Sunset Graphics often buys inventory after receiving a sales order from the customer. Suppose you are asked to prepare one UML class diagram that combines both the sales and collection process and the purchases and payments process. What would be shared among those processes? What would be unique to each process? Why?
UML diagrams are used to represent the business processes of a business. Usually, and for the purpose of modeling, business processes should be discrete and attempt to avoid too much detail if possible. This is so they can be easily understood and documented by users in the business. In this case, Sunset Graphics has identified two distinct processes, the sales and collection process and the purchases and payments process, and wants to combine them in their UML Diagram. This is possible, but generally not best practice since these two separate processes do not have much overlap between classes and functions within the business. The model may be unwieldy and confusing for some of the users. Aside from that, the users typically involved in the purchase and payments process are not generally going to be the same for those in the sales and collection process as an internal control.
There are some shared classes and functions between the two processes. In an abstract sense of a “procure to payment” process, the two processes are nearly identical in that Sunset is acting as a vendor in one process (sales and collection) and a customer (purchases and payments) in the other. Many of the same generic business functions will apply but the actor in each of the models will be different. A quote is provided in both cases, but who prepares the quote will differ. An invoice will be received but who it is received by will differ. In this case, the two processes may look almost exactly alike.
The primary difference between the two processes will be what happens in between the order received activity and the delivery activity. Where Sunset Graphics has the business activities: to Prepare Products and to Apply Graphics, their supplier may have a different activity such as, package materials, or retrieve from warehouse. These activities will be unique to the actual business that the supplier is in and may not translate to the Sunset Graphics business. Aside from that, these activities that are performed by the vendor of Sunset Graphics should not appear on their UML diagram at all.