Getting Started with ROS Part 2: Services and Actions

All robots based on ROS are programmed using five simple but core constructs, and you'll hear these often:
- Nodes
- Parameters
- Topics
- Services
- Actions
In this video we cover services and actions.

Commands used in this video:

Show services in the current ROS graph:

💻 ros2 service list

Show services and service type:

💻 ros2 service list -t
💻 ros2 service type [service; e.g., /spawn]

Filter parameter-related services from the service list:

💻 ros2 service list | grep -v param

Show actions in the current ROS graph:

💻 ros2 action list

Display message, service or action interface details:

💻 ros2 interface show [interface; e.g., turtlesim/srv/Spawn]

Call the spawn service to add a turtle named "snapper" to the turtlesim playfield:

💻 ros2 service call /spawn turtlesim/srv/Spawn "{x: 1, y: 1, theta: 3.14, name: 'snapper'}"

Discover and use the turtlesim service to kill an existing turtle

💻 ros2 service type /kill
💻 ros2 interface show turtlesim/srv/Kill
💻 ros2 service call /kill turtlesim/srv/Kill '{name: snapper}'

Send a rotation goal to turtle1 in the turtlesim simulator:

💻 ros2 action send_goal /turtle1/rotate_absolute turtlesim/action/RotateAbsolute "{theta: 3.14}"
💻 ros2 action send_goal /turtle1/rotate_absolute turtlesim/action/RotateAbsolute "{theta: 0.00}" --feedback

Retrieve detailed information about the turtlesim node:

💻 ros2 node info /turtlesim

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[underlecht]

Great. Would love more robotics videos from Canonical.