private void CloseConnection()
{
if (sender == null)
{
return;
}
senderSema.Wait();
WriteLog(LogStrings.CloseConnection());
WriteLog(LogStrings.AttemptingToSendMessage(endMessage));
byte[] bytes = Encoding.UTF8.GetBytes(endMessage);
sender.BeginSend(bytes, 0, bytes.Length, 0, new AsyncCallback(CloseConnectionCallback), sender);
}