How sampling packages work

A package has four parts:

Part	Class	Job
Package	SamplingPackage	Lists the measure types, their default sampling configuration, and creates probes
Data	Data subclass	The measurement payload
Probe	Probe	Reads the sensor
Device manager	DeviceManager	Connects to the device. The default is the phone itself

From measure to probe

1. You write Measure(type: SensorSamplingPackage.STEP_EVENT) in a BackgroundTask.
2. At runtime the BackgroundTaskExecutor calls SamplingPackageRegistry().create('dk.cachet.carp.stepevent').
3. The registry asks each registered package; the one that supports the type returns a probe.
4. The probe emits measurements, which go to the study’s data manager.

SamplingPackageRegistry registers DeviceSamplingPackage, SensorSamplingPackage and MonitoringSamplingPackage itself. Register every other package in your app before adding a study:

SamplingPackageRegistry().register(SurveySamplingPackage());

Registering also adds the package’s data types, and its device manager to the DeviceController, and calls the package’s onRegister().

Where in the repo

File	What is in it
domain/services/sampling_package.dart	SamplingPackage, SmartphoneSamplingPackage, MonitoringSamplingPackage
runtime/sampling_package_registry.dart	SamplingPackageRegistry