The term “cloud computing” is a collective phrase used to define the computing environment in which an application or service delivered is created to be independent of physical location of the hardware used to store the content. According to the National Institute of Standards and Technology, cloud computing is defined as “Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.” This article is intended to present the general concepts of cloud computing and explain these concepts in relation to computing requirements and experiences of end-users, IT professionals, and business management.

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Cloud Delivery Models

Cloud services are delivered by one of the three primary service models based on the type of service delivered. The delivery models are Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a Service (IaaS). These models are collectively referred to as the SPI model.

Software as a service (SaaS)

SaaS is a cloud delivery model in which the service provider hosts and manages the applications, and provides the use of these applications or services to customers over the Internet. The physical location of the files, servers, and even the datacenter is “clouded” from the user and the user only experiences availability of the service from the provider.

Platform as a service (PaaS)

PaaS provides an online platform delivered over the web to develop and deploy applications without the need to manage the underlying servers, network infrastructure, and applications. The PaaS services can include creation of custom on-demand databases, workflow management tools, and other resources for quick creation and deployment of applications for the organization and customers.

Infrastructure as a service (IaaS)

The goal of IaaS is to provide on-demand computing resources, such as storage and computing infrastructure over the web. These include virtual servers that can be used to run custom application for the customer. These resources can be scaled up or down as the requirement for the application changes, thus minimizing the cost to “rent” the infrastructure.

Cloud Implementation Strategies

For end users or consumers, the cloud can be visualized as an extension of the Internet that service providers use to provide services or “apps” and can be used by users independent of the hardware or the devices used to access these service. Users can access these services using browsers from a desktop or laptop computers or installed applications on devices such as tablets, phones or other mobile devices

Private Cloud

Improvements in virtualization technologies empower IT operations departments to create a cloud service infrastructure within an organization’s firewalls. The intent of private cloud is rapid provisioning of resources, flexible administration, and maximizing hardware utilization. At the same time, this maintains security and control over the organization’s data. In addition to maximizing resource utilization, there are features that can be used to create resource utilization reports to enable departmental charge-back and reporting.

Community Cloud

Community cloud is a shared cloud infrastructure created to share resources between multiple organizations that come together to support shared business requirements or community interests. The infrastructure is managed by these organizations themselves or using external service providers. Community clouds provide the benefits of a public cloud with added security and information-sharing between organizations working together to develop solutions to common problems or in pursuit of common goals.

Public Cloud

The public cloud is, as the name suggests, a cloud that is open for general public use. The infrastructure may be hosted and managed by a business organization, government entity, or as collaboration between multiple organizations. The funding for operation and management of this infrastructure could be based upon advertisement revenues, government subsidies, or private donations.

Hybrid Cloud

A hybrid cloud attempts to integrate the benefits of multiple cloud infrastructures. An organization may decide to maintain some control on the cloud environment in-house as a private cloud and allow integration with a public cloud provider to assist with additional services, such as disaster recovery, remote cloud based backup, overflow capacity, seasonal and temporary infrastructure requirements etc. The two environments are distinctively different, are located and managed separately but are integrated to provide a seamless computing environment to the user.

The X-Factor

XaaS is a catch-all term to identify “anything” or “everything” as a service. In addition to the SPI model of cloud computing, XaaS also includes additional services delivered through the cloud such as storage, applications, security, network monitoring, testing, etc. With highly reliable and connected networks, the cloud model creates opportunities to deliver new services over the cloud.


In order to address the business demands of information management and delivery, explosive data growth, and software complexity, IT organizations need new strategies and partnerships with external providers to complement their existing IT capabilities. The traditional lock-down model of in-house infrastructure fails to meet the requirements of fast-paced modern business. Cloud computing, in its various forms, builds upon recent developments and technological advances to provide an on-demand, secure, and scalable platform. Businesses can capitalize upon this platform to maintain and enhance their market presence and their competitive position.