rmw_zenoh

Package	Status
rmw_zenoh_cpp
zenoh_cpp_vendor
zenoh_security_tools

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

Design

For information about the Design please visit design page.

Requirements

• ROS 2

[!NOTE] See available distro branches, eg. jazzy, for supported ROS 2 distributions.

Installation

rmw_zenoh can either be installed via binaries (recommended for stable development) or built from source (recommended if latest features are needed). See instructions below.

Binary Installation

Binary packages for supported ROS 2 distributions (see distro branches) are available on respective Tier-1 platforms for the distributions. First ensure that your system is set up to install ROS 2 binaries by following the instructions here.

Then install rmw_zenoh binaries using the command

sudo apt update && sudo apt install ros-<DISTRO>-rmw-zenoh-cpp # replace <DISTRO> with the codename for the distribution, eg., rolling

Source Installation

[!NOTE] By default, we vendor and compile zenoh-cpp with a subset of zenoh features. The ZENOHC_CARGO_FLAGS CMake argument may be overwritten with other features included if required. The USE_SYSTEM_ZENOH CMake argument can be used to use non-vendored system libraries instead. The user must ensure that the non-vendored libraries are found by CMake and provide the necessary features (e.g., shared-memory support). See zenoh_cpp_vendor/CMakeLists.txt for more details.

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

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

Test

Terminate ROS 2 daemon started with another RMW

pkill -9 -f ros && ros2 daemon stop

Without this step, ROS 2 CLI commands (e.g. ros2 node list) may not work properly since they would query ROS graph information from the ROS 2 daemon that may have been started with different a RMW.

Start the Zenoh router

[!NOTE] Manually launching Zenoh router won't be necessary in the future.

# terminal 1
ros2 run rmw_zenoh_cpp rmw_zenohd

[!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

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.

Configuration

By default, Zenoh sessions created by rmw_zenoh will attempt to connect to a Zenoh router to receive discovery information. To understand more about Zenoh routers and Zenoh sessions, see Zenoh documentation.

Checking for a Zenoh router.

The ZENOH_ROUTER_CHECK_ATTEMPTS environment variable can be used to configure if and how a Zenoh session checks for the presence of a Zenoh router. The behavior is explained in the table below.

ZENOH_ROUTER_CHECK_ATTEMPTS	Session behavior
0	Indefinitely waits for connection to a Zenoh router.
< 0	Skips Zenoh router check.
> 0	Attempts to connect to a Zenoh router in ZENOH_ROUTER_CHECK_ATTEMPTS attempts with 1 second wait between checks.
unset	Equivalent to 1: the check is made only once.

This is the beginning of the README. Read the rest at the original. Read the full README ↗