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long as it connected to the internet and the software that is used to serve the internet that meets the minimum requirements of Cloud. Today ' s internet browsers such as Firefox and Google Chrome are fully capable to meet the minimum requirements of any cloud server. Cloud Computing facilitates a new approach towards IT. It enables enhanced scalability and more efficient use of IT based on Virtualization of heterogeneous and spread IT resources( Stanoevska‐Slabeva et. al. 2010).
Table 2: Categories of cloud computing services
Category Infrastructure as a Service( IaaS)
Platform as a Service( PaaS)
Software as a Service( SaaS)
Table 3: Types of cloud computing
Description In this layer, products are provided through the internet such as hardware services, enabling customers to pay for usage of servers( e. g., virtual computers, virtual servers, storage devices, etc.). Products provided through this layer which involves the ability to develop and host software remotely. For instance develop web solutions and place them on a web server running server operating systems( i. e. Windows Azure, which supports the delivery of highly scalable cloudbased applications. In this this layer, application softwares are provided via Internet as a service. In which the cloud provides a complete application functionality which ranges from productivity applications( i. e., office‐type).
Category
Description Private Cloud The cloud infrastructure of this type is operated for a particular organisation comprising multiple consumer( i. e. business units). The system might be organized by its own organisation, a third party, or combination of them, and it may be exist on premise or off premise.
Community Cloud The cloud infrastructure is used by a particular community of consumers from organisations that have shared concerns( i. e., mission, security requirements, policy, and compliance considerations). It might be owned, and operated by one or many organizations or a third party and may exist on premise or off premise.
Public Cloud The cloud infrastructure is offered for general public use or a large industry group and is owned by an organization( i. e. business, academic, or government organization, or some combination of them) selling cloud services.
Hybrid Cloud The cloud infrastructure is a combination of two or more cloud infrastructure( private, community, or public) that remain unique entities, but are bound together by standardized and proprietary technology that enables data and application portability( e. g., cloud bursting for load‐balancing between clouds).
2.1 Cloud computing architecture
It is well known that cloud computing is computing over a cloud( Armbrust, et. al. 2009). The cloud architecture, the systems architecture of the software systems involved in the delivery of cloud computing includes hardware and software designed by cloud architect who typically works for a cloud integrator( Shivaji, et. al. 2010). Cloud computing can be divided into two components, the front‐end or user end and back‐end in which they are connected to each other via a network normally the internet. The front end is the computer user, or client. The back‐end is the cloud part of the system as illustrated in figure 1.
The front end comprises the users’ computer along with the application required to access the cloud computing system. When a user accesses its own email account from gmail for example, the user uses software running on the front‐end of the cloud. The same is true when user accessing its own facebook account. The cloud computing system differs in relation to the user interface. For instance services like webbased email programs existing Web browsers like internet Explorer or Firefox. Other systems have unique applications which offer network access to users.
The back‐end of the cloud system comprises hardware and software architecture that feed the interface in which the user it will see on the front‐end. The back‐end includes various computers, servers and data storage systems that create the cloud computing services. Theoretically, a cloud computing system can include practically any type of web application program from data processing to video images. Normally every application will have its own dedicated server. Because the computers are set up to work together, the applications can take advantage of all that computing power as if they were running on one particular machine. Cloud computing also allows for a lot of flexibility. Depending on the demand, user can increase how
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