Getting JNA to work with Java => C#?

Question

I\'ve written a lot of code in a C# library, which I now need to call from Java.

I saw it recommended on SO to use JNA, but I\'m having trouble even getting out of t

Answer 1

This Nugget is super easy to use and works perfectly. https://www.nuget.org/packages/UnmanagedExports

You need Visual Studio 2012 (Express works fine). Once installed, just add [RGiesecke.DllExport.DllExport] before any static function you want to export. That's it!

Example:

C#

[RGiesecke.DllExport.DllExport]
public static int YourFunction(string data)
{
     /*Your code here*/
     return 1;
}

Java

Add the import at the top:

   import com.sun.jna.Native;

Add the interface in your class. Its your C# function name preceded by the letter "I":

  public interface IYourFunction extends com.sun.jna.Library
    {
       public int YourFunction(String tStr);
    };

Call your DLL where you need it in your class:

IYourFunction iYourFunction = (IYourFunction )Native.loadLibrary("full or relative path to DLL withouth the .dll extention", IYourFunction.class);//call JNA
        System.out.println("Returned: " + IYourFunction.YourFunction("some parameter"));

Answer 2

You won't be able to call directly into your C# code from Java. JNA will only be able to access a native library (C or C++). However you could enable COM Interop in your library and link the 2 together with a native wrapper. I.e. it would look some thing like:

Java --(JNA)--> C/C++ --(COM Interop)--> C#

There are a couple of alternatives:

• Make the C# a stand alone command line app and have the Java code send/receive data from it using stdin/stdout (ProcessBuilder can help you here).
• Run the C# as a stand alone app with some form of platform neutral messaging protocol to communicate between the 2 of them, e.g. HTTP, AMQP.

Answer 3

You can use Caffeine for this http://caffeine.berlios.de/site/documentation/