Evolution Of Cloud Computing From Clustering

Published Date: 02 Nov 2017

Introduction

This chapter gives brief introduction of Cloud Computing. Cloud computing provides the facility to access shared resources and common infrastructure, offering services on demand over the network to perform operations that meet changing business needs. The location of physical resources and devices being accessed are typically not known to the end user. It also provides facilities for users to develop deploy and manage their applications, on the cloud, which entails virtualization of resources that maintains and manages itself.

Background

The general idea behind the technology dates back to the 1960s, when John McCarthy wrote that computation may someday be organized as a public utility. Then, grid computing, a concept that originated in the early 1990s as an idea for making computer power as easy to access as an electric power grid also contributed to cloud computing [1]. Figure 1.1 shows the evolution of Cloud from Clustering.

Evolution of Cloud Computing from Clustering [2]

Cloud computing is Internet-based computing, whereby shared resources, software and information are provided to computers and other devices on-demand, like the electricity grid. Cloud computing customers do not own the physical infrastructure, instead avoiding capital expenditure by renting usage from a third-party provider. They consume resources as a service and pay only for resources that they use [3]. Cloud computing has recently emer ged as a new paradigm for hosting and delivering services over the Internet. Cloud computing is attractive to business owners as it eliminates the requirement for users to plan ahead for provisioning, and allows enterprises to start from the small and increase resources only when there is a rise in service demand [4].

Typical cloud computing providers deliver common business applications online that are accessed from another Web service or software like a Web browser, while the software and data are stored on servers. Most cloud computing infrastructures consist of services delivered through common centers and built-on servers. Clouds often appear as single points of access for consumers' computing needs. Commercial offerings are generally expected to meet quality of service (QoS) requirements of customers, and typically include service level agreements (SLAs) [9]. The key characteristic of cloud computing is that the computing is "in the cloud"; that is, the processing (and the related data) is not in a specified, known or static place(s) [10]. This is in contrast to a model in which the processing takes place in one or more specific servers that are known [5].

Classification of Clouds

Clouds can be classified according to who the owner of the Cloud data centers is.

Clouds can be classified as –

Private Clouds

Public Clouds

Hybrid Clouds

Federation of Clouds

Private Clouds

Private Clouds are internal Clouds. A Private Cloud is fully owned by a single company who has total control over the applications run on the infrastructure, the place where they run, and the people or organizations using it. A Private Cloud relies on virtualization of an organization’s existing infrastructure. The key advantage of a Private Cloud is to gain all advantages of virtualization, while retaining full control over the infrastructure [6].

Public Clouds

A Public Cloud is a data centre, hardware and software run by third parties, e.g. Google, which expose their services to companies and consumers via the Internet. A Public Cloud is not restricted to a limited user base. It is made available in a pay-as- you-go manner to the general public [6].

Hybrid Clouds

Hybrid Clouds combine Public and Private Clouds and allow an organization to both run some applications on an internal Cloud infrastructure and others in a Public Cloud. Thus, companies can benefit from scalable IT resources offered by external Cloud providers while keeping specific applications or data inside the firewall. A mixed Cloud environment adds complexity regarding the distribution of applications across different environments, monitoring of the internal and external infrastructure involved, security and privacy, and may therefore not be suited for applications requiring complex databases or synchronization [6].

Federations of Clouds

The terms Federated Clouds or Feder ation of Clouds denote collaboration among Public Clouds even though Private Clouds may be involved. Federated Clouds are a collection of single Clouds that can interoperate i.e. Exchange data and computing resources through defined interfaces. According to basic federation principles, in a Federation of Clouds each single Cloud remains independent, but can interoperate with other Clouds in the federation through standardized interfaces. There is no common Cloud interoperability standard [6].

Different Levels of Cloud Computing

Cloud computing has three levels of service offerings: Software as a Service (SaaS), Platform as a Service (PaaS), and Infrastructure as a service (IaaS).These levels support virtualization and management of differing levels of the solution stack.

Software as a Service (SaaS)

A SaaS provider hosts and manages a given application in their own data center and makes it available to multiple users over the Web. Some SaaS providers run on another cloud provider’s PaaS or IaaS service offerings [7].

Platform as a Service (PaaS)

Platform as a Service is an application development and deployment platform delivered as a service to developers over the Web. It facilitates development and deployment of applications without the cost and complexity of buying and managing the underlying infrastructure, providing all of the facilities required to support the complete life cycle of building and delivering web applications and services entirely available from the Internet. This platform consists of infrastructure software, and typically includes a database, middleware and development tools [7].

Infrastructure as a Service (IaaS)

Infrastructure as a Service is the delivery of hardware (server, storage and network), and associated software (operating systems virtualization technology, file system), as a service. It is an evolution of traditional hosting that does not require any long term commitment and allows users to provision resources on demand. Unlike PaaS services, the IaaS provider does very little management other than keep the data center operational and users must deploy and manage the software services themselves--just the way they would in their own data center. Amazon Web Services them--just the way they would in their own data center. Amazon Web Services Elastic Compute Cloud (EC2) and Secure Storage Service (S3) are examples of IaaS offerings [7].

Cloud Computing Advantages

Following advantages of Cloud Computing have been identified by Dr. Wendy A.Warr [8]:

Economies of scale – Reduces cost of setting up physical data center

Software as a Subscription (SaaS) - SaaS deployments usually take less time than in-house ones, upgrades are easier, and users are always using the most recent version of the application.

Pay-As-You-Go - Little or no capital investment and maintenance cost is needed.

Portability/Accessibility - Files and softwares are available anywhere provided that there is an active internet connection.

Efficient Use of Computer Resources - Users no longer require separate servers for different applications. With virtualization multiple server technologies can run from a single server.

Elasticity – Cloud has the ability to add capacity or applications almost at a moment’s notice.