Keep ionic app always running in the background

I’m developing ionic app for both android and ios. I have SignalR configured which is sending data to my app at run time.
Using this data, I am able to show notification when app is running or minimized.
But when I close my app I’m not able to display notifications (and also I’m not able to check if I’m receiving the data when app is closed, as I cannot debug the app ).

Any suggestions on this ?

PS: I dont want to use firebase or any other push notifications services.