Jython 2.7 and techniques for integrating with Java - Frank Wierzbicki

Jython 2.7 Update Frank WierzbickiWednesday, May 9, 2012

Why use Jython? • Massive amounts of Java code out there • Some really useful Java libs • Great JVM ecosystem • But we’d all rather be writing Python code, right?Wednesday, May 9, 2012

Status • Jython 2.7 is progresing well • bytearray and io are the last missing big features • 2.7 Unit test compliance • 684 failing tests out of 10786 (~6%) • Most of these are due to bytearray/ioWednesday, May 9, 2012

Dates • Jython 2.7 work is being sponsored by Adconion. (Thanks!) • Jython 2.7 alpha should be out this month • The target for a production release is July 15 - which happens to be the ﬁnal day of my contract to get Jython to 2.7 :)Wednesday, May 9, 2012

Why is Adconion sponsoring Jython? • Adconion is a hybrid Java/Python shop based out of LA • They use Python version 2.7 and Jython 2.5 • They have internal Django apps that access Java libraries • The 2.5/2.7 differences are a pain • They’d like to give back to the communityWednesday, May 9, 2012

Collaborators • Major apps • Implementations - CPython, PyPy • Other Java dynamic languages - JRuby • Tooling support • Java Virtual Machine development • Academic research - gradual typingWednesday, May 9, 2012

Features • Abstract Base Classes • Bytearray • __format__ • OrderedDict • lots of Lib updates • See CPython 2.6/2.7 what’s new for moreWednesday, May 9, 2012

Not in Jython 2.7 • multiprocessing • buffer (so far never has been in Jython) • memoryview (though there is a start, we’ll see)Wednesday, May 9, 2012

java.util.concurrent not interpreted Java Platform no GIL -J for setting options like one of 20 or so GCs heap size etc • Starting to (optionally) use invokedynamic • Everything is compiled to Java Bytecode • Use a choice of Java garbage collectors • Always uses Java native threads • All cores are usedWednesday, May 9, 2012

Java Integration • Jython integrates well with Java • Jython makes calling into Java look like standard Python code • Java classes and interfaces can be subclassed from JythonWednesday, May 9, 2012

builtin Java interfaces • Jython’s list implements Java List<Object> • Jython’s dict implements Map and ConcurrentMap • Jython’s set implements Java SetWednesday, May 9, 2012

//Java interface package org.acme; public interface MyInterface { public List strList(); } #From Python in file “acme.py” from org.acme import MyInterface class pyobject(MyInterface): def strList(self): return [‘a’, ‘b’, ‘c’] //From Java PythonInterpreter interpreter = new PythonInterpreter (); interpreter.exec ("from acme import pyobject"); MyInterface pythonObject = interpreter.get ("pyobject"); List pywords = pythonObject.strList() for (Object o : pyList){ String string = ((PyObject)o).__toJava__(String.class); //Do something with the now Java native strings. }Wednesday, May 9, 2012

PlyJy • For a more sophisticated approach to calling into Python code from Java in Jython see the PlyJy projectWednesday, May 9, 2012

import org.plyjy.factory.JythonObjectFactory; JythonObjectFactory factory = JythonObjectFactory.getInstance(); MyInterface pythonObject = (MyInterface) factory.createObject( MyInterface.class, "acme.pyobject");Wednesday, May 9, 2012

Jython package cache[frank jython]$ ./dist/bin/jython*sys-package-mgr*: processing new jar, /home/frank/hg/jython/jython/dist/jython-dev.jar*sys-package-mgr*: processing new jar, /home/frank/hg/jython/jython/dist/javalib/antlr-2.7.7.jar*sys-package-mgr*: processing new jar, /home/frank/hg/jython/jython/dist/javalib/antlr-3.1.3.jar*sys-package-mgr*: processing new jar, /home/frank/hg/jython/jython/dist/javalib/antlr-runtime-3.1.3.jar*sys-package-mgr*: processing new jar, /home/frank/hg/jython/jython/dist/javalib/asm-4.0.jar*sys-package-mgr*: processing new jar, /home/frank/hg/jython/jython/dist/javalib/asm-commons-4.0.jar ...Wednesday, May 9, 2012

Java package cache • Goes through all jars and classes and ﬁgures out Java package contents • enables “from java.foo import *” • Java does not have a package.getClasses() • If cache is disabled “from java import *” will not work from Jython • * import for pure python still worksWednesday, May 9, 2012

zxJDBC • zxJDBC implements DB-API • integrated into Jython’s core • A crucial piece for SQLAlchemy, Pyramid and Django support.Wednesday, May 9, 2012

Modjy • Modjy implements WSGI for Jython • Acts as a bridge to Java Servlets • integrated into Jython’s core • Pyramid and Django supportWednesday, May 9, 2012

Working apps • SQLAlchemy • Pyramid, DJango • setuptools, ez_install, distribute • virtualenv • pip • many more pure python appsWednesday, May 9, 2012

ez_install • Get ez_setup.py • run “jython ez_setup.py” • In Jython’s bin directory will be an ez_install that runs from JythonWednesday, May 9, 2012

Install Django • Get 1.3+ Django - run “jython setup.py install” • From http://django-jython.googlecode.com get django-jython-1.3.tar.gz, untar it and run “jython setup.py install” • see the django-jython project on googlecode.com for more detailWednesday, May 9, 2012

Deploy Django • 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 Tomcat, Jetty or Glassfish)Wednesday, May 9, 2012

Pyramid on Jython • jython ez_install pyramid • Note that you should not try to use Chameleon with Jython - use Mako for templates.Wednesday, May 9, 2012

Creating an executable Jar • Make a copy of jython.jar • copy Lib/ into jython.jar • copy a __run__.py ﬁle into new jar • in the future it will be a __main__.py to ﬁt with the new CPython convention as of 2.6/3.0Wednesday, May 9, 2012

Add Jython install stuff to a new jar $ cd $JYTHON_HOME $ cp jython.jar app.jar $ zip -r app.jar LibWednesday, May 9, 2012

Add modules and paths to the jar ﬁle $ cd $MY_APP_DIRECTORY $ zip app.jar *.py # Add path to additional jar ﬁle. $ jar ufm myapp.jar othermanifest.mf #Where, othermanifest.mf contains the following: Class-Path: ./otherjar.jarWednesday, May 9, 2012

Add runner ﬁle, and run! $ zip myapp.jar __run__.py #in 2.7/3.x $ zip myapp.jar __main__.py $ java org.python.util.jython -jar app.jarWednesday, May 9, 2012

Jython 3000 • We already have a Jython 3 branch • It has a nearly complete parser • Not much else yet • Can’t wait to delete old style classes and fake str suppot! • I’d like to target 3.3 and support only JDK7 or above (maybe even JDK8 if it takes long)Wednesday, May 9, 2012

Jython 3 changes? • All of the same changes as Python3 • unicode for all strings • no old style classes • new metaclass syntax • many iterators instead of lists • much moreWednesday, May 9, 2012

Jython speciﬁc changes • Better way to call into Jython? Project Lambda maybe? • Default to not scan packages? • Get rid of swing speciﬁc helper functions • Remove Lib gunkWednesday, May 9, 2012

Jython/CPython collaboration • Break out the CPython standard Lib into a shared Lib - merge all of Jython’s customizations into CPython Lib • Share CPython’s 3.3 import implementation • PEP 420 implicit namespace packages for Java packagesWednesday, May 9, 2012

Where to Find Out More • http://www.jython.org • http://wiki.python.org/jython • http://fwierzbicki.blogspot.com • Twitter: fwierzbicki • frank@python.orgWednesday, May 9, 2012

Jython 2.7 and techniques for integrating with Java - Frank Wierzbicki

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