Add EDA data type and documentation on the process

carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/CarpDataTypes.kt

@@ -57,6 +57,12 @@ object CarpDataTypes : DataTypeMetaDataMap()
      */
     val NON_GRAVITATIONAL_ACCELERATION = add( NON_GRAVITATIONAL_ACCELERATION_TYPE_NAME, "Acceleration without gravity", DataTimeType.POINT )
 
+    internal const val EDA_TYPE_NAME = "$CARP_NAMESPACE.eda"
+    /**
+     * Single-channel electrodermal activity, represented as skin conductance.
+     */
+    val EDA = add( EDA_TYPE_NAME, "Electrodermal activity", DataTimeType.POINT )
+
     internal const val ACCELERATION_TYPE_NAME = "$CARP_NAMESPACE.acceleration"
     /**
      * Rate of change in velocity, including gravity, along perpendicular x, y, and z axes in the device's coordinate system.

carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/EDA.kt

@@ -0,0 +1,13 @@
+package dk.cachet.carp.common.application.data
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+
+/**
+ * Holds single-channel electrodermal activity (EDA) data, represented as skin conductance.
+ * Among others, also known as galvanic skin response (GSR) and skin conductance response/level.
+ */
+@Serializable
+@SerialName( CarpDataTypes.EDA_TYPE_NAME )
+data class EDA( val microSiemens: Double ) : Data

carp.common/src/commonMain/kotlin/dk/cachet/carp/common/infrastructure/serialization/Serialization.kt

@@ -28,6 +28,7 @@ val COMMON_SERIAL_MODULE = SerializersModule {
         subclass( AngularVelocity::class )
         subclass( CompletedTask::class )
         subclass( ECG::class )
+        subclass( EDA::class )
         subclass( Geolocation::class )
         subclass( HeartRate::class )
         subclass( NonGravitationalAcceleration::class )

carp.common/src/commonTest/kotlin/dk/cachet/carp/common/application/TestInstances.kt

@@ -23,6 +23,7 @@ val commonInstances = listOf(
     AngularVelocity( 42.0, 42.0, 42.0 ),
     CompletedTask( "Task", null ),
     ECG( 42.0 ),
+    EDA( 42.0 ),
     Geolocation( 42.0, 42.0 ),
     HeartRate( 60 ),
     NoData,

docs/carp-common.md

@@ -11,19 +11,20 @@ When a data type describes data over the course of a time interval, the time int
 
 All the built-in data types belong to the namespace: **dk.cachet.carp**.
 
-| Name | Description |
-| --- | --- |
-| [geolocation](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/Geolocation.kt) | Geographic location data, representing longitude and latitude. |
-| [stepcount](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/StepCount.kt) | The number of steps a participant has taken in a specified time interval. |
-| [ecg](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/ECG.kt) | Electrocardiogram data of a single lead. |
-| [heartrate](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/HeartRate.kt) | Number of heart contractions (beats) per minute. |
-| [interbeatinterval](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/InterbeatInterval.kt) | The time interval between two consecutive heartbeats. |
-| [sensorskincontact](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/SensorSkinContact.kt) | Whether a sensor requiring contact with skin is making proper contact at a specific point in time. |
-| [nongravitationalacceleration](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/NonGravitationalAcceleration.kt) | Acceleration excluding gravity along perpendicular x, y, and z axes. |
-| [angularvelocity](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/AngularVelocity.kt) | Rate of rotation around perpendicular x, y, and z axes. |
-| [signalstrength](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/SignalStrength.kt) | The received signal strength of a wireless device. |
-| [triggeredtask](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/TriggeredTask.kt) | A task which was started or stopped by a trigger, referring to identifiers in the study protocol. |
-| [completedtask](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/CompletedTask.kt) | An interactive task which was completed over the course of a specified time interval. |
+| Name                                                                                                                                        | Description                                                                                        |
+|---------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------|
+| [geolocation](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/Geolocation.kt)                                   | Geographic location data, representing longitude and latitude.                                     |
+| [stepcount](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/StepCount.kt)                                       | The number of steps a participant has taken in a specified time interval.                          |
+| [ecg](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/ECG.kt)                                                   | Electrocardiogram data of a single lead.                                                           |
+| [heartrate](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/HeartRate.kt)                                       | Number of heart contractions (beats) per minute.                                                   |
+| [interbeatinterval](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/InterbeatInterval.kt)                       | The time interval between two consecutive heartbeats.                                              |
+| [sensorskincontact](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/SensorSkinContact.kt)                       | Whether a sensor requiring contact with skin is making proper contact at a specific point in time. |
+| [nongravitationalacceleration](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/NonGravitationalAcceleration.kt) | Acceleration excluding gravity along perpendicular x, y, and z axes.                               |
+| [eda](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/EDA.kt)                                                   | Single-channel electrodermal activity, represented as skin conductance.                            | 
+| [angularvelocity](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/AngularVelocity.kt)                           | Rate of rotation around perpendicular x, y, and z axes.                                            |
+| [signalstrength](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/SignalStrength.kt)                             | The received signal strength of a wireless device.                                                 |
+| [triggeredtask](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/TriggeredTask.kt)                               | A task which was started or stopped by a trigger, referring to identifiers in the study protocol.  |
+| [completedtask](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/CompletedTask.kt)                               | An interactive task which was completed over the course of a specified time interval.              |
 
 ## Device configurations
 

docs/development-checklists.md

@@ -54,3 +54,33 @@ These generated test resources will be used to verify the migrations (step 3) of
 5. Update the affected JSON schemas. At a minimum you will need to change the request object's API version (e.g., `StudyServiceRequest.json`).
 These schemas are useful for non-Kotlin clients.
 If you forget to do this, `JsonSchemasTest` will fail; this test validates generated JSON output, known to be correct, using the schemas.
+
+## Add a new measure data type
+
+Keep in mind that CARP data types should be device-agnostic.
+The goal is that they can be reused for devices by different vendors.
+They act as a common data format.
+Therefore, don't include device-specific information in new [`Data`](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/application/data/Data.kt) types.
+
+If device-specific data is needed, infrastructures built using CARP Core can still specify these in their own codebase.
+Furthermore, all [extendable domain objects](../docs/carp-protocols.md#extending-domain-objects) can be uploaded to CARP backends that [use the recommended CARP serializers](../docs/serialization.md#unknownpolymorphicserializer-deserializing-unknown-types);
+they don't need the types at compile time or runtime, although then the data won't be validated on upload.
+
+Failing tests and static code analysis (`detektPasses`) will guide you to make sure newly introduced data types are immutable, serializable, registered, and tested.
+But, below are the necessary steps to follow:
+
+1. Add data type meta data to `CarpDataTypes`, following the template of existing data types.
+2. Add a new class extending from `Data` (or object in case the measure contains no data) to the `dk.cachet.carp.common.application.data` namespace in the `carp.common` subsystem (e.g., `AngularVelocity`). 
+   - Make sure to name the class after the collected _data_, and not the _sensor_ which collects the data (e.g., `AngularVelocity` vs `Gyro`).
+   - Add clear KDoc documentation on how the data should be interpreted.
+     For data fields, use/document SI units wherever appropriate, and choose sufficiently precise units so that no data is lost when unit conversions from raw data to the `Data` are done.
+   - Ensure that the class is immutable (contains no mutable fields) and is a `data class` or `object`.
+   - Make the class serializable using `kotlinx.serialization`.
+     For basic types, this should be as easy as marking it as `@Serializable`.
+   - Specify `@SerialName` using the data type specified in step 1.
+3. Register the new data type for polymorphic serialization in [`COMMON_SERIAL_MODULE`](../carp.common/src/commonMain/kotlin/dk/cachet/carp/common/infrastructure/serialization/Serialization.kt).
+4. Add a test instance of the new `Data` type to [`commonInstances`](../carp.common/src/commonTest/kotlin/dk/cachet/carp/common/application/TestInstances.kt).
+5. Include the data type [in the README](../docs/carp-common.md#data-types).
+6. Add a JSON schema in [`rpc/schemas/common/data`](../rpc/schemas/common/data) corresponding to the class name (e.g., `AngularVelocity.json`).
+   - _Warning_: the presence or validity of this schema [is not yet tested](https://github.com/imotions/carp.core-kotlin/issues/404).
+     It is recommended to serialize an instance of the new data type (e.g., by running a slightly modified polymorphic serialization test in `DataSerializationTest`) and [validate the output manually for now](https://www.jsonschemavalidator.net/).

rpc/schemas/common/data/EDA.json

@@ -0,0 +1,10 @@
+{
+  "$schema": "https://json-schema.org/draft/2019-09/schema",
+  "type": "object",
+  "properties": {
+    "__type": { "const": "dk.cachet.carp.eda" },
+    "microSiemens": { "type": "number" }
+  },
+  "required": [ "__type", "microSiemens" ],
+  "additionalProperties": false
+}