[C#] Hướng dẫn truyền dữ liệu giữa hai ứng dụng

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.Serialization.Formatters.Binary;
using System.Runtime.InteropServices;
using System.Diagnostics;

public class MessageHelper
{

    [DllImport("User32.dll")]
    private static extern int RegisterWindowMessage(string lpString);
    [DllImport("User32.dll", EntryPoint = "FindWindow")]
    public static extern Int32 FindWindow(String lpClassName, String lpWindowName);
    //For use with WM_COPYDATA and COPYDATASTRUCT
    [DllImport("User32.dll", EntryPoint = "SendMessage")]
    public static extern int SendMessage(int hWnd, int Msg, int wParam, ref COPYDATASTRUCT lParam);
    //For use with WM_COPYDATA and COPYDATASTRUCT
    [DllImport("User32.dll", EntryPoint = "PostMessage")]
    public static extern int PostMessage(int hWnd, int Msg, int wParam, ref COPYDATASTRUCT lParam);
    [DllImport("User32.dll", EntryPoint = "SendMessage")]
    public static extern int SendMessage(int hWnd, int Msg, int wParam, int lParam);
    [DllImport("User32.dll", EntryPoint = "PostMessage")]
    public static extern int PostMessage(int hWnd, int Msg, int wParam, int lParam);
    [DllImport("User32.dll", EntryPoint = "SetForegroundWindow")]
    public static extern bool SetForegroundWindow(int hWnd);
    public const int WM_USER = 0x400;
    public const int WM_COPYDATA = 0x4A;

    //Used for WM_COPYDATA for string messages

    public struct COPYDATASTRUCT
    {
        public IntPtr dwData;
        public int cbData;
        [MarshalAs(UnmanagedType.LPStr)]
        public string lpData;
    }
    public bool bringAppToFront(int hWnd)
    {
        return SetForegroundWindow(hWnd);
    }
    public int sendWindowsStringMessage(int hWnd, int wParam, string msg)
    {
        int result = 0;
        if (hWnd > 0)
        {
            byte[] sarr = Encoding.UTF8.GetBytes(msg);
            int len = sarr.Length;
            COPYDATASTRUCT cds;
            cds.dwData = (IntPtr)100;
            cds.lpData = msg;
            cds.cbData = len + 1;
            result = SendMessage(hWnd, WM_COPYDATA, wParam, ref cds);
        }
        return result;
    }
    public int sendWindowsMessage(int hWnd, int Msg, int wParam, int lParam)
    {
        int result = 0;
        if (hWnd > 0)
        {
            result = SendMessage(hWnd, Msg, wParam, lParam);
        }
        return result;
    }
    public int getWindowId(string className, string windowName)
    {
        return FindWindow(className, windowName);
    }

}

private void txtMessage_TextChanged(object sender, EventArgs e)
{
    MessageHelper msg = new MessageHelper();
    int result = 0;
    int hWnd = msg.getWindowId(null, "WinApp2 - https://laptrinhvb.net");
    result = msg.sendWindowsStringMessage(hWnd, 0, txtMessage.Text);
}

protected override void WndProc(ref Message m)
{
    switch (m.Msg)
    {
        case WM_USER:

            break;
        case WM_COPYDATA:
            COPYDATASTRUCT mystr = new COPYDATASTRUCT();
            Type mytype = mystr.GetType();
            mystr = (COPYDATASTRUCT)m.GetLParam(mytype);

            byte[] bytes = Encoding.UTF8.GetBytes(mystr.lpData);
            string myString = Encoding.UTF8.GetString(bytes);

            label1.Text = myString;
            break;
    }
    base.WndProc(ref m);