1. Modeling the Grocery Checkout System COP 4232 © Dr. David A. Workman School of Electrical Engineering and Computer Science October 3, 2005

2. August 22, 2005COP 4232 (C) Dr. David A. Workman2 Grocery Store – The Virtual World Entry Exit Aisle 1 Aisle 2 Cart Pool Conveyor 0 1 2 9 Aisle Delta Checkout Queue clerk Aisle n Aisle Width Starting Point Sales Register Bagging Bin bagger Shopper Enters Bagger Returns Cart Bagger & Shopper Exit Checkout Subsyste m Shopper & Cart

3. August 22, 2005COP 4232 (C) Dr. David A. Workman3 Checkout Station Model Conveyor Scales & Scanner Clerk Bagging Bin Sales Terminal Bagger Shopper Cart 1: Shopper unloads grocery items, if there is room on conveyor. 2: Shopper places plastic divider on conveyor after last grocery item. 3: Conveyor has a fixed capacity in numbers of items and transports them at a constant rate to the clerk’s station. 4:Clerk removes grocery items from conveyor and enters their identity and price into the sales system. Some items are identified and priced by bar codes. Other items must by manually identified and weighed. 5: When all items have been processed by the clerk, the shopper is presented with the total amount of the purchase. 6: The shopper pays for the groceries and is given a sales receipt. 7: When the cart has been unloaded, the shopper gives the cart to the bagger to be filled with bags of groceries. 8:The bagger loads grocery bags with items that have been priced by the clerk. Bags are held in the bin until the cart becomes available from the shopper. 9:When the payment transaction has been completed and all bags have been loaded in the cart, the shopper leaves the store with the bagged groceries.

4. August 22, 2005COP 4232 (C) Dr. David A. Workman4 Use Case Diagram Unload Items for Pricing Grocery Checkout System * Customer Price Check Grocery Items Pay By Cash Deliver Sacked Grocery * Customer Pay For Groceries Pay By Credit Sack Grocery Items «specialize» * Credit Co.

5. August 22, 2005COP 4232 (C) Dr. David A. Workman5 System State Diagram U1: Shopper removes Groceries from Cart and places them on Conveyor. Clerk removes Groceries from Conveyor and price checks them. Priced Groceries are placed in bin for Bagger. U2: Shopper places Plastic Bar on Conveyor and releases empty Cart to Bagger. Bagger fills sacks with Groceries and moves filled Sacks into Cart. U3: Clerk removes Plastic Bar and presents cost of groceries to the Customer. Bagger continues sacking Groceries and loading Cart. U4: Shopper makes payment and, if necessary, Clerk returns change. Clerk gives a Receipt to Customer and signals Bagger to release loaded Cart (when ready). U5: Bagger completes sacking Groceries and continues loading Sacks into Cart. U6: Bagger completes loading the Cart and releases loaded Cart to Shopper. Start Shopper Unloading Items Clerk Pricing Items Bagger Sacking Items U1 Shopper Waiting Clerk Pricing Items Bagger Sacking Items and loading Cart. U2 Shopper Paying Clerk Waiting Bagger sacking Items and loading Cart U3 U4 End U5 Shopper Waiting Clerk Waiting Bagger loading Cart U6 Shopper Waiting Clerk Waiting Bagger loading Cart

6. August 22, 2005COP 4232 (C) Dr. David A. Workman6 Use Case Communication Diagram Shopper Clerk 1: Pay Amount $ddd.cc 2: Accept Amount $xxx.cc 3a: Receive Change $yyy.cc 3b: Receive Receipt