Simple Node

This wrap uses the spin of an executor in a new thread. As a result, the calls of services and actions can be used synchronously. Besides, this node also includes predefined action servers and one client to make its use more user-friendly to developers.

Examples

Node

This example shows how to create a node. To block the node, join_spin is used, which blocks the main thread till the thread of the spin ends.

from simple_node import Node
import rclpy

class MyNode(Node):
    def __init__(self):
        super().__init__("my_node")

def main():
    rclpy.init()
    node = MyNode()
    node.join_spin()
    rclpy.shutdown()


if __name__ == "__main__":
    main()

Action Server

The following example shows how to create an action server that treats only one goal at the same time. If a new goal is received, the server aborts the current goal and starts treating the new one.

class MyNode(Node):
    def __init__(self):
        super().__init__("my_node")

        self.__action_server = self.create_action_server(ActionType,
                                                         "action_name",
                                                         self.__execute_cb)

    def __execute_server(self, goal_handle):
        result = ActionType.Result()

        succeed = self.do_something(goal_handle.request)

        if self.__action_server.is_canceled():
            self.__action_server.wait_for_canceling()
            goal_handle.canceled()

        else:
            if succeed:
                goal_handle.succeed()
            else:
                goal_handle.abort()

        return result

Action Client

The following example shows how to create an action client.

class MyNode(Node):
    def __init__(self):
        super().__init__("my_node")

        self.__action_client = self.create_action_client(
            ActionType, "action_name")

        goal = ActionType.Goal()

        self.__action_client.wait_for_server()
        self.__action_client.send_goal(goal)
        self.__action_client.wait_for_result()

        self.__action_client.is_succeeded():