Question$3$

a$)$ Consider the following business rules for the Hong Kong $($HK$)$ Hospital for patient appointment. Because of the COVID$19,$ the HK hospital have a special rule to handle pandemic situation. HK hospital have several doctors. Each doctor can be scheduled for many appointments to check potential COVID$19$ patients. If there are no COVID$19$ Patients, the doctor may not have any schedule. Each appointment is scheduled with exactly one doctor at the HK hospital. A potential COVID$19$ patient can schedule one or more appointments. One appointment is scheduled with exactly one COVID$19$ patient at the HK hospital. An appointment must generate$1$ bill only. Each bill is generated by one appointment only. One payment is applied to exactly one bill, and one bill can be paid off over time by several payments or may not be paid off at all. One patient can make many payments or may not make any payments, but a single payment is made by one patient only. Some COVID$19$ patients are insured by an insurance company. If the COVID$19$ patients are insured, they can only have insurance with one company only. An insurance Company can provide insurance to many COVID$19$ patients. For patients that carry insurance, the insurance company will make payments, each single payment is made by exactly one insurance company. Given the functional description of the processes of HK hospital, do the following.

Identify all of the main entities and draw a neat and clean Entity Relationship Diagram $($ERD$)$ with Crow's Foot Notations. Identify and draw all relations in ERD properly. $(20$ marks$)$

b$)$ Define client server system. List THREE different architectures of client$-$server model.