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.
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()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 resultThe 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():