jep 3.0.0

Jep embeds CPython in Java

Jep embeds CPython in Java. It is safe to use in a heavily threaded environment, it is quite fast and its stability is a main feature and goal.

Some benefits of CPython over Java-based languages:

• Using the native Python interpreter may be much faster.

• Python is mature and well supported, so there’s no fear the interpreter will suddenly change widely-used features.

• Access to the high quality Python modules, both native and Python-based.

• Compilers and assorted Python tools are as mature as the language.

• Python is an ideal language for your business logic. It is easy to learn, readable and generally immune to programming gotchas.

Patches, comments and other help is greatly appreciated. If you need help, post to the SourceForge mailing list or forums. Please include code snippets for the most accurate response.

Jep is licensed zlib/libpng license to avoid linking issues.

Dependencies

• Python version >= 2.6

• JNI >= 1.4

Installation

Simply run pip install jep.

Building on Mac OS X

OS X requires the Java Developer Package and Xcode from Apple. They are free to download.

Windows

You’ll need to use the same compiler that your Python is built with. That’s usually MSVC.

Note that Oracle is now building Java with a MSVCRT version that is not easily linked with using tools that I have. Using native modules on Windows has not worked in recent years because the compilers are not widely available. If an OpenJDK build used MinGW, that’d be much more likely to work.

Running on *nix

Due to some (common) difficulties with Java and C projects that dlopen libraries, you may need to set LD_PRELOAD environment variable. That’s in addition to setting LD_LIBRARY_PATH if you’ve installed libjep into a directory not cached by ld.so.

For example, my Tomcat startup.sh script starts with this:

#!/bin/sh
# force system to load python
export LD_PRELOAD=/usr/lib/libpython2.7.so

# this is where my libjep.so is.
export LD_LIBRARY_PATH=/usr/local/lib

The libpython used here is whatever you’ve compiled jep against. If you don’t know, try this command:

$ ldd /usr/local/lib/libjep.so | grep python
    /usr/lib/libpython2.7.so (0x00007f74adfbd000)

That’s the libpython you want to set in LD_PRELOAD.

Running the tests

The tests are run from setup.py:

$ python setup.py test

Running scripts

There is a jep shell script to make launching Java and Python a little easier.

$ jep
>>> from java.lang import System
>>> System.out.println('hello, world')
hello, world
>>>

Support

For issues and source control, use github:

https://github.com/mrj0/jep/

There’s also a Sourceforge mailing list that is the best way to get support for Jep:

https://sourceforge.net/mail/?group_id=109839

Mike Johnson