ROS 2 Python 서비스/클라이언트 실습 요약 (py_srvcli)

📁 1. 프로젝트 구조

ros2_ws/
├── src/
│   └── py_srvcli/
│       ├── package.xml
│       ├── setup.py
│       ├── resource/py_srvcli
│       └── py_srvcli/
│           ├── __init__.py
│           ├── service_member_function.py
│           └── client_member_function.py

---

🔧 2. package.xml

• ROS 2 패키지 정보를 정의
• 서비스 인터페이스와 Python API를 사용하므로 다음 의존성 포함:

<depend>rclpy</depend>
<depend>example_interfaces</depend>

---

🛠️ 3. setup.py

• ament_python 방식으로 Python 패키지 설치
• 실행 엔트리포인트 등록:

entry_points={
    'console_scripts': [
        'service = py_srvcli.service_member_function:main',
        'client = py_srvcli.client_member_function:main',
    ],
}

 

🧠 4. 서비스 노드 (service_member_function.py)

import rclpy
from rclpy.node import Node
from example_interfaces.srv import AddTwoInts

class AddTwoIntsService(Node):
    def __init__(self):
        super().__init__('add_two_ints_service')
        self.srv = self.create_service(AddTwoInts, 'add_two_ints', self.add_callback)

    def add_callback(self, request, response):
        response.sum = request.a + request.b
        self.get_logger().info(f'Received request: a={request.a}, b={request.b}')
        return response

def main(args=None):
    rclpy.init(args=args)
    node = AddTwoIntsService()
    rclpy.spin(node)
    node.destroy_node()
    rclpy.shutdown()

---

🤖 5. 클라이언트 노드 (client_member_function.py)

import rclpy
from rclpy.node import Node
from example_interfaces.srv import AddTwoInts
import sys

class AddTwoIntsClient(Node):
    def __init__(self):
        super().__init__('add_two_ints_client')
        self.cli = self.create_client(AddTwoInts, 'add_two_ints')
        while not self.cli.wait_for_service(timeout_sec=1.0):
            self.get_logger().info('service not available...')
        self.req = AddTwoInts.Request()

    def send_request(self, a, b):
        self.req.a = a
        self.req.b = b
        future = self.cli.call_async(self.req)
        rclpy.spin_until_future_complete(self, future)
        return future.result()

def main(args=None):
    rclpy.init(args=args)
    minimal_client = AddTwoIntsClient()
    a = int(sys.argv[1]) if len(sys.argv) > 1 else 2
    b = int(sys.argv[2]) if len(sys.argv) > 2 else 3
    response = minimal_client.send_request(a, b)
    minimal_client.get_logger().info(f'Result: {response.sum}')
    minimal_client.destroy_node()
    rclpy.shutdown()

---

⚙️ 6. 빌드 및 실행 흐름

# 1. 빌드
cd ~/ros2_ws
colcon build --packages-select py_srvcli --symlink-install

# 2. 환경 설정
source install/setup.bash

# 3. 서비스 실행
ros2 run py_srvcli service

# 4. 클라이언트 실행
ros2 run py_srvcli client 3 7