Cloud Computing
Cloud computing is the delivery of computing services over the Internet. Cloud
services allow individuals and businesses to use software and hardware that are
managed by third parties at remote locations. Examples of cloud services include
online file storage, social networkingsites, webmail, and online business
applications. The cloud computing model allows access to information and computer
resources from anywhere that a network connection is available. Cloud computing
provides a shared pool of resources, including data storage space, networks,
computer processing power, and specialized corporate and user applications.
The following definition of cloud computing has been developed by the U.S. National
Institute of Standards and Technology (NIST):
Cloud computing is a model for enabling convenient, on-demand network
access to a shared pool of configurable computing resources (e.g., networks,
servers, storage, applications, and services) that can be rapidly provisioned
and released with minimal management effort or service provider interaction.
This cloud model promotes availability and is composed of five essential
characteristics, three service models, and four deployment models.
Characteristics
The characteristics of cloud computing include on-demand self service, broad
network access, resource pooling, rapid elasticity and measuredservice. On-demand
self service means that customers (usually organizations) can request and manage
their own computing resources. Broad network access allows services to be offered
over the Internet or private networks. Pooled resources means that customers draw
from a pool of computing resources, usually in remote data centres. Services can be
scaled larger or smaller; and use of a service is measured and customers are billed
accordingly.
Service models
The cloud computing service models are Software as a Service (SaaS), Platform as a
Service (PaaS) and Infrastructure as a Service (IaaS). In a Software as a Service
model, a pre-made application, along withany required software, operating system,
hardware, and network are provided. In PaaS, an operating system, hardware, and
network are provided, and the customer installs or develops its own software and
applications. The IaaS model provides just the hardware and network; the customer
installs or develops its own operating systems, software and applications.
Deployment of cloud services:
Cloud services are typically made available via a private cloud, community cloud,
public cloud or hybrid cloud.
Generally speaking, services provided by a public cloudare offered over the
Internet and are owned and operated by a cloud provider. Some examples include
services aimed at the general public, such as online photo storage services, e-mail
services, or social networking sites. However, services for enterprises can also be
offered in a public cloud.
In a private cloud, the cloud infrastructure is operated solely for a specific
organization, and is managed by the organization or a third party.
In a community cloud, the service is shared by several organizations and made
available only to those groups. The infrastructure may be owned and operated by the
organizations or by a cloud service provider.
A hybrid cloud is a combination of different methods of resource pooling (for
example, combining publicand community clouds).
Why cloud services are popular
Cloud services are popular because they can reduce the cost and complexity of
owning and operating computers and networks. Since cloud users do not have to
invest in information technology infrastructure, purchase hardware, or buy software
licences, the benefits are low up-front costs, rapid return on investment, rapid
deployment, customization, flexible use, and solutions that can make use of new
innovations. In addition, cloud providers that have specialized in a particular area
(such as e-mail) can bring advanced services that a single company might not be
able to afford or develop.
Some other benefits to users include scalability, reliability, and efficiency. Scalability
means that cloud computing offers unlimited processing and storage capacity. The
cloud is reliable in that it enables access to applications and documents anywhere in
the world via the Internet. Cloud computing is often considered efficient because it
allows organizations to free up resources to focus on innovation and product
development.
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