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websockets

Python

1.0.0

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websockets

What is `websockets`?

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

Built on top of asyncio, Python's standard asynchronous I/O framework, the default implementation provides an elegant coroutine-based API.

An implementation on top of threading and a Sans-I/O implementation are also available.

Documentation is available on Read the Docs.

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.get_running_loop().create_future()  # run forever

asyncio.run(main())

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

#!/usr/bin/env python

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()

Does that look good?

Get started with the tutorial!

websockets for enterprise

Available as part of the Tidelift Subscription

The maintainers of websockets and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.

(If you contribute to websockets and would like to become an official support provider, let me know.)

Why should I use `websockets`?

The development of websockets is shaped by four principles:

Correctness: websockets is heavily tested for compliance with RFC 6455. Continuous integration fails under 100% branch coverage.
Simplicity: all you need to understand is msg = await ws.recv() and await ws.send(msg). websockets takes care of managing connections so you can focus on your application.
Robustness: websockets is built for production. For example, it was the only library to handle backpressure correctly before the issue became widely known in the Python community.
Performance: memory usage is optimized and configurable. A C extension accelerates expensive operations. It's pre-compiled for Linux, macOS and Windows and packaged in the wheel format for each system and Python version.

Documentation is a first class concern in the project. Head over to Read the Docs and see for yourself.

Why shouldn't I use `websockets`?

If you prefer callbacks over coroutines: websockets was created to provide the best coroutine-based API to manage WebSocket connections in Python. Pick another library for a callback-based API.
If you're looking for a mixed HTTP / WebSocket library: websockets aims at being an excellent implementation of RFC 6455: The WebSocket Protocol and RFC 7692: Compression Extensions for WebSocket. Its support for HTTP is minimal — just enough for an HTTP health check.

If you want to do both in the same server, look at HTTP frameworks that build on top of websockets to support WebSocket connections, like Sanic.