How to implement sending and receiving Push notifications from the server to the Android application?

Question

PHP

How to implement sending and receiving Push notifications from the server to the Android application? There is a site on which information changes periodically and there is an application that displays this information through api.
How to implement notification of changes to users through PUSH notifications? If the service works only on the phone and periodically polls the server, then this eats up both traffic and device resources. How to send notifications from the server regardless of whether the application is running or not.

Answer 1

fcm