Communication between Java and Python
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This document discusses various approaches for enabling communication between Java and Python programs, including: 1. Using bindings like JPE and JPI that allow calling Python from Java. 2. Using Jython, which is a Python interpreter written in Java that allows embedding Python scripts in Java applications. 3. Using JPype or Jepp which embed the CPython interpreter in Java via JNI to allow full access to Java classes from Python. 4. Using client-server approaches like Spiro and Pyro that allow Java and Python programs to communicate over a network.
![Introduction (3/4) "Hello World!"-Code Java Python print("Hello World!") public class HelloWorld { public static void main(String[] args) { System.out.println("Hello World!"); } }](https://image.slidesharecdn.com/techtalk03062008eifer-1212585494173481-9/85/Communication-between-Java-and-Python-5-320.jpg)
![Jython (3/4) Running Python scripts import org.python.util.PythonInterpreter; import org.python.core.*; class TestPython { public static void main ( String[] args ) { try { org.python.util.PythonInterpreter python = new org.python.util.PythonInterpreter(); python.execfile ( "testscript.py" ); } catch ( Exception e ) { System.out.println ( "An error was encountered." ); } } }](https://image.slidesharecdn.com/techtalk03062008eifer-1212585494173481-9/85/Communication-between-Java-and-Python-11-320.jpg)
![Jepp (3/4) Features Using the console ( console.py script) Creating new exception types on the fly $ java -jar jep.jar console.py >>> from java.lang import * >>> s = String('do crazy stuff') >>> print String(s.toCharArray()[3:8]) crazy >>> from java.io import FileInputStream >>> try: ... FileInputStream('no such file') ... except(jep.FileNotFoundException): ... print 'File not found.' ... File not found.](https://image.slidesharecdn.com/techtalk03062008eifer-1212585494173481-9/85/Communication-between-Java-and-Python-15-320.jpg)
Communication between Java and Python
- 1. TechTalk: Communication between Java and Python Anastasia Eifer, DLR Simulations- und Softwaretechnik 03.06.2008
- 2. Contents Introduction Motivation Communication through bindings (JPE, JPI) Jython (JPython) Jepp JPype Client-server communication (SPYRO, Pyro) Summary
- 3. Introduction (1/4) Java Object-oriented Platform-independent Robust Distributed Secure One of the most popular programming languages today
- 4. Introduction (2/4) Python Dynamic multi-paradigm programming language Object-oriented Functional Aspect-oriented Scripting language … Remarkably clean syntax Short development time Extensive standard libraries Highly readable language Can be learned in a few days
- 5. Introduction (3/4) "Hello World!"-Code Java Python print("Hello World!") public class HelloWorld { public static void main(String[] args) { System.out.println("Hello World!"); } }
- 6. Introduction (4/4) Print the integers from 1 to 9 Java Python for (int i = 1; i < 10; i++) { System.out.println(i); } for i in range (1,10): print i
- 7. Motivation Java and Python: a perfect couple Building software from existing components Combination of a system programming language (Java) and a scripting language (Python) Rapid application development Creating automated tests Embedded scripting
- 8. Communication through bindings JPE Java-Python Extension JNI-based wrapper Integration of Java and standard Python (CPython) http://jpe.sourceforge.net/ JPE project does not appear to be active JPI Java-Python Interface JNI-based wrapper JPI project is no longer developed
- 9. Jython (1/4) What is Jython? Complete re-implementation of the Python programming language in Java Embedded scripting Interactive experimentation Rapid application development Home http://www.jython.org
- 10. Jython (2/4) Interactive experimentation C:\jython>jython Jython 2.0 on java1.2.1 Type "copyright", "credits" or "license" for more information. >>> from java.util import Random >>> r = Random() >>> r.nextInt()-790940041 >>> for i in range(3): ... print r.nextDouble() ... 0.23347681506123852 0.8526595592189546 0.3647833839988137 >>>
- 11. Jython (3/4) Running Python scripts import org.python.util.PythonInterpreter; import org.python.core.*; class TestPython { public static void main ( String[] args ) { try { org.python.util.PythonInterpreter python = new org.python.util.PythonInterpreter(); python.execfile ( "testscript.py" ); } catch ( Exception e ) { System.out.println ( "An error was encountered." ); } } }
- 12. Jython (4/4) Current state of development The current release is Jython-2.2.1 It is equivalent to the 2.2 release of CPython CPython 2.5 is targeted for the next release Jython-2.2.1 supports a large majority of the standard Python library Jython-2.2.1 doesn't support a number of Python's built-in modules ! (e.g. those that are written in C for CPython)
- 13. Jepp (1/4) What is Jepp? Java Embedded Python Embeds CPython in Java Communication through interfacing at the native level in both Virtual Machines Home http://jepp.sourceforge.net /
- 14. Jepp (2/4) Using Jepp from within Java „ Hello World!“-Code Running Python scripts Jep jep = new Jep(); jep.eval("print 'Hello World!'"); jep.close(); Jep jep = new Jep(false); jep.runScript("C:\\tempguatda.com/cmx.p\\testscript.py"); jep.close();
- 15. Jepp (3/4) Features Using the console ( console.py script) Creating new exception types on the fly $ java -jar jep.jar console.py >>> from java.lang import * >>> s = String('do crazy stuff') >>> print String(s.toCharArray()[3:8]) crazy >>> from java.io import FileInputStream >>> try: ... FileInputStream('no such file') ... except(jep.FileNotFoundException): ... print 'File not found.' ... File not found.
- 16. Jepp (4/4) Summary Very good scripting solution for Java Run your existing Python scripts from Java Access to high-quality Python extensions Jepp's console provides an easy way to examine scripts and learn how to use new APIs
- 17. JPype (1/3) What is JPype? JNI-based wrapper Communication through interfacing at the native level in both Virtual Machines Full access to java class libraries Home http://jpype.sourceforge.net /
- 18. JPype (2/3) „ Hello World!“-Code from jpype import * startJVM(path to jvm.dll, "-ea") java.lang.System.out.println("Hello World") shutdownJVM()
- 19. JPype (3/3) Running Python scripts import jpype #start JVM with class path startJVM(path to jvm.dll, "-ea") #create reference to java package javaPackage = jpype.JPackage(" JavaPackageName " ) #create reference to java class javaClass = javaPackage. JavaClassName #create instance of java class javaObject = javaClass() #call java methods javaObject. JavaMethodName() #shutdown JVM jpype.shutdownJVM()
- 20. Client-server communication SPIRO Simple Python Interface to Remote Objects Handy bridge between CPython and Java (via Jython) http://www.freenet.org.nz/python/spiro Pyro Python Remote Objects http://pyro.sourceforge.net /
- 21. Python Interpreter Python Interpreter Java Virtual Machine (JVM) Java Code (Anwendung) Jepp JNI Python Code JPype Jython Python Code Interface/Protokoll Python Code Python Code (Autor: Andreas Schreiber)
- 22. Summary Reimplementation of Python (Jython) (+) Very tight integration with Java (+) One runtime environment (-) Jython-2.2.1 doesn't support a number of Python's built-in modules, it is slower in comparison to CPython Communication through Virtual Machines (JPype, Jepp, JPE) (+) CPython‘s speed (+) Access to high-quality Python extensions (-) Two runtime environments Client-server communication (+) System- and language independence (-) Significant overhead, development time-consuming
- 23. Links Exploring Python Markus Nix (Hrsg.), Markus Nix, Martin Grimme, Torsten Marek, Michael Weigend, Wolfgang Weitz ( Download ) Communication between Java and Python