custom_as.py

#! /usr/bin/env python
import rospy
import time
import actionlib

from my_custom_action_msg_pkg.msg import CustomActionMsgFeedback, CustomActionMsgResult, CustomActionMsgAction
from std_msgs.msg import Empty

class MoveUpDownClass(object):

    def __init__(self):
        rospy.loginfo("Start Class")
        # creates the action server
        self._feedback = CustomActionMsgFeedback()
        self._result = CustomActionMsgResult()
        self._as = actionlib.SimpleActionServer("/action_custom_msg_as", CustomActionMsgAction, self.goal_callback, False)
        self._as.start()
        self.ctrl_c = False
        self.rate = rospy.Rate(10)
        rospy.loginfo("Start Class---END")

    def publish_once_in_cmd_vel(self, cmd):
        """
        This is because publishing in topics sometimes fails teh first time you publish.
        In continuos publishing systems there is no big deal but in systems that publish only
        once it IS very important.
        """
        while not self.ctrl_c:
            connections = self._pub_cmd_vel.get_num_connections()
            if connections > 0:
                self._pub_cmd_vel.publish(cmd)
                rospy.loginfo("Publish in cmd_vel")
                break
            else:
                self.rate.sleep()

    def up_drone(self):
        i = 0
        while not i == 3:
            self._pub_takeoff.publish(self._takeoff_msg)
            rospy.loginfo("Taking off")
            time.sleep(1)
            i += 1

    def down_drone(self):
        i = 0
        while not i == 3:
            self._pub_land.publish(self._land_msg)
            rospy.loginfo("Landing")
            time.sleep(1)
            i += 1

    def goal_callback(self, goal):
        self._pub_takeoff = rospy.Publisher("/drone/takeoff", Empty, queue_size=1)
        self._takeoff_msg = Empty()
        self._pub_land = rospy.Publisher("/drone/land", Empty, queue_size=1)
        self._land_msg = Empty()
        word = goal.goal
        if word == "TAKEOFF":
            self.up_drone()
            rospy.loginfo("ca va monter")

        if word == "LAND":
            self.down_drone()
            rospy.loginfo('ca va descendre')

if __name__ == "__main__":
    rospy.init_node("move_drone_up_down", log_level=rospy.DEBUG)
    MoveUpDownClass()
    rospy.spin()