Information Technology Reference
In-Depth Information
4 Cloud Basics - An Introduction to Cloud Computing
Katarina Stanoevska-Slabeva, Thomas Wozniak
4.1 Introduction
Cloud Computing has attracted a lot of attention in recent times. The media as well
as analysts are generally very positive about the opportunities Cloud Computing
is offering. In May 2008, Merrill Lynch (2008) estimated the cost advantages of
Cloud Computing to be three to five times for business applications and more than
five times for consumer applications. According to a Gartner press release from
June 2008, Cloud Computing will be “no less influential than e-business” (Gartner
2008a).
The positive attitude towards the importance and influence of Cloud Computing
resulted in optimistic Cloud-related market forecasts. In October 2008, IDC (2008b)
forecasted an almost threefold growth of spending on Cloud services until 2012,
reaching $42 billion. Same analyst firm reported that the cost advantage associated
with the Cloud model becomes even more attractive in the economic downturn (IDC
2008b). Positive market prospects are also driven by the expectation that Cloud
Computing might become the fundamental approach towards Green IT.
Despite of the broad coverage of Cloud Computing in commercial press, there is
still no common agreement on what exactly Cloud Computing is and how it relates
to Grid Computing. To gain an understanding of what Cloud Computing is, we first
look at several existing definitions of the term. Based on those definitions, we iden-
tify key characteristics of Cloud Computing. Then we describe the common archi-
tecture and components of Clouds in detail, discuss opportunities and challenges
of Cloud Computing, and provide a classification of Clouds. Finally, we make a
comparison between Grid Computing and Cloud Computing.
4.2 Cloud Definitions
The term Cloud Computing has been defined in many ways by analyst firms,
academics, industry practitioners, and IT companies. Table 4.1 shows how selected
analyst firms define or describe Cloud Computing.
