title: Delphi and Indy - How can I send something from IdTCPServer to a specific IdTCPClient
body: <p>I started playing with Indy 10 (from Delphi XE3) and TCP connections recently. I already could, with your help (special thanks to Remy Lebeau), build a simple server application for manage client connections (see here <a href="https://stackoverflow.com/questions/27208595/delphi-simple-tcp-client-server-using-indy-to-check-clients-status">Delphi - Simple TCP client / server using Indy to check clients status</a>). I am using a listbox to add connected clients. See the code:</p>
  
  <pre><code>procedure TfrmMain.TCPServerConnect(AContext: TIdContext);
  var
    Host: String;
  begin
    Host := UpperCase(GStack.HostByAddress(AContext.Binding.PeerIP));
    TThread.Queue(nil,
      Procedure
      begin
        ListBox.Itens.Add(Host);
        Log('Connected - ' + Host);
        With TCPServer.Contexts.LockList Do
        Try
          StatusBar.Panels[0].Text := 'Connected Clients: ' + IntToStr(Count);
        Finally
          TCPServer.Contexts.UnlockList;
        end;
      end
    );
  end;
  </code></pre>
  
  <p>Now I am trying to send a "hello" from server to a specific client in the list. My idea was to click to select a client hostname in the listbox, then click a button to send the message. But what I am researching is that things are not so easy as I am thinking...</p>
  
  <p>Please, can some Indy expert point me the correct direction (with Indy 10)?</p>
  
  <p>Thanks!</p>