iPhone presence detection

[DGrandes]

Here is Bluetooth device presence script which changes value of respective grp addresses based on Bluetooth device appearance.

Code:

require('ble')

-- enable ble
ble.up()

list = {}

-- mac -> group address mapping
known = {
 ['88:0F:10:10:F2:8A'] = '1/1/1',
 ['88:0F:10:4A:2C:36'] = '1/1/2',
}

ctime = os.time()

function callback(addr)
 local now, delta

 now = os.time()
 delta = now - ctime

 if addr then
   if not list[ addr ] then
     log('BLE found ' .. addr)

     if known[ addr ] then
       grp.write(known[ addr ], true, dt.bool)
     end
   end

   list[ addr ] = now
 end

 -- check for missing devices each 5 seconds
 if delta < 0 or delta > 5 then
   for addr, time in pairs(list) do
     delta = now - time

     if delta < 0 or delta > 60 then
       log('BLE missing ' .. addr)
       list[ addr ] = nil

       if known[ addr ] then
         grp.write(known[ addr ], false, dt.bool)
       end
     end
   end

   ctime = now
 end
end

ble.scan(callback)

Where should i put that code? In Common Functions or in Resident script?
This code is executed once or like resident script?