What is Cloud Computing?

The cloud computing system is an important part of modern communication systems. This article explains an introduction to cloud computing system. Summary of the article:

• What is Cloud Computing?
• History of Cloud Computing
• Examples of Cloud Computing
• Types of Cloud Computing
• Deployment Model
• Advantages of Cloud Computing
• Disadvantages of Cloud Computing

What is Cloud Computing?
Cloud computing is the use of computing resources (hardware and software) that are delivered as a service over a network (typically the Internet). Here some computers are connected according to grid system.

History of Cloud Computing
The idea of Cloud Computing was first come in 1960. But it was implemented in 20th century. In 2006 Elastic Compute Cloud (EC2) was implemented by amazon.com.

Examples of Cloud Computing
Different types of cloud computing services are available today. Some providers offer cloud computing services totally free while others require a paid subscription. Some famous cloud services are given bellow:

• Amazon Elastic Compute Cloud (EC2) – virtual IT
• Google App Engine – application hosting
• Google Apps – software as a service
• Apple MobileMe – network storage

Types of Cloud Computing
Bases on their service Cloud Computing can be divided in 3 types:

1. Infrastructure-as-a-Service (IaaS)
2. Platform-as-a-Service (PaaS)
3. Software-as-a-Servoce (SaaS)

Infrastructure-as-a-Service (IaaS)
The IaaS provider offer computer (physical or virtual machine) and other recourses. User can install OS, software etc according to his choice. It is like a new PC.

Example- Amazon Elastic Compute Cloud (EC2)

Platform-as-a-Service (PaaS)
The PaaS provider offer Computing Platform including OS, API, Database, and Web Server. Programmer can develop his application and run without hardware & software cost.

Example- Google App Engine, Windows Azure Compute, Force.com

Software-as-a-Servoce (SaaS)
The SaaS provider offer application software. They install & manage it. Client only uses them.

Example- Google Apps, Microsoft Office 365, Onlive, GT Nexus, Marketo, and TradeCard.

Deployment Model
According to cloud user the deployment models are given bellow:

• Public Cloud
• Community Cloud
• Private Cloud
• Hybrid Cloud

Public Cloud
It is design for general public. These services are free or offered on pay-per-use. Public Cloud providers like Google. Microsoft, Amazon operates the infrastructure and offer access only via internet.

Community Cloud
It is design for a specific community. Its cost if higher than public Cloud.

Private Cloud
It is designed for a single organization. Here security and cost is high.

Hybrid Cloud
It is the combination of public or privet cloud. First time public cloud is applied. When it needs more resources than public cloud is used. Its cost is high.

Advantages of Cloud Computing
The cloud computing system provides numerous facilities. Some advantages of cloud computing systems are given bellow:

• It reduces operational cost. Some clouds are free or pay-on-use. Its cost is low near about 2 cent per hour
• It reduces start up cost. No need to invest lot of money to purchase computer hardware and software. This money can be used for other purposes
• Good solution for small investor
• Great opportunity for scientist

Disadvantages of Cloud Computing
The cloud computing systems have some disadvantages also. Some drawbacks of cloud computing systems are given bellow:

• Security is low
• Cloud provider or hacker can access our data
• Data can be changed
• Need high speed Internet