foxglove2zmq 0.1.1

A relay for forwarding Foxglove WebSocket messages to a ZMQ server.

Foxglove to ZMQ Relay

A Python utility to connect to a Foxglove WebSocket server, decode messages (JSON and Protobuf), and relay them to a ZMQ server using either a PUSH/PULL or PUB/SUB pattern.

This is useful for integrating Foxglove data streams with other backend services, logging systems, or robotics frameworks that use ZMQ for messaging. Also includes a command-line interface (foxglove2zmq) for easy setup and configuration!

Features

• Connects to any Foxglove WebSocket Server: Natively connects using the foxglove.sdk.v1 subprotocol.
• Automatic Channel Discovery: Discovers all available channels on connect.
• Topic Filtering: Easily blocklist topics you don't want to relay.
• Multi-Encoding Support: Decodes both standard json and protobuf encoded messages on the fly.
• Dynamic Protobuf Decoding: Parses Protobuf schemas (FileDescriptorSet) provided by the server to decode binary payloads into JSON.
• Flexible ZMQ Patterns:
  • PUSH/PULL: Relays all messages to a single stream for worker distribution.
  • PUB/SUB: Publishes messages on their original Foxglove topic for selective subscription.
• Handles Large Messages: Configured to accept WebSocket messages of any size.

Todo

• Add support for bi-directional messaging with ClientPublish messages and Parameter updates.
• Add support for other binary messages:
  • 0x02 - Time
  • 0x03 - Service call responses
  • 0x04 - Fetch asset responses

Installation

You can install the package from PyPI:

pip install foxglove-zmq-relay

Alternatively, you can install it directly from the GitHub repository:

pip install git+https://github.com/helkebir/foxglove2zmq.git

Usage

The relay is designed to be run as a standalone script. You can import and use the classes in your own applications.

Command-Line Examples

A basic script is provided to run the relay from the command line. You can choose which ZMQ pattern to use. Currently, the PUSH/PULL and PUB/SUB patterns are implemented.

A command-line interface is available via the foxglove2zmq command after installation.

foxglove2zmq --help

usage: foxglove2zmq [-h] -p {push,pub} [-w FOXGLOVE_WS] -z ZMQ_BIND [-v VERBOSITY] [-b [BLOCKLIST ...]] [--timeout TIMEOUT]

Relay Foxglove WebSocket messages to a ZMQ server.

optional arguments:
  -h, --help            show this help message and exit
  -p {push,pub}, --pattern {push,pub}
                        The ZMQ socket pattern to use ('push' for PUSH/PULL or 'pub' for PUB/SUB).
  -w FOXGLOVE_WS, --foxglove-ws FOXGLOVE_WS
                        The WebSocket URL of the Foxglove server (e.g., ws://localhost:8765).
  -z ZMQ_BIND, --zmq-bind ZMQ_BIND
                        The TCP address for the ZMQ server to bind to (e.g., tcp://localhost:5555).
  -v VERBOSITY, --verbosity VERBOSITY
                        The verbosity level (0 = errors only, 1 = info, 2 = debug).
  -b [BLOCKLIST ...], --blocklist [BLOCKLIST ...]
                        A space-separated list of topics to ignore (e.g., /diagnostics /debug).
  --timeout TIMEOUT     Time in seconds to wait for channel advertisements.

PUSH/PULL Relay

This is the simplest pattern. It sends all messages from all topics to any connected ZMQ PULL client.

# In one terminal, run the relay
foxglove2zmq --pattern push --foxglove-ws ws://localhost:8765 --zmq-bind tcp://localhost:5555

And in another terminal, run a ZMQ PULL client to receive messages:

# ZMQ PULL client example (client.py)
import zmq
import json

context = zmq.Context()
socket = context.socket(zmq.PULL)
socket.connect("tcp://localhost:5555")

print("Receiving messages...")
while True:
    msg_str = socket.recv_string()
    msg_obj = json.loads(msg_str)
    print(json.dumps(msg_obj, indent=2))

PUB/SUB Relay

This pattern publishes each message on its original Foxglove topic. ZMQ SUB clients can then subscribe to specific topics.

# In one terminal, run the relay
foxglove2zmq --pattern pub --foxglove-ws ws://localhost:8765 --zmq-bind tcp://localhost:5555

And in another terminal, run a ZMQ SUB client to receive messages from a specific topic:

# ZMQ SUB client example (client.py)
import zmq
import json

context = zmq.Context()
socket = context.socket(zmq.SUB)
socket.connect("tcp://localhost:5555")

# Subscribe to a specific topic (e.g., /sensor/camera)
# To subscribe to all topics, use b""
socket.setsockopt(zmq.SUBSCRIBE, b"/sensor/camera")

print("Receiving messages...")
while True:
    topic, msg_str = socket.recv_multipart()
    msg_obj = json.loads(msg_str)
    print(f"Topic: {topic.decode()}")
    print(json.dumps(msg_obj, indent=2))

Library Usage

You can also import the classes into your own Python application for more advanced control.

import asyncio
from src.foxglove2zmq import FoxgloveToZMQPushRelay, FoxgloveToZMQPubSubRelay


async def main():
    # Example for PUSH relay
    push_relay = FoxgloveToZMQPushRelay(
        foxglove_address="ws://localhost:8765",
        zmq_address="tcp://localhost:5555",
        topic_blocklist=["/diagnostics"],
        discovery_timeout=5.0
    )
    await push_relay.run()


if __name__ == "__main__":
    try:
        asyncio.run(main())
    except KeyboardInterrupt:
        print("Relay stopped by user.")

Library Example

You can find example scripts in the examples/ directory that demonstrate how to use the relay in different scenarios, including both PUSH/PULL and PUB/SUB patterns. First install the package, then run the examples:

1. zmq_relay.py: A simple script to run the relay, must be run first. Defaults to PUSH/PULL mode on ZMQ bind tcp://localhost:5555.
2. zmq_puller.py: A ZMQ PULL client that connects to the relay and prints received messages.
3. zmq_subber.py: A ZMQ SUB client that connects to the relay and subscribes to all topics.

Project Structure

foxglove2zmq/
├── src/
│   └── foxglove2zmq/
│       ├── __init__.py
│       ├── relay.py
│       └── cli.py
├── examples/
│   ├── zmq_puller.py 
│   └── zmq_relay.py
├── LICENSE.md
├── pyproj.toml
├── README.md
└── requirements.txt  

License

This project is licensed under the MIT License; see the LICENSE file for details.