National institute of standard and technology defines cloud computing as enabling convenient, on demand network access to a shared pool of configurable resources (e.g. Network,server, storage,applications and services) that can be rapidly provisioned and released with minimal management effort pr service provider interaction. Economically, the main appeal of cloud computing is that customers only use what they need, and only pay for what they actually use. Resources are available to be accessed from the cloud at any time, and from any location via the internet. There’s no need to worry about how things are being maintained behind the scenes – you simply purchase the IT service you require as you would any other utility. Because of this, cloud computing has also been called utility computing, or ‘IT on demand
What does it comprise?
Cloud computing can be visualized as a pyramid consisting of three sections:
Cloud Application - This is the apex of the cloud pyramid, where applications are run and interacted with via a web browser, hosted desktop or remote client. A hallmark of commercial cloud computing applications is that users never need to purchase expensive software licenses themselves. Instead, the cost is incorporated into the subscription fee. A cloud application eliminates the need to install and run the application on the Cloud Application Cloud Platform Cloud Infrastructure customer's own computer, thus removing the burden of software maintenance, ongoing operation and support.
Cloud Platform - The middle layer of the cloud pyramid, which provides a computing platform or framework as a service. A cloud computing platform dynamically provisions, configures, reconfigures and de-provisions servers as needed to cope with increases or decreases in demand. This in reality is a distributed computing model, where many services pull together to deliver an application or infrastructure request.
Cloud Infrastructure - The foundation of the cloud pyramid is the delivery of IT infrastructure through virtualisation. Virtualisation allows the splitting of a single physical piece of hardware into independent, self governed environments, which can be scaled in terms of CPU, RAM, Disk and other elements. The infrastructure includes servers, networks and other hardware appliances delivered as either Infrastructure “Web Services”, “farms” or "cloud centers". These are then interlinked with others for resilience and additional capacity.
Types of Cloud Computing
Public Cloud Public cloud (also referred to as ‘external’ cloud) describes the conventional meaning of cloud computing: scalable, dynamically provisioned, often virtualized resources available over the Internet from an off-site third-party provider, which divides up resources and bills its customers on a ‘utility’ basis. An example is ThinkGrid, a company that provides a multi-tenant architecture for supplying services such as Hosted Desktops, Software as a Service and Platform as a Service. Other popular cloud vendors include Salesforce.com, Amazon EC2 and Flexiscale.
Private Cloud Private cloud (also referred to as ‘corporate’ or ‘internal’ cloud) is a term used to denote a proprietary computing architecture providing hosted services on private networks. This type of cloud computing is generally used by large companies, and allows their corporate network and data centre administrators to effectively become in-house ‘service providers’ catering to ‘customers’ within the corporation. However, it negates many of the benefits of cloud computing, as organizations still need to purchase, set up and manage their own clouds.
Hybrid Cloud It has been suggested that a hybrid cloud environment combining resources from both internal and external providers will become the most popular choice for enterprises. For example, a company could choose to use a public cloud service for general computing, but...