypts and dispatches a push event in your service worker (a special
JavaScript file that helps to execute JavaScript even if the browser is
closed.

12. Thank You