Class-based modeling identifies classes, attributes and relationships that the system will use. In the airline application example, the traveler/user and the boarding pass represent classes. The traveler's first and last name, and travel document type represent attributes, characteristics that describe the traveler class. The relationship between traveler and boarding pass classes is that the traveler must enter these details into the application in order to get the boarding pass, and that the boarding pass contains this information along with other details like the flight departure gate, seat number etc.

Class based modeling represents the object. The system manipulates the operations.

The elements of the class based model consist of classes and object, attributes, operations, class – responsibility - collaborator (CRS) models.

Classes

Classes are determined using underlining each noun or noun clause and enter it into the simple table.

Classes are found in following forms:

External entities: The system, people or the device generates the information that is used by the computer based system.

Things: The reports, displays, letter, signal are the part of the information domain or the problem.

Occurrences or events: A property transfer or the completion of a series or robot movements occurs in the context of the system operation.

Roles: The people like manager, engineer, salesperson are interacting with the system.

Organizational units: The division, group, team are suitable for an application.

Places: The manufacturing floor or loading dock from the context of the problem and the overall function of the system.

Structures: The sensors, computers are defined a class of objects or related classes of objects.

Attributes

Attributes are the set of data objects that are defining a complete class within the context of the problem.

For example, 'employee' is a class and it consists of name, Id, department, designation and salary of the employee are the attributes.

Operations

The operations define the behavior of an object.

The operations are characterized into following types:

• The operations manipulate the data like adding, modifying, deleting and displaying etc.

• The operations perform a computation.

• The operation monitors the objects for the occurrence of controlling an event

CRS Modeling

• The CRS stands for Class-Responsibility-Collaborator.

• It provides a simple method for identifying and organizing the classes that are applicable to the system or product requirement.

• Class is an object-oriented class name. It consists of information about sub classes and super class

• Responsibilities are the attributes and operations that are related to the class.

• Collaborations are identified and determined when a class can achieve each responsibility of it. If the class cannot identify itself, then it needs to interact with another class.