public Cart getCartById(String rawCartId) {
   long cartId = -1;
   try {
     cartId = Long.parseLong(rawCartId);
   } catch (NumberFormatException e) {
     throw new IllegalArgumentException(e);
   }
   return cartDao.getCartById(cartId);
 }
 public void deleteCart(Cart cart) {
   cartDao.deleteCart(cart);
 }
 public void saveOrUpdateCart(Cart cart) {
   cartDao.saveOrUpdateCart(cart);
 }