Cloud Computing

Cloud Computing :

“Cloud computing is a type of computing that relies on sharing computing resources rather than having local servers or personal devices to handle applications.”( By Vangie Beal)

In cloud computing, the word cloud (also phrased as "the cloud") is used as a metaphor for "the Internet," so the phrase cloud computing means "a type of Internet-based computing," where different services — such as servers, storage and applications — are delivered to an organization's computers and devices through the Internet.

·         The storing and accessing of applications and computer data often through a Web browser rather than running installed software on your personal computer or office server

·         Internet-based computing whereby information, IT resources, and software applications are provided to computers and mobile devices on-demand

·         Using the Internet to access web-based applications, web services, and IT infrastructure as a service.

Essential Characteristics:

Ø  On-demand self-service -- A consumer can independently and unilaterally provision computing capabilities, such as compute time, network connectivity and storage, as needed automatically without requiring human interaction with each service’s provider.

Ø  Broad network access -- Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms.

Ø  Resource pooling -- The provider’s computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. There is a sense of location independence in that the customer generally has no control or knowledge over the exact location of the provided resources, but may be able to specify location at a higher level of abstraction (e.g., country, state, region or datacenter). Examples of computing resources include storage, processing (compute), memory, network bandwidth, and virtual machines.

Ø  Rapid elasticity -- Capabilities can be rapidly and elastically provisioned, in some cases automatically, to quickly scale out, and rapidly released to quickly scale in. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be purchased in any quantity at any time.

Ø  Measured Service -- Cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, compute, bandwidth, active user accounts, etc.). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and consumer of the utilized service.

The diagram below depicts the Cloud Computing stack – it shows three distinct categories within Cloud Computing: Software as a Service, Platform as a Service and Infrastructure as a Service.

Service:

Services are divided into three categories:

q  SaaS (Cloud Software as a Service)

q  PaaS (Cloud Platform as a Service)

q  IaaS (Cloud Infrastructure as a Service)

·         Cloud Software as a Service (SaaS)--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 a thin client interface such as a web browser (e.g., web-based email). 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 provider-defined user-specific application configuration settings

·         Cloud Platform as a Service (PaaS)--The capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages and tools supported by the provider. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, or storage, but has control over the deployed applications and possibly application hosting environment configurations

·         Cloud Infrastructure as a Service (IaaS)--The capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the underlying cloud physical infrastructure but has control over operating systems, storage, deployed applications, and possibly limited control of select networking components.