Cloud Computing – A Definition

Everyone is ‘in the cloud’ today. But what does this mean and how will it help? First, a common way to talk about cloud computing is needed. We need a way to further define how to look at cloud services.

First, what is cloud computing and how does it differ from a traditional model? Cloud computing is purely services based as opposed to product (or a combination of product/ services) based. Cloud services are elastic and can fluctuate up and down with demand. Charges for cloud services follow a classic ‘pay as you go’ model. A customer only pays for the services they use. As demand changes, supply adapts accordingly. This on-demand, pay-as-you-go supply model provides an organization with increased flexibility beyond their existing systems.

The cloud computing architecture is made up of three tiers:

SaaS: Software as a Service

PaaS: Platform as a Service

IaaS: Infrastructure as a Service

It helps to start at the bottom and work your way up. IaaS refers to the hardware and operating system that support the next tier (PaaS). IaaS contains the software required to interface with the hardware similar to classic virtualization products. PaaS provides a common platform that applications can be developed upon. Examples would be Ruby on Rails, mySQL, Java, etc. PaaS also includes the interlaying infrastructure. An organization leveraging PaaS would develop on these platforms. SaaS is the top of the framework. SaaS requires no development on behalf of the end user. There may be minimal configuration at most. But the idea is that SaaS can be used right out of the box…or cloud.

An interesting twist is that SaaS and PaaS providers could potentially leverage services lower in the framework. For example, a SaaS provider might leverage services from a PaaS provider. And a PaaS provider might, in turn, leverage services from an IaaS provider.

There is also the potential for intermediate service offerings that bridge between SaaS/ PaaS and PaaS/ IaaS. Examples of this would be management services that allow usage of multiple PaaS or IaaS services. It is also possible that a management service could roll-up several SaaS service offerings into a more comprehensive offering.

There are a number of ways to leverage cloud services. How will you use it?

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