High-performance WebSockets for your Flask apps powered by uWSGI.
Project description
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(msg)
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)
Note that you cannot use multiple threads with gevent loop engine.
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.
Examples
There are several examples available here.
API
flask_uwsgi_websocket.WebSocket
Applies WebSocketMiddleware to your Flask App, allowing you to decorate routes with the route method, turning them into WebSocket handlers.
Additionally monkey-patches app.run, to run your app directly in uWSGI.
route(url)
run(debug, host, port, **kwargs) **kwargs are passed to uWSGI as command line arguments.
flask_uwsgi_websocket.WebSocketMiddleware
WebSocket Middleware which automatically performs WebSocket handshake and passes WebSocketClient instances to your route.
flask_uwsgi_websocket.WebSocketClient
Exposes the uWSGI WebSocket API.
recv() (alias WebSocket.receive())
recv_nb()
send(msg)
send_binary(msg)
recv_nb()
send_from_sharedarea(id, pos)
send_binary_from_sharedarea(id, pos)
flask_uwsgi_websocket.GeventWebSocket
Fancier WebSocket abstraction that takes advantage of Gevent loop engine. Requires uWSGI to be run with --uwsgi option.
flask_uwsgi_websocket.GeventWebSocketMiddleware
Automatically performs WebSocket handshake and passes a GeventWebSocketClient instance to your route.
flask_uwsgi_websocket.GeventWebSocketClient
WebSocket client abstraction with fully non-blocking methods.
receive()
send(msg)
close()
connected
Advanced Usage
Normally websocket routes happen outside of the normal request context. You can get a request context in your websocket handler by using app.request_context:
app = Flask(__name__) ws = GeventWebSocket(app) @ws.route('/websocket') def websocket(ws): with app.request_context(ws.environ): print request.args
Project details
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