Cloud is a frequently-used term in the IT industry, which has different meanings to different people. Does it mean web-based applications or web-hosted services, or does it mean centralized server farms and data centers or platforms for developing and running scalable applications? Actually, the cloud can span all these things and more! Basically, cloud computing is a way of providing and consuming IT services, which includes certain attributes, service models and deployment approaches. A definition of cloud computing has emerged from the National Institute of Standards and Technology (NIST) that consists 5 key characteristics, 3 service models, and 4 deployment models. Cloud computing consolidates resources – Compute Infrastructure, Storage and Network – to optimally adjust the fluctuation in system workload by dynamically modifying the capacity requirements. The end-purpose of cloud computing is to provide real-time, high-availability access to computing infrastructure and IT services. Cloud services feature the following characteristics that distinguish it from traditional hosting:

• Cloud services are delivered on demand, usually on time-basis
• Cloud computing is flexible i.e. the user has the freedom to choose the extent of service at any given time.
• Cloud services are fully managed by the provider, while the user just requires internet and a PC.

Cloud computing technology – the value proposition The value proposition of cloud computing technology includes provisioning of agile compute infrastructure or instantaneous resource availability. Using these concepts, cloud computing readily recycles resources into higher value computing needs, by which inherent value is derived from oversubscribing the resources in an intelligent and optimized manner. This increases the returns on investment and optimizes the capabilities of the asset in terms of efficiency and flexibility.

Cloud Services The cloud services include Infrastructure as a Service, Platform as a Service, and Software as a Service. Alternatively, the cloud is about providing a pool of computing resources that all operate together effectively as one PC or machine. The cloud is referred to as the next step in enterprise computing with a greater emphasis on information management. It is about having the storage, application development environment, applications, and security available to you when you need them-all from an information technology grid.

What is Infrastructure as a Service (IaaS)?

IaaS is a cloud service model that abstracts hardware (server, storage, and network infrastructure) into a pool of computing hardware, storage, and networking capabilities that are delivered as services for a usage-based cost. The purpose of Infrastructure as a Service is to provide a scalable, virtualized computing environment that can become a foundation for PaaS and SaaS. The consumer assumes the ownership for configuration and operations of the guest Operating System (OS), software, and Database (DB). Compute capabilities – performance, bandwidth, and storage access – are also homogenized. Service levels cover the performance and availability of the virtualized infrastructure. The consumer assumes the operating risks.

Platform as a Service (PaaS)

Platform as a Service (PaaS) is a cloud service model that delivers application execution services – application runtime, storage, and integration – for programs written for a pre-defined framework. PaaS provides an agile tactic to operate scale-out applications in a predictable and economic manner. Service level agreements and operating risks are shared because the consumer must take responsibility for the stability, compliance, and operations of the application while the provider delivers the platform capability (including the infrastructure and operational functions) at a predictable service level and cost. Software as a Service (SaaS) Software as a Service (SaaS) is a cloud service model that delivers business processes and services – CRM, collaboration, and e-mail – as standardized capabilities for a usage-based cost at a mutually defined service level. SaaS provides considerable efficiencies in cost and delivery in exchange for minimal personalization, and shows a shift of risks from the consumer to the service provider.