[foxy-devel] transport scoped parameters

[bmegli]

Aim

• fix [ROS2] parameter namespace not scoped with transport used #140
• support new transport scoped parameters and current behavior (to be deprecated)

Reason

• following ROS1 image_transport documentation in ROS2 way
• avoiding clash between parameters from image_transport plugins

Details in #140

Scope

• only CompressedPublisher

If agreed on implementation I may rework the rest within this pull.

Short Description

• <image>.<transport>.<param> as future replacement of <image>.<param>
• support both ways for now
• emit deprecation warnings on setting through non-transport scoped parameter

Example

ros2 launch realsense2_camera rs_launch.py

# ...
realsense2_camera_node-1] [WARN] [1680595074.360039582] [CompressedPublisher]: parameter `.depth.image_rect_raw.format` is deprecated; use transport qualified name `.depth.image_rect_raw.compressed.format`
[realsense2_camera_node-1] [WARN] [1680595074.360153760] [CompressedPublisher]: parameter `.depth.image_rect_raw.png_level` is deprecated; use transport qualified name `.depth.image_rect_raw.compressed.png_level`
[realsense2_camera_node-1] [WARN] [1680595074.360203519] [CompressedPublisher]: parameter `.depth.image_rect_raw.jpeg_quality` is deprecated; use transport qualified name `.depth.image_rect_raw.compressed.jpeg_quality`
# ...
[realsense2_camera_node-1] [WARN] [1680595074.412855043] [CompressedPublisher]: parameter `.color.image_raw.format` is deprecated; use transport qualified name `.color.image_raw.compressed.format`
[realsense2_camera_node-1] [WARN] [1680595074.412951851] [CompressedPublisher]: parameter `.color.image_raw.png_level` is deprecated; use transport qualified name `.color.image_raw.compressed.png_level`
[realsense2_camera_node-1] [WARN] [1680595074.413044543] [CompressedPublisher]: parameter `.color.image_raw.jpeg_quality` is deprecated; use transport qualified name `.color.image_raw.compressed.jpeg_quality`

ros2 param list
/camera/camera:
  .color.image_raw.compressed.format
  .color.image_raw.compressed.jpeg_quality
  .color.image_raw.compressed.png_level
  .color.image_raw.format
  .color.image_raw.jpeg_quality
  .color.image_raw.png_level
  .depth.image_rect_raw.compressed.format
  .depth.image_rect_raw.compressed.jpeg_quality
  .depth.image_rect_raw.compressed.png_level
  .depth.image_rect_raw.format
  .depth.image_rect_raw.jpeg_quality
  .depth.image_rect_raw.png_level
# ...

Implementation

• parameter event handler emitting deprecation warnings on setting non-scoped parameters
• declare and sync value
  • transport scoped parameter
  • non-scoped parameter

[bmegli]

Now, if we intended only to make parameters transport scoped the fix is trivial 3 liner.

The difficulty lies in having both types support, ensuring values are synced on init and emitting deprecation warnings.

[bmegli]

There is alternative way to implement through add_on_set_parameters_callback but:

• it will flood the user with deprecation warnings
• as those events are generated multiple times with combinations of parameters

The ParameterEvent handler way may be also used to reimplement ROS1 dynamic reconfigure behavior in ROS2

---

Edit - stroked through, a much simpler way for runtime reconfiguration was implemented in rolling

[bmegli]

And finally, I am not entirely happy with templated function to set parameters in a header.

I now see a way to avoid it with:

• this declare_parameters override
• which should leave the header clean

[ijnek]

@bmegli I see this PR is targetting the foxy-devel branch. Could you retarget it to the rolling branch?

[bmegli]

Re-targeted to rolling in #143

Closing this one