Below Figure 4.3 shows the Use case diagram of actor’s customer and cashier and the subsystem checkout trolley combined together.
Key point to be noted from the Figure 3.4 are:
• The use case “Get the checkout trolley”, must perform the use cases of the subsystem Checkout Trolley.
• The use case “Pay bill” of customer and handle payment use case of the Cashier must perform the use cases, Cash payment and Card payment.
• Similarly scan product use case of cashier involves further use case add product and remove product
Figure 4.3: Use Case of Regular Checkout system vs Checkout Trolley System
4.3.2 Structural Design
The structural design is the graphical representation of static structure of a system and it is shown with the help of objects, attributed and operation of the system (Fowler and Scott, 1997). The structural design of the POS system is explained in form of two class diagrams below:
4.3.2.1 Class Diagram (with Checkout Trolley)
• First of all Customer and CheckoutTrolley has one to one or many relationship as one customer can take one or more checkout Trollies.
• Customer and CreditDebitcard has one to one or many relationship as in this case customer should have at least one card.
• CheckoutTrolley and the CreditDebitCard class will have one to one relationship, as one …show more content…
To achieve this the bar code scanner, the LCD display, the card payment machine and the receipt printer should be combined and attached to the supermarket Trollies/Baskets, so that during the shopping, customer can choose to checkout anytime and pay the amount using the new checkout trolley system, get the receipt and leave the supermarket without waiting in the queue for the scanning, payment and receipt (Zdravkovic, p.891). Figure 4.6 shows how the new Checkout Trolley system would look