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Cloud computing is Internet-based ("cloud") development and use of computer technology ("computing"). 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. It is a style of computing in which IT-related capabilities are provided “as a service”, allowing users to access technology-enabled services from the Internet ("in the cloud") without knowledge of, expertise with, or control over the technology infrastructure that supports them. According to a 2008 paper published by IEEE Internet Computing "Cloud Computing is a paradigm in which information is permanently stored in servers on the Internet and cached temporarily on clients that include desktops, entertainment centers, tablet computers, notebooks, wall computers, handhelds, sensors, monitors, etc."

Cloud computing is a general concept that 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. For example, Google Apps provides common business applications online that are accessed from a web browser, while the software and data are stored on the servers.

Brief

Comparisons

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 are today powered by grids, have autonomic characteristics and are billed 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 currently consists of reliable services delivered through data centers that are built on computer and storage 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 forego 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. By sharing "perishable and intangible" computing power between multiple tenants, utilization rates can be improved, 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

Cloud computing is being driven by providers including Amazon, Google, and Salesforce as well as traditional vendors including HP, IBM, Intel and Microsoft. It is being adopted by individual users through large enterprises including General Electric, L'Oréal, Procter & Gamble and Valeo.

History

The Cloud is a metaphor for the Internet, derived from its common depiction in network diagrams, or more generally components which are managed by others, 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, and the term cloud was already in commercial use in the early 1990s to refer to large ATM networks. By the turn of the 21st century, cloud computing solutions had started to appear on the market, 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 centers 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, including 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 "organisations 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 globalisation". As such it is the subject of complex geopolitical issues, whereby 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 science-fiction classic novel Cryptonomicon.

Although there have been efforts to harmonise the legal environment, such as US-EU Safe Harbor, providers like Amazon Web Services are currently catering to the major markets, typically the United States and 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. It received a "Notice of Allowance" in July 2008 which was subsequently 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.

Key characteristics

• Customer capital expenditure is minimized and thus lowers barriers to entry, as infrastructure is owned by the provider and does not need to be purchased for one-time or infrequent intensive computing tasks. Services are typically available to or specifically targeted to retail consumers and small businesses.
• Device and location independence enables users to access systems regardless of their location or what device they are using, e.g., PC, mobile.
• Multi-tenancy enables sharing of resources, and costs, among a large pool of users, allowing for:
  • Centralization of infrastructure in areas with lower costs, e.g., real estate, electricity, etc.
  • Peak-load capacity increases (users need not engineer for highest possible load levels)
  • Utilisation and efficiency improvements for systems that are often only 10-20% utilised.
• Performance is monitored and consistent, but can be affected by insufficient bandwidth or high network load.
• Reliability is enhanced by way of multiple redundant sites, which makes it suitable for business continuity and disaster recovery, however IT and business managers are able to do little when an outage hits them. Historical data on cloud outages is tracked in the Cloud Computing Incidents Database.
• Scalability meets changing user demands, e.g., Flash crowds, quickly without users having to engineer for peak loads. Massive scalability and large user bases are common, but not an absolute requirement.
• Security typically improves due to centralization of data, increased security-focused resources, etc., but raises concerns about loss of control over certain sensitive data. Accesses are typically logged but accessing the audit logs themselves can be difficult or impossible.
• Sustainability is achieved through improved resource utilisation, more efficient systems, and carbon neutrality. Nonetheless, computers and associated infrastructure are major consumers of energy.

Components

Application

A cloud application leverages The Cloud 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:

• Peer-to-peer/volunteer computing (Bittorrent, SETI@home, Skype)
• Web application (Facebook)
• Software as a service (Google Apps, Salesforce)
• Software plus services (Microsoft Online Services)

Client

A cloud client is computer hardware and/or computer software which relies on The Cloud for application delivery, or which is specifically designed for delivery of cloud services, and which in either case is essentially useless without it. For example:

• Mobile (Android, iPhone, Windows Mobile)
• Thin client (CherryPal, Zonbu gOS-based systems)
• Thick client/Web browser (Google Chrome,Mozilla Firefox)

Infrastructure

Cloud infrastructure, e.g., Infrastructure as a service, is the delivery of computer infrastructure, typically a platform virtualization environment, as a service. For example:

• Full virtualization (GoGrid, Skytap)
• Grid computing (Sun Grid)
• Management (RightScale)
• Paravirtualization (Amazon Elastic Compute Cloud)

Platform

A cloud platform, e.g., Platform as a service, the delivery of a computing platform, and/or solution stack as a service, facilitates deployment of applications without the cost and complexity of buying and managing the underlying hardware and software layers. For example:

• Web application frameworks
  • Ajax (Caspio)
  • Python Django (Google App Engine)
  • Ruby on Rails (Heroku)
• Web hosting (Mosso)
• Proprietary (Azure, Force.com)

Service

A cloud service, e.g., Web Service, is "software system designed to support interoperable machine-to-machine interaction over a network" which may be accessed by other cloud computing components, software, e.g., Software plus services, or end users directly. For example:

• Identity (OAuth, OpenID)
• Integration (Amazon Simple Queue Service)
• Payments (Amazon Flexible Payments Service, Google Checkout, PayPal)
• Mapping (Google Maps, Yahoo! Maps)
• Search (Alexa, Google Custom Search, Yahoo! BOSS)
• Others (Amazon Mechanical Turk)

Storage

Cloud storage is the delivery of data storage as a service, including database-like services, often billed on a utility computing basis, e.g., per gigabyte per month. For example:

• Database (Amazon SimpleDB, Google App Engine's BigTable datastore)
• Network attached storage (MobileMe iDisk component, Nirvanix CloudNAS)
• Synchronisation (Live Mesh Live Desktop component, MobileMe push functions)
• Web service (Amazon Simple Storage Service, Nirvanix SDN)

Traditional storage vendors have recently begun to offer their own flavor of cloud storage, typically supporting existing software products, e.g., Symantec's Online Storage for Backup Exec, or on delivering cloud storage services, e.g., EMC's Atmos).

Architecture

Cloud architecture is the systems architecture of the software systems involved in the delivery of cloud computing, e.g., hardware, software, as 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 is very similar to the Unix philosophy of having multiple programs 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 are used to 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.

Roles

Provider

A cloud computing provider or cloud computing service provider owns and operates live cloud computing systems to deliver service to third parties. Usually this requires significant resources and expertise in building and managing next generation data centers. Some organisations are realising a subset of the benefits of cloud computing by becoming "internal" cloud providers and servicing themselves, although they do not benefit from the same economies of scale and still have to engineer for peak loads. The barrier to entry is also significantly higher with capital expenditure required and billing and management creates some overhead. Nonetheless, significant operational efficiency and agility advantages can be realised, even by small organisations, and server consolidation and virtualization rollouts are already well underway. Amazon.com was the first such provider, modernising its data centers which, like most computer networks, were using as little as 10% of its capacity at any one time just to leave room for occasional spikes. This allowed small, fast-moving groups to add new features faster and easier, and they went on to open it up to outsiders as Amazon Web Services in 2002 on a utility computing basis.

The companies listed in the Components section are providers.

User

A user is a consumer of cloud computing. The privacy of users in cloud computing has become of increasing concern. The rights of users is also an issue, which is being addressed via a community effort to create a bill of rights, currently in draft.

Vendor

A vendor sells products and services that facilitate the delivery, adoption and use of cloud computing. For example:

• Computer hardware (Dell, HP, IBM, Sun Microsystems)
  • Storage (3PAR, EMC, MogileFS)
  • Infrastructure (Solace Systems, Layer 7 Technologies, F5 Networks)
• Computer software (3tera, GigaSpaces, Hadoop)
  • Operating systems (Solaris, Linux including Red Hat)
  • Platform virtualisation (Citrix, Microsoft, VMware, Sun xVM)

Standards

A cloud standard is one of a number of existing, typically lightweight, open standards that have facilitated the growth of cloud computing, including:

• Application
  • Communications (HTTP, XMPP)
  • Security (OAuth, OpenID, SSL/TLS)
  • Syndication (Atom)
• Client
  • Browsers (AJAX)
  • Offline (HTML 5)
• Infrastructure
  • Virtualization (OVF)
• Platform
  • Solution stacks (LAMP, Space-based architecture)
• Service
  • Data (XML, JSON)
  • Web Services (REST)
• Storage

Risks

While cloud computing has many benefits for companies and individual consumers alike, many IT professionals and academics have expressed concerns about some of the risks still associated with the concept. One must look at all the risks which are inherent in the current cloud computing world before deciding to make an investment in it. Most of these risks involve data security. Where is a company’s data stored? What happens if the vendor’s servers go down? What happens to the user’s data if the vendor must shut down operations or is absorbed by another company? All of these situations could deeply affect a corporation’s operating activities or their privacy.

In February of 2008, Amazon.com’s cloud storage program, S3 (Simple Storage Service) suffered a major outage during which users and corporations could not access their data. This affected many businesses, including the popular networking site . Gmail, Yahoo, and Apple’s MobileMe service have also had similar issues wherein users were not able to access their data or operate. While all the issues which caused these previous outages have been resolved, one can see that cloud-computing is still vulnerable to problems.

The best way for a corporation or end-user to avoid losing or not being able to access their data is to know a vendor’s policies on data security before using their services. The technology analyst and consulting firm, Gartner, lists seven security issues which one should discuss with a cloud-computing vendor: 1.) Privileged user access—inquire about who has specialized access to data and about the hiring and management of such administrators 2.) Regulatory compliance—make sure a vendor is willing to undergo external audits and/or security certifications 3.) Data location—ask if a provider allows for any control over the location of data 4.) Data segregation—make sure that encryption is available at all stages and that these “encryption schemes were designed and tested by experienced professionals.” 5.) 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 6.) Investigative Support—inquire as to whether a vendor has the ability to investigate any inappropriate or legal activity 7.) Long-term viability—ask what will happen to data if the company goes out of business; how data be returned and in what format

In addition, a user should carefully determine what should or should not be put “into the cloud.” Dan Woods, chief technology officer and founder of Evolved Media, states that “If you can live without an application for 2 days, it is probably safe to put into the cloud.” Woods also suggests that users review any Service Level Agreements (SLAs) that a vendor provides. These are usually thin and do not provide much coverage for the user. Therefore, a user should always make sure their data is backed up either on disk or with another cloud vendor. Some cloud computing vendors offer multi-cloud offerings or multi-cloud support in which the infrastructure which is created on one cloud is duplicated on others, providing redundancy for their customers in case of an emergency. Entrusting data to a single source is the “equivalent to storing it on a single hard drive. It introduces a single point of failure into the system.”

Cloud computing has many exciting advantages for both corporations and private users, but users must always be cautious before entrusting data and operations to a company that is not under their own control.

See also

• Web operating system
• Web desktop
• Autonomic computing
• Everything as a service
  • Infrastructure as a service
  • Platform as a service
  • Software as a service
• Grid computing
• Utility computing

References

1. The Internet Cloud
2. Gartner Says Cloud Computing Will Be As Influential As E-business
3. What's the difference Between Cloud Computing and SaaS?
4. Distinguishing Cloud Computing from Utility Computing
5. ORGs for Scalable, Robust, Privacy-Friendly Client Cloud Computing
6. "It's probable that you've misunderstood "Cloud Computing" until now". TechPluto.
7. What's In A Name? Utility vs. Cloud vs Grid
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9. ACM Ubiquity: Emergence of The Academic Computing Cloud
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11. Open source fuels growth of cloud computing, software-as-a-service
12. Cloud Computing: The Evolution of Software-as-a-Service
14. Google Apps makes its way into big business
15. Google, Inc. Q2 2008 Earnings Call
16. Cloud Computing: When Computers Really Do Rule
17. What cloud computing really means
18. The Internet Cloud
19. July, 1993 meeting report from the IP over ATM working group of the IETF
20. Internet Critic Takes on Microsoft
21. ^ Jeff Bezos' Risky Bet
22. Google and I.B.M. Join in ‘Cloud Computing’ Research
23. Keep an eye on cloud computing
24. Gartner Says Worldwide IT Spending On Pace to Surpass $3.4 Trillion in 2008
25. ^ Computers without borders
26. Feature Guide: Amazon EC2 Availability Zones
27. Cloud computing is a trap, warns GNU founder Richard Stallman, Guardian, September 30, 2008
28. The new geek chic: Data centers
29. Cloud Computing: Small Companies Take Flight
30. Google Apps Admins Jittery About Gmail, Hopeful About Future
31. New Resource, Born of a Cloud Feud
32. Exari: Death By Laptop
33. Google to go carbon neutral by 2008
34. What is Cloud Computing?
35. Shut off your computer
36. ^ Nimbus Cloud Guide
37. Google's Open Source Android OS Will Free the Wireless Web
38. In Sync to Pierce the Cloud
39. Microsoft demos mobile cloud sync client
40. CherryPal brings cloud computing to the masses
41. Zonbu has alluring features, price
42. GOS cloud computing
43. Google Chrome Aims to Break Microsoft Windows
44. EMC buys Pi and forms a cloud computing group
45. Google angles for business users with 'platform as a service'
46. "Web Services Glossary".
47. The Emerging Cloud Service Architecture
48. Google, Microsoft and Apple building online storage havens: you win
49. Building GrepTheWeb in the Cloud, Part 1: Cloud Architectures
50. Cloud Maturity Is Accelerating: More Than Just Reaction To The Hype?
51. ACM Queue - Beyond Server Consolidation
52. ORGs for Scalable, Robust, Privacy-Friendly Client Cloud Computing
53. Google Privacy Practices Worse Than ISP Snooping, AT&T Charges
54. Draft Cloud Computing: Bill of Rights Now Available
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56. List of Cloud Platforms, Providers and Enablers
57. Red Hat chief: 'The clouds will all run Linux'
58. The Cloud and Standards
59. Lock-in, security loom as dark side of Compute Cloud
60. LinuxWorld/Next Generation Data Center attendees get schooled in cloud computing
61. Brandel, Mary . "Stormy Weather." computerworld 3 Nov. 2008: 22-28.
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63. Arnold, Steve . "A Risky Cloud Approach?." KM World : 1, 20.
64. Arnold, Steve . "A Risky Cloud Approach?." KM World : 1, 20.
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66. Woods, Dan. "Disaster-Proofing The Cloud - Forbes.com." Business News and Financial News at Forbes.com. 3 Dec. 2008 <http://www.forbes.com/cionetwork/2008/11/24/cio-cloud-disaster-tech-cio-cx_dw_1125cloud.html>.

External links

• Chappell, David (August 2008). "A Short Introduction to Cloud Platforms" (PDF). David Chappell & Associates. Retrieved 2008-08-20. {{cite journal}}: Cite has empty unknown parameter: |1= (help); Cite journal requires |journal= (help)
• Jones, M. Tim, Cloud Computing with Linux from IBM DeveloperWorks (2008-09-10).
• Cloud Computing Community Wiki is a "new resource put together by several industry executives and bloggers".
• Cloud Computing Incidents Database (CCID) tracks and "provides historical data on cloud outages".
• What is Cloud Computing ? - Web 2.0 expo - A video where Tim O’Reilly, Dan Farber, Matt Mullenweg and others answer this question.

1. ^ Cite error: The named reference cloudfeud was invoked but never defined (see the help page).

• Articles needing cleanup from November 2008
• Articles with sections that need to be turned into prose from November 2008
• Cloud computing
• Distributed computing