Django and the Real-Time Web

Note

Very thoughtful talk. Zachary scored some very critical points.

WWW: Changelog

  • Since July 2008 Chrome has stolen the market from IE.
  • Chrome is about to take over IE in the desktop.
  • JavaScript and long polling has come around.

Can’t miss this opportunity

But If we spend all your time playing with bright and shiny we’ll lose our existing customer base.

Zachary’s definition of Real-Time

  • UI before technology
  • Proactive, not reactive
  • Synchronized with the ‘real world’.

Stories

MVC

  • Parc 1978-1979
  • Originally part of Smalltalk-80
  • Now the dominant UI design pattern

How it works on the web:

  • Listen for reqursts

    • Load session state for this user
    • Persist session state, clean up objects

REST

  • **RE**presentational **S**tate **T**ransfer

  • Roy T Fielding (2000)

  • Descriptive, not prescriptive

  • Constraints

    • Client-server
    • Stateless
    • Cacheable
    • Layered
    • Code-on-demand (optional)
    • Uniform

WebSockets

  • Real TCP connection
  • Magic HTTP request to port 80
  • Reduces latency
  • Enables real-time push

REST & WebSockets

  • Full-duplex communication
  • Long-running connections
  • Direct TCP connection
  • TODO missed

Version Control

  • Centralized VCS (CVS, SVN, etc)
  • Distributed VCS (Git, Mercurial, etc)

Summary of the stores

  • Imagine a system where the client is a full MVC stack, as is the server.
  • Content is a matter of pushing/pulling like with DVCS
  • Backbone.js does this, as well as Cappucino

Caching

  • Read RFC 2616

  • Seriously.

  • Etags

  • Cache-Control

  • Conflict resolution:

    (uri, etag, dirty?)

Implications

  • Assumption of orthogonality
  • Lossless representations
  • Authn & Authz are hard topics
  • Pub/sub
  • Resource-oriented client

Pub/Sub

  • AMQP
  • 0MQ
  • Django Signals

Barriers

  • Django ORM - be opinionated!

  • Content Negotiation

    • Don’t have a separate API app
    • Created separately from the standard architecture
    • This is a good use case for Django CBVs

  • JavaScript

  • proxies and middleware