24-02-2011, 03:13 PM
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Cloud computing
Cloud computing is Internet-based computing, whereby shared resources, software, and information are provided to computers and other devices on demand, like theelectricity grid.
Cloud computing is a paradigm shift following the shift from mainframe to client–serverin the early 1980s. Details are abstracted from the users, who no longer have need for expertise in, or control over, the technology infrastructure "in the cloud" that supports them.[1] Cloud computing describes a new supplement, consumption, and delivery model for IT services based on the Internet, and it typically involves over-the-Internetprovision of dynamically scalable and often virtualized resources.[2][3] It is a byproduct and consequence of the ease-of-access to remote computing sites provided by the Internet.[4] This frequently takes the form of web-based tools or applications that users can access and use through a web browser as if it were a program installed locally on their own computer.[5]. NIST provides a somewhat more objective and specific definition here. The term "cloud" is used as a metaphor for the Internet, based on the cloud drawing used in the past to represent the telephone network,[6] and later to depict the Internet in computer network diagrams as anabstraction of the underlying infrastructure it represents.[7] Typical cloud computing providers deliver common business applications online that are accessed from another Web service or software like a Web browser, while the software and data are stored on servers. A key element of cloud computing is customization and the creation of a user-defined experience.
Most cloud computing infrastructures consist of services delivered through common centers and built on servers. 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 include SLAs.[8] The major cloud service providers
Overview
Comparisons
Cloud computing derives characteristics from, but should not be confused with:
1. Autonomic computing — "computer systems capable of self-management".[12]
2. Client–server model – Client–server computing refers broadly to any distributed application that distinguishes between service providers (servers) and service requesters (clients).[13]
3. Grid computing — "a form of distributed computing and parallel computing, whereby a 'super and virtual computer' is composed of acluster of networked, loosely coupled computers acting in concert to perform very large tasks"
4. Mainframe computer — powerful computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.[14]
5. 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";[15]
6. Peer-to-peer – a distributed architecture without the need for central coordination, with participants being at the same time both suppliers and consumers of resources (in contrast to the traditional client–server model).
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 asubscription 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.[16] In addition, "increased high-speed bandwidth" makes it possible to receive the same response times from centralized infrastructure at other sites.[citation needed]
Cloud engineering is a field of engineering that generally deals with the lifecycle of cloud computing solutions, including analysis, design, development, testing, integration, buildout, delivery, operation and consumption of cloud products and services.
Economics
Cloud computing users 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.[17][18]
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.[19]
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.[20][21]
Among the items that some cloud hosts charge for are instances (often with extra charges for high-memory or high-CPU instances); data transfer in and out; storage (measured by the GB-month); I/O requests; PUT requests and GET requests; IP addresses; and load balancing. In some cases, users can bid on instances, with pricing dependent on demand for available instances.[citation needed]
Cloud computing
Cloud computing is Internet-based computing, whereby shared resources, software, and information are provided to computers and other devices on demand, like theelectricity grid.
Cloud computing is a paradigm shift following the shift from mainframe to client–serverin the early 1980s. Details are abstracted from the users, who no longer have need for expertise in, or control over, the technology infrastructure "in the cloud" that supports them.[1] Cloud computing describes a new supplement, consumption, and delivery model for IT services based on the Internet, and it typically involves over-the-Internetprovision of dynamically scalable and often virtualized resources.[2][3] It is a byproduct and consequence of the ease-of-access to remote computing sites provided by the Internet.[4] This frequently takes the form of web-based tools or applications that users can access and use through a web browser as if it were a program installed locally on their own computer.[5]. NIST provides a somewhat more objective and specific definition here. The term "cloud" is used as a metaphor for the Internet, based on the cloud drawing used in the past to represent the telephone network,[6] and later to depict the Internet in computer network diagrams as anabstraction of the underlying infrastructure it represents.[7] Typical cloud computing providers deliver common business applications online that are accessed from another Web service or software like a Web browser, while the software and data are stored on servers. A key element of cloud computing is customization and the creation of a user-defined experience.
Most cloud computing infrastructures consist of services delivered through common centers and built on servers. 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 include SLAs.[8] The major cloud service providers
Overview
Comparisons
Cloud computing derives characteristics from, but should not be confused with:
1. Autonomic computing — "computer systems capable of self-management".[12]
2. Client–server model – Client–server computing refers broadly to any distributed application that distinguishes between service providers (servers) and service requesters (clients).[13]
3. Grid computing — "a form of distributed computing and parallel computing, whereby a 'super and virtual computer' is composed of acluster of networked, loosely coupled computers acting in concert to perform very large tasks"
4. Mainframe computer — powerful computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.[14]
5. 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";[15]
6. Peer-to-peer – a distributed architecture without the need for central coordination, with participants being at the same time both suppliers and consumers of resources (in contrast to the traditional client–server model).
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 asubscription 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.[16] In addition, "increased high-speed bandwidth" makes it possible to receive the same response times from centralized infrastructure at other sites.[citation needed]
Cloud engineering is a field of engineering that generally deals with the lifecycle of cloud computing solutions, including analysis, design, development, testing, integration, buildout, delivery, operation and consumption of cloud products and services.
Economics
Cloud computing users 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.[17][18]
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.[19]
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.[20][21]
Among the items that some cloud hosts charge for are instances (often with extra charges for high-memory or high-CPU instances); data transfer in and out; storage (measured by the GB-month); I/O requests; PUT requests and GET requests; IP addresses; and load balancing. In some cases, users can bid on instances, with pricing dependent on demand for available instances.[citation needed]
