April 28, 2001

I am pleased to announce the first beta release of JPE,
the Java-Python Extension.

JPE is at once:
    - A Python module (named 'java') providing access to all Java
services
      from Python
    - A Java package (named 'python') providing access to all Python
services
      from Java


Computing Paradigm
==================

JPE relies on the following computing paradigm:
One Python VM (PyInterp* pointer) an one Java VM (JavaVM* pointer) are
in the same process.
The virtual machines act as common process resources, shared by the
threads.

Each virtual machine has its own thread-specific execution environment
(PyThreadState* pointer in Python, JNIEnv* pointer in Java).
Each thread is attached to zero or one thread environment
from each virtual machine; each thread environment is attached
to one thread.

The paradigm is generic.
I have not done much research in the literature in this regard,
but I am not aware of a similar pattern.
I'll baptize it the "symmetrical virtual machine" pattern :))

This is different from Jython, for instance, in the sense that Jython
is an emulation of the Python VM, written in Java, and entirely running
within the Java VM.

The advantage of the symmetrical virtual machine approach
over the emulation is that we get to work with the actual,
full-featured Python VM, rather than with an emulation on top of
another virtual machine, emulation which necesseraly suffers
from limitations inherited from the emulating environment.

Object semantics are the same in both environments.

Voila!

Frederic Giacometti
frederic.giacometti@[...].com

The home of JPE is http://www.arakne.com/jpe
JPE can be downloaded directly at http://sourceforge.net/projects/jpe




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