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cloud computing,the delivery of shared computing resources over a network in a manner that makes accessing and configuring those resources convenient and largely independent of the use of a required location, device, and the like. Although paralleling in some ways the use of multiple terminals to access mainframe computers and client-server computer networks, cloud computing is distinguished from them by the relative ease of access to the computing resources, which may be shared by many individuals and organizations using a wide range of devices, and the relative ease with which these users may increase (or decrease) the type and volume of computing resources to which they have access. Cloud-computing resources, which include both hardware infrastructure, such as data storage, servers, and networks, as well as operating systems, computer programs, and services provided by such programs, are typically provided over the Internet by third-party companies.
Individuals, for example, may subscribe to services that allow them to use an Internet connection or a cellular phone network to upload and store files, whether documents, music, or pictures, on the services' computer servers. These files may then be accessed by the individual in another location on a different device, or the individual may permit others to access and download the files. Computers, tablets, and smartphones, using either web browers or specialized applications, can be used to access the files as long as they can establish a connection to the service's network. Internet music services, blogging and social-networking websites, and email services all provide direct consumer services using the resources of cloud computing.
Businesses may subscribe to a range of cloud-computing services, such as offsite data storage, hosting services for running web applications, an email service, or a suite of business applications. Cloud computing allows a company to readily increase or decrease the computing resources to which they have access based upon the company's changing needs. Costs may be reduced if a company pays only for the software and hardware resources that they need at a given time instead of making significant investments in computers, software, and support personnel that may be underutilized much of the time. Companies may have concerns about the security and privacy of their data when it is stored on a provider's servers, but in the case of smaller companies, a large provider of cloud-computing resources may be better equipped to provide security. Another cloud-computing concern is the possible interruption of a company's access to its applications and data, though this can be avoided to some degree through the establishment of appropriate redundancies. Some larger companies create so-called private clouds to provide computing resources from a common corporate pool to individual business units within the company, with the provision of these resources based on the changing needs of the business units.
cloud computingHardware and software services from a provider on the Internet (the "cloud"). Cloud computing comprises "software as a service" (SaaS), "infrastructure as a service" (IaaS) and "platform as a service" (PaaS), all of which are explained below.
Is Every Function on the Internet Cloud Computing?
Not necessarily. Although almost any computing performed in the cloud might be labeled cloud computing, it really came about in two ways. It first arose when software applications were made available to companies over the Internet in the late 1990s (SaaS), and for the first time, the internal IT department was no longer responsible for maintenance of that application. Later on, companies with a massive Internet presence such as Amazon and Google offered to lease their own datacenter infrastructure by the bits and bytes of usage per month after developing extraordinary expertise in their own online business (IaaS/PaaS).
Three Distinguishing Features
(Scalability) Cloud computing servers can be quickly configured to process more data or to handle a larger, temporary workload such as Web traffic over the holidays.
(Speed) Major cloud providers are connected to the Internet via multiple Tier 1 backbones for fast response times and fault tolerance.
(Self Service) The customer (end user or IT professional) can sign up online, activate and use applications and services from start to finish without phoning a provider to set up an account. Of course, phone support is essential when problems arise.
SaaS - Software as a Service
SaaS providers deliver the entire application to the end user, relieving the organization of all hardware and software maintenance. Myriad applications running from a Web browser use this model, including Web-based e-mail, Google Apps and Salesforce.com's CRM. For IT, this has been a paradigm shift, because security and privacy issues arise when company data are stored in the cloud.
IaaS/PaaS - Infrastructure/Platform as a Service
Also called "cloud hosting" and "utility computing," infrastructure as a service (IaaS) provides the servers and operating systems, while platform as a service (PaaS) adds the databases, runtime engines and other necessary system software for the customer to deploy its applications.
Instead of purchasing and operating its own servers, it can be much more economical for a company to use the cloud for computing and eliminate the security, maintenance, network and environmental issues with inhouse datacenters. In addition, commercial cloud facilities may be able to withstand natural disasters that meet and exceed military standards.
For both small and large Web publishers, cloud providers such as Amazon and Google are invaluable. Their hardware can be configured to handle tiny amounts of traffic or huge amounts of traffic. In either case, IaaS/PaaS providers charge for actual usage, and there is no wasted expense with underutilized inhouse servers. See Amazon Web Services and Google App Engine.
The cloud employs server virtualization, which, among other benefits, allows application workloads to be easily added and removed as self-contained modules. In fact, virtualization has been a major enabler of the cloud computing model. However, the amount of work required by the customer differs greatly. Configuring virtual implementations on servers can range from being almost entirely automatic to requiring that the IT administrator be thoroughly familiar with very technical software. See server virtualization.
Private and Hybrid Clouds
Enterprises can create private clouds in their datacenters that employ the same cloud computing infrastructure used on the Internet. The private cloud provides the same flexibility and self-service capabilities, but with complete control of privacy.
A hybrid cloud is both private and public. If the private cloud is overloaded, applications are activated on the Internet cloud. Extending software and databases from internal servers to a providers' servers and managing both venues from a central console are major issues in cloud computing administration. See fog computing, cloud management system, personal cloud, Windows Azure, thin client, cloud storage, colocation, Open Cloud Manifesto and Web application.