Object Oriented Design Essay Example

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Software Engineering 1

Object Oriented Design


System Design

OOSD involves the definition of the context of a system. This context definition is then followed closely by the design process of the system architecture. In essence, classes are templates for defining the characteristics and operations of an object. Often, classes and objects are used interchangeably, one synonymous with the other. In actuality, a class is a specification that an object implements. The below are some of the key terms and their definitions used in OOSD;

1. Context Part: The context of a system is constituted by both the dynamic and the static part. The static context of the system is designed using a simple block diagram of the whole system which is expanded into a hierarchy of subsystems. The subsystem model is represented by UML packages. The dynamic context describes how the system interacts with its environment. It is modelled using use case diagrams.

2. System Architecture part: This part of the system architecture is designed on the basis of the context of the system in accordance with the principles of architectural design as well as domain knowledge. Typically, a system is partitioned into layers and each layer is decomposed to form the subsystems.

Classes or Objects

Object-oriented classes support the object-oriented principles of abstraction, encapsulation, polymorphism and reusability. They do so by providing a template, or blueprint, that defines the variables and the methods common to all objects that are based on it. Classes specify knowledge (attributes) — they know things — and behavior (methods) — they do things.

In regards the above exercise the below are some of the key objects identified;

  1. Customers: this is the central object in this system. He/she is the one that books the reservation be it a hotel, a car, or an airline. The attributes associated with this object are;

  • Passport number

  1. Reservations: this is an object that will be used keeping track of all the reservations done by the client. The attributes that constitute this object are;

  • Reservation_id

  • Reservation_number

  • Primary_client

  • Reservation_date

  • Reservation_type

  • Reservation_detail

  1. Car: this is a means of transport object. The attributes that constitute this object are;

  • Car_number

  • Car_model

  • Car_capacity

  • Car_colour

  • Availability

  • Comments

  1. Hotel: this is a place or object that can be used as a resting place for the customers. Attributes here include

  • Hotel_number

  • Hotel_address

  • Hotel_location

  1. Airline: This is another means of transport that traverses the skies. The attributes are;

  • Airline_number

  • Airline_capacity

  • Seat_number

Activity Diagram

Activity diagram is a kind of UML diagram that shows flow of control from activity to activity. It shows concurrency, branch, control flow and object flow. Furthermore, swim lane is used for partitioning actions based on the participants involved.

Object Oriented Design

Class Diagram

A class diagram is a kind of UML diagram that shows the objects that are required and the relationships between them. Since it provides detailed information about the properties and interfaces of the classes, it can be considered as the main model and regard the other diagrams as supplementary models.

Object Oriented Design 1

Sequence Diagrams

A sequence diagram is a kind of UML diagram that is used primarily to show the interactions between objects that are represented as lifelines in a sequential order.

Object Oriented Design 2


Faulkner, Christien. Software Engineering. 1st ed., Chandni Chowk, Delhi, Global Media, 2009,.

Teorey, Toby J et al. Database Modeling & Design. 1st ed., Amsterdam, Elsevier, 2005,.