The document defines cloud computing and its key characteristics, service models, and deployment models. Specifically, it provides definitions for cloud computing and its essential characteristics of on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured service. It also describes the three cloud computing service models of Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). Finally, it outlines the four deployment models of private cloud, public cloud, hybrid cloud, and community cloud.

1. Cloud Computing
Explained*
Juan Pablo García González
Juan_p_garcia@dell.com
*Base on W115 The Open Group, May, 2011.

2. Cloud
Computing
Definition
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3. Defining 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.”

4. Essential Cloud Computing
Characteristics
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5. 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 re-assigned 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 data center). Examples of resources include storage,
processing, memory, network bandwidth, and virtual
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6. Essential Characteristics
• Rapid elasticity: Capabilities can be rapidly and
elastically provisioned, in some cases automatically,
to quickly scale out and be 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.
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7. Service Models
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8. Service Models
• 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.
• 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
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9. Service Models
• 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).
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10. Deployment Models
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11. 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. Could be custom
• 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. Standard!
• 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).
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12. Deployment Models
• 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.
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13. Cloud
Computing
Benefits
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14. Cloud Computing Benefits
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15. Cloud Computing Benefits
• Reduced capital outlay • Shorter provisioning
times
• Allows more use of “try
before you buy” • Better architecture and
design
• Reduces the cost of “one-
off” activities • Consolidation and central
administration
• Costs associated with
testing can be reduced • Greener IT
• Improved financial • Improved administration
control and maintenance
• Reduction in internal data • Better quality services
center capacity available
• Better security
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16. Cloud
Computing
Issues
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17. Cloud Computing Issues
• IT security and compliance
• Not mature
• Lack of clear definition of components
• Software licensing
• Service delivery clarity
• Calculating costs of service
• Lack of experience
• Data access
• Integration

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19. References
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20. References
• NIST Definition of Cloud Computing, by Peter Mell and Tim France, Version
15, October 2009; http://csrc.nist.gov/groups/SNS/cloud-computing/cloud-
def-v15.doc (accessed February 2011)
• The Open Group Service Integration Maturity Model (OSIMM), Technical
Standard (C092), August 2009, published by The Open Group;
http://www.opengroup.org/bookstore/catalog/c092.htm
• Amazon Web Services (AWS) Economics Center
http://aws.amazon.com/economics.
• The Economics of the AWS Cloud versus Owned IT Infrastructure, Amazon
Web Services (AWS) White Paper, December 2009;
http://media.amazonwebservices.com/The_Economics_of_the_AWS_Cloud_v
s_Owned_IT_Infrastructure.pdf.
• McKinsey & Company Report: Clearing the Air on Cloud Computing, March
2009.
• Building Return on Investment from Cloud Computing, White Paper by The
Open Group Cloud Business Artifacts Project (W104), April 2010, published
by The Open Group; www.opengroup.org/bookstore/catalog/w104.htm.
• The Open Group Cloud Work Group;
http://www.opengroup.org/cloudcomputing.