Allow action servers without execute callback

[Timple]

Just like rclcpp and ros1, allow action servers without execute callback.

Example like:

• Display a message until a button is pressed
• Actuate a motor until an endstop is reached

are typical cases where an action is succeeded based on information outside of the execute_cb.

It makes more sense to succeed these from outside the execute_cb in this case. And this would be in line with ros1 and rclcpp where this is possible.

I kept the execute_callback in args for backwards compatibility.

[fujitatomoya]

@Timple thanks for the contribution.

i think this is reasonable and aligns with rclcpp, but i would like to have another review from maintainers.

[Timple]

Alright, we'll wait for those 🙂

[Timple]

Subtle ping 🙂

[Timple]

Sorry for subtle bump again, but Jade is coming up. And I'm afraid breaking changes won't be accepted anymore soon.

[fujitatomoya]

@clalancette @sloretz @ahcorde either of you, can you take a look at this? i think this is reasonable and more flexibility for rclpy client.

[fujitatomoya]

@Timple can you rebase this to rolling? almost 100 commits are behind.

[Timple]

@Timple can you rebase this to rolling? almost 100 commits are behind.

Done!

[ros-discourse]

This pull request has been mentioned on ROS Discourse. There might be relevant details there:

https://discourse.ros.org/t/upcoming-feature-freeze-for-ros-2-jazzy-jalisco-on-15th-april-2024/37075/2

[Timple]

So I missed the jazzy release 😿

But this PR had some proper traction. Can we still get this in rolling?

_{If everybody is very busy doing release stuff for jazzy, I also fully understand. Then I'll apply some sort of exponential backoff to my pings 🙂}

[fujitatomoya]

@Timple sorry we missed this to jazzy. i will start the CI.

CC: @sloretz

[fujitatomoya]

CI:

• Linux
• Linux-aarch64
• Windows

[Timple]

It's green! 😄

[fujitatomoya]

@sloretz @clalancette friendly ping.

[Timple]

Joehoe ❤️