TTcpServer.LocalPort Property

Specifies the ID number of the port used by the socket connection.

Pascal

property LocalPort: TSocketPort;

C++

__property TSocketPort LocalPort;

Description

Use LocalPort to determine the port number that is bound to the socket connection. For server endpoints of listening connections, LocalPort is the ID associated with the service the server socket provides. For client or server endpoints of connections to another socket, LocalPort is usually an arbitrary value picked when the connection was made.

Many values of LocalPort are associated by convention with a particular service such as FTP or HTTP.

C++ Examples:

Copy Code

/*
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:

Copy Code

{
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;