Introduction to information systems T. Cornford, M. Shaikh is1 060 2013

Cloud computing: In the wider world beyond science and engineering, 
a similar idea to a GRID is today at the forefront of computing and the 
development of new information systems – called cloud computing. In 
this case, a large network of computing resources (processors and storage 
devices) is made available for multiple users to use by the minute or by 
the kilobyte of data – just as you pay for phone calls by the second or 
electricity by the kilowatt. Thus it is possible for a business organisation 
to ‘rent’ processing power and data storage capacity on an as-needed 
basis from a supplier of such services. There may be no need to build and 
manage a data centre of your own. Two well-known companies that offer 
such services for business users are Amazon and Microsoft, and they have 
many clients both big and small. Using the cloud (a public ‘for rent’ cloud) 
just to obtain processing power and storage (infrastructure in the jargon 
– hence Infrastructure as a Service or IaaS), or it may be to also rent the 
use of software or a specific service – called Software as a Service or SaaS 
(see Laudon and Laudon (2013), Sections 5.3 and 5.4). Individual people 
too may rent storage capacity and software services; for example, in photo 
sharing sites such as Picasa or general file sharing sites such as DropBox 
(www.picasa.com; www.dropbox.com). Another example of cloud services 
for providing software include Google Apps: www.google.com/apps/

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Chapter 4: Contemporary trends in information and communication technologies
51
4.2.4 Client server computing
As noted above, today all computers are usually connected to networks, 
and thus we can also describe them by their role within the network. 
It is usual to identify two roles – that of a client computer, which 
provides the interface to the user, and that of a server computer, 
which provides services across the network. Thus, my desktop PC is a 
client computer, when it connects to a mail server computer across the 
network at the university so I can send or receive email. Figures 5.2 and 
5.3 in Laudon and Laudon (2013) show schematic descriptions of the 
client–server approach and more generally describe the period from about 
the mid-1980s as the ‘client–server era’, as networked units of computing 
resources were used to build the basic computing capacity, rather than 
relying on centralised mainframes. Of course, the internet itself is based 
on the principles of the client–server approach. This era is then overtaken 
by what Laudon and Laudon (2013) refer to as the ‘enterprise Internet 
era’ from the mid-1990s. For a more detailed description of client-server 
computing and the general distributed approach, see Curtis and Cobham 
(2008) Chapter 4. 
Laudon and Laudon (2013) end up with the final era named as the ‘Cloud 
and Mobile era’, and that quite well categorises the contemporary leading 
edge in technology and infrastructure terms. Although, as they make 
clear, earlier generations of technology are in use and remain important, 
still. The cloud model is sometimes termed as a utility model, with a 
parallel drawn between the way we gain electricity or water from a utility 
company. Just plug in and use what you want. Use of cloud computing 
may also have some benefits in terms of global and local environmental 
impacts – noting that Laudon and Laudon (2013, Section 5.3) report that 
in the USA data centres use more than 2 per cent of all electrical power. 
If cloud computer centres are located where hydroelectricity is generated 
and cheap, and data and work is sent to them using networks, then we 
may save the pollution of running computers on expensive electricity 
that is generated using carbon fuels (oil, gas, coal). As with most issues 
associated with global warming, greenhouse gases and CO
2
levels, green 
computing is a contentious issue with many different viewpoints.