Polymorphic dispatch

main.cs

class Program
    {
        static void Main(string[] args)
        {
            var p1 = new ChatServerProcess();
            p1.When(new NewMessage(){Text = "Hello"});
            p1.When(new NewMessage(){Text = "World"});

            var p2= new ChatServerProcess();
            p2.HydrateState(p1.HandOffState());

            var transportMessage = BinarySerializer.Serialize(new UserJoin() { Name = "Russel" });
            p2.Dispatch(transportMessage);

            Console.ReadKey();
        }

    }

    public class DistributedProcess<T>
    {
        public T Data { get; set; }

        public void HydrateState(string state)
        {
            Data = (T)BinarySerializer.Deserialize(state);
        }

        public string HandOffState()
        {
            return BinarySerializer.Serialize(Data);
        }

        public void Dispatch(string transportMessage)
        {
            var command = BinarySerializer.Deserialize(transportMessage);
            ((dynamic)this).When((dynamic)command);
        }
    }

    public class BinarySerializer
    {
        public static string Serialize(object obj)
        {
            using (var stream = new MemoryStream())
            {
                var formatter = new BinaryFormatter();
                formatter.Serialize(stream, obj);
                stream.Flush();
                stream.Position = 0;
                return Convert.ToBase64String(stream.ToArray());
            }
        }

        public static object Deserialize(string payload)
        {
            var b = Convert.FromBase64String(payload);
            using (var stream = new MemoryStream(b))
            {
                var formatter = new BinaryFormatter();
                stream.Seek(0, SeekOrigin.Begin);
                return formatter.Deserialize(stream);
            }
        }
    }
    
    // example
    public class ChatServerProcess : DistributedProcess<ChatServerState>  
    {
        public ChatServerProcess()
        {
            Data = new ChatServerState();
        }

        public List<string> GetHistory()
        {
            return Data.RoomMessages;
        }

        public void When(NewMessage message)
        {
            Data.RoomMessages.Add(message.Text);
        }

        public void When(UserJoin message)
        {
            Data.OnlineUsers.Add(message.Name);
        }

        public void When(UserLeft message)
        {
            Data.OnlineUsers.Add(message.Name);
        }
    }

    [Serializable]
    public class NewMessage
    {
        public string Text { get; set; }
    }

    [Serializable]
    public class UserJoin
    {
        public string Name { get; set; }
    }

    [Serializable]
    public class UserLeft
    {
        public string Name { get; set; }
    }

    [Serializable]
    public class ChatServerState
    {
        public List<string> RoomMessages = new List<string>();
        public List<string> OnlineUsers = new List<string>();
    }