Flask-Sockets
=============
Elegant WebSockets for your Flask apps.
.. image:: http://farm4.staticflickr.com/3689/9755961864_577e32a106_c.jpg
Simple usage of ``route`` decorator:
.. code-block:: python
from flask import Flask
from flask_sockets import Sockets
app = Flask(__name__)
sockets = Sockets(app)
@sockets.route('/echo')
def echo_socket(ws):
while not ws.closed:
message = ws.receive()
ws.send(message)
@app.route('/')
def hello():
return 'Hello World!'
if __name__ == "__main__":
from gevent import pywsgi
from geventwebsocket.handler import WebSocketHandler
server = pywsgi.WSGIServer(('', 5000), app, handler_class=WebSocketHandler)
server.serve_forever()
Usage of `Flask blueprints`_:
.. code-block:: python
from flask import Flask, Blueprint
from flask_sockets import Sockets
html = Blueprint(r'html', __name__)
ws = Blueprint(r'ws', __name__)
@html.route('/')
def hello():
return 'Hello World!'
@ws.route('/echo')
def echo_socket(socket):
while not socket.closed:
message = socket.receive()
socket.send(message)
app = Flask(__name__)
sockets = Sockets(app)
app.register_blueprint(html, url_prefix=r'/')
sockets.register_blueprint(ws, url_prefix=r'/')
if __name__ == "__main__":
from gevent import pywsgi
from geventwebsocket.handler import WebSocketHandler
server = pywsgi.WSGIServer(('', 5000), app, handler_class=WebSocketHandler)
server.serve_forever()
Combining WebSockets with Ajax (XHR) endpoints also comes handy with the support of session handling built-in to sockets as well. As an example you could use an Ajax login call which would create a new session and accordingly set a secure HttpOnly cookie to the browser. After authorization, you can connect to the WebSocket endpoint and reuse the session handling from Flask there as well (as shown here: https://pythonhosted.org/Flask-Session/). Access to other custom cookies is also possible via Flasks ``request.cookies`` property.
Serving WebSockets in Python was really difficult. Now it's not.
Installation
------------
To install Flask-Sockets, simply::
$ pip install Flask-Sockets
Deployment
----------
A custom Gunicorn worker is included to make deployment as friendly as possible::
$ gunicorn -k flask_sockets.worker hello:app
Production services are provided by `gevent <http://www.gevent.org>`_
and `gevent-websocket <https://bitbucket.org/noppo/gevent-websocket>`_.
The given example can run standalone as main.
Anything that inserts ``wsgi.websocket`` into the WSGI environ is
supported, but gevent-websocket is recommended.
Development / Testing
---------------------
Because the Werkzeug development server cannot provide the WSGI environ with
a websocket interface, it is not possible to run a Flask app using the standard
``app.run()``.
If you try to, Flask will still try to serve on all the specified routes, and
throw a ``KeyError`` whenever a client tries to connect to a websocket route.
Instead, just use the included gunicorn worker (explained above), or anything that
can insert ``wsgi.websocket`` into the WSGI environ.
WebSocket Interface
-------------------
The websocket interface that is passed into your routes is
`provided by gevent-websocket <https://bitbucket.org/noppo/gevent-websocket>`_.
The basic methods are fairly straightforward —
``send``, ``receive``, ``send_frame``, and ``close``.
Release History
---------------
v0.2.1
~~~~~~
- Add support of `Flask blueprints`_.
v0.2.0
~~~~~~
- Add request context into the socket handler.
- Fallback to Flask logic if websocket environment is not available.
- Use Flask routing to allow for variables in URL
v0.1.0
~~~~~~
- Initial release.
.. _Flask blueprints: http://flask.pocoo.org/docs/latest/blueprints/