IT: Note on CLOUD COMPUTING

(My colleague from our IT Wing, Mr B. Arun Kumar, had prepared a brief note on ‘Cloud Computing’ for my consumption, at my request. Thought of sharing Mr Arun's note (verbatim) with others through this blog; of course, I have taken his permission to do so before posting this blog.)

QUOTE:
Based on computing needs, a company decides on the technology:

Generation One------Mainframes Technology

Generation Two------Client-Server Technology

Generation Three----Cloud Computing Technology

Cloud Computing is Internet-based computing, whereby shared resources, software and information are provided to computers and other devices on-demand, like the electricity grid. It is a byproduct and consequence of the ease-of-access to remote computing sites provided by the Internet.

Cloud computing is a general term for anything that involves delivering hosted services over the Internet. These services are broadly divided into three categories: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). The name cloud computing was inspired by the cloud symbol that's often used to represent the Internet in flowcharts and diagrams.

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, and later to depict the Internet in computer network diagrams as an abstraction of the underlying infrastructure it represents. Typical cloud computing providers deliver common business applications online which are accessed from another web service or software like a web browser, while the software and data are stored on servers.

Most cloud computing infrastructure consists of reliable services delivered through data 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 offer SLAs (Service Level Agreements). The major cloud service providers include Amazon, Google and Microsoft.

In general, cloud computing customers do not own the physical infrastructure; instead they avoid 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 a subscription 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. In addition, "increased high-speed bandwidth" makes it possible to receive the same response times from centralized infrastructure at other sites.

Please visit the following website for understanding the cloud computing services offered by Microsoft & Google.
http://www.microsoft.com/virtualization/en/us/cloud-computing.aspx
http://www.microsoft.com/online/default.mspx
http://www.google.com/services/
UNQUOTE

Jaikishan