Getting Started

simple-websocket includes a collection of WebSocket servers and clients for Python, including support for both traditional and asynchronous (asyncio) workflows. The servers are designed to be integrated into larger web applications if desired.

Installation

This package is installed with pip:

pip install simple-websocket

Server Example #1: Flask

The following example shows how to add a WebSocket route to a Flask application.

from flask import Flask, request
from simple_websocket import Server, ConnectionClosed

app = Flask(__name__)

@app.route('/echo', websocket=True)
def echo():
    ws = Server.accept(request.environ)
    try:
        while True:
            data = ws.receive()
            ws.send(data)
    except ConnectionClosed:
        pass
    return ''

Integration with web applications using other WSGI frameworks works in a similar way. The only requirement is to pass the environ dictionary to the Server.accept() method to initiate the WebSocket handshake.

Server Example #2: Aiohttp

The following example shows how to add a WebSocket route to a web application built with the aiohttp framework.

from aiohttp import web
from simple_websocket import AioServer, ConnectionClosed

app = web.Application()

async def echo(request):
    ws = await AioServer.accept(aiohttp=request)
    try:
        while True:
            data = await ws.receive()
            await ws.send(data)
    except ConnectionClosed:
        pass
    return web.Response(text='')

app.add_routes([web.get('/echo', echo)])

if __name__ == '__main__':
    web.run_app(app, port=5000)

Server Example #3: ASGI

The next server example shows an asynchronous application that supports the ASGI protocol.

from simple_websocket import AioServer, ConnectionClosed

async def echo(scope, receive, send):
    ws = await AioServer.accept(asgi=(scope, receive, send))
    try:
        while True:
            data = await ws.receive()
            await ws.send(data)
    except ConnectionClosed:
        pass

Client Example #1: Synchronous

The client example that follows can connect to any of the server examples above using a synchronous interface.

from simple_websocket import Client, ConnectionClosed

def main():
    ws = Client.connect('ws://localhost:5000/echo')
    try:
        while True:
            data = input('> ')
            ws.send(data)
            data = ws.receive()
            print(f'< {data}')
    except (KeyboardInterrupt, EOFError, ConnectionClosed):
        ws.close()

if __name__ == '__main__':
    main()

Client Example #2: Asynchronous

The next client uses Python’s asyncio framework.

import asyncio
from simple_websocket import AioClient, ConnectionClosed

async def main():
    ws = await AioClient.connect('ws://localhost:5000/echo')
    try:
        while True:
            data = input('> ')
            await ws.send(data)
            data = await ws.receive()
            print(f'< {data}')
    except (KeyboardInterrupt, EOFError, ConnectionClosed):
        await ws.close()

if __name__ == '__main__':
    asyncio.run(main())