2.1.2. Activity Tracker

The commercial Fitbit One is used as activity tracker that registers the daily number of steps and the number of stairs climbed [10]. Users receive an account on the Fitbit website. The Fitbit device uses Bluetooth LE to automatically synchronize activity data with the Fitbit servers, either via the Fitbit mobile phone app, or via a Bluetooth LE dongle and a pc. After the first login to the Active2Gether system, the user is asked to connect to his/her Fitbit account with the Active2Gether system. A connection is established through an open authentication mechanism. Once the connection is made, Fitbit provides an authentication key for the user. This key is stored in the database, so the Active2Gether system can directly access the Fitbit web service to receive activity data for a user and store it into the Active2Gether database. A script runs every hour to update the database with the most recent activity data. Another script periodically checks whether the battery level is low or whether the last synchronization is more than three days ago, and, in that case, a reminder is sent.
