Information Technology Reference
In-Depth Information
Table 4.1:
Cloud
Computing definitions by selected analyst firms
Source
Definition
Gartner
“a style of computing in which massively scalable IT-related capabilities
are provided “as a service” using Internet technologies to multiple external
customers” (Gartner 2008b)
IDC
“an emerging IT development, deployment and delivery model, enabling real-
time delivery of products, services and solutions over the Internet (i.e., enabling
cloud services)” (Gens 2008)
The 451 Group
“a service model that combines a general organizing principle for IT delivery,
infrastructure components, an architectural approach and an economic model
- basically, a confluence of grid computing, virtualization, utility computing,
hosting and software as a service (SaaS)” (Fellows 2008)
Merrill Lynch
“the idea of delivering personal (e.g., email, word processing, presentations.)
and business productivity applications (e.g., sales force automation, customer
service, accounting) from centralized servers” (Merrill Lynch 2008)
All these definitions have a common characteristic: they try to describe and define
Cloud Computing from the perspective of the end users and their focus is on how
it might be experienced by them. According to these definitions, core feature of
Cloud Computing is the provision of IT infrastructure and applications as a service
in a scalable way.
The definition of Cloud Computing has been subject of debate also in the scien-
tific community. Similar to the commercial press, there are different opinions about
what Cloud Computing is and which features distinguish a Cloud. Compared to the
definitions from the commercial press, the definitions in scientific literature include
not only the end user perspective, but also architectural aspects. For example,
Berkeley RAD Lab define Cloud Computing as follows:
“Cloud Computing refers to both the applications delivered as services over the Internet
and the hardware and systems software in the datacenters that provide those services.
The services themselves have long been referred to as Software as a Service (SaaS). The
datacenter hardware and software is what we will call a Cloud. When a Cloud is made
available in a pay-as-you-go manner to the general public, we call it a Public Cloud; the
service being sold is Utility Computing. We use the term Private Cloud to refer to internal
datacenters of a business or other organization, not made available to the general public.
Thus, Cloud Computing is the sum of SaaS and Utility Computing, but does not include
Private Clouds. People can be users or providers of SaaS, or users or providers of Utility
Computing.” (Armbrust et al. 2009)
This definition unites different perspectives on a Cloud: from the perspective of a
provider, the major Cloud component is the data centre. The data centre contains
the raw hardware resources for computing and storage, which together with
software are offered in a pay-as-you-go manner. From the perspective of their
purpose, Clouds are classified into private and public. Independent of the purpose
of Clouds, one most important characteristic of Clouds is the integration of hard-
ware and system software with applications, i.e. integration of utility computing
and SaaS.
