Cloud Computing: An Overview

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Mohsin Nazir, Prashant Tiwari, Shakti Dhar Tiwari, Raj Gaurav Mishra

Cloud Computing: An

Overview

Mohsin Nazir

1

, Prashant Tiwari

2

, Shakti Dhar Tiwari

3

,

Raj Gaurav Mishra

4

Abstract

Cloud computing is a group of IT services which have been presented to a person on the network with a leased basis current ability to scale up or down their service requirements. Usually Cloud Computing services are delivered by way of a alternative party provider the master of the infrastructure. IBM defines cloud computing as it is simply “the cloud,” may be the delivery of on-demand computing resources—everything from applications to data centres—online using a pay-for-use basis. Webopedia's definition for cloud computing - Cloud computing it is usually typically defined as a kind of computing that utilizes sharing computing resources as opposed to having local servers or personal devices to handle applications. In cloud computing, the word cloud (also phrased as "the cloud") is used as a metaphor for "the web," therefore the phrase cloud computing means "a form of Internet-based computing," where different services — such as servers, storage and applications — are shipped to an organization's computers and devices over the Internet. Cloud computing is similar to grid computing, a form of computing where unused processing cycles off computers in the network are harnesses to fix problems too intensive for virtually every stand-alone machine.

Keywords

Overview of Cloud Computing, Cloud Architecture, Cloud Computing, Introduction

1

Department of Information Technology, Central University of Kashmir, India 2

M.Tech. Scholar, Central University of Jharkhand, India 3

M.Tech. Scholar, Graphic Era University – Dehradun, India 4

Editor for HCTL Open eBook: Cloud Computing: Reviews, Surveys, Tools, Techniques and Applications.

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Introduction

Internet is a power towards various technologies which are developed. Arguably, essentially the most discussed among these is Cloud Computing. During the last couple of years, cloud computing paradigm has witnessed a large shift towards its adoption and has now turn into trend in the IT space mainly because it promises significant cost reductions and new business possible ways to its users and providers [23]. Benefits of cloud computing includes - less hardware requirements and low maintenance cost, easy worldwide accessibility, high flexibility, automated processes and almost no software up-gradations, etc. [15, 34].

Cloud Computing [4, 17] can be a wave to deploy and maintain software and is also being adopted from the industry for instance Google, IBM, Microsoft, and Amazon. Several prototype applications and platforms, including the IBM ―Blue Cloud infrastructure, the Google App Engine, the Amazon Cloud, plus the Elastic Computing Platform [42]. Cloud Computing is regarded as the subsequent progression that can impact organizational businesses and exactly how they manage their IT infrastructures.

However, there are numerous variations for that specification of Cloud Computing; some fundamental principles characterize this emerging technology. The technological capabilities that are provided by Cloud Computing, which is generally maintained off-the premises - which may be delivered any time they want, be described as a service through the Internet. Consumers of such services tend not to possess resources within the cloud model but are invited to rent the services per-use basis by the third party owners that manage public cloud services. Thus virtualization with the resources is paramount concept [37]. From the real scenario, they are renting the physical infrastructure, platforms and applications in a shared architecture. Cloud Service providers offers a computing platforms, virtual infrastructure, centralized data centres, Web-Services and applications and a number of other useful and focused computing services.

Cloud Computing is applied to solve a number of real-time problems in numerous domains of Information Technology such as Geographical Information Systems, e-Governance Systems [19], Scientific Research [7], ERP [17], Decision Support Systems [42], Mobile Technology [36], Web Application Development [21], etc.

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Overview of Cloud Computing

Based on U.S. National Institute of Standards and Technology (NIST) definition of Cloud Computing, it is a model for enabling convenient and on-demand network that makes use of a shared pool of configurable computing resources (such as, networks, servers, storage devices, applications, services, etc.). It might be rapidly provisioned and utilized with minimal management of effort or cloud service provider's interaction [27]. In simple words, Cloud Computing is the mix of a technology, platform that delivers hosting and storage service on the web [14].In such an environment users do not need to own the infrastructure for assorted computing services. In fact, they are often accessed from any computer in almost any part of the world. Cloud Computing integrates features that supports multi-tenancy and high scalability. It also offers improved flexibility when compared with the existing computing technologies. It may deploy, allocate or reallocate resources dynamically through an capacity to continuously monitor their performance [27]. Moreover, cloud computing minimizes the administrative centre expenditure. This strategy is device and user-location independent. Definitive goal in the cloud computing would be to provide scalable and inexpensive on-demand computing infrastructures with good quality and services information levels [9, 18]. Cloud Computing is usually a general term for any price which involves delivering hosted services over the Internet. Cloud Computing on contrary to the static system architecture, supports the chances to dynamically improve and quickly scale down. This offers cloud consumers higher reliability and fastest response times along with the flexibility to handle high traffic fluctuations and demand [22]. Cloud Computing will also support multi tenancy, providing systems configured to the extent that they may be pooled being shared by many organizations or individuals [8]. In Cloud Computing, virtualization technology allows cloud service providers to change one server into multiple virtual machines. This features eliminates the need of client-server computing with a single-purpose computing systems [17]. Virtualization in cloud computing maximizes hardware capacity, also allows customers to control economies of scale [22].

Important things about Cloud computing are enormous. The most crucial an example may be that the customers don’t have to purchase the resource at a alternative party vendor, instead they might utilize resource and shell out the dough like a service thus helping the customer to save time and money. Cloud isn’t only for Multinational companies however it’s also used by small and medium enterprises [30].

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Building Blocks of Cloud Computing

Deployment Models

Within a Cloud Deployment model as shown in Figure 1, networking, platform, storage and software infrastructure are considered as services which can be further scale up or down as per the consumer demands. The Cloud Computing model has four main deployment models that happen to be:

1. Private Cloud: Private cloud may be the phrase utilized to describe a cloud computing platform that's implemented inside the corporate firewall, under the power over the IT department. An exclusive cloud was designed to provide the same product or service benefits of public cloud systems, but removes numerous objections on the cloud computing model including control over enterprise and customer data, worries about security, and issues connected to regulatory compliance [52]. Only the organization and designated stakeholders may have access to operate on a concrete Private cloud [38]. One of the best examples of a private cloud is Eucalyptus Systems [3].

2. Public Cloud: A type of cloud computing where a company relies on a third-party cloud company for services including servers, data storage and applications, which are shipped to the corporation through the Internet. A public cloud can free companies from the potentially expensive costs of needing to purchase, manage and gaze after on-premises hardware and software infrastructure. Public clouds could also typically be deployed faster with more scalability and accessibility than you are on-premises infrastructure due to the population cloud provider’s expertise and existing infrastructure. Public cloud subscribers may pay pay-as-you-go fees or fixed monthly fees for your public cloud services they utilize. Public cloud describes cloud computing in the traditional mainstream sense, whereby resources are dynamically provisioned on a fine-grained, self-accommodation substratum over the Internet, via web applications/web accommodations, from an off-site third-party provider who apportions resources and bills on a fine-grained utility computing substratum [53]. It is basically a pay-per-use model, similar to a prepaid electricity metering system which is user-flexible to cater the demand for cloud optimization [1]. Security of public clouds are more vulnerable than the other cloud models because the measures to prevent malicious attacks on public clouds are technically more difficult and of course expensive to handle. Examples of a public cloud include Microsoft Azure, Google App Engine.

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3. Hybrid Cloud: A combined way of private clouds and public clouds in which some critical data resides within the enterprise’s private cloud while other results are held in and accessible at a public cloud. Hybrid clouds seek to offer the advantages of scalability, reliability, rapid deployment and potential personal savings of public clouds with all the security and increased control and management of private clouds. An example of a Hybrid Cloud includes Amazon Web Accommodations (AWS) [12, 54].

4. Community Cloud: Infrastructure shared by a few organizations for just a shared cause and may be managed by them or even a third party service provider and rarely offered cloud model. These clouds tend to be based on an agreement between related business organizations for instance banking or educational organizations. A cloud environment operating as outlined by this model may exist locally or remotely. One particular community cloud includes Facebook.

Moreover, using the technological advancements, we can easily see derivative cloud deployment models emerging out of the various demands along with the requirements of users. A similar example to be a virtual-private cloud wherein a public cloud is used in a very virtual-private manner, attached to the internal resources from the customer’s data-centre [40]. With the emergence of high-end network technologies such as 2G, 3G, Wi-Fi, Wi-Max etc. a new derivative of cloud computing has been emerged named as Mobile computing. That is popularly referred as – Mobile Cloud Computing (MCC). It can be looked as a composition of mobile technology and cloud computing infrastructure where data along with the related processing could happen from the cloud simply with very that they be accessed by having a mobile tool and hence known as mobile cloud computing [16]. It’s transforming into a trend now-a-days and a lot of organizations are keen to produce option of their employees to gain access to office network by having a mobile device from anywhere.

Recent advancements in technology including the emergence of HTML5 and many other browser development tools just have increased the market for mobile cloud-computing. An ever-increasing trend on the feature-phone adoption [16] has additionally ramped the MCC market.

Service Models

In line with the different types of services offered, cloud computing can be considered to incorporate three layers: software being a service (SAAS), platform being a Service (PAAS), and infrastructure like a Service (IAAS) (Iyer and Henderson, 2010; Han, 2010, Mell and Grance, 2010).

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Infrastructure as a Service (IaaS) is the lowest layer that delivers basic infrastructure support service. The middle layer is Platform as a Service (PaaS) which provides environment for hosting end-user’s applications. Software like a Service (SaaS) may be the topmost layer which comes with a complete application offered as service at will [2, 24].

1. Software-as-a-Service (SaaS): Short for Software as a Service, SaaS is usually a software delivery method to provide entry to software as well as functions remotely to be a Web-based service. Software as a Service allows organizations to access business functionality at a cost typically less than spending money on licensed applications since SaaS pricing is founded on a monthly fee. Also, because the software program is hosted remotely, users don't need to put money into additional hardware. Software as a Service removes the advantages of organizations to deal with the installation, set-up and infrequently daily upkeep and maintenance. Software as a Service will also be termed as simply hosted applications [11, 33, 35, 55].

2. Storage-as-a-Service (SaaS): SaaS is often a term used to explain a storage model where a business or organization (you) rents or leases safe-keeping coming from a third-party provider. Results are transferred on the client to the vendor through the Internet and also the client would then access their stored data using software supplied by the storage provider. The software program is used to perform common tasks related to storage, for instance data backups and data transfers. Storage as being a Service is well-liked by SMBs since there are usually no start-up costs (e.g., servers, devices, IT staff and many others) involved. Businesses pay for the service based only within the level of space for storing used. Storage to be a Service is often called hosted storage. Examples of SaaS includes: Salesforce.com, Google Apps [11, 33, 35, 55].

3. Platform as a Service (PaaS): Platform as a service (PaaS) is really a group of cloud computing services that delivers a computing platform and also a solution stack being a service. Together with software as being a service (SaaS) and infrastructure as a service (IaaS), it is a service model of cloud computing. On this model, the individual creates a software or service using tools and/or libraries in the provider. The patron also controls software deployment and configuration settings. The provider provides networks, servers, storage, and also other services which can be required to host the consumer's application. PaaS offerings facilitate the deployment of applications or services without worrying about cost and complexity of purchasing and

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handling the underlying hardware and software and provisioning hosting capabilities. All "as-a-service" offerings are characterized as providing low initial cost, marginal cost as the service usage grows, self-service, best practices built-in, resource sharing, automated deployment, management services, lifecycle management, reuse. PaaS provides these capabilities for application and service development. Examples of PaaS includes: Salesforce.com, Google App Engine and Microsoft Azure [56]. 4. Infrastructure as a Service (IaaS): Infrastructure like a service

(IaaS) refers to the sharing of hardware helpful executing services using Virtualization technology. The main objective of IaaS would be to make readily accessible of resources like servers, network, storage etc. to the applications and systems more easily. Therefore IaaS includes basic infrastructure on-demand services by using Application Programming Interfaces (API) for integrations with hosts, switches, routers, also the capability of adding new equipments in the basic infrastructure in a transparent manner. On the whole, anyone does not manage the main hardware in the cloud infrastructure, but he controls the systems, storage and deployed applications. The vendor owns the gear and is liable for housing, running and it. The customer typically pays on the per-use basis. Examples of IaaS include Amazon Elastic Cloud Computing (EC2), Amazon S3, GoGrid.

Figure 1: Cloud Deployment Model [1, 44]

Combining several kinds of clouds with the delivery models we obtain an all natural cloud illustration as seen in Figure 2, flanked by connectivity devices along with information security themes. Virtualized physical resources, virtualized infrastructure, along with virtualized middleware platforms and business applications are provided and consumed as services in the Cloud [26]. Cloud vendors and clients’ should maintain

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Cloud computing security whatsoever interfaces.

Figure 2: Cloud Computing Service Delivery Models [26, 44]

An Overview of Cloud Computing Architecture

Cloud computing can be separated into two sections, anyone as well as the cloud. Practically in most scenarios, anyone is attached to the cloud via the internet. It is an easiest option for an organization to run a private cloud in which an end-user can connect with the help of intranet. However, both scenarios are identical besides using a private and public network or cloud [10]. The consumer sends requests towards cloud plus the cloud provides service. Within the cloud, a central server is answerable to administering the device along with plenty of different ways functions because of the specific cloud network. Examples include Google App Engine and Amazon EC2 [10].

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Figure 3: Cloud Architecture [10, 44]

Entities of Cloud Computing

Cloud providers and consumers are the two main entities available market. Service brokers and Service resellers are also classified as two newly emerging service level entities in the Cloud computing environments. These include discussed the following:

1. Cloud Providers: Cloud Providers includes Internet service providers (ISPs), telecommunication organizations, and large BPOs that include media (Internet connections) or infrastructure (hosted data centres). This enables end-users to gain access to cloud services. Companies also can include systems integrators that build and support data centres to host private clouds and they can offer different services (e.g., SaaS, PaaS, IaaS, and etc.) to their consumers or to the service brokers, resellers, etc [29]. 2. Cloud Service Brokers: Cloud Service Brokers includes

technology consultants, business organizations, registered brokers, agents, service agencies and promoters which guide consumers within the selection of cloud computing services. Service brokers give full attention to the negotiation from the relationships between consumers and providers without owning or handling the whole cloud infrastructure. Also, they add extra services together with Cloud providers.

3. Cloud Resellers: Resellers can be a key point through the Cloud market if the Cloud providers will further grow their business across continents. Cloud providers may also choose local IT consultancy companies or resellers in their existing products to act as new resellers to promote their Cloud-based products inside of a

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particular region.

4. Cloud Consumers: Customers participate in the sounding Cloud consumers. However, also Cloud service brokers and resellers can participate in this category as soon as there're customers of another Cloud provider, broker or reseller.

Conclusion

Cloud computing has the possibility to be a frontrunner to advertise a secure, virtual and economically viable IT solution later on. As being the growth and development of cloud computing technology remains at a young stage, these studies effort will supply a better perception of the look challenges of cloud computing, and pave the best way for more research in this region.

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