Implementing real time web applications with Django

Implementing real time web
applications with Django
Kristian Øllegaard

1
onsdag den 6. juni 12

About me

• Software Developer/System Administrator at Divio

• Django since 0.96

• Danish, lived in Zurich 1,5 year

@oellegaard
github.com/KristianOellegaard
2

Why real time?

• Better user experience

• More options in front end

• Make the web feel like native apps

• Showing live data.

• Collaboration is much easier.

@oellegaard
3

Finding the right tool
• Criteria's

• Use websockets, but have fallbacks

• Good browser support (incl. old IE)

• Should be usable from python

• Does not require extensive changes in frontend

• “As fast as it can be”
@oellegaard
4

The tools you want

Node.js + Socket.io

@oellegaard
5

The tools you want

Node.js + Socket.io
(well, we don’t want this, but socket.io needs it)

@oellegaard
5

The tools you want
• Node.js

• Built on Chrome's JavaScript runtime

• Uses an event-driven, non-blocking I/O model

• Socket.io

• One interface for all transport methods (sockets, polling, etc.)

• Compatible with almost everything
@oellegaard
6

Why not implement it in Python?

• Already active community

• Can be used from python without too much trouble

• Most people know very basic javascript

• More importantly, frontend engineers, knows javascript and can
therefore contribute to the different browser-speciﬁc
implementations.

@oellegaard
7

Using redis for cross-language
communication
• Support for many datatypes

• Can be used both as storage and as a queue

• Implemented in many different languages

• For the usage in this talk, any other queue could have been used as
well.

@oellegaard
8

Basic concept
• Something happens, the user
Redis
must be notiﬁed in real time publish publish

•
subscribe

From e.g. django we insert the
E.g.
new value into the queue Django Node.js
Celery

• Node.js listens on the queue subscribe

and emits any content directly Browser
to the browser via socket.io

• This is btw. very fast!
@oellegaard
9

Sample node.js app

var io = require('socket.io').listen(8001);
var redis = require('redis').createClient();

redis.psubscribe("socketio_*"); // Could be any pattern

io.sockets.on('connection', function (socket) {
    redis.on('pmessage', function(pattern, channel, key){
        socket.emit(channel, key);
    });
});

@oellegaard
10

Sample HTML/JS

<script src="http://localhost:8001/socket.io/socket.io.js"></script>
<script>
  var socket = io.connect('http://localhost:8001/');
  socket.on('socketio_news', function (data) {
    console.log(data);
  });
</script>

@oellegaard
11

Sample usage from Python

import redis
import json
redis_subscribe = redis.StrictRedis()
redis_subscribe.publish("socketio_news", json.dumps({
'title': 'Djangocon 2012',
}))

@oellegaard
12

Short demo

@oellegaard
13

Hosting socket.io

• Nginx does not support websockets!

• Needs its own app, if hosted on an application cloud (e.g. heroku)

• Recommended to expose the node server directly

• But hey, it’s node.js, it scales!

@oellegaard
14

Can I use this today?

• Yes

• But, please don’t

@oellegaard
15

Client Authentication

• Socket.io handles authentication from node -> client

• Currently no authentication between django and node.

• Could possibly be solved by storing your sessions in redis and
checking them on connection.

@oellegaard
16

Notes

• Concept should work with any language/framework

• E.g. communicating between ruby and python

@oellegaard
17

Questions?

http://kristian.io
@oellegaard

@oellegaard
18

Implementing real time web applications with Django

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Implementing real time web applications with Django

Ähnlich wie Implementing real time web applications with Django (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Implementing real time web applications with Django