Slightly-less naive model implementation for Quora quesiton - http://www.quora.com/CakePHP/What-is-the-right-approach-to-consume-an-API-in-CakePHP

ecommerce-eg-2.php

<?php 

namespace Model;

class Product { /* etc... */ }
class Order { /* etc... */ }
class Customer { /* etc... */ }

/* * * * * * * * * * * * * * * * */

namespace Service;

class OrderProcessor
{
    public function createOrder(Customer $customer, array $products)
    {
        // etc...
        
        /** @var $order Model\Order */
        return $order;
    }
}