rmw_zenoh

A ROS 2 RMW implementation based on Zenoh that is written using the zenoh-c bindings.

Design

For information about the Design please visit design page.

Requirements

• ROS 2: Rolling/Iron

Setup

Install latest rustc.

Note: The version of rustc that can be installed via apt is outdated.

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

Build rmw_zenoh_cpp

mkdir ~/ws_rmw_zenoh/src -p && cd ~/ws_rmw_zenoh/src
git clone https://github.com/ros2/rmw_zenoh.git
cd ~/ws_rmw_zenoh
rosdep install --from-paths src --ignore-src --rosdistro <DISTRO> -y # replace <DISTRO> with ROS 2 distro of choice
source /opt/ros/<DISTRO>/setup.bash # replace <DISTRO> with ROS 2 distro of choice
colcon build --cmake-args -DCMAKE_BUILD_TYPE=Release

Test

Make sure to source the built workspace using the commands below prior to running any other commands.

cd ~/ws_rmw_zenoh
source install/setup.bash

Start the zenoh router

Note: Manually launching zenoh router won't be necessary in the future.

# terminal 1
ros2 run rmw_zenoh_cpp init_rmw_zenoh_router

Note: Without the zenoh router, nodes will not be able to discover each other since multicast discovery is disabled by default in the node's session config. Instead, nodes will receive discovery information about other peers via the zenoh router's gossip functionality. See more information on the session configs below.

Run the talker

# terminal 2
export RMW_IMPLEMENTATION=rmw_zenoh_cpp
ros2 run demo_nodes_cpp talker

Note: Ignore all the warning printouts.

Run the listener

# terminal 2
export RMW_IMPLEMENTATION=rmw_zenoh_cpp
ros2 run demo_nodes_cpp listener

The listener node should start receiving messages over the /chatter topic.

Note: Ignore all the warning printouts.

Graph introspection

Presently we only support limited ros2cli commands to introspect the ROS graph such as ros2 node list and ros2 topic list.

Config

The default configuration sets up the zenoh sessions with the following main characteristics:

Table:

Zenoh Config	Default
udp_multicast	disabled
gossip scouting	enabled
connect	tcp/localhost:7447

This assumes that there is a zenohd running in the system at port 7447. A custom configuration may be provided by setting the RMW_ZENOH_CONFIG_FILE environment variable to point to a custom zenoh configuration file.

TODO Features

• Publisher
• Subscription
• Client
• Service
• Graph introspection