Purpose of UML Class Diagrams

UML class diagrams are used to create a blueprint for developing a relational database that will support the collection, aggregation, and communication of process information for the purchase and payment process. The diagrams are structured around the REA framework (resources, events, and agents), which helps describe business processes in a way that meets both accounting and broader management information needs.

Basic UML Class Diagram for Purchases and Payments

A basic UML class diagram for purchases and payments begins by identifying the key elements involved:

• Agents: These include the Sunset Employee who selects the Supplier and issues a Purchase Order.

• Events: The process events include issuing the purchase order, receiving the products, and making payment. The Purchase Order and Receipt events, along with Cash Disbursement, represent the core events of the process.

• Resources: Resources such as Products (inventory) and Cash are tracked within the model.

Key Elements and Associations

• The Purchase Order specifies the products and quantities ordered from a supplier.

• The Receipt of goods is recorded, triggering the recognition of the purchase and the corresponding accounts payable.

• When payment is due, an employee processes a Cash Disbursement to the supplier, reducing the accounts payable and cash balance.

Refining the UML Class Diagram

In the refined diagram, classes like Purchase Orders and Receipts may be combined if there is a one-to-one relationship. For instance, if Sunset Graphics always records a purchase order for a transaction and does not accept partial shipments, the diagram can be simplified by collapsing these events into a single Purchases class.

This diagram provides a structured approach to modeling the data needed to manage and document the purchase and payment process, ensuring that information flows and controls are clearly represented​​ .