Problem: Judging by the diagrams provided, this system is for inventory management, processing orders, and sales. This system will allow a customer to process an order from the retailer which would be routed to the supplier and make a payment for the order. The retailer would simply facilitate the transfer of goods. Therefore, the actors involved would be the retailer, supplier, and customer. Because this system allows the retailer to order the goods from the supplier, that makes the retailer and supplier actors, the customer becomes an actor when they start an order for those goods and makes as payment to the retailer which is then used to purchase the goods from the supplier.
The entities that are a part of this system would be the retailer and supplier. The orders would be objects used and stored by the supplier and retailer. The retailer's inventory and price for each product as well as the customer information would also be stored as objects by the retailer. The supplier would store quantities of the goods they supply to the retailer.
The sequence of events that will transpire is initiated when the retailer places an order on the supplier's system. The supplier would then fulfill the order and ship it to the retailer. The retailer then arranges and applies to price to the individual items and adds the items to their inventory. The customer may then make orders through the retailer's system which would need payment from the customer before shipping. On payment confirmation, the system would then ship the goods and the customer order will have been fulfilled.