natemurthy/sse_flask.py

## sse_flask.py
# author: oskar.blom@gmail.com
#
# Make sure your gevent version is >= 1.0
import gevent
from gevent.wsgi import WSGIServer
from gevent.queue import Queue

from flask import Flask, Response

import time


# SSE "protocol" is described here: http://mzl.la/UPFyxY
class ServerSentEvent(object):

    def __init__(self, data):
        self.data = data
        self.event = None
        self.id = None
        self.desc_map = {
            self.data : "data",
            self.event : "event",
            self.id : "id"
        }

    def encode(self):
        if not self.data:
            return ""
        lines = ["%s: %s" % (v, k)
                 for k, v in self.desc_map.iteritems() if k]

        return "%s\n\n" % "\n".join(lines)

app = Flask(__name__)
subscriptions = []

# Client code consumes like this.
@app.route("/")
def index():
    debug_template = """
     <html>
       <head>
       </head>
       <body>
         <h1>Server sent events</h1>
         <div id="event"></div>
         <script type="text/javascript">

         var eventOutputContainer = document.getElementById("event");
         var evtSrc = new EventSource("/subscribe");

         evtSrc.onmessage = function(e) {
             console.log(e.data);
             eventOutputContainer.innerHTML = e.data;
         };

         </script>
       </body>
     </html>
    """
    return(debug_template)

@app.route("/debug")
def debug():
    return "Currently %d subscriptions" % len(subscriptions)

@app.route("/publish")
def publish():
    #Dummy data - pick up from request for real data
    def notify():
        msg = str(time.time())
        for sub in subscriptions[:]:
            sub.put(msg)

    gevent.spawn(notify)

    return "OK"

@app.route("/subscribe")
def subscribe():
    def gen():
        q = Queue()
        subscriptions.append(q)
        try:
            while True:
                result = q.get()
                ev = ServerSentEvent(str(result))
                yield ev.encode()
        except GeneratorExit: # Or maybe use flask signals
            subscriptions.remove(q)

    return Response(gen(), mimetype="text/event-stream")

if __name__ == "__main__":
    app.debug = True
    server = WSGIServer(("", 5000), app)
    server.serve_forever()
    # Then visit http://localhost:5000 to subscribe
    # and send messages by visiting http://localhost:5000/publish
	# author: oskar.blom@gmail.com
	#
	# Make sure your gevent version is >= 1.0
	import gevent
	from gevent.wsgi import WSGIServer
	from gevent.queue import Queue

	from flask import Flask, Response

	import time


	# SSE "protocol" is described here: http://mzl.la/UPFyxY
	class ServerSentEvent(object):

	def __init__(self, data):
	self.data = data
	self.event = None
	self.id = None
	self.desc_map = {
	self.data : "data",
	self.event : "event",
	self.id : "id"
	}

	def encode(self):
	if not self.data:
	return ""
	lines = ["%s: %s" % (v, k)
	for k, v in self.desc_map.iteritems() if k]

	return "%s\n\n" % "\n".join(lines)

	app = Flask(__name__)
	subscriptions = []

	# Client code consumes like this.
	@app.route("/")
	def index():
	debug_template = """
	<html>
	<head>
	</head>
	<body>
	<h1>Server sent events</h1>
	<div id="event"></div>
	<script type="text/javascript">

	var eventOutputContainer = document.getElementById("event");
	var evtSrc = new EventSource("/subscribe");

	evtSrc.onmessage = function(e) {
	console.log(e.data);
	eventOutputContainer.innerHTML = e.data;
	};

	</script>
	</body>
	</html>
	"""
	return(debug_template)

	@app.route("/debug")
	def debug():
	return "Currently %d subscriptions" % len(subscriptions)

	@app.route("/publish")
	def publish():
	#Dummy data - pick up from request for real data
	def notify():
	msg = str(time.time())
	for sub in subscriptions[:]:
	sub.put(msg)

	gevent.spawn(notify)

	return "OK"

	@app.route("/subscribe")
	def subscribe():
	def gen():
	q = Queue()
	subscriptions.append(q)
	try:
	while True:
	result = q.get()
	ev = ServerSentEvent(str(result))
	yield ev.encode()
	except GeneratorExit: # Or maybe use flask signals
	subscriptions.remove(q)

	return Response(gen(), mimetype="text/event-stream")

	if __name__ == "__main__":
	app.debug = True
	server = WSGIServer(("", 5000), app)
	server.serve_forever()
	# Then visit http://localhost:5000 to subscribe
	# and send messages by visiting http://localhost:5000/publish