Examples

The repo contains runnable scripts in examples/ (numbered in recommended learning order).

Start a router in a ROS2 environment:

ros2 run rmw_zenoh_cpp rmw_zenohd

Run an example:

python3 examples/01_publish_string.py
python3 examples/02_subscribe_string.py

For the full list (including services, queue-mode services, and compressed image subscription), see examples/README.md.

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Topic list and topic info (discovery)

You can list topics and get topic info without a ROS 2 install using the zenoh-ros2 CLI or the Python API.

CLI

After pip install zenoh-ros2-sdk, the zenoh-ros2 command is available:

zenoh-ros2 topic list                    # topic names only
zenoh-ros2 topic list -t                 # with types
zenoh-ros2 topic list -v                 # verbose (published / subscribed sections)
zenoh-ros2 topic list -c                 # count only
zenoh-ros2 topic info /chatter           # info for one topic
zenoh-ros2 topic info -v /chatter        # verbose (publisher/subscriber details)
zenoh-ros2 --router 127.0.0.1:7447 topic list -t
zenoh-ros2 --domain-id 1 --timeout 5 topic info -v /my_topic
zenoh-ros2 daemon start
zenoh-ros2 --no-daemon topic list

Python API

from zenoh_ros2_sdk import get_topic_names_and_types, get_topic_info

# List all topics (and types)
for name, types in get_topic_names_and_types():
    print(name, types)

# Info for one topic
info = get_topic_info("/chatter", verbose=True)
if info:
    print("Type:", info.topic_types)
    print("Publishers:", info.publisher_count, "Subscribers:", info.subscriber_count)
    for p in info.publishers:
        print("  Publisher:", p.node_name, p.node_namespace, p.topic_type)

Runnable discovery example

python3 examples/19_discovery_topic_list.py

Optional: pass a topic name to show info for that topic only:

python3 examples/19_discovery_topic_list.py /chatter

See docs/TOPIC_LIST_AND_INFO.md for full API and CLI options.