Question

I have a C# reply server that can pack an object and send it to a requester C# client. Can I do the same thing, but with a C# reply server communicating with a C++ requester client?

Here’s an example of my C# reply server:

using System;
using System.Text;
using ZMQ;
using MsgPack;

namespace zmqMpRep
{
    public class Weather
    {
        public int zipcode;
        public int temperature;
        public int humidity;
    }
    public class zmqMpRep
    {
        public static void Main(string[] args)
        {

            Socket replier  = new Socket( SocketType.REP );
            replier.Bind( "tcp://127.0.0.1:9293" );
            while( true ) {
                Weather weather = new Weather { zipcode = 60645, temperature = 67, humidity = 50 };
                CompiledPacker packer   = new CompiledPacker( false );
                byte[] packWeather  = packer.Pack<Weather> ( weather );
                string request  = replier.Recv(Encoding.Unicode);
                Console.WriteLine( request.ToString() );
                replier.Send( packWeather );
                Weather test    = packer.Unpack<Weather>( packWeather );
                Console.WriteLine( "The temp of zip {0} is {1}", test.zipcode, test.temperature );
            }
        }
    }
}

Here’s my C# request client:

using System;
using System.Text;
using ZMQ;
using MsgPack;

namespace zmqMpReq
{
    public class Weather
    {
        public int zipcode;
        public int temperature;
        public int humidity;
    }
    public class zmqMpReq
    {
        public static void Main(string[] args)
        {
            CompiledPacker packer   = new CompiledPacker( false );
            Socket requester        = new Socket( SocketType.REQ );
            requester.Connect( "tcp://127.0.0.1:9293" );
            string request          = "Hello";
            requester.Send( request, Encoding.Unicode );
            byte[] reply            = null;
            try {
                reply        = requester.Recv();
            }
            catch( ZMQ.Exception e) {
                Console.WriteLine( "Exception: {0}", e.Message );
            }
            Weather weather     = packer.Unpack<Weather>( reply );
            Console.WriteLine( "The temp of zip {0} is {1}", weather.zipcode, weather.temperature );
            System.Threading.Thread.Sleep( 5000 );
        }
    }
}

Answer 1

Most programs written in any language can communicate over sockets. So a C# socket listener can listen to C++ sender. They do by exchanging a sequence of bytes (Very simplified)

What you are doing here is serializing a C# object using MsgPack in a byte array and sending it over. On the other end the same MsgPack is used to deserialize the C# object.

This will not work across programming languages unless your serializing/deserializing library supports it, which in your case MsgPack doesn’t.

Take this C# class

public class Weather
{
    public int zipcode;
    public int temperature;
    public int humidity;
}

An equivalent C++ class

  class Weather
    {
    public:
       int zipcode;
       int temperature;
       int humidity;
    }

Depending on your OS.. sizeof(int) in C++ will be 4 bytes(chars). sizeof(int) in C# is 4 bytes as well.

So it theory you can exchange 12 ( 4 * 3 ) bytes over a socket connection between a C++ and C# program so that weather object is pretty much the same on both sides