Model the following process. After a supplier notifies a retailer of the approval of a purchase order, the supplier can either receive an order confirmation, an order change or an order cancellation from the retailer. It may happen that no response is received at all. If no response is received after 48 hours, or if an order cancellation is received, the supplier will cancel the order. If an order confirmationis received within 48 hours, the supplier will process the order normally. If an order change is received within 48 hours, the supplier will update the order and ask again the retailer forconfirmation. The retailer is allowed to change an order at most three times. Afterwards, the supplier will automatically cancel the order.

Exercise 4.35 (optional)

 Model the choreography for the following process. A build-to-order (BTO) process, also known as make-to-order process, is an “order-to-cash”process where the products to be sold are manufactured on the basis of a confirmed purchaseorder. In other words, the manufacturer does not maintain any ready-to-ship products in theirstock. Instead, the products are manufactured on demand when the customer orders them.This approach is used in the context of customized products, such as metallurgical products,where customers often submit orders for products with very specific requirements.We consider a BTO process at a company called MetalWorks. The process starts whenMetalWorks receives a purchase order (PO) from one of its customers. This PO is called the“customer PO”. The customer PO may contain one or multiple line items. Each line itemrefers to a different product.Upon receiving a customer PO, a sales officer checks the PO to determine if all the lineitems in the order can be produced within the timeframes indicated in the PO. As a resultof this check, the sales officer may either confirm the customer PO or ask the customerto revise the terms of the PO (for example: change the delivery date to a later date). Insome extreme cases, the sales officer may reject the PO, but this happens very rarely. Ifthe customer is asked to revise the PO, the BTO process will be put in “stand-by” until thecustomer submits a revised PO. The sales officer will then check the revised PO and eitheraccept it, reject it, or ask again the customer to make further changes.Once a PO is confirmed, the sales officer creates one “work order” for each line item in thecustomer PO. In other words, one customer PO gives place to multiple work orders (oneper line item). The work order is a document that allows employees at MetalWorks to keeptrack of the manufacturing of a product requested by a customer.In order to manufacture a product, multiple raw materials are typically required. Some ofthese raw materials are maintained in stock in the warehouse of MetalWorks, but others needto be sourced from one or multiple suppliers. Accordingly, each work order is examined by aproduction engineer. The production engineer determines which raw materials are requiredin order to fulfill the work order. The production engineer annotates the work order with alist of required raw materials. Each raw material listed in the work order is later checkedby a procurement officer. The procurement officer determines whether the required rawmaterial is available in stock, or it has to be ordered. If the material has to be ordered, theprocurement officer selects a suitable supplier for the raw material and sends a PO to theselected supplier. This “PO for a raw material” is called a “material PO”, and it is differentfrom the customer PO. A material PO is a PO sent by MetalWorks to one of its suppliers,whereas a customer PO is a PO received by MetalWorks from one of its customers.Once all materials required to fulfill a work order are available, the production can start.The responsibility for the production of a work order is assigned to the same productionengineer who previously examined the work order. The production engineer is responsiblefor scheduling the production. Once the product has been manufactured, it is checked by aquality inspector. Sometimes, the quality inspector finds a defect in the product and reportsit to the production engineer. The production engineer then decides whether: (i) the productshould undergo a minor fix; or (ii) the product should be discarded and manufactured again.Once the production has completed, the product is shipped to the customer. There is no needto wait until all the line items requested in a customer PO are ready before shipping them.As soon as a product is ready, it can be shipped to the corresponding customer.At any point in time (before the shipment of the product), the customer may send a “cancelorder” message for a given PO. When this happens, the sales officer determines if the ordercan still be canceled, and if so, whether or not the customer should pay a penalty. If theorder can be canceled without penalty, all the work related to that order is stopped and thecustomer is notified that the cancellation has been successful. If the customer needs to pay apenalty, the sales officer first asks the customer if they accept to pay the cancellation penalty.If the customer accepts to pay the cancellation penalty, the order is canceled and all workrelated to the order is stopped. Otherwise, the work related to the order continues.