【C#】Send data between applications

This sample shows how to send data between different applications, including object data——transform object into byte[] and then transport its CPU location.

Now I'll paste the programs here.(Thanks the blogger Sir.jevan for the template he/she provide,what I have done is just make the object-transportation available.Here is his page.)

Sender:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.IO;  //The following four usings are important.So are they in Reciever and dll.
using System.Runtime.Serialization.Formatters.Binary;
using System.Runtime.Serialization;
using ClassLibrary1;

namespace cdn_send
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }        

        private void Form1_Load(object sender, EventArgs e)
        {
        }

        private const int WM_COPYDATA = 0x004A;
        private const uint flag = 0x8000; //I can't understand it.Please tell me(if you got it).
        [DllImport("User32.dll", EntryPoint = "SendMessage")]
        private static extern int SendMessage(int hWnd, int Msg, int wParam, ref COPYDATASTRUCT lParam);
        [DllImport("User32.dll", EntryPoint = "FindWindow")]
        private static extern int FindWindow(string lpClassName, string lpWindowName);
        [DllImport("kernel32.dll")]
        static extern uint GetTickCount();

        private void button1_Click(object sender, EventArgs e)
        {
            int WINDOW_HANDLER = FindWindow(null, @"xxx");  //Find target window.Well,by the way,it's called 'xxx'.
            if (WINDOW_HANDLER == 0)
            {
                MessageBox.Show("xxx");
            }
            else
            {
                
                data dd=new data();  //Process data.
                dd.x = (int)this.Handle;
                dd.y = DateTime.Now;
                dd.tx = textBox1.Text;
                dd.tk = GetTickCount();
                byte[] bt=(new switcher()).Object2Bytes((object)dd);  //Type switch.

                COPYDATASTRUCT cds;
                cds.dwData = (IntPtr)flag;
                cds.cbData = bt.Length;
                cds.lpData = Marshal.AllocHGlobal(bt.Length);  //Allocate space.

                Marshal.Copy(bt, 0, cds.lpData, bt.Length);  //Memory copy.
                SendMessage(WINDOW_HANDLER, WM_COPYDATA, 0, ref cds);  //Send message out.
            }
        }
    }
    
}

Reciever:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.IO;  //Important.
using System.Runtime.Serialization.Formatters.Binary;
using System.Runtime.Serialization;
using ClassLibrary1;

namespace cdn_receiver
{
    public partial class Form1 : Form
    {

        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {

        }

        const int WM_COPYDATA = 0x004A;
        private const uint flag = 0x8000;
        [DllImport("kernel32.dll")]
        public static extern uint GetTickCount();

        protected override void DefWndProc(ref System.Windows.Forms.Message m)
        {
            switch (m.Msg)
            {
                case WM_COPYDATA:

                    COPYDATASTRUCT cds = new COPYDATASTRUCT();
                    cds = (COPYDATASTRUCT)m.GetLParam(cds.GetType()); //Receive information.

                    byte[] bt = new byte[cds.cbData];
                    Marshal.Copy(cds.lpData,bt,0,bt.Length);  //Get data array.

                    data dd = (data)((new switcher()).Bytes2Object(bt));  //Transform back.
                    long xx = GetTickCount() - dd.tk;  //This line is used to calculate its delay,although mostly it is 0ms.
                    textBox1.Text = (dd.x.ToString() + " " + dd.y.ToString() + " " + dd.tx);
                    textBox1.Text += "
" + xx.ToString() + "ms";
                    
                    break;
                default:
                    base.DefWndProc(ref m);  //Don't forget this line,or it cannot run properly.
                    break;
            }

        }
    }
    

}

Dll:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;
using System.Runtime;
using System.IO; //Important
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;
namespace ClassLibrary1
{
        
    [Serializable]  //My datastructure which contains different types.Don't forget this line.
    public struct data  
    {
        public int x;
        public DateTime y;
        public string tx;
        public long tk;
    }

    [StructLayout(LayoutKind.Sequential)]  //The datastructure which used as a media to transport.
    public struct COPYDATASTRUCT
    {
        public IntPtr dwData;
        public int cbData;
        public IntPtr lpData;
    }

    public class switcher  //The switcher object which contains two main switcher function.
    {
        public byte[] Object2Bytes(object obj)
        {
            IFormatter fmt = new BinaryFormatter();
            MemoryStream ms = new MemoryStream();
            fmt.Serialize(ms, obj);
            return ms.GetBuffer();

        }

        public object Bytes2Object(byte[] bt)
        {
            IFormatter fmt = new BinaryFormatter();
            MemoryStream ms = new MemoryStream(bt);
            return (object)fmt.Deserialize(ms);
        }

        public switcher(){
        }
    }

}

It is tested that there is no problem with the correction of the transported data.(My vs version is 2012 ultimate,OS version is win7)