Question: Model the choreography and collaboration diagrams for the following business process at MetalWorks.

Keep in mind that the purpose of this BPMN diagram is to serve as a means of communication between the business stakeholders and the IT team who has to build a software system to automate this 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 purchase order. In other words, the manufacturer does not maintain any ready-to-ship products in their stock. 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 when MetalWorks 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 item refers to a different product. Upon receiving a customer PO, a sales officer checks the PO to determine if all the line items in the order can be produced within the timeframes indicated in the PO. As a result of this check, the sales officer may either confirm the customer PO or ask the customer to revise the terms of the PO (for example: change the delivery date to a later date). In some extreme cases, the sales officer may reject the PO, but this happens very rarely. If the customer is asked to revise the PO, the BTO process will be put in "stand-by" until the customer submits a revised PO. The sales officer will then check the revised PO and either accept 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 the customer PO. In other words, one customer PO gives place to multiple work orders (one per line item). The work order is a document that allows employees at MetalWorks to keep track of the manufacturing of a product requested by a customer.

In order to manufacture a product, multiple raw materials are typically required. Some of these raw materials are maintained in stock in the warehouse of MetalWorks, but others need to be sourced from one or multiple suppliers. Accordingly, each work order is examined by a production engineer. The production engineer determines which raw materials are required in order to fulfill the work order. The production engineer annotates the work order with a list of required raw materials. Each raw material listed in the work order is later checked by a procurement officer. The procurement officer determines whether the required raw material is available in stock, or it has to be ordered. If the material has to be ordered, the procurement officer selects a suitable supplier for the raw material and sends a PO to the selected supplier. This "PO for a raw material" is called a "material PO", and it is different from 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 production engineer who previously examined the work order.

The production engineer is responsible for scheduling the production. Once the product has been manufactured, it is checked by a quality inspector. Sometimes, the quality inspector finds a defect in the product and reports it to the production engineer. The production engineer then decides whether:

(i) the product should 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 need to 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 "cancel order" message for a given PO. When this happens, the sales officer determines if the order can still be canceled, and if so, whether or not the customer should pay a penalty. If the order can be canceled without penalty, all the work related to that order is stopped and the customer is notified that the cancellation has been successful. If the customer needs to pay a penalty, 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 work related to the order is stopped. Otherwise, the work related to the order continues.