Database Reference
In-Depth Information
Essential Characteristics
According to the NIST, cloud computing has five essential characteristics. Let's look at each in some detail:
On-demand self-service : Cloud consumers should be able to consume the cloud services
on demand, without requiring human interaction with the cloud service provider.
Broad network access : Cloud services should be accessed over the network and through
various commonly used interfaces (for example, the Web, mobile devices, software clients,
and so forth).
Resource pooling : Cloud providers pool computing resources to efficiently serve multiple
consumers.
Rapid elasticity : Cloud services should be elastically provisioned and released to meet the
business demand.
Measured service : Cloud resources should be monitored for usage and can later be
reported, with users potentially billed for the utilized service.
The NIST definition also lists three service models (software, platform, and infrastructure) and four deployment
models (private, community, public, and hybrid) that, combined, categorize ways to deliver cloud services. These are
discussed in the following sections.
Service Models
For the cloud to be a viable option for any enterprise organization, that organization needs to choose which service
model to provide. A service model is an approach that can be used to satisfy a specific requirement. Within the cloud
architecture, three primary service models can be used— Software as a Service (SaaS), Platform as a Service (PaaS),
and Infrastructure as a Service (IaaS):
Software as a Service (SaaS) : In this model, the consumer of cloud services uses the
software application. The consumer does not manage or control any of the underlying
infrastructures to include network, servers, application servers, operating systems, storage,
or even individual application capabilities, with the possible exception of limited
user-specific application configuration settings. SaaS examples include the Web-based
e-mail services provided by Yahoo!, Google, and other vendors.
Platform as a Service (PaaS) : In this model, the consumer of the cloud builds and operates
end-user applications leveraging the software platform—including database, middleware,
programming languages, libraries, services, and tools—offered by the cloud provider. The
consumer does not manage or control the software platform or the underlying infrastructure
including network, servers, operating systems, or storage, but has control over the deployed
applications and possibly configuration settings for the application-hosting environment.
PaaS examples include Google Apps, which enables customers to work from a platform
while being mobile.
Infrastructure as a Service (IaaS) : In this model, the consumer of the IaaS cloud has the
responsibility to manage the software platform (database, middleware, tools, and so forth)
and develop and operate the end-user applications. The consumer does not manage
or control the underlying cloud infrastructure but has control over operating systems,
storage, and deployed applications, and possibly limited control of select networking
components (for example, host firewalls). Amazon Elastic Compute Cloud, which provides
developers with servers and databases, is an example of IaaS.
 
Search WWH ::




Custom Search