it is possible to do something so that an activity is in the background, and not killed by the system, or try to last as long as possible on background.
It is simple example with timer (do something in every 1 min).
Starter:
B4X:
Sub Process_Globals
Dim note As Notification
Dim ph As PhoneWakeState
Dim tmr As Timer
End Sub
Sub Service_Start (StartingIntent As Intent)
note.Initialize
note.Icon="icon"
note.SetInfo("title","body",Main)
note.Notify(1)
Service.StartForeground(1,note)
ph.PartialLock
' - Your code...
tmr.Initialize("tmr",60000)
tmr.Enabled=True
End Sub
Sub tmr_Tick
'do something
End Sub