fredrocious / sockjs-tornado

WebSocket emulation - Python server

SockJS-tornado server

SockJS-tornado is a Python server side counterpart of SockJS-client browser library running on top of Tornado framework.

Simplified echo SockJS server could look more or less like:

from tornado import web, ioloop
from sockjs.tornado import SockJSRouter, SockJSConnection

class EchoConnection(SockJSConnection):
    def on_message(self, msg):
        self.send(msg)

if __name__ == '__main__':
    EchoRouter = SockJSRouter(EchoConnection, '/echo')

    app = web.Application(EchoRouter.urls)
    app.listen(9999)
    ioloop.IOLoop.instance().start()

(Take look at examples for a complete version).

Subscribe to SockJS mailing list for discussions and support.

SockJS-tornado API

SockJS provides slightly different API than _tornado.websocket_. Main differences are:

1. Depending on transport, actual client connection might or might not be there. So, there is no _self.request_ and other _tornado.web.RequestHandler_ properties.
2. Changed _open_ callback name to _on_open_ to be more consistent with other callbacks.
3. Instead of _write_message_, all messages are sent using _send_ method. Just in case, _send_ in _tornado.web.RequestHandler_ sends raw data over the connection, without encoding it.
4. There is handy _broadcast_ function, which accepts list (or iterator) of clients and message to send.

Settings

You can pass various settings to the _SockJSRouter_, in a dictionary:

MyRouter = SockJSRouter(MyConnection, '/my', dict(disabled_transports=['websocket']))

Deployment

sockjs-tornado properly works behind haproxy and it is recommended deployment approach.

Sample configuration file can be found here.

If your log is full of "WARNING: Connection closed by the client", pass _no_keep_alive_ as _True_ to _HTTPServer_ constructor:

HTTPServer(app, no_keep_alive=True).listen(port)

or:

app.listen(port, no_keep_alive=True)