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Java Python Integration

I have a Java app that needs to integrate with a 3rd party library. The library is written in Python, and I don't have any say over that. I'm trying to figure out the best way to integrate with it. I'm trying out JEPP (Java Embedded Python) - has anyone used that before? My other thought is to use JNI to communicate with the C bindings for Python.

Any thoughts on the best way to do this would be appreciated. Thanks.

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Frankly **most ways to somehow run Python directly from within JVM don't work**. They are either not-quite-compatible (new release of your third party library can use python 2.6 features and will not work with Jython 2.5) or hacky (it will break with cryptic JVM stacktrace not really leading to solution).

**My preferred way to integrate the two would use RPC**. [XML RPC][2] is not a bad choice here, if you have moderate amounts of data. It is pretty well supported &mdash; Python has it in its standard library. Java libraries are also easy to find. Now depending on your setup either Java or Python part would be a server accepting connection from other language.

A less popular but worth considering alternative way to do RPCs is Google protobuffers, which have 2/3 of support for [nice rpc][3]. You just need to provide your transport layer. Not that much work and the convenience of writing is reasonable.

Another option is to write a C wrapper around that pieces of Python functionality that you need to expose to Java and use it via JVM native plugins. You can ease the pain by going with SWIG  [SWIG][1].

Essentially in your case it works like that: 

 1. Create a SWIG interface for all method calls from Java to C++.
 2. Create C/C++ code that will receive your calls and internally call python interpreter with right params.
 3. Convert response you get from python and send it via swig back to your Java code.

This solution is fairly complex, a bit of an overkill in most cases. Still it is worth doing if you (for some reason) cannot afford RPCs. RPC still would be my preferred choice, though.



  [1]:  http://www.swig.org/
  [2]:  http://en.wikipedia.org/wiki/XML-RPC
  [3]:  http://code.google.com/apis/protocolbuffers/docs/reference/java-generated.html#service

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6

This non-JVM compatibility is the biggest shortcoming of Python. Thats why we decided to use Scala. It is even better.

Jus12
– Jus12

2012-06-04 14:40:33 +00:00
Commented Jun 4, 2012 at 14:40
Marcin, the remote call way is not desireable for big data implementations (algorithms or applications) for performance and scalability reasons. Indeed "not-quite-compatible" is an issue but "break with cryptic JVM stacktrace" requires some explanation and examples please. You mean hard to debug or does not run? I am trying out Jep which does JNI in-process and seems like the best thing. github.com/mrj0/jep/wiki/How-Jep-Works. Thoughts?

SemanticBeeng
– SemanticBeeng

2017-08-04 06:31:45 +00:00
Commented Aug 4, 2017 at 6:31

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Java Python Integration

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