Can zenoh-bridge-ros2dds bridge topics from bare DDS applications (not ROS 2 nodes)?

[jabrail-chumakov]

Description

I'm trying to wirelessly bridge ROS 2 topics from a robot to a remote PC using zenoh-bridge-ros2dds. The robot's topics are published by the board computer using bare DDS (direct CycloneDDS API, not ROS 2 nodes). The bridge discovers all DDS topics but only creates routes for topics declared by actual ROS 2 nodes.

Setup

Robot (Jetson):

• ROS 2 Foxy
• CycloneDDS (rmw_cyclonedds_cpp)
• zenoh-bridge-ros2dds v1.7.2 in router mode
• Configuration: ROS_LOCALHOST_ONLY=0, ROS_AUTOMATIC_DISCOVERY_RANGE=SUBNET

PC:

• ROS 2 Jazzy
• zenoh-bridge-ros2dds v1.7.2 in peer mode
• Configuration: ROS_LOCALHOST_ONLY=1

Network:

• Both on same WiFi (192.168.8.x)
• Bridges connect successfully over TCP

Observed Behavior

On Jetson:

$ ros2 node list
# Empty - no ROS 2 nodes running

$ ros2 topic list | wc -l
121  # All topics visible to ROS 2 tools

$ ros2 topic info /lowstate --verbose
Node name: _CREATED_BY_BARE_DDS_APP_
Node namespace: _CREATED_BY_BARE_DDS_APP_

Bridge Logs (DEBUG mode):

The bridge discovers all 121 DDS topics:

DEBUG Discovered DDS publication ... on rt/lowstate
DEBUG Discovered DDS publication ... on rt/utlidar/cloud
... (100+ more)

But only creates routes for the 2 topics from the ROS daemon node:

INFO Node /_ros2cli_daemon_0 declares Publisher /parameter_events - Allowed
INFO Route Publisher (ROS:/parameter_events -> Zenoh:parameter_events) created
INFO Node /_ros2cli_daemon_0 declares Publisher /rosout - Allowed
INFO Route Publisher (ROS:/rosout -> Zenoh:rosout) created

No routes are created for the 119 bare DDS topics.

On PC:

$ ros2 topic list
/parameter_events
/rosout
# Only 2 topics - the ones from ROS daemon, not the 119 bare DDS topics

Question

Is it possible to configure zenoh-bridge-ros2dds to bridge topics from bare DDS applications?

System Info

• Platform: Ubuntu 20.04 (Focal) on Jetson Xavier NX (arm64)
• zenoh-bridge-ros2dds: v1.7.2 (installed via apt)
• ROS Distro: Foxy (robot), Jazzy (PC)
• DDS Implementation: CycloneDDS
• Use case: jetson robot with bare DDS board computer

Thank you for any guidance!

[evshary]

Hi @jabrail-chumakov

Not in the roadmap as far as I know. If you want to see the raw DDS topic, it would be better to use zenoh-bridge-dds directly. Note that we don't do any optimization for ROS 2 on that bridge.

Just out of curiosity, why do you want to see the raw DDS topic? The robot you use only provides raw DDS communication?

[jabrail-chumakov]

Thank you @evshary,

To answer your question, the robot uses a proprietary board computer that exports telemetry and sensor data directly via bare DDS. On the Jetson, I can see all 120 topics using ros2 topic list (appearing under the node name CREATED_BY_BARE_DDS_APP), and communication works perfectly over a wired LAN using CycloneDDS with my PC. However, for the wireless setup, I need Zenoh's stability over WiFi (board PC -> Jetson -> (WiFi) -> PC).

The issue is that zenoh-bridge-ros2dds discovers the DDS publications but refuses to create routes because they aren't associated with a formal ROS 2 node. That's why I'm looking for a way to bridge these 'bare' topics.