First of all I would like to mention that this would be done with the consent of all users!
That being said, what I am trying to create is an application where the users would see their location and the location of all the other connected users (latitude and longitude).
I am pretty sure the best way to do that would be to send data to a server and then have each device retrieve that data but I would like to know if there exist other ways of doing this. Or perhaps someone could point me in the right direction on how to create such a system with a server retrieving and sending data to android devices ?