Definition “Cloud computing is an emerging computing technology that uses the internet and central remote servers to maintain data and applications”.

The underlying concept of cloud computing dates back to 1960, when John McCarthy opined that "computation may someday be organized as a public utility"; indeed it shares characteristics with service bureaus that date back to the 1960s. The actual term "cloud" borrows from telephony in that telecommunications companies, who until the 1990s primarily offered dedicated point-to-point data circuits, began offering VIRTUALPRIVATE NETWORK (VPN)´ services with comparable quality of service but at a much lower cost.

The cloud symbol was used to denote the demarcation point between that which was the responsibility of the provider from that of the user. Cloud computing extends this boundary to cover servers as well as the network infrastructure. Cost is claimed to be greatly reduced and capital expenditure is converted to operational expenditure. Device and location independence enable users to access systems using a web browser regardless of their location or what device they are using

In General An Internet based Computing environment where you pay only for resources that you use A set of pooled computing resources delivered over the internet Resource allocation can be adjusted

Cloud Computing Defined In its simplest form, cloud computing consists of shared computing resources that are virtualized and accessed as a service, through an API. The cloud enables users in an organization to run applications by deploying them to the cloud, a virtual datacenter.

The physical resources may reside in a number of locations inside and outside of an organization: on local hardware, in an enterprise data center, or at remote or managed service providers on a pay-to-use basis. Cloud computing resources are offered as a service on an as-needed basis, and delivered by IP-based connectivity, providing highly scalable, reliable on- demand services with agile management capabilities.

Cloud Application Characteristics Because cloud computing is related to a number of other technologies, it is best defined by the presence of a number of characteristics. These represent ideals that people want for the applications that run on the cloud: Incremental Scalability. Cloud environments allow users to access additional compute resources on-demand in response to increased application loads Agility. As a shared resource, the cloud provides flexible, automated management to distribute the computing resources among the cloud's users.

Reliability and Fault-Tolerance Reliability and Fault-Tolerance. Cloud environments take advantage of the built-in redundancy of the large numbers of servers that make them up by enabling high levels of availability and reliability for applications that can take advantage of this. Service-oriented. The cloud is a natural home for service-oriented applications, which need a way to easily scale as services get incorporated into other applications. Utility-based. Users only pay for the services they use, either by subscription or transaction-based models.

Shared. By enabling IT resources to be consolidated, multiple users share a common infrastructure, allowing costs to be more effectively managed without sacrificing the security of each user's data. SLA-driven. Clouds are managed dynamically based on service-level agreements that define policies like delivery parameters, costs, and other factors. APIs. Because clouds virtualize resources as a service they must have an application programming interface (API).

Related Technologies Although the term 'cloud computing' is relatively new, the technologies that make it possible have been used for some time. For example, cloud computing is enabled by grid computing, virtualization, utility computing, hosting and software as a service (SaaS). Yet these technologies differ from cloud computing in the following ways:

Grid Computing: Originally designed for computationally intensive batch applications, grid computing was developed as a way to share computers and data. Modern grid computing technologies have evolved as a way to harness inexpensive servers in a data center to solve a variety of business problems. Traditionally, grids have lacked the automation, agility and simplicity characterized by cloud computing

Virtualization: Hosting: Virtualized infrastructures are available on-demand and capable of supporting multiple users, but lack the automation required for the self-managing, self-healing property of the cloud. Hosting: Hosting services provide space on servers for use by clients as well as providing IP-based connectivity, typically in a data center. Because hosting does not enable on-demand, elastic scalability, it cannot be considered cloud computing.

Utility Computing: In the utility computing model, computing resources like applications, infrastructure and storage are packaged and sold as a service, with users paying only for what they consume, like electricity. In many respects, cloud computing is closely related to the utility computing model, with cloud computing being a broader concept that relates to the underlying architecture in which the services are designed.

SaaS: Although Software-as-a-Service offerings are often hosted on true clouds, SaaS is an application as a service and cloud computing is IT infrastructure as a service.

Public Clouds vs. Private Clouds Public and private clouds are two different types of cloud computing available today and each offers distinct advantages for businesses. A public cloud computing environment is open for use by the general public, which could include individuals, corporations or other types of organizations. Amazon Web Services and Google's AppEngine are examples of a public cloud.

The public cloud offers startups and SMBs an opportunity to take advantage of the scalability, agility and automated management of the cloud by essentially renting computing resources and avoiding costly hardware expenditures. However, security and compliance are serious issues with public cloud computing and are among the factors driving the adoption of private clouds. For example, Amazon's S3 service was recently down for six hours dues to an increased volume of authenticated calls, which pushed the authentication service over its maximum capacity before Amazon could solve the issue.

In contrast, a private cloud computing environment exists within the boundaries of an organization, typically for its exclusive usage. Often, private clouds are driven by C-level executives' concerns about the security and reliability of public clouds, since private clouds can deliver many of the benefits of public cloud computing, without the downside. Interest in private clouds is also driven by IT departments' attempts to develop utility-like IT environments, where computing resources and applications can be provisioned with greater efficiency

While private clouds solve the issues of security and reliability by keeping data safely behind an organization's firewall, their development requires initial hardware investments and in- house expertise.

Cloud Features Highly virtualized and standardized infrastructures Massive scalability Fault tolerant & highly reliable Intra- & Inter- cloud load balance Instant application development

Cloud Benefits Simplified, more efficient IT and application management Deliver more applications to large number of users Excellent service quality Higher utilization at reduced cost Time-to-market

No need to install or update SW or HW; access from any browser Unlimited use Always on Access from anywhere Many services to choose from

Types of Cloud Offerings: Bare Operating System Web or Portal Infrastructure Applications Web Services Database Services Customizable Application Services

Bare Operating System- RackspaceCloud http://www.rackspacecloud.com Formerly Mosso, a division of Rackspace Provide various Linux Distributions Also Support “Sites” Web Server, Both Linux and Windows O/S Managed by hosting service

Web or Portal Infrastructure - Microsoft SharePoint Online Rich Portal Capabilities Excel Services Forms Services Visio Services Access Services Business Data Services Search Services

Applications – Google Apps http://www.google.com/a Pre-built, fully functional applications Mail Calendar Word Processing Dynamic Web Pages Etc.

Expand your Infrastructure! Buy new servers, increase your software costs, provision more data centre capacity!!

Look to the cloud! Pay for the bandwidth and server resources that you need. When your push is done then turn the whole thing off!

What is Cloud Computing? IT as a service Cloud allows access to services without user technical knowledge or control of supporting infrastructure Best described in terms of what happened to mechanical power over 100 yrs ago Now computers are simple devices connected to the larger cloud Data processing, storage and software applications that used to run locally are now being supplied by big central computing stations. They're becoming, in essence, computing utilities. What is Cloud Computing?

What is Cloud Computing “Cloud” is simply a metaphor for the internet Users do not have or need knowledge, control, ownership in the computer infrastructure Users simply rent or access the software, paying only for what they use Simple Introduction to Cloud Computing

History of Cloud Computing Concept dating back to the 1960’s by John McCarthy, a computer scientist, brought up the idea that "computation may someday be organized as a public utility” Idea that revolutionized Cloud Computing: Moving from clustering computing to grid computing - Clustering - Grid “In some ways, the cloud is a natural next step from the grid-utility model,” said Frank Gens, an analyst at the research firm IDC

What Technologies is Cloud Computing Replacing : Cloud computing is replacing large Corporate Data Centers and unnecessary, expensive private server infrastructure. Web 2.0, SaaS, Enterprise and government users are adopting cloud computing because it eliminates capital investment in hardware and facilities as well as reduces operations labor

Uses Helps to use applications without installations. Access the personal files at any computer with internet access. This technology allows much more efficient computation by centralizing storage, memory, processing and band width.

Layers A cloud  client consists of computer hardware and/or computer software that relies on cloud computing for application delivery

Infrastructure as a Service SaaS Software as a Service PaaS Platform as a Service IaaS Infrastructure as a Service

Increasingly popular with SMEs No hardware or software to manage Software delivery model Increasingly popular with SMEs No hardware or software to manage Service delivered through a browser SaaS

SaaS Examples CRM Financial Planning Human Resources Word processing Commercial Services: Salesforce.com emailcloud

PaaS Platform delivery model Platforms are built upon Infrastructure, which is expensive Estimating demand is not a science! Platform management is not fun!

PaaS Examples Google App Engine Mosso AWS: S3

IaaS Computer infrastructure delivery model Access to infrastructure stack: Full OS access Firewalls Routers Load balancing

IaaS Examples Flexiscale AWS: EC2

Applications Cloud application services or “Software as Service(SaaS)” deliver ‘Software’ as a service over the Internet, eliminating the need to install and run the application on the customer’s own computer and simplifying maintenance and support.

Platform Cloud platform services or “Platform as a Service (PaaS)” deliver a computing platform and/or solution stack as a service, often consuming cloud infrastructure and sustaining cloud applications. It facilitates deployment of applications without the cost and complexity of buying and managing the underlying hardware and software layers

Infrastructure Cloud infrastructure services or "Infrastructure as a Service (IaaS)" delivers computer infrastructure, typically a platform virtualization environment, as a service. Rather than purchasing servers, software, data center space or network equipment, clients instead buy those resources as a fully outsourced service. The service is typically billed on a utility computing basis and amount of resources consumed (and therefore the cost) will typically reflect the level of activity. It is an evolution of virtual private server offerings.

Server The servers layer consists of computer hardware and/or computer software products that are specifically designed for the delivery of cloud services, including multi-core processors, cloud-specific operating systems and combined offerings

Development Models COMMUNITY CLOUD:  A community cloud may be established where several organizations have similar requirements and seek to share infrastructure so as to realize some of the benefits of cloud computing. With the costs spread over fewer users than a public cloud, this option is more expensive but may offer a higher level of privacy, security and/or policy compliance. Examples of  community cloud include Google's "Gov Cloud”.

Hybrid Cloud & Private Cloud A hybrid cloud environment consists of multiple internal and/or external providers "will be typical for most enterprises". By integrating multiple cloud services, users may be able to ease the transition to public cloud services

Private cloud: Private cloud and Internal cloud are expressions that some vendors have recently used to describe offerings that emulate cloud computing on private networks. These products claim to "deliver some benefits of cloud computing without the pitfalls", capitalizing on data security, corporate governance, and reliability concerns. They have been criticized on the basis that users "still have to buy, build, and manage them" and as such do not benefit from lower up-front capital costs and less hands-on management