The term cloud is used as a metaphor for the Internet, based on how the Internet is depicted in computer network diagrams and is an abstraction for the complex infrastructure it conceals.
The first academic use of this term appears to be by Prof. Ramnath K. Chellappa (currently at Goizueta Business School, Emory University) who originally defined it as a computing paradigm where the boundaries of computing will be determined by economic rationale rather than technical limits.
Developers must be able to refactor their applications so that they can best use the architectural and deployment paradigms that cloud computing supports. The benefits of deploying applications using cloud computing include reducing run time and response time, minimizing the risk of deploying physical infrastructure, lowering the cost of entry, and increasing the pace of innovation.
It can be the ability to rent a server or a thousand servers and run a geophysical modeling application on the most powerful systems available anywhere. It can be the ability to rent a virtual server, load software on it, turn it on and off at will, or clone it ten times to meet a sudden workload demand. It can be storing and securing immense amounts of data that is accessible only by authorized applications and users. It can be supported by a cloud provider that sets up a platform that includes the OS, Apache, a MySQL database, Perl, Python, and PHP with the ability to scale automatically in response to changing workloads. Cloud computing can be the ability to use applications on the Internet that store and protect data while providing a service — anything including email, sales force automation and tax preparation. It can be using a storage cloud to hold application, business, and personal data. And it can be the ability to use a handful of Web services to integrate photos, maps, and GPS information to create a mash up in customer Web browsers. Cloud computing can be provided using an enterprise datacenter’s own servers, or it can be provided by a cloud provider that takes all of the capital risk of owning the infrastructure. Some of the vendors providing this service are SUN, Microsoft, Google, Yahoo, Zoho etc.,
