Django on Jython
Frank Wierzbicki
frank.wierzbicki@sun.com

Who am I?
• Frank Wierzbicki
• Project lead for Jython
• I work at Sun (Oracle?) on Jython fulltime

What is Jython?
• Python that runs on the JVM
• Compiled to Java bytecodes instead of
Python bytecodes
• Call Java code seamlessly from Python code

Jython Status
• Current prod version 2.2 is not useful for
Django
• Jython 2.5 beta4 is out
• First RC as early as this Friday
• So production release real-soon-now

Modjy
• Modjy implements WSGI for Jython
• Acts as a bridge to Java Servlets
• integrated into Jython’s core
• This is a big part of how we get Django
working.

zxJDBC
• zxJDBC implements DB-API
• integrated into Jython’s core
• Another crucial piece to get Django
working.

Jython on Django
Status
• Works well with Django 1.0.3 and
postgresql
• Other databases in progress: MySQL,
Oracle, SQLite, MS SqlServer
• Django 1.1 has some refactorings that
Jython will need to catch up on...

Why Jython?
• Massive amounts of Java code out there
• Some really useful Java libs
• Great JVM ecosystem
• Internal Java apps that are not yet exposed
to the web

What can I use?
• setuptools
• ez_install
• virtualenv
• pip
• many more pure Python tools

What can’t I use yet?
• c-extensions
• PIL
• ctypes (but we’re working on this one!)
• iPython (working on this too!)

Configure Jython
• Get ez_setup.py
• run “jython ez_setup.py”
• In Jython’s bin directory will be an
ez_install that runs from Jython

Installing Django on
Jython
• Get 1.0.3+ Django - run “jython setup.py
install”
• From http://django-jython.googlecode.com
get django-jython-1.0b1.tar.gz, untar it and
run “jython setup.py install”
• see the django-jython project on
googlecode.com for more detail

Java Platform
• Now takes advantage of Java 5 libraries
• Java 5 concurrency libs: No GIL!
• Use a choice of Java garbage collectors
• Use Java native threads
• -J flag namespace for JVM config

Java Integration
• Jython integrates well with Java
• Java classes and interfaces can be
subclassed from Jython
• These subclasses are now “new style”
classes.

Example: The Java lib
poi can read Excel

Deployment
• run “jython manage.py war --include-java-
libs=jdbcdriver.jar”
• This will produce a “war file”
• Copy this war file to the auto-deploy
directory for most application servers (like
GlassFish)

war format for doj
|-- WEB-INF
| |-- lib
| `-- lib-python
| |-- Lib
| |-- django
| |-- doj
| `-- mysite
`-- media

Why Django on Jython?
• Lots of ops departments out there that
want to deploy to Java App Servers - “give
us a war file”
• They have lots of tools for monitoring, etc
• Jython has a good story for threading and
performance - and it’s getting better.

Da Vinci Machine
• JVM gets friendlier to dynamic languages
• On the project plan for JDK 7 -- some of it
has already there in a hidden state for JDK6
• Method Handles, Invokedynamic, etc
• Hotspot is one of the world’s best tuned
VMs - about to be tuned better for us!

Jython Book due in
2009 from Apress
• Josh Juneau
• Jim Baker
• Leo Soto
• Victor NG
• Frank Wierzbicki

Where to Find Out
More
• http://www.jython.org
• http://wiki.python.org/jython
• http://fwierzbicki.blogspot.com
• Twitter: fwierzbicki
• http://www.netbeans.org/features/python/
• https://glassfish.dev.java.net/