Cloud computing

Cloud computing is Internet ("cloud") based development and use of computer technology ("computing"), whereby dynamically scalable virtualised resources are provided “as a service” over the Internet. Users need not have knowledge of, expertise in, or control over the technology infrastructure ("in the cloud") that supports them^.

The concept incorporates software as a service (SaaS), Web 2.0 and other recent, well-known technology trends, in which the common theme is reliance on the Internet for satisfying the computing needs of the users. An often-quoted example is Google Apps, which provides common business applications online that are accessed from a web browser, while the software and data are stored on Google servers.

The cloud is a metaphor for the Internet, based on how it is depicted in computer network diagrams, and is an abstraction for the complex infrastructure it conceals.

Comparisons

A formal definition appeared in ACM Computer Communication Review . There, the Cloud is defined as "Clouds are a large pool of easily usable and accessible virtualized resources (such as hardware, development platforms and/or services). These resources can be dynamically reconfigured to adjust to a variable load (scale), allowing also for an optimum resource utilization. This pool of resources is typically exploited by a pay-per-use model in which guarantees are offered by the Infrastructure Provider by means of customized SLAs.". The authors also provide a detailed comparison of Clouds and Grids in several aspects.

Cloud computing is often 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") and autonomic computing ("computer systems capable of self-management").

Indeed many cloud computing deployments as of 2009^[update] depend on grids, have autonomic characteristics and bill like utilities — but cloud computing can be seen as a natural next step from the grid-utility model.Some successful cloud architectures have little or no centralised infrastructure or billing systems whatsoever, including peer-to-peer networks like BitTorrent and Skype and volunteer computing like SETI@home.

Architecture

The majority of cloud computing infrastructure as of 2009^[update] consists of reliable services delivered through data centers and built on servers with different levels of virtualization technologies. The services are accessible anywhere in the world, with The Cloud appearing as a single point of access for all the computing needs of consumers. Commercial offerings need to meet the quality of service requirements of customers and typically offer service level agreements. Open standards and open source software are also critical to the growth of cloud computing.

Characteristics

As customers generally do not own the infrastructure, they merely access or rent, they can avoid capital expenditure and consume resources as a service, paying instead for what they use. Many cloud-computing offerings have adopted the utility computing model, which is analogous to how traditional utilities like electricity are consumed, while others are billed on a subscription basis. Sharing "perishable and intangible" computing power among multiple tenants can improve utilization rates, as servers are not left idle, which can reduce costs significantly while increasing the speed of application development. A side effect of this approach is that "computer capacity rises dramatically" as customers do not have to engineer for peak loads. Adoption has been enabled by "increased high-speed bandwidth" which makes it possible to receive the same response times from centralized infrastructure at other sites.

Companies

Providers including Amazon, Google and Yahoo exemplify the use of cloud computing. It is being adopted by individual users through large enterprises including General Electric, L’Oreal, and Procter & Gamble. Recently, Microsoft has introduced its new Cloud Computing service as a part of Windows Azure. These services can be accessed through Microsoft Visual Studio by installing the Windows Azure SDK and Windows Azure Tools for Visual Studio.

History

The Cloud is a term with a long history in telephony, which has in the past decade, been adopted as a metaphor for internet based services, with a common depiction in network diagrams as a cloud outline.

The underlying concept 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 which date back to the 1960s. The term cloud had already come into commercial use in the early 1990s to refer to large ATM networks. By the turn of the 21st century, the term "cloud computing" had started to appear, although most of the focus at this time was on Software as a service.

Amazon.com played a key role in the development of cloud computing by modernizing their data centre’s after the dot-com bubble and, having found that the new cloud architecture resulted in significant internal efficiency improvements, providing access to their systems by way of Amazon Web Services in 2002 on a utility computing basis.

2007 saw increased activity, with Google, IBM, and a number of universities embarking on a large scale cloud computing research project, around the time the term started gaining popularity in the mainstream press. It was a hot topic by mid-2008 and numerous cloud computing events had been scheduled.

In August 2008, Gartner observed that "organizations are switching from company-owned hardware and software assets to per-use service-based models" and 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: providers must satisfy a myriad of regulatory environments in order to deliver service to a global market. This dates back to the early days of the Internet, where libertarian thinkers felt that "cyberspace was a distinct place calling for laws and legal institutions of its own"; author Neal Stephenson envisaged this as a tiny island data haven called Kinakuta in his classic science-fiction novel Cryptonomicon.

Despite efforts (such as US-EU Safe Harbor) to harmonise the legal environment, providers like Amazon Web Services cater as of 2009^[update] to the major markets (typically the United States and the European Union) by deploying local infrastructure and allowing customers to select "availability zones." Nonetheless, there are still concerns about security and privacy from individual through governmental level, e.g., the USA PATRIOT Act and 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" (U.S. Trademark 77,139,082) in the United States. The "Notice of Allowance" it received in July 2008 got canceled on August 6, resulting in a formal rejection of the trademark application less than a week later.

Richard Stallman, founder of the Free Software Foundation, believes that cloud computing endangers liberties because users sacrifice their privacy and personal data to a third party. In November 2007, the Free Software Foundation released the Affero General Public License, a version of GPLv3 designed to close a perceived legal loophole associated with Free software designed to be run over a network, particularly software as a service. An application service provider is required to release any changes they make to Affero GPL open source code.

Risk mitigation

Corporations or end-users wishing to avoid losing or not being able to access their data should research vendors' policies on data security before using vendor services. The technology analyst and consulting firm, Gartner, lists seven security issues which one should discuss with a cloud-computing vendor:

Privileged user access—inquire about who has specialized access to data and about the hiring and management of such administrators

Regulatory compliance—make sure a vendor is willing to undergo external audits and/or security certifications

Data location—ask if a provider allows for any control over the location of data

Data segregation—make sure that encryption is available at all stages and that these "encryption schemes were designed and tested by experienced professionals"

Recovery—find out what will happen to data in the case of a disaster; do they offer complete restoration and, if so, how long that would take

Investigative Support—inquire as to whether a vendor has the ability to investigate any inappropriate or illegal activity

Long-term viability—ask what will happen to data if the company goes out of business; how will data be returned and in what format.

In practice, one can best determine data-recovery capabilities by experiment: asking to get back old data, seeing how long it takes, and verifying that the checksums match the original data. Determining data security is harder. A tactic not covered by Gartner is to encrypt the data yourself. If you encrypt the data using a trusted algorithm, then regardless of the service provider's security and encryption policies, the data will only be accessible with the decryption keys. This leads to a follow-on problem: managing private keys in a pay-on-demand computing infrastructure.