Scenario: -

1. After login to the SPS, the lab technician selects to make a request for services.

2. The SPS displays the services it provides. Each service has a code [SC], a description [DESC], and a price per unit [PR]. For instance, the service S1 price is 5 OMR per unit.

3. To make a request, the technician selects one or more services. For each selected service, the technician enters the number of units [NU] requested. Once the technician completes the request, the SPS displays the summary, including all the information of the request for services with the total to pay [AMT] for the request.

4. Once the technician confirms, the SPS saves the request with a request ID [RID], the technician user name [UN], the date of the request [RDATE], the total amount [TAMT], and a status [STA] with initial value is ‘Unpaid’. Then it updates the balance [BAL] of the account of the technician by increasing it with the amount [TAMT] of the request.

5. At any time, the technician can pay a request. S/he enters the request RID. The SPS displays the amount for this RID. Before entering the amount to pay [PAMT], the technician may request to use a discount code, in this case a discount is computed and the new amount is displayed. If the payment is by card, the card is checked against an authorization system (e.g., visa). The SPS updates the amount [TAMT] of the request with the PAMT (TAMT-=PAMT), its status [STA] ‘paid’ or ‘partially paid’, and the balance [BAL] of the technician (BAL-= PAMT), prints out a receipt, and records the payment with a RID, a receipt reference [REF], payment date (PDATE), and amount paid [PAMT].

Note

request may have many services and a service is requested in many requests. NU (Number of Units) may be different for each service in each request. For instance, in the request R1, the service S1 requires 2 units whereas in the request R2, the service S1 requires 3 units. Also, a technician may have many requests but a request belongs to only one technician.

Q3 Draw a Design Class Diagram, limiting to the classes from where you instantiate the objects involved in the realization of this use case, showing their attributes, operations, and relationships.