ROS Action Server

03_01_ros_action_server.ipynb
Running the cell code

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import rospy
import actionlib
import actionlib_tutorials.msg

Import rospy modules
Import the actionlib and actionlib_tutorials.msg modules

class FibonacciAction(object):
    # Generate messages for use in publishing feedback and results
    _feedback = actionlib_tutorials.msg.FibonacciFeedback()
    _result = actionlib_tutorials.msg.FibonacciResult()

    def __init__(self, name):
        self._action_name = name
        self._as = actionlib.SimpleActionServer(self._action_name, actionlib_tutorials.msg.FibonacciAction, execute_cb=self.execute_cb, auto_start = False)
        self._as.start()

    def execute_cb(self, goal):
        r = rospy.Rate(1)
        success = True

        # Add the starting point of the Fibonacci sequence
        self._feedback.sequence = []
        self._feedback.sequence.append(0)
        self._feedback.sequence.append(1)

        # console publish information for users
        rospy.loginfo('%s: Executing, creating fibonacci sequence of order %i with seeds %i, %i' % (self._action_name, goal.order, self._feedback.sequence[0], self._feedback.sequence[1]))

        # start action execution
        for i in range(1, goal.order):
            # Check if there is no request from the client
            if self._as.is_preempt_requested():
                rospy.loginfo('%s: Preempted' % self._action_name)
                self._as.set_preempted()
                success = False
                break
            self._feedback.sequence.append(self._feedback.sequence[i] + self._feedback.sequence[i-1])
            # publish feedback
            self._as.publish_feedback(self._feedback)
            r.sleep()

        if success:
            self._result.sequence = self._feedback.sequence
            rospy.loginfo('%s: Succeeded' % self._action_name)
            self._as.set_succeeded(self._result)

Fibonacci operation
Reference

http://wiki.ros.org/actionlib_tutorials/Tutorials/Writing%20a%20Simple%20Action%20Server%20using%20the%20Execute%20Callback%20(Python)

rospy.init_node('fibonacci')
server = FibonacciAction(rospy.get_name())
rospy.spin()

Execute fibonacci Action Node for Fibonacci operation
Output success result after Fibonacci operation