Implementing real time web applications with Django

Implementing real time web applications with Django

• 1.
  Implementing real timeweb applications with Django Kristian Øllegaard 1 onsdag den 6. juni 12
• 2.
  About me • Software Developer/System Administrator at Divio • Django since 0.96 • Danish, lived in Zurich 1,5 year @oellegaard github.com/KristianOellegaard 2 onsdag den 6. juni 12
• 3.
  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 github.com/KristianOellegaard 3 onsdag den 6. juni 12
• 4.
  Finding the righttool • 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 github.com/KristianOellegaard 4 onsdag den 6. juni 12
• 5.
  The tools youwant Node.js + Socket.io @oellegaard github.com/KristianOellegaard 5 onsdag den 6. juni 12
• 6.
  The tools youwant Node.js + Socket.io (well, we don’t want this, but socket.io needs it) @oellegaard github.com/KristianOellegaard 5 onsdag den 6. juni 12
• 7.
  The tools youwant • 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 github.com/KristianOellegaard 6 onsdag den 6. juni 12
• 8.
  Why not implementit 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 github.com/KristianOellegaard 7 onsdag den 6. juni 12
• 9.
  Using redis forcross-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 github.com/KristianOellegaard 8 onsdag den 6. juni 12
• 10.
  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 github.com/KristianOellegaard 9 onsdag den 6. juni 12
• 11.
  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 github.com/KristianOellegaard 10 onsdag den 6. juni 12
• 12.
  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 github.com/KristianOellegaard 11 onsdag den 6. juni 12
• 13.
  Sample usage fromPython import redis import json redis_subscribe = redis.StrictRedis() redis_subscribe.publish("socketio_news", json.dumps({    'title': 'Djangocon 2012', })) @oellegaard github.com/KristianOellegaard 12 onsdag den 6. juni 12
• 14.
  Short demo @oellegaard github.com/KristianOellegaard 13 onsdag den 6. juni 12
• 15.
  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 github.com/KristianOellegaard 14 onsdag den 6. juni 12
• 16.
  Can I usethis today? • Yes • But, please don’t @oellegaard github.com/KristianOellegaard 15 onsdag den 6. juni 12
• 17.
  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 github.com/KristianOellegaard 16 onsdag den 6. juni 12
• 18.
  Notes • Concept should work with any language/framework • E.g. communicating between ruby and python @oellegaard github.com/KristianOellegaard 17 onsdag den 6. juni 12
• 19.
  Questions? http://kristian.io @oellegaard @oellegaard github.com/KristianOellegaard 18 onsdag den 6. juni 12