This document discusses using Comet techniques with Python, Django and Orbited to enable real-time data pushing to web browsers. It describes how AJAX polling, long polling and HTTP pushing work. Orbited is introduced as a framework that uses Twisted and supports STOMP, IRC and XMPP protocols to simplify building Comet applications with ready-made JavaScript clients. An example app built with Django and Orbited is also described.

1. Comet web applications with Python, Django & Orbited @ PyCon Italia Qu4ttro http://www.pycon.it/ Massimo Scamarcia http://www.webright.it /

2. Comet web applications with Python, Django & Orbited How to push real-time data to web browsers?

3. Comet web applications with Python, Django & Orbited AJAX Polling Client: sends AJAX request.

4. Server: Data available: sends response.

5. No data: sends empty response. Client: sends AJAX request again.

6. Comet web applications with Python, Django & Orbited Latency, bandwidth, memory usage and scaling issues!

7. Comet web applications with Python, Django & Orbited What about Comet?

8. Comet web applications with Python, Django & Orbited Not a technology in itself

9. Long Polling, IFRAME stream, HTMLFile, XHR Streaming, HTML5 SSE

10. Comet web applications with Python, Django & Orbited It's an hack!

11. Still waiting for an unanimous way to do it.

12. Comet web applications with Python, Django & Orbited Long Polling Client: sends AJAX request.

13. Server: holds the request. Data available: sends response.

14. Timeout reached: empty response. Client: sends AJAX request again.

15. Comet web applications with Python, Django & Orbited Http Push (HTTP Streaming*) Client: sends HTTP request.

16. Server: doesn't terminate the connection.

17. Server: sends data when available.

18. Connection closed: Data is queued.

19. Client reconnects. [*] http://ajaxpatterns.org/HTTP_Streaming

20. Comet web applications with Python, Django & Orbited HTTP Push: better for heavily-loaded apps. Not cross-browser. Long Polling: cross-browser and easy. Bandwidth usage.

21. Too many connections. Async Python servers* are better for both: Twisted, Tornado, Dieselweb, Eventlet, Concurrence, Circuits, Gevent, Cogen. [*] http://nichol.as/asynchronous-servers-in-python

22. Comet web applications with Python, Django & Orbited What about Orbited?

23. Comet web applications with Python, Django & Orbited He's here to solve problems!

24. Comet web applications with Python, Django & Orbited Based on Twisted.