Cloud computing logical diagram
Cloud computing is
Internet- ("cloud-") based development and use of
computer technology ("
computing"). In
concept, it is a
paradigm shift
whereby details are abstracted from the users who no longer need
knowledge of, expertise in, or control over the technology
infrastructure "in the cloud" that supports them. It typically
involves the provision of dynamically
scalable and often
virtualized resources
as a service over the
Internet.
The term
cloud is used as a
metaphor for the Internet, based on how the
Internet is depicted in
computer network diagrams and is an
abstraction of the underlying
infrastructure it conceals. Typical cloud computing providers
deliver common
business
applications online which are accessed from a
web browser, while the
software and
data are stored on
the
servers.
These applications are broadly divided into the following
categories:
Software as a
Service (SaaS), Utility Computing, Web Services,
Platform as a Service (PaaS), Managed
Service Providers (MSP), Service Commerce, and Internet
Integration. The name cloud computing was inspired by the cloud
symbol that is often used to represent the Internet in flow charts
and diagrams."
Overview
Comparisons
Cloud computing can be confused with:
- Grid computing — "a form of
distributed computing, whereby
a 'super and virtual computer' is composed of a cluster of networked, loosely coupled computers acting in concert
to perform very large tasks"
- Utility computing — the
"packaging of computing
resources, such as computation and storage, as a metered
service similar to a traditional public
utility, such as electricity";
- Autonomic computing —
"computer systems capable of self-management".
Indeed, many cloud computing deployments depend on
grids,
have
autonomic
characteristics, and bill like
utilities, but cloud computing tends to
expand what is provided by grids and utilities. Some successful
cloud architectures have little or no centralized infrastructure or
billing systems whatsoever, including
peer-to-peer networks such as
BitTorrent and
Skype, and
volunteer computing such as
SETI@home.
Characteristics
In general, cloud computing customers do not own the physical
infrastructure, instead avoiding
capital expenditure by renting usage
from a third-party provider. They consume resources
as a service and pay only for
resources that they use. Many cloud-computing offerings employ the
utility computing model, which is
analogous to how traditional utility services (such as
electricity) are consumed, whereas others bill
on a
subscription basis. Sharing
"perishable and intangible" computing power among
multiple tenants can improve utilization rates,
as servers are not unnecessarily left idle (which can reduce costs
significantly while increasing the speed of application
development). A side-effect of this approach is that overall
computer usage rises dramatically, as customers do not have to
engineer for peak load limits. In addition, "increased high-speed
bandwidth" makes it possible to receive the same response times
from centralized infrastructure at other sites.
Economics
Cloud computing users can avoid
capital expenditure (CapEx) on hardware,
software, and services when they pay a provider only for what they
use. Consumption is usually billed on a
utility (resources consumed, like
electricity) or
subscription
(time-based, like a newspaper) basis with little or no upfront
cost. Other benefits of this
time
sharing-style approach are low
barriers to entry, shared infrastructure
and costs, low management overhead, and immediate access to a broad
range of applications. In general, users can terminate the contract
at any time (thereby avoiding
return on investment risk and
uncertainty), and the services are often covered by
service level agreements (SLAs) with
financial penalties.
According to
Nicholas Carr, the
strategic importance of
information technology is diminishing
as it becomes standardized and less expensive. He argues that the
cloud computing
paradigm shift is
similar to the displacement of
electricity generators by
electricity grids early in the 20th
century.
Although companies might be able to save on upfront capital
expenditures, they might not save much and might actually pay more
for operating expenses. In situations where the capital expense
would be relatively small, or where the organization has more
flexibility in their capital budget than their operating budget,
the cloud model might not make great fiscal sense. Other factors
impacting the scale of any potential cost savings include the
efficiency of a company’s data center as compared to the cloud
vendor’s, the company's existing operating costs, the level of
adoption of cloud computing, and the type of functionality being
hosted in the cloud.
Architecture
The majority of cloud computing infrastructure, , consists of
reliable services delivered through
data
centers and built on servers with different levels of
virtualization technologies. The
services are accessible anywhere that provides access to networking
infrastructure. Clouds often appear as single points of access for
all consumers' computing needs. Commercial offerings are generally
expected to meet
quality of
service (QoS) requirements of customers and typically offer
SLAs.
Open standards are critical to
the growth of cloud computing, and
open source software has provided the
foundation for many cloud computing implementations.
History
The Cloud is a term that borrows from
telephony. Up to the 1990s, data circuits
(including those that carried Internet traffic) were hard-wired
between destinations. Then, long-haul telephone companies began
offering
Virtual Private
Network (VPN) service for data communications. Telephone
companies were able to offer VPN-based services with the same
guaranteed bandwidth as fixed circuits at a lower cost because they
could switch traffic to balance utilization as they saw fit, thus
utilizing their overall network bandwidth more effectively. As a
result of this arrangement, it was impossible to determine in
advance precisely which paths the traffic would be routed over. The
cloud symbol was used to denote that which was the responsibility
of the provider, and cloud computing extends this to cover servers
as well as the network infrastructure.
The underlying concept of cloud computing dates back to
1960, when
John McCarthy opined that
"computation may someday be organized as a
public utility"; indeed it shares
characteristics with
service bureaus
that date back to the 1960s. In 1997, the first academic definition
was provided by
Ramnath K.
Chellappa who called it a
computing paradigm where the boundaries of computing will be
determined by economic rationale rather than technical limits.
The term
cloud had already come into commercial use in the
early 1990s to refer to large
Asynchronous Transfer Mode (ATM)
networks.
Loudcloud, founded in 1999 by Marc Andreessen, was one of the first
to attempt to commercialize cloud computing with an Infrastructure
as a Service model. By the turn of the 21st century, the term
"cloud computing" began to appear more widely, although most of the
focus at that time was limited to
SaaS, called
"ASP's" or Application Service Providers, under the terminology of
the day.
In the early 2000s,
Microsoft extended the
concept of
SaaS through the development of
web services .
IBM
detailed these concepts in 2001 in the
Autonomic Computing Manifesto, which described
advanced automation techniques such as self-monitoring,
self-healing, self-configuring, and self-optimizing in the
management of complex IT systems with heterogeneous storage,
servers, applications, networks, security mechanisms, and other
system elements that can be virtualized across an enterprise.
Amazon played a key role in the
development of cloud computing by modernizing their
data centers after the
dot-com bubble, which, like most
computer networks, were using as little as
10% of their capacity at any one time just to leave room for
occasional spikes. Having found that the new cloud architecture
resulted in significant internal efficiency improvements whereby
small, fast-moving "two-pizza teams" could add new features faster
and easier, Amazon started providing access to their systems
through
Amazon Web Services on a
utility computing basis in
2005. This characterization of the genesis of
Amazon Web Services has been characterized as an extreme
over-simplification by a technical contributor to the Amazon Web
Services project .
In
2007,
Google,
IBM, and a number of universities embarked on a large
scale cloud computing research project. By mid-2008, Gartner saw an
opportunity for cloud computing "to shape the relationship among
consumers of IT services, those who use IT services and those who
sell them", and observed that "[o]rganisations are switching from
company-owned hardware and software assets to per-use service-based
models" so that the "projected shift to cloud computing ... will
result in dramatic growth in IT products in some areas and in
significant reductions in other areas."
Political issues
The Cloud spans many borders and "may be the ultimate form
of globalization." As such, it becomes subject to complex
geopolitical issues, and providers are pressed
to satisfy myriad regulatory environments in order to deliver
service to a global market. This dates back to the early days of
the Internet, when
libertarian thinkers
felt that "cyberspace was a distinct place calling for laws and
legal institutions of its own".
Despite
efforts (such as US-EU Safe
Harbor) to harmonize the legal environment, , providers such as
Amazon cater to major markets
(typically the United
States
and the European
Union) by deploying local infrastructure and allowing customers
to select "availability zones." Nonetheless, concerns
persist about security and privacy from individual through
governmental levels (e.g., the
USA
PATRIOT Act, the use of
national security letters, and the
Electronic
Communications Privacy Act's
Stored Communications
Act).
Legal issues
In March
2007, Dell applied to trademark the term "cloud computing" ( ) in the
United
States. The "Notice of Allowance" the company
received in July 2008 was cancelled in August, resulting in a
formal rejection of the trademark application less than a week
later.
In November 2007, the
Free
Software Foundation released the
Affero General Public License,
a version of
GPLv3
intended to close a perceived
legal
loophole associated with
free
software designed to be run over a network. Founder and
president,
Richard Stallman has
also warned that cloud computing "will force people to buy into
locked, proprietary systems that will cost more and more over
time".
Key characteristics
- Agility improves with
users able to rapidly and inexpensively re-provision technological
infrastructure resources..
- Cost is claimed to be
greatly reduced and capital
expenditure is converted to operational expenditure. This
ostensibly lowers barriers to
entry, as infrastructure is typically provided by a third-party
and does not need to be purchased for one-time or infrequent
intensive computing tasks. Pricing on a utility computing basis is fine-grained
with usage-based options and fewer IT skills are required for
implementation (in-house).
- Device and location
independence enable users to access systems using a web
browser regardless of their location or what device they are using
(e.g., PC, mobile). As infrastructure is off-site (typically
provided by a third-party) and accessed via the Internet, users can
connect from anywhere.
- Multi-tenancy
enables sharing of resources and costs across a large pool of users
thus allowing for:
- Centralization of infrastructure in locations
with lower costs (such as real estate, electricity, etc.)
- Peak-load capacity increases (users need not
engineer for highest possible load-levels)
- Utilization and efficiency improvements for
systems that are often only 10–20% utilized.
- Reliability
improves through the use of multiple redundant sites, which makes
cloud computing suitable for business continuity and disaster recovery. Nonetheless, many major
cloud computing services have suffered outages, and IT and business
managers can at times do little when they are affected.
- Scalability via
dynamic ("on-demand") provisioning of
resources on a fine-grained, self-service basis near real-time,
without users having to engineer for peak loads. Performance is monitored, and
consistent and loosely-coupled architectures are constructed using
web services as the system
interface.
- Security
typically improves due to centralization of data, increased
security-focused resources, etc., but concerns can persist about
loss of control over certain sensitive data, and the lack of
security for stored kernels. Security is often as good as or better
than under traditional systems, in part because providers are able
to devote resources to solving security issues that many customers
cannot afford. Providers typically log accesses, but accessing the
audit logs themselves can be difficult or
impossible. Furthermore, the complexity of security is greatly
increased when data is distributed over a wider area and / or
number of devices.
- Sustainability
comes about through improved resource utilization, more efficient
systems, and carbon neutrality.
Nonetheless, computers and associated infrastructure are major
consumers of energy.
Layers
Clients
A
cloud client consists of
computer hardware and/or
computer software that relies on cloud
computing for application delivery, or that is specifically
designed for delivery of cloud services and that, in either case,
is essentially useless without it. For example:
Application
A
cloud application leverages cloud computing in
software architecture, often
eliminating the need to install and run the application on the
customer's own computer, thus alleviating the burden of software
maintenance, ongoing operation, and support. For example:
Platform
A
cloud platform (
PaaS) delivers a
computing platform and/or
solution stack as a service, generally consuming
cloud infrastructure and supporting
cloud
applications. It facilitates deployment of applications
without the cost and complexity of buying and managing the
underlying hardware and software layers. For example:
Infrastructure
Cloud infrastructure (
IaaS) is the delivery of
computer infrastructure, typically a
platform virtualization environment,
as a service. For
example:
Servers
The
servers layer consists of
computer hardware and/or
computer software products that are
specifically designed for the delivery of cloud services. For
example:
Architecture
Cloud computing sample
architecture
Cloud architecture, the
systems architecture of the
software systems involved in the delivery
of
cloud computing, comprises hardware and software
designed by a
cloud architect who typically works for a
cloud integrator. It typically involves multiple
cloud
components communicating with each other over
application programming
interfaces, usually
web
services.
This closely resembles the
Unix
philosophy of having multiple programs each doing one thing
well and working together over universal interfaces. Complexity is
controlled and the resulting systems are more manageable than their
monolithic counterparts.
Cloud architecture extends to the client, where
web browsers and/or
software applications access
cloud
applications.
Cloud storage architecture is loosely coupled, where
metadata operations are centralized
enabling the data nodes to scale into the hundreds, each
independently delivering data to applications or users.
Types
Cloud computing types
Public cloud
Public cloud or
external cloud describes cloud
computing in the traditional mainstream sense, whereby resources
are dynamically provisioned on a fine-grained, self-service basis
over the Internet, via
web
applications/
web services, from an
off-site third-party provider who
shares
resources and bills on a fine-grained
utility computing basis.
Hybrid cloud
A
hybrid cloud environment consisting of multiple internal
and/or external providers "will be typical for most enterprises". A
hybrid cloud can describe configuration combining a local device,
such as a
Plug computer with cloud
services. It can also describe configurations combining virtual and
physical,
colocated assets—for
example, a mostly virtualized environment that requires physical
servers,
routers, or
other hardware such as a network appliance acting as a firewall or
spam filter.
Private cloud
Private cloud and
internal cloud are
neologisms that some vendors have recently used
to describe offerings that emulate cloud computing on private
networks. These (typically
virtualisation automation) products claim to "deliver some
benefits of cloud computing without the pitfalls", capitalising on
data security, corporate governance, and reliability concerns. They
have been criticized on the basis that users "still have to buy,
build, and manage them" and as such do not benefit from lower
up-front capital costs and less hands-on management, essentially
"[lacking] the economic model that makes cloud computing such an
intriguing concept".
While an analyst predicted in 2008 that private cloud networks
would be the future of corporate IT, there is some uncertainty
whether they are a reality even within the same firm. Analysts also
claim that within five years a "huge percentage" of
small and medium enterprises
will get most of their computing resources from external cloud
computing providers as they "will not have economies of scale to
make it worth staying in the IT business" or be able to afford
private clouds.. Analysts have reported on
Platform's view that private clouds are a
stepping stone to external clouds, particularly for the financial
services, and that future datacenters will look like internal
clouds.
The term has also been used in the logical rather than physical
sense, for example in reference to
platform as a service offerings,
though such offerings including
Microsoft's
Azure Services Platform are not
available for on-premises deployment.
See also
References
- Distinguishing Cloud Computing from Utility
Computing
- Gartner Says Cloud Computing Will Be As Influential As
E-business
- The Internet Cloud
-
http://searchcloudcomputing.techtarget.com/sDefinition/0,,sid201_gci1287881,00.html
- What's In A Name? Utility vs. Cloud vs
Grid
- I.B.M. to Push ‘Cloud Computing,’ Using Data From
Afar
- Overheard: What the heck is computing in a
cloud?
- ACM Ubiquity: Emergence of The Academic Computing
Cloud
- Cloud Computing: The Evolution of
Software-as-a-Service
- Forrester's Advice to CFOs: Embrace Cloud Computing
to Cut Costs
- Five cloud computing questions
- Nicholas Carr on 'The Big Switch' to cloud
computing
- 1 Midsize Organization Busts 5 Cloud Computing
Myths
- Cloud Computing Savings - Real or
Imaginary?
- Open source fuels growth of cloud computing,
software-as-a-service
- July, 1993 meeting report from the IP over ATM
working group of the IETF
- [1]
- Internet Critic Takes on Microsoft
- Jeff Bezos' Risky Bet
- [2]
- Google and I.B.M. Join in ‘Cloud Computing’
Research
- Keep an eye on cloud computing, Amy Schurr,
Network World, 2008-07-08, citing the Gartner report, “Cloud Computing Confusion Leads to
Opportunity”. Retrieved 2009-09-11.
- Gartner Says Worldwide IT Spending On Pace to Surpass $3.4
Trillion in 2008, Gartner, 2008-08-18. Retrieved 2009-09-11.
- Computers without borders
- Feature Guide: Amazon EC2 Availability
Zones
-
http://www.guardian.co.uk/technology/2008/sep/29/cloud.computing.richard.stallman
- Infrastructure Agility: Cloud Computing as a Best
Practice
- Recession Is Good For Cloud Computing – Microsoft
Agrees
- Defining “Cloud Services” and “Cloud Computing”
- The new geek chic: Data centers
- Cloud Computing: Small Companies Take
Flight
- Google Apps Admins Jittery About Gmail, Hopeful
About Future
- New Resource, Born of a Cloud Feud
- Exari: Death By Laptop
- Encrypted Storage and Key Management for the
cloud
- Cloud computing security forecast: Clear
skies
- Google to go carbon neutral by 2008
- What is Cloud Computing?
- Shut off your computer
- Nimbus Cloud Guide
- Google's Open Source Android OS Will Free the
Wireless Web
- In Sync to Pierce the Cloud
- Microsoft demos mobile cloud sync client
- CherryPal brings cloud computing to the
masses
- Zonbu has alluring features, price
- GOS cloud computing
- Google angles for business users with 'platform as
a service'
- The Emerging Cloud Service Architecture
- EMC buys Pi and forms a cloud computing
group
- Building GrepTheWeb in the Cloud, Part 1: Cloud
Architectures
- Cloud Maturity Is Accelerating: More Than Just
Reaction To The Hype?
- IBM Embraces Juniper For Its Smart 'Hybrid Cloud',
Disses Cisco (IBM)
- Blend the strengths of virtual and physical
- Private Clouds Take Shape
- Just don't call them private clouds
- There's No Such Thing As A Private Cloud
- Private cloud networks are the future of corporate
IT
- Private Cloud Computing: The Only Thing Real so Far
is the Desire
- Million-Dollar Private Clouds
- From Grid to Cloud (Gridipedia)
- Google opens private cloud to coders
- Microsoft Nixes Private Azure Clouds
External links
- M. D. Dikaiakos, D. Katsaros, G. Pallis, A. Vakali, P. Mehra:
Guest Editors Introduction: "Cloud Computing, IEEE Internet Computing",
12(5), Sep. 2009.
- San Murugesan (Editor), "Cloud Computing: IT's Day in the Sun?", Cutter
Consortium, 2009.
- Luis M. Vaquero et al., A Break in the Clouds: Toward a Cloud Definition, ACM
SIGCOMM Computer Communication Review, Volume 39, Issue 1 (January
2009), Pages 50–55, ISSN:0146-4833
- What is Cloud Computing ? - Web 2.0 expo - A video where Tim O’Reilly,
Dan Farber, Matt Mullenweg and others answer this question.
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