using System;

using System.Collections.Generic;

public class Program

{

    public interface IMessage

    {

    };

​

    public class MessageBroker

    {

        private Dictionary<Type, List<Action<IMessage>>> m_messageHandlers = new Dictionary<Type, List<Action<IMessage>>>();

        public void RegisterHandler(Type messageType, Action<IMessage> handler)

        {

            List<Action<IMessage>> handlers = null;

            if (!m_messageHandlers.TryGetValue(messageType, out handlers))

            {

                handlers = new List<Action<IMessage>>();

                m_messageHandlers[messageType] = handlers;

            }

            handlers.Add(handler);

        }

        public void HandleMessage(IMessage message)

        {

            List<Action<IMessage>> handlers = null;

            var messageType = message.GetType();

            if (m_messageHandlers.TryGetValue(messageType, out handlers))

            {

                foreach (var handler in handlers)

                    handler(message);

            }

            else

            {

                Console.WriteLine(string.Format("No handler found for message of type {0}", messageType.FullName));

            }

        }

    };

​

    public interface IComponent

    {

        void Register(MessageBroker messageBroker);

    }

​

    public class ExampleMessageA : IMessage

    {

    };

    public class ExampleMessageB : IMessage

    {

    };

​

    public class ExampleComponent : IComponent

    {

        public void Register(MessageBroker messageBroker)

        {

            messageBroker.RegisterHandler(typeof(ExampleMessageA), HandleMessageA);

            messageBroker.RegisterHandler(typeof(ExampleMessageB), HandleMessageB);

        }

​

        private void HandleMessageA(IMessage message)

        {

            var exampleMessageA = (ExampleMessageA)message;

            Console.WriteLine("Handling message of type ExampleMessageA");

        }

        private void HandleMessageB(IMessage message)

        {

            var exampleMessageB = (ExampleMessageB)message;

            Console.WriteLine("Handling message of type ExampleMessageB");

        }

    }

​

    public static void Main()

    {

        var messageBroker = new MessageBroker();

​

        // In reality you would find all types that implement IComponent in some assembly (for example).

        var myComponent = new ExampleComponent();

        myComponent.Register(messageBroker);

​

        // A message has been received and deserialised into the correct type. For prototyping here we will just instantiate it.

        var messageA = new ExampleMessageA();

        messageBroker.HandleMessage(messageA);

        var messageB = new ExampleMessageB();

        messageBroker.HandleMessage(messageB);

    }

}