roscon2024_workshop

Exercise 3 - Remote Connection via the Cloud

A Zenoh router deployed in the Cloud with a public IP can act as a relay between two rmw_zenoh systems.

cloud-connectivity

Configuration

For this workshop, we’ve deployed a Zenoh router on roscon.zenoh.io. Update your zenoh_confs/ROUTER_CONFIG.json5 to include the following in the connect.endpoints configuration:

  connect: {
    endpoints: [
      "tcp/roscon.zenoh.io:7448"
    ],
  },

Run

In your container, run the following commands:

Start the router (with the custom configuration): ZENOH_ROUTER_CONFIG_URI=/ros_ws/zenoh_confs/ROUTER_CONFIG.json5 ros2 run rmw_zenoh_cpp rmw_zenohd
Publish your own message: ros2 topic pub /chatter std_msgs/msg/String "data: Hello from <YOUR_NAME>"
Echo all the messages ros2 topic echo /chatter

Bonus

Try setting a different ROS_DOMAIN_ID (e.g., export ROS_DOMAIN_ID=42). What happens, and why?

Answer

Zenoh has no concept of Domain such as DDS. However, `rmw_zenoh` integrates the `ROS_DOMAIN_ID` in the mapping from topic/service names to zenoh key expressions. As a result, even if nodes use the same topic name, they won’t communicate if they are in different domains, even when connected through Zenoh.

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