CLOUD COMPUTING

              CLOUD COMPUTING

DEFINITION:
Wikipedia defines cloud computing as “cloud computing” is Internet- (“cloud-”) based
development and use of computer technology (computing).
If you are doing something without installing hardware on your computer or a computer on your local network, you are involved with cloud computing.
Example:
Email – if you use Gmail, Hotmail, AOL mail, Yahoo mail or anything similar you are using cloud computing.

SUPPORTS OF CLOUD COMPUTING:
 1.Cloud computing environments support grid computing by quickly providing physical and virtual servers on which the grid applications can run.
 2.Cloud computing should not be confused with grid computing.
 Grid computing involves dividing a large task into many smaller tasks that run in parallel on separate servers.
 3.Clouds also support non grid environments, such as a three-tier Web architecture running standard or Web 2.0 applications.

TYPES OF CLOUD COMPUTING:
Cloud computing is typically divided into three levels of service offerings:
A.Software as a Service (SaaS)
B. Platform as a Service (PaaS)
C. Infrastructure as a service (IaaS).

A. Software as a Service(SaaS)
It means to use a complete application running on someone else's system. Zoho is another well-known SaaS provider offering a variety of office applications online.
Ex:
Web-based email and Google Documents.
B. Platform as a Service(PaaS)
It means to develop applications using Web-based tools so they run on systems software and hardware provided by another company.
Ex:
Force.com (from salesforce.com) and the Google App Engine are examples of PaaS.
C. Infrastucture as a service(Iaas)
Infrastructure as a Service (IaaS) is the delivery of hardware (server, storage and network), and associated software (operating systems virtualization technology, file system), as a service.
Ex:
Ordinary web hosting

CLOUD COMPUTING INFRASTRUCTURE MODELS.
As we focus on building the cloud, a number of models have been developed for a cloud infrastructure.

o Private Clouds
o Public Clouds
o Hybrid Clouds

A. Private Clouds.
In a private cloud, the infrastructure for implementing the cloud is controlled completely by the enterprise.

B. Public Clouds.
Public clouds are run by third parties, and applications from different customers are likely to be mixed together on the cloud’s servers, storage systems, and networks

C. Hybrid Clouds.
Hybrid clouds combine both public and private cloud models. They can help to provide on-demand, externally provisioned scale. The ability to augment a private cloud with the resources of a public cloud can be used to maintain service levels in the face of rapid workload fluctuations.

The Benefits of the Cloud
 Savings Through Reduced Energy Usage
 Easy Backup & Recovery
 Easy Deployment
 Slashing Of Hardware Costs
 Maintenance & Management Made Easy:
 Lesser Space Demands
 Hardware Standardization
 Easy Replacement and Upgrading

DISADVANTAGES:
• Security: Is there a security standard?
• Reliance on 3rd Party: Control over own data is lost in the hands of an “difficult-to-trust” provider.
• Cost of transition: Is it feasible for me to move from the existing architecture of my data center to the architecture of the cloud?
• Certainty of benefits: Are there any long term benefits?

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