zrm 2.0.0

A minimal, single-file communication middleware built on Zenoh

ZRM (Zenoh ROS-like Middleware)

A minimal, single-file communication middleware built on Zenoh, providing a clean and simple API inspired by ROS2 patterns.

https://github.com/user-attachments/assets/3e41d9a7-f553-457b-a879-cae2af45bf63

Features

• Minimalist: Single-file implementation
• Type-safe: Protobuf-based serialization with runtime type checking
• Ergonomic: Pythonic API with sensible defaults

Installation

pip install zrm

Quick Start

import zrm
from zrm.msgs import geometry_pb2

node = zrm.Node("my_node")

# Publish
pub = node.create_publisher("robot/pose", geometry_pb2.Pose2D)
pub.publish(geometry_pb2.Pose2D(x=1.0, y=2.0, theta=0.5))

# Subscribe
sub = node.create_subscriber("robot/pose", geometry_pb2.Pose2D)
if pose := sub.latest():
    print(f"Position: x={pose.x}, y={pose.y}")

node.close()

Protobuf definition:

message Pose2D {
  double x = 1;
  double y = 2;
  double theta = 3;
}

CLI Tools

zrm-topic list                    # List topics
zrm-topic echo robot/pose         # Echo messages
zrm-service list                  # List services
zrm-service call add 'a: 1 b: 2'  # Call service
zrm-action list                   # List actions
zrm-action send fib 'order: 10'   # Send action goal
zrm-node list                     # List nodes

More Examples

See examples/ for complete working examples including services, actions with feedback/cancellation, and graph discovery.

---

Services

Services use nested Request/Response messages:

import zrm
from zrm.srvs import examples_pb2

def add_callback(req):
    return examples_pb2.AddTwoInts.Response(sum=req.a + req.b)

node = zrm.Node("service_node")
server = node.create_service("add_two_ints", examples_pb2.AddTwoInts, add_callback)
client = node.create_client("add_two_ints", examples_pb2.AddTwoInts)

response = client.call(examples_pb2.AddTwoInts.Request(a=5, b=3))
print(f"Sum: {response.sum}")  # Output: 8

node.close()

Protobuf definition:

message AddTwoInts {
  message Request { int32 a = 1; int32 b = 2; }
  message Response { int32 sum = 1; }
}

Actions

Actions support long-running goals with feedback and cancellation:

import zrm
from zrm.actions import examples_pb2

def execute_fibonacci(goal_handle: zrm.ServerGoalHandle) -> None:
    goal_handle.execute()
    sequence = [0, 1]
    for i in range(1, goal_handle.goal.order):
        if goal_handle.cancel_requested:
            goal_handle.cancel(examples_pb2.Fibonacci.Result(sequence=sequence))
            return
        sequence.append(sequence[i] + sequence[i - 1])
        goal_handle.publish_feedback(examples_pb2.Fibonacci.Feedback(partial_sequence=sequence))
    goal_handle.succeed(examples_pb2.Fibonacci.Result(sequence=sequence))

node = zrm.Node("action_node")
server = node.create_action_server("fibonacci", examples_pb2.Fibonacci, execute_fibonacci)
client = node.create_action_client("fibonacci", examples_pb2.Fibonacci)

goal_handle = client.send_goal(
    examples_pb2.Fibonacci.Goal(order=10),
    feedback_callback=lambda fb: print(f"Progress: {list(fb.partial_sequence)}")
)
result = goal_handle.get_result(timeout=30.0)
print(f"Result: {list(result.sequence)}")

node.close()

Protobuf definition:

message Fibonacci {
  message Goal { int32 order = 1; }
  message Result { repeated int32 sequence = 1; }
  message Feedback { repeated int32 partial_sequence = 1; }
}

Message Organization & Proto Generation

Directory Structure

src/<package>/
├── proto/                 # Proto definitions
│   ├── msgs/              # Message definitions
│   ├── srvs/              # Service definitions
│   └── actions/           # Action definitions
├── msgs/                  # Auto-generated *_pb2.py
├── srvs/                  # Auto-generated *_pb2.py
└── actions/               # Auto-generated *_pb2.py

Generating Python Code

zrm-proto              # Generate from local protos
zrm-proto --dep zrm    # Include dependency protos

Standard Messages

Category	Module	Types
Messages	zrm.msgs.header_pb2	Header
Messages	zrm.msgs.geometry_pb2	Point, Vector3, Quaternion, Pose, Pose2D, Twist, PoseStamped
Messages	zrm.msgs.sensor_pb2	Imu, Image, CompressedImage, CameraInfo, JointState
Messages	zrm.msgs.vision_pb2	Point2D, BoundingBox2D
Services	zrm.srvs.std_pb2	Trigger
Services	zrm.srvs.examples_pb2	AddTwoInts
Actions	zrm.actions.examples_pb2	Fibonacci

Development

git clone https://github.com/JafarAbdi/zrm.git
cd zrm
uv sync

# Linting
uv run pre-commit run -a

# Testing
uv run pytest tests/ -v

Acknowledgements

• Graph class inspired by ros-z
• Built on Eclipse Zenoh