public string PlaceOrder(int customerId, long productId, int quantity)
{
OrderValidator.EnsureOrderParameters(customerId, productId, quantity);
EnsureProductIsSupported(productId);
var orderNumber = DataFacade.PlaceOrder(customerId, productId, quantity);
WarehouseServiceGateway.Ship(orderNumber);
Emailer.SendEmail(customerId, subject: "Order Confirmation", body: "Your order: " + orderNumber + ", has been received and confirmed. The shipment is on its way!");
return(orderNumber);
}