Revision history [back]

Based on the ROS2 service/client tutorial and the work of clyde, I've created a complete ROS2 python client to spawn an entity:

import sys
import rclpy
from gazebo_msgs.srv import SpawnEntity

from rclpy.node import Node


class MinimalClientAsync(Node):

    def __init__(self):
        super().__init__('spawn_entity')
        self.client = self.create_client(SpawnEntity, 'spawn_entity')
        while not self.client.wait_for_service(timeout_sec=1.0):
            self.get_logger().info('service not available, waiting again...')
        self.req = SpawnEntity.Request()

    def send_request(self):
        self.req.name = str(sys.argv[1])
        self.req.xml = str(sys.argv[2])
        self.future = self.client.call_async(self.req)


def main(args=None):
    rclpy.init(args=args)

    minimal_client = MinimalClientAsync()
    minimal_client.send_request()

    while rclpy.ok():
        rclpy.spin_once(minimal_client)
        if minimal_client.future.done():
            try:
                response = minimal_client.future.result()
            except Exception as e:
                minimal_client.get_logger().info(
                    'Service call failed %r' % (e,))
            else:
                minimal_client.get_logger().info(
                    'Test {}'.format(minimal_client.req.xml))
            break

    minimal_client.destroy_node()
    rclpy.shutdown()


if __name__ == '__main__':
    main()

To spawn a sphere in Gazebo:

1. Start gazebo:

     gazebo --verbose -s libgazebo_ros_factory.so
   

2. Run the client node:

     ros2 run my_package my_client_name entity_name xml_description
   

   Example usage :

     ros2 run my_package my_client my_model "<?xml version=\"1.0\" ?><sdf version=\"1.5\"><model name=\"will_be_ignored\"><static>true</static><link name=\"link\"><visual name=\"visual\"><geometry><sphere><radius>1.0</radius></sphere></geometry></visual></link></model></sdf>"
   

Based on the ROS2 service/client tutorial tutorial: 'Writing a simple service and client (python)' and the work of clyde, I've created a complete ROS2 python client to spawn an entity:

import sys
import rclpy
from gazebo_msgs.srv import SpawnEntity

from rclpy.node import Node


class MinimalClientAsync(Node):

    def __init__(self):
        super().__init__('spawn_entity')
        self.client = self.create_client(SpawnEntity, 'spawn_entity')
        while not self.client.wait_for_service(timeout_sec=1.0):
            self.get_logger().info('service not available, waiting again...')
        self.req = SpawnEntity.Request()

    def send_request(self):
        self.req.name = str(sys.argv[1])
        self.req.xml = str(sys.argv[2])
        self.future = self.client.call_async(self.req)


def main(args=None):
    rclpy.init(args=args)

    minimal_client = MinimalClientAsync()
    minimal_client.send_request()

    while rclpy.ok():
        rclpy.spin_once(minimal_client)
        if minimal_client.future.done():
            try:
                response = minimal_client.future.result()
            except Exception as e:
                minimal_client.get_logger().info(
                    'Service call failed %r' % (e,))
            else:
                minimal_client.get_logger().info(
                    'Test {}'.format(minimal_client.req.xml))
            break

    minimal_client.destroy_node()
    rclpy.shutdown()


if __name__ == '__main__':
    main()

To spawn a sphere in Gazebo:

1. Start gazebo:

     gazebo --verbose -s libgazebo_ros_factory.so
   

2. Run the client node:

     ros2 run my_package my_client_name entity_name xml_description
   

   Example usage :

     ros2 run my_package my_client my_model "<?xml version=\"1.0\" ?><sdf version=\"1.5\"><model name=\"will_be_ignored\"><static>true</static><link name=\"link\"><visual name=\"visual\"><geometry><sphere><radius>1.0</radius></sphere></geometry></visual></link></model></sdf>"