CLOUD COMPUTING: The term “Cloud Computing” is made of word “cloud” which is referred as “metaphor” for “THE INTERNET”. Cloud computing is a term that is used to describe a service in which hosted services like storage, servers and applications are provided over the internet. Cloud computing has gained huge success  as well as achieved mass appeal in corporate data centers.


The reason behind the massive growth of “Cloud Computing” is the availability of low cost computers, presence of fast working networking system, autonomic and utility computing, architecture which were service oriented, storage devices and hardware virtualization. These factors promoted the growth of “cloud computing”. A cloud can be public or private. A public cloud provides its service to anyone over the Internet whereas private cloud supplies its hosted service to limited number of people. Whether the public or private data center, the aim of cloud computing is to deliver easy, accessible computing resources and IT services. 



The deployment model of cloud computing is differentiated into 3 types:

  1. Private cloud
  2. Public cloud
  3. Hybrid cloud

In Private clouds: services are provided from business data centers to the internal user’s. Private cloud delivers convenience of the cloud, control and security to local data centers. Some of the common private cloud providing companies are: VMware and OpenStack. 


In Public cloud: cloud services are provided by a third-party of cloud service provider over the Internet. Public cloud services are provided on the basis of time i.e. for a minute or for an hour. But for long period of time, services are also provided by the Public cloud service provider. Payment is taken from the customers on the basis of consumption of CPU cycles and bandwidth. Some of the prominent public cloud service provider are: AMAZON WEB SERVICE (AWS), IBM, MICROSOFT AZURE, and GOOGLE CLOUD PLATFORM. 


In Hybrid cloud: hybrid means mixture of two. Hybrid cloud is a combination of both public and private cloud service. Under hybrid cloud, using private clouds companies can solve sensitive applications or some heavy workloads along with it using public clouds for maintaining work and spikes in demand. Rackspace, Amazon Web Service, Microsoft corporation are some of the prominent vendors of hybrid cloud. 



Cloud computing has several attractive features which makes it popular among the data operators. Some of its feature are:

  1. ELASTICITY: Cloud computing is elastic in feature as companies can use it in the amount which is required. Scaling can be decrease or increase as computing will require. It saves the companies from making investment in local infrastructure which might be active or not active in its working.
  2. PAY PER USE: It makes the customer to pay for the resources and workloads they have used. It is measured on the basis of granular level.
  3. SELF-SERVICE PROVISIONING: This feature removes the need of IT administrators for managing the computer resources. 
  4. MIGRATION FLEXIBILITY: It is platform independent. Workloads can be migrated from one cloud platform to other cloud platform by organizations. It checks cost savings and new services.
  5. WORKLOAD RESILIENCE: Cloud service providers provides resources for ensuring resilient storage and user’s important working system in running.



Cloud computing services is divided mainly divided into three types:

  1. IaaS (Infrastructure as a service)
  2. PaaS(Platform as a service)
  3. SaaS(Software as a service)

IaaS providers: It provides virtual server instance and storage. It delivers small, medium, large, extra large and memory in its instances for different workload needs.

PaaS providers: It is used for the purpose of software development and its also hosts the software when it is developed. Common companies which are PaaS providers: Salesforce’s, Google App Engine, AWS Beanstalk Engine.


SaaS providers: NIST defines SaaS as:

“The capability provided to the consumer is to use the provider’s applications running on a cloud infrastructure. The applications are accessible from various client devices through either a thin client interface, such as a web browser (e.g., web-based email), or a program interface. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings”.