Pyrolite

Java and .NET client interface for Pyro5 protocol

Programming language: Java

License: MIT License

Tags: Interoperability    

Latest version: v5.0

README

Pyrolite - Pyro5 client library for Java and .NET

Pyrolite is written by Irmen de Jong ([email protected]). This software is distributed under the terms written in the file LICENSE.

Introduction: Pyro

This library allows your Java or .NET program to interface very easily with a Python program, using the Pyro protocol to call methods on remote objects (see https://github.com/irmen/Pyro5).

Pyrolite only implements a part of the client side Pyro library, hence its name 'lite'... For the full Pyro experience (and the ability to host servers and expose these via Pyro) you have to run Pyro itself in Python. But if you don't need Pyro's full feature set, and don't require your Java/.NET code to host Pyro objects but rather only call them, Pyrolite could be a good choice to connect Java or .NET and Python!

Pyro4 ?

If you are still using Pyro4 and want to use Pyrolite with it, you should stick to an older version of this library (versions 4.xx). The current 5.xx version only supports Pyro5.

In Github, use the pyro4-legacy branch.

Installation and usage

Precompiled libraries are available:

• Java: from Maven, group id net.razorvine artifact id pyrolite.
• .NET: nuget Razorvine.Pyrolite; https://www.nuget.org/packages/Razorvine.Pyrolite/

Some Java example code:

import net.razorvine.pyro.*;

NameServerProxy ns = NameServerProxy.locateNS(null);
PyroProxy remoteobject = new PyroProxy(ns.lookup("Your.Pyro.Object"));
Object result = remoteobject.call("pythonmethod", 42, "hello", new int[]{1,2,3});
String message = (String)result;  // cast to the type that 'pythonmethod' returns
System.out.println("result message="+message);
remoteobject.close();
ns.close();

Some C# example code:

using Razorvine.Pyro;

using( NameServerProxy ns = NameServerProxy.locateNS(null) )
{
    // this uses the statically typed proxy class:
    using( PyroProxy something = new PyroProxy(ns.lookup("Your.Pyro.Object")) )
    {
        object result = something.call("pythonmethod", 42, "hello", new int[]{1,2,3});
        string message = (string)result;  // cast to the type that 'pythonmethod' returns
        Console.WriteLine("result message="+message);
        result = something.getattr("remote_attribute");
        Console.WriteLine("remote attribute="+result);
    }

    // but you can also use it as a dynamic!
    using( dynamic something = new PyroProxy(ns.lookup("Your.Pyro.Object")) )
    {
        object result = something.pythonmethod(42, "hello", new int[]{1,2,3});
        string message = (string)result;  // cast to the type that 'pythonmethod' returns
        Console.WriteLine("result message="+message);
        result = something.remote_attribute;
        Console.WriteLine("remote attribute="+result);
    }
}

More examples can be found in the examples directory. You could also study the unit tests.

"Where is Pickle?"

Until version 5.0, Pyrolite included a pickle protocol implementation that allowed your Java or .NET code to read and write Python pickle files (pickle is Python's serialization format). From 5.0 onwards, this is no longer included because Pyro5 no longer uses pickle.

If you still want to read or write pickled data, have a look at the now separate pickle library: https://github.com/irmen/pickle

Required dependency: Serpent serializer

The serializer used is 'serpent' (a special serilization protocol that I designed for the Pyro library) So this requires the Razorvine.Serpent assembly (.NET) or the net.razorvine serpent artifact (serpent.jar, Java) to be available.

Serpent is a separate project (als by me), you'll have to install this dependency yourself. You can find it at: https://github.com/irmen/Serpent Download instructions are there as well.

Dealing with exceptions

Pyrolite also maps Python exceptions that may occur in the remote object. It has a rather simplistic approach:

all exceptions, including the Pyro ones (Pyro4.errors.*), are converted to PyroException objects. PyroException is a normal Java or C# exception type, and it will be thrown as a normal exception in your program. The message string is taken from the original exception. The remote traceback string is available on the PyroException object in the _pyroTraceback field.