#. GoalDSL is an external Domain-Specific Language (DSL) for the behaviour verification of IoT-enabled CPS applications and systems, based on a goal-driven approach. The general idea is that goal-driven rules can be defined for entities (smart objects, virtual artefacts, etc.) in a CPS, a smart environment or a digital twin.

Goal-driven verification scenarios can be defined based on messages arriving at specific topics of a message broker. For example, a goal may define a rule to wait until receiving a message from the in-house robot or until the temperature in the bedroom reaches a specific value. To expand this idea to the context of Cyber-Physical Systems and Smart Home Automation, beyond topic-related goals, it is useful to be able to define goals for mobile smart objects (e.g. robots) and for monitoring the state of smart objects and act on them. For example, in robotics it is common to require definition of goals related to the pose of the robot, or to follow a trajectory, to pass from a specific point or reach a destination target. Concerning smart home specific goals, the language supports goals which monitor the attribute values of entities. In a nutshell, our approach can be used to verify that the implementation meets expected functional standards, regarding application development for smart environments.

Entity definitions follow the syntax of the below examples, for both sensor and actuator types. The difference between the two is that sensors are considered "Producers" while actuators are "Consumers" in the environment. Sensor Entities have an extra property, that is the freq to set the publishing frequency of either physical or virtual.

Entity weather_station
    type: sensor
    freq: 5
    topic: "bedroom.weather_station"
    broker: cloud_broker
    attributes:
        - temperature: float
        - humidity: float
        - pressure: float
end

Entity bedroom_lamp
    type: actuator
    topic: "bedroom.lamp"
    broker: cloud_platform_issel
    attributes:
        - power: bool
end

type: The Entity type. Currently supports sensor, actuator or hybrid
topic: The Topic in the Broker used by the Entity to send and receive messages. Note that / should be substituted with . (e.g: bedroom/aircondition -> bedroom.aircondition).
broker: The name property of a previously defined Broker which the Entity uses to communicate.
attributes: Attributes have a name and a type. As can be seen in the above example, HA-Auto supports int, float, string, bool, list and dictionary types. Note that nested dictionaries are also supported.
description (Optional): A description of the Entity
freq (Optional): Used for Entities of type "sensor" to set the msg publishing rate

Notice that each Entity has it's own reference to a Broker, thus the metamodel allows for communicating with Entities which are connected to different message brokers. This allows for definining automation for multi-broker architectures.

Supported data types for Attributes:

int: Integer numerical values
float: Floating point numerical values
bool: Boolean (true/false) values
str: String values
time: Time values (e.g. 01:25)
list: List / Array
dict: Dictionary

Attribute value generation for virtual Entities

SmAuto provides a code generator which can be utilized to transform Entities models into executable source code in Python. This feature of the language enables end-to-end generation of the objects (sensors, actuators, robots) which send and receive data based on their models. Thus it can be used to generate while virtual smart environments and directly dig into defining and testing automations.

For this purpose, the language supports (Optional) definition of a Value Generator and a Noise to be applied on each attribute of an Entity of type sensor separately.

Entity weather_station
    type: sensor
    freq: 5
    topic: "smauto.bme"
    broker: home_mqtt_broker
    attributes:
        - temperature: float -> gaussian(10, 20, 5) with noise gaussian(1,1)
        - humidity: float -> linear(1, 0.2) with noise uniform (0, 1)
        - pressure: float -> constant(0.5)
end

The above example utilizes this feature of the language. Each attribute can define it's own value and noise generators, using a simple grammar as evident below:

-> <ValueGenerator> with noise <NoiseGenerator>

Supported Value Generators:

Constant: constant(value). Constant value
Linear: linear(min, step). Linear function
Saw: saw(min, max, step). Saw function.
Gaussian: gaussian(value, maxValue, sigma). Gaussian function
Replay: replay([values], times). Replay from a list of values. The times parameter can be used to force replay iterations to a specific value. If times=-1 then values will be replayed infinitely.
ReplayFile: replayFile("FILE_PATH"). Replay data from a file.

Supported Noise Generators:

Uniform: uniform(min, max).
Gaussian: gaussian(mean, sigma).

Value generation and Noise are optional in the language and are features used by the Virtual Entity generator to transform Entity models into executable code.

Conditions

Conditions are very similar to conditions in imperative programming languages such as Python, Java, C++ or JavaScript. You can use Entity Attributes in a condition just like a variable by referencing it in the Condition using it's Fully-Qualified Name (FQN) in dot (.) notation.

entity_name.attribute_name

Condition Formatting:

You can combine two conditions into a more complex one using logical operators. The general format of the Condition is:

(condition_1) LOGICAL_OP (condition_2)

Make sure to not forget the parenthesis.

condition_1 AND condition_2 AND condition_3

will have to be rephrased to an equivalent like:

((condition_1) AND (condition_2)) AND (condition_3)

Lists and Dictionaries:

The language has support for Lists and Dictionaries and even nesting them. However, for now the use of lists and dictionaries in conditions are treated as full objects and their individual elements cannot be accessed and used in conditions. This means that you can compare a List to a full other List, but cannot compare individual list items. Similarly, you can compare a full dictionary to another but cannot use individual dictionary items in conditions.

Nested in-language reference to Dict and List items will be supported in a future release of the language.

Operators

String Operators: ~, !~, ==, !=, has
Numeric Operators: >, >=, <, <=, ==, !=
Logical Operators: AND, OR, NOT, XOR, NOR, XNOR, NAND
BooleanValueOperator: is , is not;
List and Dictionary Operators: ==, !=

Build-in attribute processing functions

The language provides buildi-in functions which can be applied to attribute references when defining a Condition.

condition:
    (mean(bedroom_temp_sensor.temperature, 10) > 28) AND
    (std(bedroom_temp_sensor.temperature, 10) > 1)

condition:
    bedroom_humidity_sensor.humidity in range(30, 60)

condition:
    bedroom_temp_sensor.temperature in range(24, 26) AND
    bedroom_humidity_sensor.humidity in range(30, 60)

condition:
    var(mean(bedroom_temp_sensor.temperature, 10), 10) >= 0.1

Supported Functions:

mean: The mean of the attribute buffer
std: The standard deviation of the attribute buffer
var: The variance of the attribute buffer
min: The minimum value in the attribute buffer
max: The maximum value in the attribute buffer

Writing Conditions

Bellow you will find some example conditions.

(bedroom_humidity.humidity < 0.3) AND (bedroom_humidifier.state == 0)

((bedroom_human_detector.position != []) AND
    (bedroom_thermometer.temperature < 27.5)
) AND (bedroom_thermostat.state == 0)

Goal Types

Entity Goals
- EntityStateChange
- EntityStateCondition
Area Goals
- RectangleArea
- CircularArea
- PolylineArea
- StraightLineArea
- MovingArea
Pose Goals
- PositionGoal
- OrientationGoal
- PoseGoal
Trajectory Goals
- StraightLineTrajectoryGoal
- StraightLineTrajectoryGoal
Complex Goal

Entity Goals

EntityStateChange

This Goal is considered REACHED when a message arrives at a specific topic, without any considerations of the payload of the message.

Goal<EntityStateChange> Goal_1
    entity: TempSensor1
end

EntityStateCondition

Set this Goal for cases where you want to filter messages arrived at a topic based on an exppression.

Goal<EntityStateCondition> Goal_2
    condition:
        (AirQualitySensor1.gas < 10) AND (AirQualitySensor1.humidity < 30)
end

Goal<EntityStateCondition> Goal_3
    condition: ((TempSensor1.temp > 10) AND (TempSensor2.temp > 10))
        AND (TempSensor3.temp > 10)
end

Goal<EntityStateCondition> Goal_4
    condition:
        (mean(TempSensor1.temp, 10) > 0.5 ) AND
            (mean(TempSensor2.temp, 10) > 30)
end

Area Goals

An AreaGoal is related areas in the environment which have a meaning for an application. An example would be the avoidance of specific areas. All Area Goals have a tag that gives a meaning to the goal

Tag:

AVOID
ENTER
EXIT
STEP

The first defines area goals which have to be avoided by mobile things, while the latter an area that has to be "entered". All Area Goals have a tag property.

Rectangle Area

A rectangle area defined by (centerPoint, radius) that has to either be reached or avoided.

Goal<RectangleArea> GoalA
    entity: my_robot
    bottomLeftEdge: Point2D(2.0, 6.0)
    lengthX: 3.0
    lengthY: 4.0
    tag: ENTER
end

Circular Area

A circular area defined by (centerPoint, radius).

Goal<CircularArea> GoalB
    entity: my_robot
    center: Point2D(2.0, 6.0)
    radius: 3.0
    tag: AVOID
end

Polyline Area

A polyline area defined by a list of Points.

Goal<PolylineArea> GoalC
    entity: my_robot
    points: [Point2D(0.0, 0.0), Point2D(2.0, 4.0), Point2D(4.0,  0.0)]
    tag: AVOID
end

Straight Line

A straight line in the environment, defined by (startPoint, finishPoint) that has to be either reached or avoided.

Goal<StraightLine> GoalD
    entity: my_robot
    startPoint: Point2D(2.0, 7.6);
    endPoint: Point2D(2.0, 7.6);
    tag: AVOID;
end

Mobile Area

This type of Goal can be used for mobile objects, such as robots.

Goal<MobileArea> GoalD
    radius: 46;  // 46cm
    tag: AVOID;
}

Pose Goals

Pose goals are those related to the pose of a specific thing. Mostly used in mobile robot applications.

PositionGoal

Reach a specific position in space.

Goal<Position> Goal_5
    entity: RobotArmPose
    position: Point3D(0, 0, 0)
    maxDeviation: 0.1
    timeConstraints:
        - FROM_GOAL_START(<60)
end

OrientationGoal

Reach a specific orientation in space.

Goal<Orientation> Goal_5
    orientation: Orientation2D(1.0);  // rad
    maxDeviation: 0.2; // rad
end

PoseGoal

Reach a specific pose (orientation, position) in space.

PoseGoal ExamplePoseGoal -> {
    position: Point2D(0.0, 0.0);
    orientation: Orientation2D(1.0);  // rad?
    maxDeviationPos: 0.2;
    maxDeviationOri: 0.2;
}

Trajectory Goals

Use this type to define goals for a thing to follow/track a trajectory. Mostly used in mobile robot applications.

StraightLineTrajectoryGoal

A straight line trajectory goal, defined by (startPoint, finishPoint, maxDeviation).

WaypointTrajectoryGoal

A custom trajectory goal, defined by (list of points, maxDeviation).

Complex Goals

The ComplexGoal is used to defined goals which are a collection of goals. For example, using complex goals, we can define a collection of Goals, from which at least one has to be accomplished.

Below are the possible types of algorithms to apply for a ComplexGoal definition.

ALL_ACCOMPLISHED
ALL_ACCOMPLISHED_ORDERED
NONE_ACCOMPLISHED
AT_LEAST_ONE
EXACTLY_X_ACCOMPLISHED
EXACTLY_X_ACCOMPLISHED_ORDERED

Goal<EntityStateChange> Goal_1
    entity: TempSensor1
end

Goal<EntityStateCondition> Goal_2
    condition:
        (AirQualitySensor1.gas < 10) AND
        (AirQualitySensor1.humidity < 30)
end

Goal<EntityStateCondition> Goal_3
    condition: ((TempSensor1.temp > 10) AND (TempSensor2.temp > 10))
        AND (TempSensor3.temp > 10)
end

Goal<Complex> CG1
    goals:
        - Goal_1
        - Goal_2
        - Goal_3
    strategy: ALL_ACCOMPLISHED_ORDERED
end

In case of Ordered algorithms, which is the cases of ALL_ACCOMPLISHED_ORDERED, EXACTLY_X_ACCOMPLISHED_ORDERED, the execution of inner Goals is sequential.

Time Constraints

Goals can have time constraints, like maximum duration from previous goal. For this reason we introduce the TimeConstraint concept, which allows the definition of time constraints.

Goal<EntityStateCondition> Goal_3
    condition:
        (TemperatureSensorList.regionA < 20) AND
        (HumiditySensorList.regionA < 0.8)
    timeConstraints:
        - FROM_GOAL_START(<1800)
end

In the above example the constraint indicates that The duration of the Goal must not exceed 10 seconds.

Each TimeConstraint can measure time relative to either the start of the application or the start of the current goal. This can be defined using the type property of TimeConstraint classes and can have one of the following values.

FROM_APP_START
FROM_GOAL_START

The expression can use one of the values >, <, >=, <= and ==.

Communication Middleware / Message Broker

The Broker acts as the communication layer for messages where each device has its own Topic which is basically a mailbox for sending and receiving messages. SmartAutomation DSL supports Brokers which support the MQTT, AMQP and Redis protocols. You can define a Broker using the syntax in the following example:

Broker<MQTT> hassio_mqtt
    host: "localhost"
    port: 1883
    auth:
        username: "my_username"
        password: "my_password"
end

type: The first line can be MQTT, AMQP or Redis according to the broker type
host: Host IP address or hostname for the Broker
port: Broker Port number
auth: Authentication credentials. Unified for all communication brokers
- username: Username used for authentication
- password: Password used for authentication
vhost (Optional): Vhost parameter. Only for AMQP brokers
ssl (Optional): Enable/Disable ssl channel encryption
topicExchange (Optional): (Optional) Exchange parameter. Only for AMQP brokers
rpcExchange (FUTURE SUPPORT): Exchange parameter. Only for AMQP brokers
db (Optional): Database number parameter. Only for Redis brokers

Scenario

Scenario defines a set of goals which are assigned to be executed for a specific target/application. A scenario needs to be linked to a specific middleware (message broker),

A Scenario is defined by a list of Goals and a communication middleware.

Scenario ScenarioB
    goals:
        - Goal_1 -> 0.2
        - Goal_2 -> 0.2
        - Goal_3 -> 0.2
        - Goal_4 -> 0.2
        - Goal_5 -> 0.2
    broker: MyMQTTBroker
    concurrent: false
end

A scenario can have multiple Goals, which are executed concurrently or in a sequential order. This is defined for each scenario via the concurrent property.

Other Concepts of the Language

Point

In order to be able to define points in 2D and 3D space, the Point2D and Point3D classes are introduced.

The syntax for defining a Point.

Point2D(x, y)

Point3D(x, y, z)

Orientation

In order to be able to define the orientation of things in 2D and 3D space, the Orientation2D and Orientation3D classes are introduced.

The syntax for defining a Point.

Orientation2D(z)  // In 2D space only zAxes rotation is allowed.

Orientation3D(x, y, z)

Multiple model files - Import models

The language supports multi-file models via model imports. A nested model import layer is implemented, enabling pythonic imports of models defined in other files.

// File area_goals.goal

RectangleAreaGoal GoalA -> {
    centerPoint: Point2D(2.0, 6.0);
    sideLength: 3.0;
    type: ENTER;
}

CircularAreaGoal GoalB -> {
    centerPoint: Point2D(2.0, 6.0);
    radius: 3.0;
    type: AVOID;
}

// File complex_goals.goal

// area_goals.goal file exists in current directory.
// Includes GoalA and GoalB goals
import area_goals.goal as area_goals;

ComplexGoal GoalC -> {
    algorithm: ALL_ACCOMPLISHED;
    addGoal(area_goals.GoalA);
    addGoal(area_goals.GoalB);
}

Validation

To validate a model description file, simply execute:

textx check target.goal --language goal_dsl

If the model passes the validation rules (grammar) you should see something like:

[I] ➜ textx check target.goal --language goal_dsl
target.goal: OK.

Code Generation

The code-generator is shipped as a separate package which you will have to manually install. Once installed, it will be listed in textx generators and can be used via the textx cli.

Install Goal-DSL python source generator from: https://github.com/robotics-4-all/goal-gen

Then execute the following command:

textx generate target.goal --target goalee

Metamodel

The abstract metamodel of the DSL, that defines the concepts, their relations and top-level constraints, is shown below.

Examples

Several examples can be found here.

Extra

goal-dsl.vim Vim syntax support for goal-dsl

Name		Name	Last commit message	Last commit date
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docs/images		docs/images
examples		examples
goal_dsl		goal_dsl
.gitignore		.gitignore
CHANGELOG.md		CHANGELOG.md
Dockerfile		Dockerfile
LICENSE		LICENSE
README.md		README.md
build.sh		build.sh
docker-compose.yml		docker-compose.yml
requirements.txt		requirements.txt
setup.cfg		setup.cfg
setup.py		setup.py
start.sh		start.sh

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robotics-4-all/goal-dsl

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