How to conncet few android devices?
<p>There is restaurant, and I have wrote app for them. Now my task is to create device communication: only single app (on a single device) should work at one time. I.e. when user starts to use application on one device, apps on other devices should show warning "Please, wait...". How I can do this? Any ideas? 
I am thinking about creating lock-file on some server (maybe on dropbox open folder???). At start app should look to this folder and if the lock file is exists - wait. If there isn't lock file - app will create it, performs all users tasks, delete lock file, and closes. 
Another idea - is to use bluetooth connection... Maybe at starting app should seek for bluetooth device with special name... if it isn't - open bluetooth communication with that lock-name and begin to work... But the problem is the device os 1.6.</p>
