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214 Part Two Information Technology Infrastructure

FIGURE 5.10 CLOUD COMPUTING PLATFORM

In cloud computing, hardware and software capabilities are a pool of virtualized resources provided
over a network, often the Internet. Businesses and employees have access to applications and IT
infrastructure anywhere, at any time, and on any device.

The U.S. National Institute of Standards and Technology (NIST) defines cloud
computing as having the following essential characteristics (Mell and Grance,
2009):
• On-demand self-service: Consumers can obtain computing capabilities
such as server time or network storage as needed automatically on their
own.
• Ubiquitous network access: Cloud resources can be accessed using
standard network and Internet devices, including mobile platforms.
• Location-independent resource pooling: Computing resources are pooled
to serve multiple users, with different virtual resources dynamically assigned
according to user demand. The user generally does not know where the
computing resources are located.
• Rapid elasticity: Computing resources can be rapidly provisioned,
increased, or decreased to meet changing user demand.
• Measured service: Charges for cloud resources are based on amount of
resources actually used.

Cloud computing consists of three different types of services:
• Cloud infrastructure as a service: Customers use processing, storage,
networking, and other computing resources from cloud service providers to
run their information systems. For example, Amazon uses the spare capacity

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