Question

Identify possible objects in the following systems and develop an object- oriented design for them. You may make any reasonable assumptions about the systems when deriving the design. A group diary and time management system is intended to support the timetabling of meetings and appointments across a group of co-workers. When an appointment is to be made that involves a number of people, the system finds a common slot in each of their diaries and arranges the appointment for that time. If no common slots are available, it interacts with the user to rearrange his or her personal diary to make room for the appointment. A filling station (gas station) is to be set up for fully automated operation. Drivers swipe their credit card through a reader connected to the pump; the card is verified by communication with a credit company computer, and a fuel limit is established. The driver may then take the fuel required. When fuel delivery is complete and the pump hose is returned to its holster, the driver's credit card account is debited with the cost of the fuel taken. The credit card is returned after debiting. If the card is invalid, the pump returns it before fuel is dispensed.

Short answer

Key objects are Users, Diary, Appointments, and Scheduler for the diary system; Pump, CreditCard, Transaction, and CardReader for the station system.

Step-by-step solution

Identify Key Objects for Group Diary System

In a group diary and time management system, the key objects can be identified as follows: - **User**: Represents a co-worker who can have appointments and meetings scheduled. - **Diary**: Records appointments and meetings for a user. - **Appointment**: Represents a meeting or event that occurs at a specific time. - **TimeSlot**: Represents available time ranges for users. - **Scheduler**: Responsible for finding suitable time slots and arranging appointments.

Define Object Relationships for Group Diary System

- The **User** object has a one-to-many relationship with the **Diary** object, as a user can have multiple diary entries. - The **Diary** object includes multiple **Appointment** objects. - **Appointment** objects have an association to **TimeSlot** objects to define the timing. - The **Scheduler** uses the **Diary** and **TimeSlot** to arrange and possibly rearrange appointments.

Identify Key Objects for Filling Station System

For a fully automated filling station, consider the following key objects: - **Pump**: Dispenses fuel and interacts with the credit card reader. - **CreditCard**: Represents a customer’s credit card used for payment. - **Transaction**: Handles the credit card verification, fuel limit establishment, and payment processing. - **Fuel**: Represents the type and quantity of fuel dispensed. - **CardReader**: Communicates with the pump and credit company for card verification.

Define Object Relationships for Filling Station System

- **Pump** has a direct association with **CardReader** for handling transactions. - **CreditCard** is used by the **CardReader** to initiate a **Transaction**. - **Transaction** checks credit card validity, sets fuel limits, and processes payments. - **Fuel** is managed by the **Pump** and is linked to the **Transaction** for billing purposes.

Key concepts

Time Management System

A time management system is designed to streamline scheduling for busy professionals. Imagine working in a team with co-workers, where everyone has various appointments, meetings, and personal commitments. This system aids in organizing all these tasks effectively by finding available time slots for all involved users.
Consider these key components:

• User: Represents every individual who needs their schedule managed.
• Diary: Acts like a personal calendar for each user where all appointments and meetings are recorded.
• Appointment: Any event or meeting planned for users.
• TimeSlot: The designated duration when an appointment can occur.
• Scheduler: The smart component that finds free times for appointments, rearranging if necessary.

In essence, the scheduler plays the hero by checking each user's diary to spot free slots, then proposing a time that fits everyone. If no common slot is found, it may interact with users to shift other meetings around. This flexibility ensures meetings are set seamlessly without constant back-and-forth emails.

Automated Filling Station

An automated filling station revolutionizes the way drivers refuel their vehicles. Picture driving up to a gas station and swiping your credit card to begin. Here's how it works:

• Pump: The core of the station that delivers fuel based on the amount needed.
• CreditCard: What the driver uses to pay for the fuel service.
• Transaction: Manages all the purchasing details – confirms the card, sets fuel limits, and processes payments.
• Fuel: Specifies the type and quantity of fuel being dispensed.
• CardReader: The intermediary between the credit card and pump, ensuring smooth communication.

Once the card is swiped, the card reader validates it with the credit company, informing the pump of any fueling limits. After fueling, the pump calculates the cost and charges the driver's card, which is then debited with the transaction amount. This efficient process ensures quick and safe refueling without needing direct human intervention.

Object Relationships

Understanding object relationships is pivotal in object-oriented design. In both systems—the time management system and automated filling station—objects connect, communicate, and work together to perform complex tasks in an organized manner.

• In the Group Diary System, the User has multiple Diary entries linked to Appointments. The Scheduler bridges these entries with TimeSlots to manage events.
• For the Filling Station, the Pump and CardReader collaborate closely. The card swiped by the CreditCard activates a Transaction, which verifies and processes payments enclosing the Fuel used.

These relationships seem simple but they are vital. They ensure systems like schedulers and transactions work efficiently, avoiding errors. This organized interaction showcases the power of object-oriented design in handling real-world scenarios, creating orderly and easily scalable systems.

Group Diary System

The group diary system is an ingenious solution for managing collective schedules in a workplace. When several team members need to find a mutual time for a meeting, this system excels in doing just that.
Imagine being part of a workgroup where you want to arrange meetings without endless emails or scheduling conflicts.

• User: Any member involved in scheduling.
• Diary: A personal organizer showing user appointments.
• Appointment: The official time set aside for a meeting or event.
• TimeSlot: Specific periods available for booking.
• Scheduler: The mastermind sorting through diaries to find open slots for everyone.

With this system, once a meeting needs to be scheduled, it checks the diaries of all involved users. If no corresponding free time is found, the scheduler may suggest rescheduling other less important entries to carve out space for the meeting. Its efficiency greatly reduces the hassle of manual scheduling, helping teams stay organized and productive.