Lecture6 - ROS 2 Service and Examples

$ ros2 interface show turtlesim/srv/Spawn
float32 x
float32 y
float32 theta
string name # Optional.  A unique name will be created and returned if this is empty
---
string name

# Terminal 1 - 여러분들만의 world를 사용하시면 더욱 좋습니다.
$ ros2 launch src_gazebo empty_world.launch.py

# Terminal 2
$ colcon build --packages-select py_service_tutorial
$ source install/local_setup.bash
$ ros2 run py_service_tutorial take_picture_server
[INFO] [turtle_circle_server]: Picture Taking Node Started
[INFO] [turtle_circle_server]: KimChi~
[INFO] [turtle_circle_server]: Image saved in 1672569224.png

# Terminal 3 - rqt 실행 후 service caller 실행 (plugins => services => service caller)
$ rqt

class PictureNode(Node):

    def __init__(self):
        super().__init__('turtle_circle_server')

        self.server = self.create_service(
            SetBool, 'take_picture', self.take_picture_callback
        )

        self.subscriber = self.create_subscription(
            Image, 'logi_camera_sensor/image_raw', self.sub_callback, 10
        )

        self.br = CvBridge()
        self.is_request = False

$ ros2 interface show example_interfaces/srv/SetBool
# This is an example of a service to set a boolean value.
# This can be used for testing but a semantically meaningful
# one should be created to be built upon.

bool data # e.g. for hardware enabling / disabling
---
bool success   # indicate successful run of triggered service
string message # informational, e.g. for error messages

    def take_picture_callback(self, request, response):

        if request.data is True:
            self.get_logger().info('KimChi~')
            self.is_request = True

        response.success = True
        response.message = "Successfully image written"

        return response

def sub_callback(self, data):

    if self.is_request:
        current_frame = self.br.imgmsg_to_cv2(data, "bgr8")

        file_name = str(self.get_clock().now().to_msg().sec) + '.png'
        cv2.imwrite(file_name, current_frame)
        self.get_logger().info(f'Image saved in {file_name}')

        self.is_request = False

ros2 launch src_gazebo wall_world.launch.py
ros2 run py_service_tutorial spawn_model

from gazebo_msgs.srv import SpawnEntity
import rclpy
from rclpy.node import Node

class SpawnRobot(Node):

    def __init__(self):
        super().__init__('gazebo_model_spawner')
        self.client = self.create_client(SpawnEntity, 'spawn_entity')

        while not self.client.wait_for_service(timeout_sec=1.0):
            self.get_logger().error('service not available, waiting again...')

future = robot_spawn_node.send_req()

rclpy.spin_until_future_complete(robot_spawn_node, future)

if future.done():
    try:
        response = future.result()
    except Exception:
        raise RuntimeError(
            'exception while calling service: %r' % future.exception()
        )
    else:
        robot_spawn_node.get_logger().info('==== Service Call Done ====')
        robot_spawn_node.get_logger().info(f'Status_message : {response.status_message}')
    finally:
        robot_spawn_node.get_logger().warn('==== Shutting down node. ====')

def send_req(self):
		...
		self.future = self.client.call_async(self.req)

		return self.future

spawn_parking_lot = Node(
    package='py_service_tutorial',
    executable='spawn_model',
    name='spawn_model',
    output='screen'
)

$ ros2 pkg create --build-type ament_cmake <package-name>
$ ros2 pkg create --build-type ament_cmake custom_interfaces

float32 width
float32 height
---
bool success

find_package(rosidl_default_generators REQUIRED)
rosidl_generate_interfaces(${PROJECT_NAME}
  "msg/Num.msg"
  "srv/AddThreeInts.srv"
  "srv/TurningControl.srv"
  "srv/TurtleJail.srv"
  "action/Fibonacci.action"
  "action/Maze.action"
)

<build_depend>rosidl_default_generators</build_depend>
<exec_depend>rosidl_default_runtime</exec_depend>
<member_of_group>rosidl_interface_packages</member_of_group>

$ colcon build --packages-select custom_interfaces && rosfoxy
Starting >>> custom_interfaces
Finished <<< custom_interfaces [0.62s]

Summary: 1 package finished [0.84s]

$ ros2 interface show custom_interfaces/srv/TurtleJail
float32 width
float32 height
---
bool success

# Terminal 1 – turtlesim실행
ros2 run turtlesim turtlesim_node

# Terminal 2 - turtle_teleop 실행
ros2 run turtlesim turtle_teleop_key

# Terminal 3 - 과제 프로그램 실행
ros2 run py_service_tutorial turtle_jail
[INFO] [turtle_jail_node]: === [Service Client : Ready to Call Service Request] ===
[INFO] [turtle_jail_node]: ==== [Service Server : Ready to receive Service Request] ====

# Terminal 4 - rqt의 service caller 실행 후 /turtle_jail_size에게 service call
cd ~/ros2_ws
source install/local_setup.bash
rqt