49
and released with minimal management effort or service provider
interaction.”
14
More details can be found in the document “The NIST Definition of Cloud
Computing” by Peter Mell and Timothy Grance (September 2011).
15
Their
Cloud model is composed of five 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 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,
tablets, laptops, and workstations).
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 datacentre). Examples of resources include
storage, processing, memory, and network bandwidth.
Rapid elasticity
.
Capabilities can be elastically provisioned and
released, in some cases automatically, to scale rapidly outward and
inward commensurate with demand. To the consumer, the
capabilities available for provisioning often appear to be unlimited
and can be appropriated in any quantity at any time.
Measured service
.
Cloud systems automatically control and optimize
resource use by leveraging a metering capability
16
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.
14
15
16
Typically this is done on a pay‐per‐use or charge‐per‐use basis.
