Skip to main content

Quick Start: Client

This walk-through connects a Python client to a SignalR hub, calls a server method, and reacts to server-initiated messages.

1. Create a connection​

import asyncio

from aiosignalr.client import HubConnection


async def main() -> None:
    connection = HubConnection()
    await connection.start("http://127.0.0.1:8080/hub")

    # ... use the connection ...

    await connection.stop()


asyncio.run(main())

start() performs the POST /negotiate handshake, selects the best transport and completes the protocol handshake before returning. By default the client tries the transports in server-declared order (WebSocket → SSE → Long Polling).

2. Call a server method​

Use invoke() to call a method and wait for its result:

result = await connection.invoke("Add", 40, 2)
print("Add(40, 2) =", result)  # 42

Use send() for fire-and-forget calls (no result is expected):

await connection.send("Notify", "hello")

3. Stream results​

Server methods that return an async iterator can be consumed with stream():

async for item in await connection.stream("Counter", 3):
    print("stream item:", item)

4. Receive messages from the server​

Register handlers with on(). When the server calls a method, every matching handler runs with the arguments:

connection.on("message", lambda text: print("got:", text))

# An async handler is supported too.
async def on_joined(user: str) -> None:
    print(f"{user} joined the room")

connection.on("userJoined", on_joined)

If a handler returns a non-None value, it is sent back to the server as the invocation result (a client result).

5. Full example​

import asyncio

from aiosignalr.client import HubConnection


async def main() -> None:
    connection = HubConnection()
    connection.on("message", lambda text: print("got:", text))

    await connection.start("ws://127.0.0.1:8080/hub")

    result = await connection.invoke("Add", 40, 2)
    print("Add(40, 2) =", result)

    async for item in await connection.stream("Counter", 3):
        print("stream item:", item)

    await connection.send("Notify", "hello")
    await connection.stop()


asyncio.run(main())

Next steps​