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TTcpClient.OnCreateHandle Event

Occurs when the handle to a socket becomes active.

Pascal
property OnCreateHandle: TSocketNotifyEvent;
C++
__property TSocketNotifyEvent OnCreateHandle;

Write an OnCreateHandle event handler to take specific action when the handle to a socket becomes active.  

C++ Examples: 

 

/*
This example demonstrated the use of TTcpServer in order to receive
a buffer (stream) and process it. It is to be used with the example
from TTcpClient section.
This example uses three buttons, one for activating the server, one
for deactivating it and the third for clearing the Memo.
*/
__fastcall TForm3::TForm3(TComponent* Owner)
    : TForm(Owner)
{
    Memo1->Lines->Clear();

    //server initialization
    TcpServer1 = new TTcpServer(this);
    TcpServer1->OnAccept = TcpServer1Accept;
    TcpServer1->OnCreateHandle = TcpServer1CreateHandle;
    TcpServer1->OnDestroyHandle = TcpServer1DestroyHandle;

}
//---------------------------------------------------------------------------
void __fastcall TForm3::TcpServer1Accept(TObject *Sender,
                                        TCustomIpClient *ClientSocket)
{
    byte a[10];
    ClientSocket->ReceiveBuf(a,10,0);
    TDateTime now = TDateTime::CurrentDateTime();
    Memo1->Lines->Add(DateTimeToStr(now) + " Data added width " +
                        IntToStr(a[9]));
    for (int i=0; i < 9; i++)
    {
        Memo1->Lines->Add(IntToStr(a[i] + a[9]));
    }
    Memo1->Lines->Add("--------------------");

}
//---------------------------------------------------------------------------
void __fastcall TForm3::Button1Click(TObject *Sender)
{
    TcpServer1->LocalPort = DEFAULT_PORT;
    TcpServer1->Active = true;
}
//---------------------------------------------------------------------------
void __fastcall TForm3::Button2Click(TObject *Sender)
{
    TcpServer1->Active = false;
}

//---------------------------------------------------------------------------
void __fastcall TForm3::Button3Click(TObject *Sender)
{
    Memo1->Lines->Clear();
}
//---------------------------------------------------------------------------

void __fastcall TForm3::TcpServer1CreateHandle(TObject *Sender)
{
    TDateTime now = TDateTime::CurrentDateTime();
    Memo1->Lines->Add(DateTimeToStr(now) + " Server started.");
}
//---------------------------------------------------------------------------

void __fastcall TForm3::TcpServer1DestroyHandle(TObject *Sender)
{
    TDateTime now = TDateTime::CurrentDateTime();
    if(this->Memo1)
    {
        Memo1->Lines->Add(DateTimeToStr(now) + " Server stopped.");
    }
}
//---------------------------------------------------------------------------

 

Delphi Examples: 

{
This example demonstrated the use of TTcpServer in order to receive
a buffer (stream) and process it. It is to be used with the example
from TTcpClient section.
}

const DEFAULT_PORT = 2501;

{$R *.dfm}

procedure TForm3.Button1Click(Sender: TObject);
begin
  //connectiong the server
  TcpServer1.Active := true;
end;

procedure TForm3.Button2Click(Sender: TObject);
begin
  //disconnecting the server
  TcpServer1.Active := false;
end;

procedure TForm3.Button3Click(Sender: TObject);
begin
  //clearing the memo
  Memo1.Lines.Clear;
end;

procedure TForm3.FormCreate(Sender: TObject);
begin
  Memo1.Lines.Clear;

  //server initialization
  TcpServer1 := TTcpServer.Create(Self);
  TcpServer1.OnAccept := TCpServer1Accept;
  TcpServer1.OnCreateHandle := TcpServer1CreateHandle;
  TcpServer1.OnDestroyHandle := TcpServer1DestroyHandle;
  TcpServer1.LocalPort := IntToStr(DEFAULT_PORT);
end;

procedure TForm3.TcpServer1Accept(Sender: TObject;
  ClientSocket: TCustomIpClient);
var
  a : array[0..9] of byte;
  I : Cardinal;
begin

  ClientSocket.ReceiveBuf(a,10,0);
  Memo1.Lines.Add(DateTimeToStr(now) + ' Data added with ' +
                  IntToStr(a[9]));
  for I := 0 to 8 do
  begin
    Memo1.Lines.Add(IntToStr(a[I] + a[9]));
  end;
  Memo1.Lines.Add('--------------------');

end;

procedure TForm3.TcpServer1CreateHandle(Sender: TObject);
begin
  Memo1.Lines.Add(DateTimeToStr(now) + ' Server started.');
end;

procedure TForm3.TcpServer1DestroyHandle(Sender: TObject);
begin
  if Self.Memo1 <> nil then
    Memo1.Lines.Add(DateTimeToStr(now) + ' Server stopped.');
end;

 

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