Building an android app to control devices


I’m new to exosite and is a bit lost at this point. I am basically looking how to load all the devices on the mobile app side. I didn’t quite understand how I could retrieve my device list. Also I am wondering what’s the best way to go about getting real time updates from devices, wether to use Californium and implement observed reads on the mobile app side or keep polling for real time device uptaes.