The current trend of the information technology industry (IT) is to go component based. Component can be defined as unit which do has the functionality for which it is designed. A component example can be a credit card processing component. The credit card processing component will have the functionalities such as

     Checking the validity of the credit card number
     Checking the amount charged against the authorised credit
     Performing the transaction with the credit card company
     Giving the status of the transaction.

This credit card component can be used in various areas. This component can be used in online retail stores,subcription services, online service providers etc.

This credit card component will used with other components to provide a full fledged services to the customer. This component may be deployed with other components such as

     Catalog component
     Sales component
     Inventory component
     Customer component
     Billing component

The component can be looked at as a one unit which provides some agreed upon functionality. This functionality of the component can be provided by one component or by multiple components. The components when drilled out contains objects for each individual functionality.

An analogy of the component can be thought of as a distribution from the supplier to the retailer using a truck give it a fancy name logistics component. Ley us use this logistics component in a beverage sales business.


Component : logistics component.
Functionality : To move the beverage from the supplier to the retailer
components : credit card component, sales component, inventory component, customer component, billing component

How components work
All the components introduced such as credit card component, sales component, inventory component, customer component, billing component and the logistics component can work together in harmony to provide a software to handle the beverage sales business.

Object
An object has data and methods to operate on the data. In our logistics component a truck object will be used to move the beverages. The truck class can be defined to have the following data

Truck Vechicle information number
licence plate number
Insurance policy number
Insurance amount
Insurance due date
Insurance company
Maximum load carrying capacity
Driver

Starting place
Destination
Start time
Start Date
Arrival time
Arrival date

The details can be grouped together which when grouped can be used in aother areas of the business operation. For example when the insurance details such as Insurance policy number
Insurance amount
Insurance due date
Insurance company
is grouped then this group of data can be used to represent the various insurance in the business

Truck insurance
Building Insurance
Flood insurance
Fire Insurance
Practice Insurance

The insurance class be defined with the above data. The Truck class can use this insurance class to define its insurance.

The class can consist of the following

Truck id
License
Insurance
Capacity
logistics
Service
Operation

in which
Truck id can be represented by an Indentity class
License can be represented by an license class
Insurance can be represented by an insurance class
Capacity can be represented by an capacity class
logistics can be represented by an logistics class
Service can be represented by an service class
Operation can be represented by an operation class

This defines the component can contain other colloborating components. Components can contain objects. Objects can contain other fine objects. This chain goes on till we go to the native data types such as string, int and boolean.

Class defined A class is a collection of data and method to operate on the data.