PostMessage # How to pass Message back to Caller EXE??

Hello,
I am new to .net n working with Framework 3.5 Sniff

Currently working on Application developed in Borland Delphi.
We have 2 exe's named as DBPro.exe and Data.exe

I am rewriting Data.exe which deal with Data Interaction with SQL Server.

Now the project work like, We have button in DBPro.exe which Opens up Data.exe n while doing this it Passes the Message to it using Post Message. I dont have code for DBPro.exe

After All work wen we close Data.Exe it is suppose to PostBack message to Calling Exe i.e. DBPro.exe which will reinitialize it.

I found line PostMessage(HWND_BROADCAST, dbmesg, 0, 0); in Data.exe, in the Form End section which is suppose to Post Back the Message. Now I want to do the same with my new Data.exe. So far I found I can use some invoke method but have no idea how to use it. D'Oh! Cry

I'll appriciate any pointers on this issue. Roll eyes

Thanks.

Some declarations look like this.. Confused

 PostMessage(HWND_BROADCAST, dbmesg, 0, 0);
  strpcopy(mstr, 'WM_DBMESG');
  dbmesg:=RegisterWindowMessage (mstr);

I am not able to found any declaration for HWND_BROADCAST

private void btnClose_Click(object sender, EventArgs e)
{
const int dbmesg=49706;
const int HWND_BROADCAST=65535;
Win32.PostMessage(HWND_BROADCAST,dbmesg, 0, 0);
this.Close();
}

public class Win32
{
[DllImport("user32", EntryPoint = "PostMessage")]
public static extern int PostMessage(int hwnd, int wMsg, int wParam, int lParam);
}

This will Close the Data.Exe and Broadcast Message. I Defined the same constant I found in Old code, even when I dont really know what they really mean.. Shucks

But this code is working for me..

To Import Win32.dll need to add using System.Runtime.InteropServices; namespace!!

Guys.. any one know how exactly this work.. to give more understanding..!!

Thanks