To learn Google AppEngine I decided to build a finite state machine. When the state changes it calls a webhook. Transitions are triggered by webhook too.
However it needed a practical application. So I built a way of tracking when I enter and leave my home, updated by tapping a card against an RFID reader, using the same gesture used for tapping in and out of the underground on an Oyster card.
There is a demo version available that tracks if I am asleep or awake. I figure this data has less safety implications than showing if my home is free to be robbed.
