The NIST Definition of Cloud Computing

The NIST Definition of Cloud Computing

Authors: Peter Mell and Tim Grance

Version 15, 10-7-09

National Institute of Standards and Technology, Information Technology Laboratory

Note
1: Cloud computing is still an evolving paradigm. Its definitions, use
cases, underlying technologies, issues, risks, and benefits will be
refined in a spirited debate by the public and private sectors. These
definitions, attributes, and characteristics will evolve and change over
time.

Note
2: The cloud computing industry represents a large ecosystem of many
models, vendors, and market niches. This definition attempts to
encompass all of the various cloud approaches.

Definition of Cloud Computing:

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
.

Essential Characteristics:



On-demand self-service.

A consumer can unilaterally provision computing capabilities, such as
server time and network storage, as needed automatically without
requiring human interaction with each service’s provider.

Broad network access.

Capabilities are available over the network and accessed through
standard mechanisms that promote use by heterogeneous thin or thick
client platforms (e.g., mobile phones, laptops, and PDAs).

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, or datacenter).
Examples of resources include storage, processing, memory, network
bandwidth, and virtual machines.

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.

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, processing, bandwidth, and active user
accounts). Resource usage can be monitored, controlled, and reported
providing transparency for both the provider and consumer of the
utilized service.

Service Models:



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 limited 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 infrastructure but has control over
operating systems, storage, deployed applications, and possibly limited
control of select networking components (e.g., host firewalls).

Deployment Models:



Private cloud.

The
cloud infrastructure is operated solely for an organization. It may be
managed by the organization or a third party and may exist on premise or
off premise.

Community cloud.

The cloud infrastructure is shared by several organizations and
supports a specific community that has shared concerns (e.g., mission,
security requirements, policy, and compliance considerations). It may be
managed by the organizations or a third party and may exist on premise
or off premise.

Public cloud.

The
cloud infrastructure is made available to the general public or a large
industry group and is owned by an organization selling cloud services.

Hybrid cloud

.
The cloud infrastructure is a composition of two or more clouds
(private, community, or public) that remain unique entities but are
bound together by standardized or proprietary technology that enables
data and application portability (e.g., cloud bursting for
load-balancing between clouds).

Note:
Cloud software takes full advantage of the cloud paradigm by being
service oriented with a focus on statelessness, low coupling,
modularity, and semantic interoperability.