## 3 Overview of Information Systems
### Stages of Implementing an Information System
It contains components related to the overall functionality of the system, such as patients, doctors, appointments, and schedules. * Entities represents a sub-package within the medical system package. It contains classes representing the main entities or domain objects of the system, such as patient, doctor, appointment, and schedule. The arrows indicate dependencies between packages, with components inside the medical system package depending on the entities package. This package diagram provides a high-level view of how the components of the medical appointment booking system are organized into packages or modules, helping to manage the complexity of the system and facilitate maintenance and development. * State diagram describes the states through which a particular object passes. Diagram example is presented in Figure 9.  
In this state diagram:  
* Patient Appointment Booking represents the overall process of a patient booking an appointment. Figure 2:0 Package diagram for an appointment booking in a medical information system. Figure 2:1 State diagram for an appointment booking in a medical information system. * Start represents the initial state when the booking process begins. * Pending represents the state when the patient has selected an appointment slot but has not confirmed it yet. * Confirmed represents the state when the patient has confirmed the appointment. * Canceled represents the state when the patient cancels the appointment. * Books Appointment: Transition from the start state to the Pending state when the patient selects an appointment slot. * Confirm Appointment: Transition from the Pending state to the confirmed state when the patient confirms the appointment. * Cancel Appointment: Transition from the Pending or confirmed state to the Canceled state when the patient cancels the appointment. This state diagram provides a visual representation of the different states a patient's appointment booking can be in and the transitions between those states. It helps to understand the lifecycle of an appointment booking process within the system. * Entity Relationship diagram presents entities (such as tables in a database), their attributes, and the relationships between entities. ERD is commonly used in database design and data modeling. Diagram example is presented in Figure 2:2  
In this ERD:  
* Patient and doctor are entities representing patients and doctors, respectively. They have attributes such as id, name, gender, age, and specialty. * Appointment represents appointments booked by patients with doctors. It has attributes such as id, date, time, and foreign keys referencing the patient and doctor entities. * Schedule represents the schedules of doctors. It has attributes such as id, doctor id, day, and time slots. Relationships:
* Appointment is associated with patient and doctor entities through the patient id and doctor id, representing the patient who booked the appointment and the doctor involved in the appointment. * Doctor is associated with schedule through the doctor id, representing the schedule of each doctor. Figure 2:3 ERD for an appointment booking in a medical information system. This ERD provides a visual representation of the entities involved in the medical appointment booking system and their relationships. It helps to understand the structure of the database schema and how the different entities are connected. Implementation:  
Component diagram illustrates the system's modules and their interaction. Diagram example is presented in Figure 2:4  
In this component diagram:  
Medical appointment booking system represents the main system. Frontend represents the user-facing components of the system. It includes modules such as user interface, patient dashboard, and doctor dashboard. Backend represents the server-side components of the system. It includes modules such as authentication, appointment service, and database access. Database represents the database used by the system to store data related to patients, doctors, appointments, etc.