Send and Observe Action Goals

Now send an action goal yourself.

With Turtlesim running:

ros2 action send_goal \
  /turtle1/rotate_absolute \
  turtlesim/action/RotateAbsolute \
  "{theta: 1.57}"

The official tutorial shows the client waiting for a server, sending the goal, receiving an accepted goal ID, and eventually receiving a result.

Ask for feedback

Use:

ros2 action send_goal \
  /turtle1/rotate_absolute \
  turtlesim/action/RotateAbsolute \
  "{theta: -1.57}" \
  --feedback

Now you should see repeated feedback values while the turtle rotates, followed by the final result.

Observe the lifecycle

Record evidence for:

goal sent
→ goal accepted
→ feedback received
→ result received
→ final status

Cancellation concept

The official Turtlesim teleop exercise demonstrates canceling an in-progress rotation and shows that action work can be canceled. You do not need to write your own action client/server in this beginner course.

Checkpoint

Explain why the feedback stream does not make an action "just a topic." Include the goal and result responsibilities in your explanation.