Handle the data payload without user tapping on the notification?

Question

When in the background, apps receive the notification payload in the notification tray, and only handle the data payload when the user taps on the notificatio

Answer 1

If you want to receive data payload when app is not running then you need to use a custom app-server with http protocol(in your case) which will send only data payload no notification and will send data to fcm endpoint like this

    { "data": { "some_key" : "some_value",
 "some_more_key" : "some_more_value" }, 
"registration_ids": ["device-token","device-token2"] } 

or just to send data from server to one client

{
   "to" : "bk3RNwTe3H0:CI2k_HHwgIpoDKCIZvvDMExUdFQ3P1...",
   "data" : {
     "Nick" : "Test",
     "body" : "Your message here",
     "Room" : "Some Test Room"
   },
 }

Then using POST you can send downstream message to your device and it will work the way you want. If you want to have a basic idea of such app server please consider this : How to push notification to client when Firebase has a new entry?

I have posted basic Java Servlet code here and also a node.js code by firebase official blog.

Hope it helps.