My thoughts on Cloud Computing . A Simple approach

In recent days there is a lot of excitement going around regarding Cloud Computing. So when I was asked to write a piece about it, I was a little confused. Where do I start?
Finally it struck me. Many have heard about it and many know that it is the most happening thing. But most don’t know what it is. So let us start simple.

What is cloud computing?
Anything that involves delivering hosted services over the Internet can be referred as Cloud computing . Users need not have knowledge of, expertise in, or control over the technology infrastructure in the “cloud” that supports them.

Cloud Computing services concept generally incorporates combinations: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) , Software-as-a-Service (SaaS) and Other recent technologies that rely on the Internet to satisfy the computing needs of users. Cloud computing services often provide common business applications online that are accessed from a web browser, while the software and data are stored on the servers.

A frequently asked question about Cloud Services is ‘What is it that makes Cloud Service different from traditional hosting?’

A cloud service has three distinct characteristics that differentiate it from traditional hosting. It is sold on demand, typically by the minute or the hour; it is elastic — a user can have as much or as little of a service as they want at any given time; and the service is fully managed by the provider (the consumer needs nothing but a personal computer and Internet access). Significant innovations in virtualization and distributed computing, as well as improved access to high-speed Internet and a weak economy, have accelerated interest in cloud computing.

A cloud can be private or public. A public cloud sells services to anyone on the Internet. (Currently, Amazon Web Services is the largest public cloud provider.) A private cloud is a proprietary network or a data center that supplies hosted services to a limited number of people. When a service provider uses public cloud resources to create their private cloud, the result is called a virtual private cloud. Private or public, the goal of cloud computing is to provide easy, scalable access to computing resources and IT services.

Infrastructure as a Service (IaaS) is the delivery of computer infrastructure (typically a platform virtualization environment) as a service. These ‘virtual infrastructure stacks’ are an example of the everything as a service trend and shares many of the common characteristics. Rather than purchasing servers, software, data center space or network equipment, clients instead buy those resources as a fully outsourced service. The service is typically billed on a utility computing basis and amount of resources consumed (and therefore the cost) will typically reflect the level of activity. It is an evolution of web hosting and virtual private server offerings.

Customers use the provider’s application program interface (API) to start, stop, access and configure their virtual servers and storage. In the enterprise, cloud computing allows a company to pay for only as much capacity as is needed, and bring more online as soon as required. Because this pay-for-what-you-use model resembles the way electricity, fuel and water are consumed; it’s sometimes referred to as utility computing.

Platform as a Service (PaaS) is the delivery of a computing platform and solution stack as a service. Without the cost and complexity of buying and managing the underlying hardware and software layers, It facilitates deployment of applications, providing all of the facilities required to support the complete life cycle of building and delivering web applications and services entirely available from the Internet. No software downloads or installation is required from the side of developers, IT managers or end-users. It’s also known as cloudware.

Developers create applications on the provider’s platform over the Internet. PaaS providers may use APIs, website portals or gateway software installed on the customer’s computer. Force.com, (an outgrowth of Salesforce.com) and GoogleApps are examples of PaaS. Developers need to know that currently, there are not standards for interoperability or data portability in the cloud. Some providers will not allow software created by their customers to be moved off the provider’s platform.

Software as a Service (SaaS, typically pronounced ’sass’) is a model of software deployment whereby a provider licenses an application to customers for use as a service on demand. SaaS software vendors may host the application on their own web servers or download the application to the consumer device, disabling it after use or after the on-demand contract expires. The on-demand function may be handled internally to share licenses within a firm or by a third-party application service provider (ASP) sharing licenses between firms.

SaaS is a very broad market. Services can be anything from Web-based email to inventory control and database processing. Because the service provider hosts both the application and the data, the end user is free to use the service from anywhere.