AP_DDS: Mode Switch Service

[arshPratap]

This PR aims to add Mode Switch service and has a dependency on #24705
@srmainwaring @Ryanf55 @tridge

[Ryanf55]

Nice! Where is the mode switch IDL at? I would like to review the message and compare to rep147

[arshPratap]

@Ryanf55 you can find the IDLs currently defined in the yaml file

[Ryanf55]

@Ryanf55 you can find the IDLs currently defined in the yaml file

Is there a way to add enums or int constants so the user knows what the modes ID's are?

[srmainwaring]

Where is the mode switch IDL at?

The service interface definition is in ./Tools/ros2/ardupilot_msgs. Perhaps as a follow up PR we could generate the IDL from this same as for other ROS msgs and then update the size and serialisation code?

[arshPratap]

@Ryanf55 , @srmainwaring and @tridge have made the changes that were requested..Would like to know your thoughts

[srmainwaring]

1. Change PR from draft to open as it's ready for review

2. Update ./libraries/AP_DDS/README.md

https://github.com/arshPratap/ardupilot/blob/4ec66c885446ab5fab7ae294f37aa43654d73826/libraries/AP_DDS/README.md?plain=1#L260

The name of the IS config file has changed to DDS_Service_IS_config.yaml.

3. Provide an example for the mode switch service. e.g.

ros2 service call /mode_switch ardupilot_msgs/srv/ModeSwitch "{mode: 1}"
requester: making request: ardupilot_msgs.srv.ModeSwitch_Request(mode=1)

response:
ardupilot_msgs.srv.ModeSwitch_Response(status=True, curr_mode=1)

with the expected output on the GSC console:

Mode ACRO
AP: DDS Client: Request for Mode Switch : SUCCESS

[arshPratap]

@srmainwaring done !

1. Update ./libraries/AP_DDS/README.md

https://github.com/arshPratap/ardupilot/blob/4ec66c885446ab5fab7ae294f37aa43654d73826/libraries/AP_DDS/README.md?plain=1#L260

The name of the IS config file has changed to DDS_Service_IS_config.yaml.

2. Provide an example for the mode switch service.

[srmainwaring]

Have replicated the examples. FWIW on macOS there are a few extra / more detailed steps needed to build and run.

macOS instructions

Build is-ros2-mix-generator:

colcon build --symlink-install --cmake-args -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_MACOSX_RPATH=FALSE -DUAGENT_USE_SYSTEM_FASTDDS=ON -DUAGENT_USE_SYSTEM_FASTCDR=ON -DMIX_ROS_PACKAGES="example_interfaces ardupilot_msgs" --packages-select is-ros2-mix-generator

Run integration-service:

LD_LIBRARY_PATH=$(pwd)/install/is-fastdds/lib ./build/is-core/integration-service ./src/ardupilot/libraries/AP_DDS/Is-Config/DDS_Service_IS_config.yaml --is-prefix-path=$(pwd)/install/is-ros2/lib/is/ros2 --is-prefix-path=$(pwd)/install/is-ros2-mix-generator/lib/is

Where I've placed the integration service package into the colcon workspace for ros2-ardupilot which reduces the need to switch between multiple projects and workspaces.

• LD_LIBRARY_PATH is needed because the library search paths are filtered out by the macOS shell security settings unless you disable SIP.
• For similar reasons the IS prefix path needs to be explicitly passed to the integration-service executable otherwise the is-ros2-mix-generator plugins will not be resolved. This is largely because eProsima seem to have implemented their own non-standard plugin resolution system for some reason?

It is worth remarking that there is an integration service build dependency on #24705, as without the updated version of ardupilot_msgs the integration service will not have the interface definitions for the service ardupilot_msgs/srv/ModeSwitch.

[Ryanf55]

The one thing I am unsure about is the circular includes.

Oddly enough, AP_Vehicle.h doesn't include AP_DDS_Client.h.

[srmainwaring]

AP_Vehicle.h forward declares AP_DDS_Client, has a pointer member variable dds_client, and pulls the include into the translation unit. So I think that's ok.

[arshPratap]

@srmainwaring thanks for the work on #24880 .. have rebased this PR over the latest changes..Hoping to have this merged soon.

[srmainwaring]

have rebased this PR over the latest changes.

LGTM @arshPratap. Tested in SITL and working fine.