The final motivating example, a realtime chat room. This example

requires <a href="http://flask.pocoo.org/">Flask</a> ( but not neccesarily so, you could use Django,

Pyramid, etc ). The corresponding Javascript and HTML files can

be found <a href="https://github.com/sdiehl/minichat">here</a>.

<code class="python"># Micro gevent chatroom.

# ----------------------

from flask import Flask, render_template, request

from gevent import queue

from gevent.pywsgi import WSGIServer

import simplejson as json

app = Flask(__name__)

app.debug = True

class Room(object):

def __init__(self):

self.users = set()

self.messages = []

def backlog(self, size=25):

return self.messages[-size:]

def subscribe(self, user):

self.users.add(user)

def add(self, message):

for user in self.users:

print user

user.queue.put_nowait(message)

self.messages.append(message)

class User(object):

def __init__(self):

self.queue = queue.Queue()

rooms = {

'python': Room(),

'django': Room(),

}

users = {}

@app.route('/')

def choose_name():

return render_template('choose.html')

@app.route('/<uid>')

def main(uid):

return render_template('main.html',

uid=uid,

rooms=rooms.keys()

)

@app.route('/<room>/<uid>')

def join(room, uid):

user = users.get(uid, None)

if not user:

users[uid] = user = User()

active_room = rooms[room]

active_room.subscribe(user)

print 'subscribe', active_room, user

messages = active_room.backlog()

return render_template('room.html',

room=room, uid=uid, messages=messages)

@app.route("/put/<room>/<uid>", methods=["POST"])

def put(room, uid):

user = users[uid]

room = rooms[room]

message = request.form['message']

room.add(':'.join([uid, message]))

return ''

@app.route("/poll/<uid>", methods=["POST"])

def poll(uid):

try:

msg = users[uid].queue.get(timeout=10)

except queue.Empty:

msg = []

return json.dumps(msg)

if __name__ == "__main__":

http = WSGIServer(('', 5000), app)

http.serve_forever()