" Clouds are vast resource pools with on-demand resource allocation. The degree of on-demandness can vary from phone calls to web forms to actual APIs that directly requisition servers.
Clouds are virtualized. On-demand requisitioning implies the ability to dynamically resize resource allocation or moving customers from one physical server to another transparently. This is all difficult or impossible without virtualization.
Clouds tend to be priced like utilities (hourly, rather than per-resource),
Scalability ->meets changing user demands quickly without users having to engineer for peak loads. If one server can process 1,000 transactions per second, two servers should be able to process 2,000 transactions per second, and so forth.
Multi-tenancy-> enables sharing of resources and costs among a large pool of users, allowing for: 1. Centralization of infrastructure
On-demand allocation and de-allocation of CPU, storage and network bandwidth.
Performance is monitored and consistent, but can suffer from insufficient bandwidth or high network load.
Service-oriented : The system allows composing applications out of discrete services that are loosely coupled (independent of each other). Changes to or failure of one service will not disrupt other services. It also means I can re-use services.
Security typically improves due to centralization of data, increased security-focused resources, etc., but raises concerns about loss of control over certain sensitive data.
A cloud platform , such as 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:
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:
A cloud service , such as Web Service, is "software system[s] 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 )
A cloud client consists of 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:
A cloud computing provider or cloud computing service provider owns and operates live cloud computing systems to deliver service to third parties.
This requires significant resources and expertise in building and managing next-generation data centers.
The barrier to entry is also significantly higher with capital expenditure required and billing and management creates some overhead.
Amazon.com was the first such provider, modernizing 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 .
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
“ Virtual Computing Laboratory (VCL) –http://vcl.ncsu.edu is an award-winning open source implementation of a secure production level on-demand utility computing and services oriented technology for wide-area access to solutions based on virtualized resources, including computational, storage and software resources.
There are VCL pilots with a number of University of North Carolina campuses, North Carolina Community College System, as well as with a number of out-of-state universities – many of which are members of the IBM Virtual Computing Initiative ”.