About gRPC

protobuf
//ParametricRobotControlService provides an interface for simulating/controlling supported robots through GRPC.
service ParametricRobotControlService {
 //Step 1: Setup the simulation/control environment.
  rpc SetupRobot (SetupRobotRequest) returns (SetupRobotReply);
  //Step 2: Define a task to be processed or simulated.
  rpc AddRobotTask (AddRobotTaskRequest) returns (AddRobotTaskReply);
  //Step 3: Subscribe to the feedback coming from the simulation/control environment.
  rpc SubscribeRobotFeedback (SubscribeRobotFeedbackRequest) returns (stream RobotFeedback);
  //Step 4: Request a simulation update, to be either provided directly or written to the feedback stream.
  rpc GetSimulatedRobotState (GetSimulatedRobotStateRequest) returns (RobotState);
  //Optional: Set a variable.
  rpc SetVariable (SetVariableRequest) returns (google.protobuf.Empty);
  //Optional: Ping the controller.
  rpc SendPing (Ping) returns (Ping);  
}

protobuf
//JointTarget contains the target position of the robot in joint space, as well as the speed and acceleration of the robot.
message JointTarget{
    //The target position of the robot in joint space.
    repeated float axis_values = 1;
    //The speed of the robot, either one value per axis or a single value for all.
    repeated float speed = 2;
    //The acceleration of the robot, either one value per axis or a single value for all.
    repeated float acceleration = 3;
    //The position of any external axes of the robot.
    repeated float external_axis_values = 4;
}

protobuf
//CartesianTarget contains the position defined as a CartesianPosition and addds information relating to the posture, speed, acceleration of the robot, as well as of its external axes.
message CartesianTarget{
    //The CartesianPosition of the target.
    CartesianPosition position = 1;
    //The posture of the robot.
    string posture = 2;
    //The speed of the robot, either one value per axis or a single value for all.
    repeated float speed = 3;
    //The acceleration of the robot, either one value per axis or a single value for all.
    repeated float acceleration = 4;
    //The position of any external axes of the robot.
    repeated float external_axis_values = 5;
}

protobuf
//CartesianPosition uses one of three definitions to define a Cartesian position, either as a matrix, through Euler values, or a coordinate system.
message CartesianPosition{
    //The frame, defined either as matrix, Euler values, or coordinate system.
    oneof frame {
        Matrix4x4 matrix = 1;
        Euler euler = 2;
        CoordinateSystem cs = 3;
    }
    //The CartesianReference enum describes if the current frame is absolute, relative, or linked to a parent.
    CartesianReference reference = 4;
    //A parent matrix can be provided.
    Matrix4x4 parent = 5;
}