The Company A sells books and CDs through online shopping. The customer adds items to her shopping cart. He/She may cancel items or go to the check-out to make his /her purchases at any time. The customer reviews her purchases, chooses a payment method and pays. The customer may check the order status. A sales employee at company A gets the order and purchase confirmation from the system, and sends the electronic order to the warehouse. The warehouse employee updates the order status. The online shopping application will support 500 concurrent users. Answer the following questions briefly. a) Identify the main actors of the proposed system b) Identify the main use cases (functional requirements (FRs))

c) List two non-functional requirements (NFRs).

d) Draw the use case diagram