websockets 11.0 documentation
Description: licence version pyversions tests docs openssf websockets is a library for building WebSocket servers and clients in Python with a focus on correctness, simplicity, robustness, and performance. It s...

Hide navigation sidebar
Hide table of contents sidebar
Back to top
Toggle table of contents sidebar

# websockets

websockets is a library for building WebSocket servers and clients in Python with a focus on correctness, simplicity, robustness, and performance.

It supports several network I/O and control flow paradigms:

1. The default implementation builds upon `asyncio`, Python’s standard asynchronous I/O framework. It provides an elegant coroutine-based API. It’s ideal for servers that handle many clients concurrently.

2. The `threading` implementation is a good alternative for clients, especially if you aren’t familiar with `asyncio`. It may also be used for servers that don’t need to serve many clients.

3. The Sans-I/O implementation is designed for integrating in third-party libraries, typically application servers, in addition being used internally by websockets.

Here’s an echo server with the `asyncio` API:

    #!/usr/bin/env python

    import asyncio
    from websockets.server import serve

    async def echo(websocket):
        async for message in websocket:
            await websocket.send(message)

    async def main():
        async with serve(echo, "localhost", 8765):
            await asyncio.Future()  # run forever

    asyncio.run(main())

Here’s how a client sends and receives messages with the `threading` API:

    #!/usr/bin/env python

    import asyncio
    from websockets.sync.client import connect

    def hello():
        with connect("ws://localhost:8765") as websocket:
            websocket.send("Hello world!")
            message = websocket.recv()
            print(f"Received: {message}")

    hello()

Don’t worry about the opening and closing handshakes, pings and pongs, or any other behavior described in the WebSocket specification. websockets takes care of this under the hood so you can focus on your application!

Also, websockets provides an interactive client:

    $ python -m websockets ws://localhost:8765/
    Connected to ws://localhost:8765/.
    > Hello world!
    < Hello world!
    Connection closed: 1000 (OK).

Do you like it? Let’s dive in!