Getting Started¶

This page is about using the SDK (pub/sub/services). If you want to build the documentation site itself, see contributing/docs.md.

Install¶

From PyPI:

pip install zenoh-ros2-sdk

From source (editable):

pip install -e .

Start a Zenoh router (optional but common)¶

Many setups use a local router. Execute the Zenoh router in a ROS2 environment:

ros2 run rmw_zenoh_cpp rmw_zenohd

If you are connecting to a remote router, pass router_ip / router_port when creating publishers/subscribers/service endpoints.

List topics and topic info¶

Without a ROS 2 install you can list topics and get topic info via the zenoh-ros2 CLI:

zenoh-ros2 topic list -t              # list topics with types
zenoh-ros2 topic info -v /chatter      # verbose info for a topic

For fast topic list/info, start the daemon once: zenoh-ros2 daemon start; then zenoh-ros2 topic list returns quickly. See DISCOVERY_CLOSE_DELAY.md for why. Use --no-daemon to always run discovery in-process.

Or from Python:

from zenoh_ros2_sdk import get_topic_names_and_types, get_topic_info

for name, types in get_topic_names_and_types():
    print(name, types)

info = get_topic_info("/chatter", verbose=True)
if info:
    print("Publishers:", info.publisher_count, "Subscribers:", info.subscriber_count)

See TOPIC_LIST_AND_INFO.md and examples.md for more examples.

Publish a topic¶

from zenoh_ros2_sdk import ROS2Publisher

pub = ROS2Publisher(
    topic="/chatter",
    msg_type="std_msgs/msg/String"
)
pub.publish(data="Hello World!")
pub.close()

from zenoh_ros2_sdk import ROS2Subscriber

def on_message(msg):
    print(f"Received: {msg.data}")

sub = ROS2Subscriber(
    topic="/chatter",
    msg_type="std_msgs/msg/String",
    callback=on_message
)

Service server¶

from zenoh_ros2_sdk import ROS2ServiceServer, get_message_class

def handler(request):
    Response = get_message_class("example_interfaces/srv/AddTwoInts_Response")
    return Response(sum=request.a + request.b)

server = ROS2ServiceServer(
    service_name="/add_two_ints",
    srv_type="example_interfaces/srv/AddTwoInts",
    callback=handler
)

Service client¶

from zenoh_ros2_sdk import ROS2ServiceClient

client = ROS2ServiceClient(
    service_name="/add_two_ints",
    srv_type="example_interfaces/srv/AddTwoInts"
)

resp = client.call(a=5, b=3)
if resp:
    print(resp.sum)
client.close()

Next steps¶

For runnable scripts (including discovery and compressed image subscription), see examples.md.
For topic list / topic info (CLI and API), see TOPIC_LIST_AND_INFO.md.
For how discovery/QoS/key-expressions work, see concepts.md.