DjangoCon wrapup

I went to DjangoCon this past week for work. Django is one of my favorite frameworks. I dropped PHP and the symfony framework to learn python and Django and I haven’t looked back. I think for Mozilla’s webdev team it would be the framework of choice. We have 100s of sites in many frameworks, but not a lot of resuability. Django apps are built to built to be reusable. If you build correctly you don’t have to refactor, it’s already done.

Here’s a collection of notes I collected through the conference.

Day one

Keynote - Avi Bryant

Frameworks lock us into RDBMS = bad

This keynote mentioned the limits of modern frameworks and modern web development. Essentially frameworks are great for getting started, but as a site grows, the framework gets replaced little by little. Sometimes it can get in the way - such as with limitation of database choices.

UR doing it wrong - James Bennet

James outlined a few key problems that many Django developers run into:

  • learning python as you go
    • doesn’t work unless you know some programming upfront
    • do the python tutorial
    • read python in a nutshell or dive into python
  • Things you should know:
    • subclasses
    • super()
    • slides went too fast… hopefully they’ll be posted

All in all RTFM for python and Django :)

Learn about other py packages… like twisted. If Twisted Matrix was implemented in Ruby it would be advertised as the second coming of Christ.

Bennet’s Django App review smoketests:

  • installable via pip, easy_install or setup.py
    • read distutils-guide
    • stay away from setuptools
  • have a README
  • INSTALL file list deps
  • Write DOCUMENTATION
    • use sphinx.pocoo.org
    • store it in your package and upload package docs
  • LICENSE (most Django apps use BSD)
  • Write unit tests
  • django-lint - to look over code (like pep8.py)

pro-django is a decent book, but not written by Bennet.

Testing - Eric Holscher

  • Django 1.1 encourages you to test by auto-creating tests.py.
  • Support for:
    • Unittests
    • Doctest
    • Tests done in a db transacation
  • Test Driven Documentation (TDD + DDD)
  • Doctest
    • easy
    • can’t use PDB
    • Hides certain failures
  • Unittests via Django TestCase
    • XUnit
    • setup/Teardown
    • adds db fixtures
    • assertions
    • mail testing/inbox testing
    • url testing
  • TestCase
    • Browserless Request/Response testing
    • Similar to sfBrowser in symfony
  • Google Summer of Code (for Django 1.2)
    • Coverage reports!
  • I need to learn PDB

Deploying Django -

Run mod_wsgi in daemon mode.

Day 2

Keynote - Ian Bicking

GNU Manifest: > I consider that the golden rule requires that if I like a program I must share it with other people who like it. Software sellers want to divide the users and conquer them, making each user agree not to share with others. I refuse to break solidarity with other users in this way. I cannot in good conscience sign a nondisclosure agreement or a software license agreement. …

So that I can continue to use computers without dishonor, I have decided to put together a sufficient body of free software so that I will be able to get along without any software that is not free.

  • GNU manifesto was the idea of sharing software amongst friends
  • GNU has purpose - BSD, etc is just a rule - free to share
  • Free is not just the absense of copyright
  • Free is not a reaction to existing rules, but a golden rule
  • Not just a fight against MS
  • Need to find morality (the why) within the practical (the law, or what you can do)
  • Open sourcing closed source code isn’t building open source
  • This might apply to Mozilla… as webkit has taken off more than Gecko.
  • Open source is person to person not company to company - despite sponsorship.

Using Django in Non-standard ways - Eric Florenzano

  • Django loosely coupled
  • Replace templating with Jinja 2
  • Copy Django methods into djangoext to easily customize Django behavior
  • Not using django.contrib.auth
    • reasons: writing a fb app - no auth needed
    • no shoehorning needed - saves time - less overhead
  • skip the orm?
    • legacy dbs
    • non standard or db (or non-relational database)
    • no database
  • wsgi middleware has some cool shit
    • repose.bitblt: autoscales images
    • repose.squeeze: will concat js/css on the fly based on statistical analysis
  • non standard Django based apps
    • YARDBird - IRCBot framework
    • djng micro framework
    • Jngo- singlefile cms
  • using admin in a nonstandard way is hard/impossible coupled with ORM and auth

Real-time web and other Buzzwords - Chris Wanstrath

  • more than just getting your rss feeds faster
  • push vs. pull
  • 1 persisting connection vs polling
  • comet/flash-xml/or html5 web socket
  • orbitted - open source python comet server
  • zeddicus - does the business logic
  • orbitted has its own js libs - its a simple port/socket thing for your server code to deal with - not request/response.
  • all connections are persisting browser/orbitted orbitted/zeddicus
  • You can even use orbitted to connect straight to IRC and write a client in JS
  • Jetty also is good for comet

Also: * see webhooks * see pubsubhubub

Pluggable, Reusable Django Apps: A Use Case and Proposed Solution - Shawn Rider and Nowell Strite

  • PBS moved from perl to django - build a lot of reusable apps
  • convincing your superiors
    • need a good story -
    • existing base of python helped
    • With Django easy to do things right without doing things slow
    • be really good…
  • built a lot of apps to be very reusable, and pluggable based on requirements PBS had

Day 3

Keynote - Ted Leung - Sun

  • Django jobs are a growing market
  • Preferred by startups
  • Bespin/wave - cool
  • APIs are big… still
  • Physically impossible to create purely server-side interactions that are usable enough - rely on rest/comet/ajax/etc to bridge gap

Scaling Django Mike Malone

  • MM from Pownce (now sixapart)
  • Slides started out as “Building Scalable Web Applications”
  • Django didn’t get in the way too much when it came to scaling
  • Django had tons of caching support
  • Cached objects by hand (memcached) and object ID lists
  • Use memache for sessions too
  • use signals to signal cache invalidation
  • race conditions…
  • Queue shit… gearman, rabbit mq, etc.
  • Memecached incr/decr operators are awesome
  • See gh/mmalone/django-caching
  • See gh:…/django-multidb
  • to combat slavelag use a memcache key to alternate between master or slave

Gearman - working later - Chris Heisel

  • Gearman - a work later alt to rabbit mq
  • Makes the most sense for something like cesium, with a bazillion worker bees foxes feeding off a single queue

Also at the con, I talked to someone about rebuilding large apps… and they took a PHP app and used URL rewriting to and a lot of PHP/Python glue code to build a seamless transitory app. The rule is, all new functionality was done up in python while the old app was in maintenance mode.

More talks here!