What is the equivalent of vb.NET "Interop User Control" on Delphi?

Question

I'm trying to make an app with event/methods/procedures to be taken from a third party application. This app needs to be an active X.

I have an working example on VB.NET and I need to make a the same on Delphi.

The vb.net Unit start with:

<ComClass(InteropUserControl.ClassId, InteropUserControl.InterfaceId, InteropUserControl.EventsId)> _
Public Class InteropUserControl

Is this completely necessary on DELPHI? is this only for register a COM class on Windows?

Also, the function used is:

Public Event msgPlugIn(ByRef Msg As String, ByRef MsgResponse As String)

And it's called later:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim Msg As String
    Dim Response As String = ""
    Msg = "<ID><infoRequest/></ID>"
    RaiseEvent MsgPlugIn(Msg, Response)
    rtb1.Text = Response
    //rtb1 is a regular label
End Sub

is this an Onclick of a regular Button?

I need to get this done in Delphi, but I try everything, Automation Object, COM Object..but the third party app doesn't make anything.

NEW INFO:

I made an Active Library and add a COM OBJECT and create a procedure:

    unit DataExchange;

    {$WARN SYMBOL_PLATFORM OFF}

    interface

uses
  Windows, ActiveX, Classes, ComObj, TEST_2_TLB, StdVcl, dialogs;

type
  TDataExchange = class(TTypedComObject, IDataExchange)
  protected
    procedure MENSAJE(out DATA: WideString); stdcall;
  end;

implementation

uses ComServ;
    
procedure TDataExchange.MENSAJE(out DATA: WideString);
begin
  showmessage(DATA);
end;

initialization
  TTypedComObjectFactory.Create(ComServer, TDataExchange, Class_DataExchange,
    ciMultiInstance, tmApartment);
end.

I create a Client to read this dll calling it this way:

procedure MENSAJE(out DATA: WideString); external 'TEST__2.ocx';

procedure TForm2.btn1Click(Sender: TObject);
var
texto : WideString;
begin
 texto := edt1.Text;
  MENSAJE (texto);
end;

Then when I execute the client an error shows up:

the Procedure entry point MENSAJEcould not be located in the dynamic library TEST__2.ocx

It Works if I create this procedure directly on the library unit, Like this:

library TEST__2;

uses
  ComServ,dialogs,
  TEST_2_TLB in 'TEST_2_TLB.pas',
  MAINFORM in 'MAINFORM.pas' {SuperActiveFORM: TActiveForm} {SuperActiveFORM: CoClass},
  DataExchange in 'DataExchange.pas' {DataExchange: CoClass};


{$E ocx}

procedure MENSAJE(out DATA: WideString); stdcall;
begin
  showmessage(DATA);
end;

exports
  DllGetClassObject,
  DllCanUnloadNow,
  DllRegisterServer,
  DllUnregisterServer,
  DllInstall,

  Mensaje;



{$R *.TLB}

{$R *.RES}

begin
end.

The thing is that if I create the procedure in the unit, I made it writing it. In the COM OBJECT I made it thru the ridl file, adding a method to the interface.

Answer 1

A COM Object inside of an ActiveX Library is the correct approach to expose functionality to outside apps. Your test client failed because you did not have it load the COM object at all, you tried to access a standalone function, but there really is none. You have to register your compiled DLL using regsvr32.exe, and then a client app can use CoCreateInstance/Ex() to instantiate the COM object when needed, call methods on it, and assign event handlers to it.

One of the better COM tutorials for Delphi (and C++Builder) is http://www.techvanguards.com, IMHO.