Getting Started

Installation

pip install daffi

# MessagePack serialisation (optional)
pip install "daffi[msgpack]"

Requires Python 3.9+. Linux and macOS are supported.

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Your first service

Create two files:

1_service.py

from daffi import Service, callback

@callback
def add(a: int, b: int) -> int:
    print(f"[service] add({a}, {b})")
    return a + b

if __name__ == "__main__":
    svc = Service(app_name="calc-service", host="127.0.0.1", port=5001)
    svc.start()
    print("Service running on 127.0.0.1:5001 — press Ctrl+C to stop.")
    svc.join()

2_client.py

from daffi import Client

if __name__ == "__main__":
    client = Client(app_name="calc-client", host="127.0.0.1", port=5001)
    conn = client.connect()

    result = conn.rpc(timeout=5).add(3, 4)
    print(f"add(3, 4) = {result}")   # → 7

    client.stop()

Run them:

python 1_service.py &
python 2_client.py

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What just happened?

1. Service starts a native TCP listener.
2. @callback registers add with the framework; it is advertised to callers during the handshake.
3. Client.connect() performs a handshake, receives the list of available callbacks.
4. conn.rpc(timeout=5) returns a proxy. Calling .add(3, 4) on it serialises the arguments, sends them to the Service, and blocks until the result arrives.

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Next steps

Topic	Link
Direct Client → Service communication	Client → Service
Scalable Router + Worker topology	Client → Router → Worker
rpc vs cast (broadcast)	Call Styles
Serialization formats	Serialization
Event subscriptions	Events
Browser / JavaScript client	JavaScript Client