Presentation about Websocket usage within Python projects, using txWebsocket, Twisted and Django.

1. Django WS
Building Single-page web-applications with Django,
Twisted and TxWebsocket
Jeroen van Veen

2. Websockets?
● Persistent TCP connection browser-server
● Data exchange
○ Handshake protocol (currently Hybi-16)
○ Both UTF-8-encoded & binary data
○ Low latency, no headers
○ Easy serializing with JSON
● Support
○ Python: TxWebsocket, Autobahn WS, Gevent-websocket
○ Browser: Chrome, Firefox, Opera, Safari, IE10
○ Browser fallback: Flash Websocket

3. Multi-page
VS
Single-page

4. Bootstrapping
● Each url routes initially to the HTML/JS bootstrap view
● The websocket connection is initialized
● During the handshake, the sessionid cookie is being
reused
● Set transport.user and add the transport to the client
Pool
● Signals are used to notify listening code for events like
connect, disconnect, view_changed, etc.
● The navigation-bar URL is routed through the javascript
application and gets the appropriate content

5. URL Routing
● Mimick Django URL routing serverside
● And clientside...
● XRegexp for named group support
● Usable with HTML5 history API
● Capture link click events
● Client URL tracking and signalling

7. Django-WS
● Django authentication during handshake with session
cookie
● Client transport pool handling
● Event subscription (f.i. client connect,disconnect)
● Websocket URL-routing protocol
● Twisted MultiFile for static resources & management
commands to integrate Twisted in Django
● dws namespace, seperate python modules
● Clientside RequireJS modules
● BSD license

8. In development
● Django-ws modules: core, misc, blog, wiki
● Narrowcaster
● ...

9. Challenges
● Integrate further with Django
○ Use existing conventions where possible
○ Compatibility modus for HTTP-based Django apps
● Cleanup design
● Proper documentation
● Usable reference Websocket CMS
● Community
● SEO

10. Questions?
Code
https://github.com/phrearch/django-ws-core
Contact
vanveen@gw20e.com
https://twitter.com/#!/jeroen_van_veen