Abstract base class for asynchronous working sample observer components,
which do depend on the service life cycle.
Main features:
can be attached as observer for samples,
does maintain an event collector to store
observed samples in a thread safe queue for further
processing,
does run asynchronously as daemon worker thread,
does implement the life cycle object behavior.
Can be extended to implement a specific kind of sample data processing in the
AbstractWorkerThread.doWork() method of the thread.
The device specific sample data of an accelerometer sensor are the
accelerations in x, y and z ( in m/s^2 ) axis direction as provided by the
Android API.