Jupiter Motors web service

In our corporate portal for Jupiter Motors, we included a design for a client application, which our delivery personnel will use to update the status of an order and to decide which customers will accept delivery of their vehicle. For accounting and insurance reasons, the order status needs to be updated immediately after a customer accepts their vehicle. To do so, the client application will call a web service to update the order status as soon as the Accepted button is clicked. Our WCF service is interconnected to other parts of our Jupiter Motors application, so we won't see it completely in action until it all comes together. In the meantime, it will seem like we're developing blind. In reality, all the components would probably be developed and tested simultaneously, but the structure of a book makes that difficult.