sse.py

import crochet
crochet.setup()

from twisted.web import resource, server
import random
from datetime import datetime
import json


def _format_sse(msg, event=None):
    data = []
    if event is not None:
        data.append("event: {}\n".format(event))
    for line in msg.splitlines():
        data.append("data: {}\n".format(line))
    data.append("\n")
    return "".join(data)

class SSEResource(resource.Resource):
    def __init__(self):
        resource.Resource.__init__(self)
        self._listeners = []


    def add_listener(self, request):
        print "listener connected", request
        self._listeners.append(request)
        request.notifyFinish().addBoth(self.remove_listener, request)

    def remove_listener(self, reason, listener):
        print "listener disconnected", listener, "reason", reason
        self._listeners.remove(listener)


    @crochet.run_in_reactor
    def broadcast_message(self, msg, event=None):
        self.broadcast_message_async(msg, event)
    

    def broadcast_message_async(self, msg, event=None):
        sse = _format_sse(msg, event)
        for listener in self._listeners:
            listener.write(sse)

    def render_GET(self, request):
        request.setHeader("Content-Type", "text/event-stream")
        self.add_listener(request)
        return server.NOT_DONE_YET