Information Technology Reference
In-Depth Information
reduce the heating generated by the hardware). ICT uses a great deal of energy and it
is rising fast as follows [1]:
1.
ICT equipment accounts for 10% of the UK's electricity consumption.
2.
Non-domestic energy consumption from ICT equipment rose by 70% from 2000-
2006, and is predicted to further grow 40% by 2020.
3.
Data centres account for about a quarter of the ICT sector's emissions.
A cloud computing infrastructure for ICT as a utility is likely to substantially reduce
all these costs, and the environmental impact alongside also reducing labour-related
costs, as less people (e.g., technicians) than existing ICT infrastructures will be
required to run a cloud-based ICT infrastructure.
In cloud computing, everything is defined and treated as a service such as SaaS
(Software as a Service), PaaS (Platform as a Service) and IaaS (Infrastructure as a
Service) [15], [18]. These services define a multi-layered infrastructure as shown in
figure 3 and the related main services are defined as follows:
1.
Software as a Service
(SaaS), where applications are hosted and delivered online
via a web browser offering traditional desktop functionality
2.
Platform as a Service
(PaaS), where the cloud provides the software platform for
systems (as opposed to just software)
3.
Infrastructure as a Service
(IaaS), where a set of virtual computing resources,
such as storage and computing capacity, are hosted in the cloud; customers
deploy and run only their own applications for obtaining the needed services.
Fig. 3.
The Cloud based Digital Infrastructure
At the infrastructure level, processing, storage, networks, and other fundamental
computing resources are defined as standardized services over the network. Cloud
providers' users can deploy and run operating systems and software for their
underlying infrastructures. The middle layer, i.e. PaaS provides abstractions and
services for developing, testing, deploying, hosting, and maintaining applications in
