Cloud computing:
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Cloud computing
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Cloud
computing is a general term for anything that involves delivering hosted
services over the Internet another defination is Cloud computing is a type of
computing that relies on sharing
computing resources rather
than having local servers or personal devices to handle applications.These
services are broadly divided into three categories.
·
Infrastructure-as-a-Service
(IaaS).
·
Platform-as-a-Service
(PasS).
·
Software-as-a-Service
(SaaS).
The
name cloud computing was inspired by the cloud symbol that's often used to
represent the Internet in flowcharts and diagrams.
A
cloud service has three distinct characteristics that differentiate it from
traditional hosting. It is sold on demand, typically by the minute or the hour;
it is elastic -- a user can have as much or as little of a service as they want
at any given time; and the service is fully managed by the provider (the
consumer needs nothing but a personal computer and Internet access).
Significant innovations in virtualization and distributed computing, as well as
improved access to high-speed Internet and a weak economy, have accelerated
interest in cloud computing.
A
cloud can be private or public. A public cloud sells services to anyone on the
Internet. (Currently, Amazon Web Services is the largest public cloud
provider.) A private cloud is a proprietary network or a data center that
supplies hosted services to a limited number of people. When a service provider
uses public cloud resources to create their private cloud, the result is called
a virtual private cloud. Private or public, the goal of cloud computing is to
provide easy, scalable access to computing resources and IT services.
Infrastructure-as-a-Service
like Amazon Web Services provides virtual server instance API to start, stop,
access and configure their virtual servers and storage. In the enterprise,
cloud computing allows a company to pay for only as much capacity as is needed,
and bring more online as soon as required. Because this pay-for-what-you-use
model resembles the way electricity, fuel and water are consumed, it's
sometimes referred to as utility computing.
Platform-as-a-service
in the cloud is defined as a set of software and product development tools
hosted on the provider's infrastructure. Developers create applications on the
provider's platform over the Internet. PaaS providers may use APIs, website portals
or gateway software installed on the customer's computer. Force.com, (an
outgrowth of Salesforce.com) and Google Apps are examples of PaaS. Developers
need to know that currently, there are not standards for interoperability or
data portability in the cloud. Some providers will not allow software created
by their customers to be moved off the provider's platform.
In the
software-as-a-service cloud model, the vendor supplies the hardware
infrastructure, the software product and interacts with the user through a
front-end portal. SaaS is a very broad market. Services can be anything from
Web-based email to inventory control and database processing. Because the
service provider hosts both the application and the data, the end user is free
to use the service from anywhere.