Cloud Computing Definition

By Dexter Duncan


With all the hoopla going around about Cloud Computing, we thought it worthwhile to share a more formal definition from a reputable body.     The below is information available from the National Institute of Standards and Technology (NIST) which is “responsible for developing standards and guidelines, including minimum requirements…for use by Federal (USA) agencies.”       The definition of cloud computing includes three service models, five essential characteristics and four deployment models.

In an earlier article, we showed how cloud computing has three service models of:

1)      Software as a Service (SaaS) – most prominent players in this area include Salesforce.com and other hosted CRM packages such as Microsoft’s CRM 2011.   The idea is that you use a web browser to access the application which is managed by someone else.   You only pay for the number of users each month and are not responsible for the infrastructure such as network, servers, operating system, storage, etc.   Most businesses will be familiar with this service model.

2)      Platform as a Service (PaaS) – Most prominent players are Google and Microsoft Azure.    This service model is more for developers as you generally use the programming language and tools of the provider which allow you to deploy a cloud service or application into the cloud.

3)      Infrastructure as a Service.    This is the on-demand hosting of your compute or storage needs.   The most common player is Amazon, but in Australia it includes Melbourne IT, Macquarie Telecom and others.   You generally have control over operating system, storage and deployed application, but do not manage or control the underlying infrastructure.

NIST covers the below five essential characteristics of cloud computing.    “The cloud infrastructure is the collection of hardware and software that enables these five essential characteristics”.   We have modified/edited to make it easier to understand.

Five Essential Cloud Characteristics

1)      Demand based self-service – dynamic provisioning allowing you to self manage or schedule your usage.     This includes pricing and accounting modules allowing you to pay as you go (PAYG).

2)      Broad Access – You can access from anywhere and on multiple devices including mobile phones, tablets, laptops and regular computers.

3)      Resource Pooling – a.k.a. Resource Sharing or ability to host multiple users and applications across the same infrastructure.    This means multiple tenants sharing same pooled compute, network bandwidth, memory and storage resources which are dynamically assigned according to demand.

4)      Rapid Elasticity – Ability to rapidly add and let go of resources based on demand and service quality.  This includes ability to look at and change the Quality of Service (QoS) based on business needs.   Ideally, this is automatic and can include adding “unlimited” resources to handle “peak” times.

5)      Measured Service – Includes the ability to monitor, reserve, meter and charge in a transparent fashion.

The NIST goes further by giving four different deployment models:

Four Deployment Models:

1)      Private Cloud – provisioned for a single organization, but may be owned and managed by third party or in-house.

2)      Community Cloud – for exclusive use by specific groups that have shared interests or concerns.   A hypothetical example is the CommonWealth Bank setting up a Community Cloud for other banks.

3)      Public Cloud – provisioned for anyone in general public.

4)      Hybrid Cloud – combination of two or more of above (private, community or public) but bound together by technology that allows data and application portability (e.g. load balancing between clouds).

Wow! That is a big definition!    If you need help understanding how you can use cloud computing to improve your business, be sure to contact your local technology partner.

See our website for more:




About the author: Dexter Duncan is a Manager at Empower IT Solutions. Contact Dexter at dd@EmpowerIT.com.au


  1. The National Institute of Standards and Technology (NIST) definition of Cloud Computing.    September 2011.  NIST special Publication 800-145, Peter Mell & Timothy Grance.
  2. Cloud Nerve Network article on “The Structure of the New IT Frontier: Market Oriented Computing.   December 2009.  Christian Vecchiola, Dexter Duncan and Rajkumar Buyya.  https://texdexter.wordpress.com/2009/12/21/cloud-computing/

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