Flask-uWSGI-WebSocket

High-performance WebSockets for your Flask apps powered by uWSGI. Low-level uWSGI WebSocket API access and flexible high-level abstractions for building complex WebSocket applications with Flask. Supports several different concurrency models including Gevent. Inspired by Flask-Sockets.

from flask import Flask
from flask.ext.uwsgi_websocket import GeventWebSocket

app = Flask(__name__)
ws = GeventWebSocket(app)

@ws.route('/echo')
def echo(ws):
    while True:
        msg = ws.receive()
        ws.send(message)

if __name__ == '__main__':
    app.run(gevent=100)

Installation

Preferred method of installation is via pip:

$ pip install Flask-uWSGI-WebSocket

Deployment

You can use uWSGI's built-in HTTP router to get up and running quickly:

$ uwsgi --master --http :8080 --http-websockets --wsgi echo:app

...which is what app.run does after wrapping your Flask app:

app.run(debug=True, host='localhost', port=8080, master=true, processes=8)

uWSGI supports several concurrency models, in particular it has nice support for Gevent. If you want to use Gevent, import flask.ext.uwsgi_websocket.GeventWebSocket and configure uWSGI to use the gevent loop engine:

$ uwsgi --master --http :8080 --http-websockets --gevent 100 --wsgi echo:app

...or:

app.run(debug=True, gevent=100)

For production you'll probably want to run uWSGI behind Haproxy or nginx, instead of using the built-int HTTP router. Explore the uWSGI documentation for more detail about the various concurrency and deployment options.

Development

It's possible to take advantage of Flask's interactive debugger by installing werkzeug's DebuggedApplication middleware:

from werkzeug.debug import DebuggedApplication
app.wsgi_app = DebuggedApplication(app.wsgi_app, True)

...and running uWSGI with only a single worker:

$ uwsgi --master --http :8080 --http-websockets --wsgi-file --workers 1 --threads 8 app.py

If you use app.run(debug=True) or export FLASK_UWSGI_DEBUG, Flask-uWSGI-Websocket will do this automatically for you.

API

flask_uwsgi_websocket.WebSocket

Automatically performs WebSocket handshake for you, but otherwise only exposes the uWSGI WebSocket API.

websocket.recv() (alias websocket.receive())

websocket.recv_nb()

websocket.send(msg)

websocket.send_binary(msg)

websocket.recv_nb()

websocket.send_from_sharedarea(id, pos)

websocket.send_binary_from_sharedarea(id, pos)

flask_uwsgi_websocket.GeventWebSocket

Fancier WebSocket abstraction that takes advantage of Gevent loop engine. Route handlers are spawned in their own greenlets and able to easily send messages to each other.

websocket.receive()

websocket.send()

websocket.close()

websocket.connected