minggangw
commented
4 years ago Thanks for your question, I'd like to talk about the history of actionlib feature first
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In ROS1, there was no concept of middleware, so each client implements its own version of actionlib achieved by client/service.
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In ROS2, we have a middleware named rcl, clients of ROS2 must wrapper this C library and expose the interfaces through different languages, e.g. C++/Pythons/JavaScript:
- At the beginning of ROS2, the actionlib was not supported by rcl and rclnodejs implemented the actionlib which has been deprecated.
- Since rcl has supported the actionlib, so as the normal way clients should leverage the C interface to offer the functionality.
Based on the background, some comments below:
What would it take to get this functionality?
The rclnodejs should implement the actionlib feature
How could one assist in the effort to support ROS2 Actions in ROS2-web-bridge?
We have to support it for rclnodejs first
Would ROS2 actions need to be implemented inside roslibjs using the topics and services that are already supported by ROS2-web-bridge and the rosbridge v2.0 protocol?
As the rosbridge v2.0 protocol doesn't support actionlib concept, so we may extend it if we want to support it (the corresponding changes may be made to roslibjs also).
Should actions support be implemented in rclnodejs first and then rosbridge v2.0 protocol be extended to support actions in some way?
That's correct.
There is already an open issue - https://github.com/RobotWebTools/rclnodejs/issues/469 to record this feature, so if you are willing to contribute to the implementation, you can submit your PR there. Currently, the rclnodejs still has a gap with Python/Cpp clients, see https://github.com/RobotWebTools/rclnodejs/issues/498, please feel free if you are interested in any of them, thanks!
mikelyndersOKCC
gautamjain
spygibas
nadavis
I have created a ROS2 package that implements ROS2 Actions and it would be great if I could call them through my webapp interface. Unfortunately, it seems ROS2 Actions are not supported yet.
What would it take to get this functionality? I have gathered that there are a couple reasons why this might be hard:
How could one assist in the effort to support ROS2 Actions in ROS2-web-bridge?
Would ROS2 actions need to be implemented inside roslibjs using the topics and services that are already supported by ROS2-web-bridge and the rosbridge v2.0 protocol? (I think this is more or less how roslibjs implemented the actionlib support)
or
Should actions support be implemented in rclnodejs first and then rosbridge v2.0 protocol be extended to support actions in some way?
I'd love to help in any way I can. I'm fairly new to ROS so please correct me if I'm misunderstanding.
In the meantime I will likely change my ROS package to provide the same functionality with a long-running service. (I know that is bad as services are meant to 'return quickly' but I'm not sure how else to do it)