The State of WebSockets in Django
- 1. The State of WebSockets in Django Rami Sayar - @ramisayar Technical Evangelist Microsoft Canada
- 2. Agenda • Where is WebSockets right now? • Where is Socket.IO? • Where does Django fit in? • Using Django SwampDragon. • Using Gevent. CONFOO - @RAMISAYAR
- 3. Assumptions • Working knowledge of Django, JavaScript & Python. Note: Slides will be made available. CONFOO - @RAMISAYAR
- 4. What is a production web app? • Django is surrounded by tons of applications, services and code in production. • Advanced Django architecture is needed to support Django in production without failing hard. • WebSockets falls apart from the rest. CONFOO - @RAMISAYAR
- 5. WebSockets • “WebSocket is a protocol for full-duplex communication channels over a single TCP connection.” Wikipedia • Image Reference CONFOO - @RAMISAYAR
- 7. Socket.IO • “Socket.IO enables real-time bidirectional event-based communication. It works on every platform, browser or device, focusing equally on reliability and speed.” Reference • Use by everyone: Microsoft Office, Yammer, Zendesk, Trello, etc… CONFOO - @RAMISAYAR
- 8. Socket.IO Version 1.0 is here! Technically, now at v1.3.4 CONFOO - @RAMISAYAR
- 9. Python, Django & WebSockets. CONFOO - @RAMISAYAR
- 10. Python and WebSockets • Python and WebSockets has notoriously been very difficult. • Two reasons: • WSGI protocol does not support WebSockets. Most popular form of web request handling in the Python web apps. Most frameworks are designed for use with FastCGI or mod_wsgi, etc. • Default Python networked apps not exactly designed for event-based communication, you have to use things like gevent and twisted/tornado. CONFOO - @RAMISAYAR
- 11. Django & WebSockets • Django applications complete HttpResponses. • Django not well suited for WebSocket event handling structure nor the channel approach in Socket.IO. CONFOO - @RAMISAYAR
- 12. Presenting 3 Methods for WebSockets in Django CONFOO - @RAMISAYAR
- 13. gevent • “gevent is a coroutine-based Python networking library that uses greenlets to provide a synchronous API on top of the libev event loop.” • Event loop based on libev (same as Node.js) • Lightweight execution units, a.k.a. “lightweight threads”. • Cooperative sockets with SSL support. • Similar programming model to Node.js. CONFOO - @RAMISAYAR
- 14. gevent-socketio • gevent-socketio is a pure Python implementation of the Socket.IO protocol. Basically, it is a port of Socket.IO and typically behind in major releases. • Designed to work with multiple different WSGI-based web frameworks. • Handles the “WSGI” problem by providing a custom gevent WSGI server for use with gevent-socketio. • Only dependencies are gevent. • Imperfect solution: Django is still blocking (monkey patching is not perfect). CONFOO - @RAMISAYAR
- 15. Demo 1: Django chat engine with gevent-socketio https://github.com/abourget/gevent-socketio/tree/master/examples/ django_chat CONFOO - @RAMISAYAR
- 16. “Native” Django Implementation • Previous approach requires significant modifications to your current Django app serving stack. Native as in you don’t need to know anything besides Django. • Building an implementation of WebSockets on top of Django. • Identified two problems for WebSockets in Django: • Problems with WSGI still present EXCEPT in uWSGI. • Networked event handling model is problematic. • Solution: • Use Nginx which follows – event-driven async architecture. • uWSGI & Gevent for event handling. CONFOO - @RAMISAYAR
- 17. Django-WebSocket-Redis • Module implements websockets on top of Django. • Use Redis as a data store for messaging behind uWSGI and Nginx. • Runs a separate Django main loop in a cooperative concurrency model using gevent -> 1 thread for all open websockets. • Django can be started as usual with ‘./manage.py runserver’. • Normal requests communication with separate main (websocket) loop through Redis. • Read: Offloading Websockets and Server-Sent Events AKA “Combine them with Django safely” CONFOO - @RAMISAYAR
- 18. Demo 2: Django-WebSockets-Redis https://github.com/jrief/django-websocket-redis CONFOO - @RAMISAYAR
- 19. SwampDragon • New project that adds websocket support • Self-publishing models • Django ORM Style Data Filter for Subscription Channels – Similar to WebSockets + Data Filter • Relies on Redis for messaging + Tornado • Angular JS Support CONFOO - @RAMISAYAR
- 20. Demo 3: Django Swampdragon https://github.com/jonashagstedt/swampdragon CONFOO - @RAMISAYAR
- 21. On Redis • Redis is extremely popular as an easy and simple publish- subscribe. • Redis is very particular about memory. Running out of memory in Redis -> CRASH AND BURN! • If you don’t have enough memory in your VM to run Redis Cache -> Change your approach, use Apache Kafka. CONFOO - @RAMISAYAR
- 22. What did we learn? • The State of WebSockets in Django. • Django and WebSockets is not impossible. CONFOO - @RAMISAYAR
- 23. Thank You! Questions? Follow @ramisayar CONFOO - @RAMISAYAR
- 24. Resources • http://swampdragon.net/ • http://django-websocket-redis.readthedocs.org/en/latest/ • https://github.com/jrief/django-websocket-redis • https://github.com/abourget/gevent-socketio/tree/master/ examples/django_chat • http://jpadilla.com/post/74391616727/the-easiest-way-to-add- websockets-to-django • http://ferretfarmer.net/2013/09/05/tutorial-real-time-chat-with- django-twisted-and-websockets-part-1/ CONFOO - @RAMISAYAR
- 25. ©2013 Microso- Corpora1on. All rights reserved. Microso-, Windows, Office, Azure, System Center, Dynamics and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The informa1on herein is for informa1onal purposes only and represents the current view of Microso- Corpora1on as of the date of this presenta1on. Because Microso- must respond to changing market condi1ons, it should not be interpreted to be a commitment on the part of Microso-, and Microso- cannot guarantee the accuracy of any informa1on provided a-er the date of this presenta1on. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.
Editor's Notes
- #5: What does a web application look like in production?