FireBase how to send push from server to android?

Question

Android

I took an example here https://gist.github.com/prime31/5675017 but I have a problem. wrote a push handler, when the application is opened or minimized, a notification arrives. but when closed/killed the push doesn't come. I've already tried a lot of options.
All the same, I do not understand, should it come when the application is closed? either not, or via php does not come

Answer 1

android should receive a push if the application is minimized, since FireBase sends a notification to the background stream of the device, on IOS it stops moving after a while, after the application is minimized, because on IOS, the background stream of the application is cut down after a certain period of time (5-10 minutes, due to the limitation of the system itself). From the server side (PHP), establishes a connection, with FireBas, in the case of android and APN, in the case of IOS, passing connection parameters (application credentials) and recipient parameters, IOS / android of the device, after which The PHP connection is cut off and FireBase takes over the control of sending the push. That is, PHP establishes a connection with FireBase, passes parameters to it, cuts off the connection -> FireBase accepted the parameters, sent a push ->