Cloud Computing Explained
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Author: Eyal Eckhaus, posted on 2/8/2010 , in category "eCommerce"
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Abstract: Cloud computing is an architectural model for deploying and accessing computer facilities through a virtual environment, providing excellent opportunities and creating a new buzz in the IT world. This article provides a summary of this concept, clarifying terms, and identifying major advantages and challenges.

Cloud computing is an architectural model for deploying and accessing computer facilities through a virtual environment, providing excellent opportunities and creating a new buzz in the IT world. This article provides a summary of this concept, clarifying terms, and identifying major advantages and challenges.

What is cloud computing

Cloud computing is an architectural model for deploying and accessing computer facilities through the Internet, enabling users to access applications all over the world through a web browser, where the cloud service provider supplies the network access, security, processing capability and data storage from a data center, which is a conventional website that provides computing and storage facilities [1]. In other words, it provides on demand access to a shared pool of configurable computing resources with minimal management effort or service provider interaction [2], where users can dynamically grow or shrink the demand, following by an adjustment of the necessary computer, storage and network capacity [3]. With its many possibilities, this concept is fundamentally changing the way institutions and companies manage their computing needs [4].

Main Advantages
  • Lower costs and less complex operating environment: this technology eliminates the need to purchase software, hardware maintenance, and acquire expertise in the technology infrastructure to use the services [5]. Today’s price focused cloud computing market is moving towards perfect competition, with the cloud providers gradually lowering prices [6], and it is also possible to pay for use of computing resources on short terms basis and release customers as needed, for example – processors by the hour and storage by day [4].

  • Agility: with the increased global competition, the sophistication of customer’s demand and the continuous changing environment, organizations emphasize the need for operational efficiency and process optimization, while their agility in response to the demand is a key competitive strength, along with the necessity of the support of technological solutions [7, 8]. The business’ agility can be improved with cloud computing, since the IT department may respond more quickly to the business’ needs, by reducing the lead time of application’s deployment, training, hardware and software acquisition, enabling the company to respond in a timely manner to market and product changes [1]. Organizations can also start projects quickly without worrying about upfront costs, starting on a small scale and adding resources later [4], providing better elasticity- as computing and storage capability can be scaled to meet demands through resource pooling [1].

  • Availability: in this context, the term availability includes the time that the facilities are available for use and the scope of resources available [1], which may be highly improved when moving to the cloud. Large cloud computing providers such as Microsoft, Google, and Amazon, have better resources that allow more up-time than other organizations [4].

  • Data safety, security and privacy: organizations can purchase storage in distant data centers, increasing safety in case of natural disasters or other factors [4]. While security issues are a major concern, as detailed below, small businesses don’t have the adequate resources to deal with security threats, disaster recovery or business continuity plans, on the other hand, the cloud vendors manage the cloud’s security, and may offer better security measures that  small businesses may afford [5]. Moreover, the sensitivity of the information can also be dealt with encryption schemes that keeps data private, allowing a third party to perform complicated processing of data without being able to see it, which may be a mean for dealing with the cloud computing privacy issue [9].   

  • Collaboration: the cloud facilitates the collaboration through network access [1], as the applications and data files reside on the server and can be easily accessed by the collaborators [10]. For example, Google Docs –offering real-time collaboration on documents, that is done entirely in the cloud [11]. The interconnectivity within the company and between partners allows more idea exchange, better collaboration and innovation, improving the operation’s productivity [3]. The cloud enables an exchange of information and accessing each other’s data, while providing mechanisms to keep data in control of the organizer and a secure access to the requestors [12].
Figure 1: Cloud computing concept and advantages
Cloud Computing Concept


With the increased ability to store, process, and exploit personal data, there is a major concern regarding privacy and security [13]. Threats as malware, spam, spoofing, man-in-middle attacks, exist in all cloud communications [5]. The security’s responsibility is divided between several parties, including the cloud user – which responsible for application-level security and the cloud provider – responsible for physical security and may enforce external firewall policies, while the user and the operator share the security for intermediate layers of the software stack , where the lower the user’s abstraction – the higher its responsibility [14]. Other aspects include the risk of inadvertent data loss, the accumulated cost of data transfer, performance unpredictability, bugs in large-scale distributed systems, levels of continuity and service availability and concern about lock-in and the difficulty of extracting data from the cloud [14]. In addition, since the business data is stored on a virtual server, the resources may be more vulnerable to cyber attack, and privacy issues are emphasized, data integrity, intellectual property management, audit trails, compatibility, and reliability, which may cause small companies to hesitate in adopting these services [3]. The vendors reliability is also a question, as cheaper and smaller providers may face operating problems such as overload capacity, delay, and breakdown [3].

Service models

There are three basic service models, each addresses a specific business need [1, 6]:
Infrastructure of service (IaaS): the most basic cloud service model, where the consumer may provision processing, storage, network, and other computing resources, while enabling him to deploy and run arbitrary software which may include operating systems and application.
Platform as a Service (PaaS): the next layer, where the end customer is purchasing an application environment on top of the infrastructure, allowing application developers to create applications that run in the cloud, or use the cloud’s platform services.
Software as a Service (SaaS): the highest layer in the cloud stack, where the end customer is purchasing the use of a working application, running on the cloud infrastructure.
The higher the layer, the further it is from cloud provider’s infrastructure, the grater the abstraction level to the users [15], and the higher the level of automation in terms of deploying and managing an application, but the substantially lower workloads come at the expense of flexibility and portability [16], as illustrated in Figure 2.

Figure 2: service models
Cloud Computing Service Models

Deployment models

There are three basic deployment models, defining the entity that operates the cloud infrastructure [15]. These include [1]: the main cloud deployment models include:
Private clouds: the cloud infrastructure operates solely for an organization, managed by the organization or a third party [1]. It requires a suitable physical infrastructure, including computers, storage, and the interconnect fabric to connect them together, and software infrastructure for provisioning resources to the users [15]. Private clouds give local users flexibility and agile private infrastructure to run service workloads inside their domains, and can support the hybrid cloud model by supplementing local infrastructure with computing capacity of a public cloud [17]
Community cloud: the cloud infrastructure is shared by organizations and supports a specific community with shared concerns, managed by the organization or a third party [1].
Public clouds: an open, externally located and publicly accessible environment, available to the public or a large industry group, and is owned by an organization selling cloud services [1, 18].
Hybrid clouds: a composition of two or more cloud infrastructures, bound together by standardized or proprietary technology enabling data and application portability [1]. It can boost the company’s existing computer infrastructure, claiming to offer the best of the worlds it combines [18].
In both public and hybrid clouds the organization needs to consider the provider’s quality of service commitment and service level agreement (SLA’s) [15].

Figure 3: A hybrid deployment model example
Cloud Computing - Hybrid


The process of globalization forces organizations to redefine their strategies in face of the increased competition. With the need for optimizing operations, technology increased the pace of developments, in order to provide proper solutions for the business environment. Cloud computing is one of the new and exciting concepts, changing the way computer needs are provisioned. There are many advantages for organizations by moving to the cloud computing, however, companies need to carefully consider the options in order to fit the proper solution, while facing the challenges.


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User Feedback
Comment posted by FRANK BATES on Monday, August 2, 2010 1:05 PM
Eyal, I'm impressed as I realize the depth and understanding you have achieved - I knew that this would be a worthwhile research project that would serve the basis for much other related research work - and might realistically enhance our joint efforts on future cases (and research papers) to be submitted for publishing.  Congrats.....Dr. Frank Bates

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