Send a message to a application

I have 2 applications, and i want to send a message from one application to the other one.
How do I do that?
brammeAsked:
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craig_capelConnect With a Mentor Commented:
var
 h: hwnd;
begin
   winexec('c:\windows\notepad.exe',1);
//   h:=getforegroundwindow;
    h:=findwindow(nil,'untitled - notepad');
   sendmessage(h,wm_close,0,0);
     //wm_hide
     //wm_show     // just look it up easy

end;


OR.... you can use DDE, and talk to it like i'm not quite sure what you mean now....

i have examples on dde if your intrested?...
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mhervaisCommented:
listening
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craig_capelCommented:
sendmessage
 brb with example, want to beat other people to it!!!
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mullet_attackCommented:
What do you mean by message? If you mean windows message, then Craig's done that. If you mean message like "hello world" then a good place to look is the chat example in Delphi5\Demos\Internet\Chat
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sburckCommented:
I think what you have in mind here is pipes - you need the Windows API functions *namedpipes -

CreateNamedPipe,
ConnectNamedPipe,
TransactNamedPipe

and the others.

If this isn't enough, I can write a small demo for you.

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mhervaisCommented:
yes sburck name the pipes :)
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mullet_attackCommented:
bear in mind that you can't create named pipe servers on '95 or '98...
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smurffCommented:
listening,
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brammeAuthor Commented:
allright craig capel
so far so right, but how do I send a string to another application that i have written, and that application has then a event?
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intheCommented:
Hi,
compile these two apps and run to see a demo of sending and recieving messages :

unit SendMsgTimeoutSendU;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

{Whoops! This function is imported in the Delphi source code incorrectly; the
 return value should be BOOL, not LRESULT}
function SendMessageTimeout(hWnd: HWND; Msg: UINT; wParam: WPARAM;
  lParam: LPARAM; fuFlags, uTimeout: UINT; var lpdwResult: DWORD):BOOL; stdcall;

var
  Form1: TForm1;
  UserMessage: UINT;  // holds our user defined message identifier

implementation

{$R *.DFM}

{re-link the external function}
function SendMessageTimeout; external user32 name 'SendMessageTimeoutA';

procedure TForm1.FormCreate(Sender: TObject);
begin
  {register the user defined Windows messsage}
  UserMessage := RegisterWindowMessage('SendMessageTimout Test Message');
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  MsgResult: DWORD;
begin
  {send the message, and time out after 300 milliseconds}
  SendMessageTimeout(HWND_TOPMOST, UserMessage, 0, 0,
                     SMTO_NORMAL, 300, MsgResult);

  {indicate that the SendMessageTimeout function has returned}
  ShowMessage('Returned');
end;

end.






unit SendMstTimeoutGetU;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ComCtrls;

type
  TForm1 = class(TForm)
    Label1: TLabel;
    ProgressBar1: TProgressBar;
    Label2: TLabel;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
    procedure DefaultHandler(var Msg); override;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  UserMessage: UINT;  // holds our user defined message identifier

implementation

{$R *.DFM}

procedure TForm1.DefaultHandler(var Msg);
var
  iLoop: Integer;  // general loop counter
begin
  {process message normally}
  inherited DefaultHandler(Msg);

  {if this is our user defined message...}
  if TMessage(Msg).Msg=UserMessage then
  begin
    {...display some user interface objects}
    ProgressBar1.Visible := TRUE;
    Label2.Visible := TRUE;
    Form1.Repaint;

    {animate the progress bar for a short time}
    for iLoop := 0 to 100 do
    begin
      ProgressBar1.Position := iLoop;
      Sleep(10);
    end;

    {turn off the user interface objects}
    ProgressBar1.Visible := FALSE;
    Label2.Visible := FALSE;

    {indicate that the message was handled}
    TMessage(Msg).Result := 1;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  {register the user defined Windows message}
  UserMessage := RegisterWindowMessage('SendMessageTimout Test Message');
end;

end.
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intheCommented:
mmm...
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craig_capelCommented:
Barry, i know how you feel, it happens to me all the time :)
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intheCommented:
;-)
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