PemJa

What is it?

PemJa is an open source cross language call framework based on FFI. It aims to provide a high-performance

framework of calling between different languages.

Where to get it

Python binary installers for the latest released version are available at the Python package index

pip install pemja

Java Maven Dependency

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>pemja</artifactId>
    <version>{version}</version>
</dependency>

Dependencies

• NumPy - Adds support for large, multi-dimensional arrays, matrices and high-level mathematical functions to operate on these arrays

Installation from sources

Prerequisites for building PemJa:

• Unix-like environment (we use Linux, Mac OS X), Windows
• Git
• Maven (we recommend version 3.2.5 and require at least 3.1.1)
• Java 8 or 11 (Java 9 or 10 may work) with $JAVA_HOME set correctly
• Python >= 3.8 (we recommend version 3.8, 3.9, 3.10, 3.11)

NOTE for windows:

• Microsoft Visual C++ 14.0 or greater is required. Get it with "Microsoft C++ Build Tools"
• The compressed package in folder dist must be uncompressed and use the following command to install pip install dist/$packageName$

git clone https://github.com/alibaba/pemja.git
cd pemja
mvn clean install -DskipTests
pip install -r dev/dev-requirements.txt
python setup.py sdist
pip install dist/*.tar.gz

Usage

String path = ...;
PythonInterpreterConfig config = PythonInterpreterConfig
    .newBuilder()
    .setPythonExec("python3") // specify python exec, use "python" on Windows
    .addPythonPaths(path) // add path to search path
    .build();

PythonInterpreter interpreter = new PythonInterpreter(config);

// set & get
interpreter.set("a", 12345);
interpreter.get("a"); // Object
interpreter.get("a", Integer.class); // Integer

// exec & eval
interpreter.exec("print(a)");

// invoke functions
interpreter.exec("import str_upper");
String result = interpreter.invoke("str_upper.upper", "abcd");
// Object invoke(String name, Object... args);
// Object invoke(String name, Object[] args, Map<String, Object> kwargs);

// invoke object methods
/*
// invoke.py
class A:
       def __init__(self):
           self._a = 0
   
       def get_value(self):
           return self._a
   
       def add(self, n):
           self._a += n
   
       def add_all(self, *args):
           for item in args:
               self._a += item
               return self._a
   
       def minus(self, n):
           self._a -= n
           return self._a
*/

interpreter.exec("import invoke");
interpreter.exec("a = invoke.A()");
interpreter.invokeMethod("a", "add", 3);
interpreter.invokeMethod("a", "minus", 2);
interpreter.invokeMethod("a", "add_all", 1, 2, 3);


// python callback java methods
/*
// invoke_callback.py
from pemja import findClass

StringBuilder = findClass('java.lang.StringBuilder')
Integer = findClass('java.lang.Integer')

def callback_java():
    sb = StringBuilder()
    sb.append('pemja')
    sb.append('java')
    sb.append('python')
    sb.append(Integer.toHexString(Integer.MAX_VALUE))
    return sb.toString()
*/
interpreter.exec("import call_back")
print(interpreter.invoke("call_back.callback_java"))

Documentation