Actions

[sloretz]

ROS 2 Action Plan

At a high level the goal for actions in Crystal is to enable porting moveit and the navigation stack to ROS 2.

Required by Crystal release

• rclpy API for action client and action server
• rclcpp API for action client and action server
• rcl has code for action server and action client that is used by client libraries
• Action server and client support features needed to make it possible to write a bridge with ROS 1
  • supports multiple goals simultaneously
• examples repo has action API examples for rclpy and rclcpp
• test_communication tests for cross client library actions
• test_communication tests for cross rmw implementation actions
• CLI ros2 topic list and ros2 service list should not show action topics by default
• Support ROS 1 .action files
• Support .idl files once the IDL pipeline for services and messages is fully functioning

Issues

• Actions rcl#306 rcl api for actions

g1

• Allow generating messages and services in the namespace action rosidl#301 Neeed to be able to generate msg and srv c and c++ code in an action namespace
• Allow generating messages services in an action folder rosidl_typesupport_fastrtps#9 Allow fastrtps typesupport to generate service in action folder
• Allow generating messages services in an action folder rosidl_typesupport_opensplice#6 Allow opensplice typesupport to generate services in action
• Allow generating messages services in an action folder  rosidl_typesupport_connext#11 Allow connext typesupport to generate services in action folder

g2

• Parse .action files rosidl#305 Parse .action files into intermediate representation

g2.5

• Allow generating messages and services in the module action rosidl_python#13 Need to be able to generate msg and srv python code in action module

g2.75

• Service and Message definitions for actions rcl_interfaces#40 Need message and service definitions for parts common to all actions

g3

• Generate C typesupport for Actions rosidl#302 C header files / typesupport for Actions
• Generate C++ typesupport for actions rosidl#303 C++ header files / typesupport for Actions
• Generate python typesupport for Actions rosidl_python#14 Python typesupport object for actions

g4

• IDL 4.2 description for actions rosidl#304 Decide how actions will be represented in IDL 4.2
  folder
• Change UUID type in action_msgs rcl_interfaces#49 Use unique_identifier_msgs for actions (Change UUID type in action_msgs rcl_interfaces#54 Change UUID type in action msgs rosidl#332 Change UUID type in action msgs rcl#338 )(held for IDL work)

g5

• Generate UUID in C that rcl can depend on in ROS 2 There is https://github.com/ros-geographic-info/unique_identifier/tree/ros2 , but it depends on boost/rospy/roscpp , will need something with fewer dependencies.
• (under consideration) Generate low-level action typesupport API rosidl#314 Generate type support conversion functions for C API

g5.5

• rclcpp API to add something which adds something to the wait set ([rclcpp] Add class Waitable rclcpp#589)
• rclpy API to add something which adds something to the wait set (Python thing that adds things to the wait set rclpy#250)

g6

• rclcpp Action Server implementation
• rclcpp Action Client implementation

g7

• rclpy (Action implementation rclpy#257)
  • Action Server implementation
  • Action Client implementation

g8

• Test communication with C++ actions across rmw implementations (add Fibonacci test for actions system_tests#316)
• Test communication with python actions accross rmw implementations (Add rclpy action communication tests system_tests#332)
• Test communication with C++ and Python action communications (Add rclpy action communication tests system_tests#332)

g9

• Create tutorial/demo (add to ROS index tutorials?)

Likely not included in Crystal release

Good places for community contribution

• ROS 1 bridge for actions
• CLI ros2 action
• SimpleActionServer and SimpleActionClient APIs in python or c++

Places for Action discussion

• Design actions API and implementation design#183
• https://discourse.ros.org/t/actions-in-ros-2/6254

[jacobperron]

rcl implementation ticket: ros2/rcl#306