Gemfile

source "https://rubygems.org"

gem "msgpack-rpc"

test_server.rb

require "msgpack/rpc"

class TestServer
  def hello(a, b)
    {"Var1" => "foo", "Var2" => "bar"}
  end
end


server = MessagePack::RPC::Server.new
server.listen("0.0.0.0", 1985, TestServer.new)

server.run

TestClient.java

import java.io.IOException;
import org.msgpack.MessagePack;
import org.msgpack.template.AbstractTemplate;
import org.msgpack.unpacker.Unpacker;
import org.msgpack.packer.Packer;
import org.msgpack.rpc.Client;
import org.msgpack.rpc.loop.EventLoop;

public class TestClient {
  public static interface RPCInterface {
    Named hello(String msg, int a);
  }

  public static class Named {
    public int length;

    public String toString() {
      return "length:" + length;
    }
  }

  public static class NamedTemplate extends AbstractTemplate<Named> {
    public Named read(Unpacker u, Named to, boolean required) throws IOException{
      if (to == null) {
        to = new Named();
      }

      to.length = u.readMapBegin();
      
      return to;
    }
    public void write(Packer pk, Named v, boolean required)  throws IOException {}
  }

  public static void main(String[] args) throws Exception{
    MessagePack msgpack = new MessagePack();
    msgpack.register(Named.class, new NamedTemplate());
    EventLoop loop = EventLoop.start(msgpack);

    Client cli = new Client("localhost", 1985, loop);
    RPCInterface iface = cli.proxy(RPCInterface.class);

    System.out.println(iface.hello("hello", 1));
  }
}