This paper will describe the drivers behind cloud computing; the various cloud types and services.

Welcome to the site about Cloud computing

     The terms "cloud" and "cloud computing" have only been around for a couple of years, but the underlying concepts of these architectures aren't new at all.

     The underlying concept of cloud computing dates back to the 1960s, when John McCarthy opined that "computation may someday be organised as a public utility." Almost all the modern-day characteristics of cloud computing (elastic provision, provided as a utility, online, illusion of infinite supply), the comparison to the electricity industry and the use of public, private, government, and community forms, were thoroughly explored in Douglas Parkhill's 1966 book, The Challenge of the Computer Utility. Other scholars have shown that cloud computing's roots go all the way back to the 1950s when scientist Herb Grosch (the author of Grosch's law) postulated that the entire world would operate on dumb terminals powered by about 15 large data centers. The actual term "cloud" borrows from telephony in that telecommunications companies, who until the 1990s offered primarily dedicated point-to-point data circuits, began offering Virtual Private Network (VPN) services with comparable quality of service but at a much lower cost. By switching traffic to balance utilisation as they saw fit, they were able to utilise their overall network bandwidth more effectively. The cloud symbol was used to denote the demarcation point between that which was the responsibility of the provider and that which was the responsibility of the user. Cloud computing extends this boundary to cover servers as well as the network infrastructure.

     After the dot-com bubble, Amazon played a key role in the development of cloud computing by modernising their data centers, which, like most computer networks, were using as little as 10% of their capacity at any one time, just to leave room for occasional spikes. Having found that the new cloud architecture resulted in significant internal efficiency improvements whereby small, fast-moving "two-pizza teams" could add new features faster and more easily, Amazon initiated a new product development effort to provide cloud computing to external customers, and launched Amazon Web Service (AWS) on a utility computing basis in 2006.

     In early 2008, Eucalyptus became the first open-source, AWS API-compatible platform for deploying private clouds. In early 2008, OpenNebula, enhanced in the RESERVOIR European Commission-funded project, became the first open-source software for deploying private and hybrid clouds, and for the federation of clouds. In the same year, efforts were focused on providing QoS guarantees (as required by real-time interactive applications) to cloud-based infrastructures, in the framework of the IRMOS European Commission-funded project, resulting to a real-time cloud environment. By mid-2008, Gartner saw an opportunity for cloud computing "to shape the relationship among consumers of IT services, those who use IT services and those who sell them" and observed that "rganisations are switching from company-owned hardware and software assets to per-use service-based models" so that the "projected shift to cloud computing... will result in dramatic growth in IT products in some areas and significant reductions in other areas.

     Parallel processing and clustering of multiple computers to form a larger, more powerful single or virtual instance are proven solutions to performance and scalability challenges. Charging for computing on a pay-per-use or subscription basis (common with grid and time-sharing environments), have been employed for decades. Hosting different cloud applications, such as email and collaboration tools for example, have also existed for years. What's new with the evolution of the Cloud is fully abstracting these technologies behind a common user interface, which frees developers and other professionals from the operational aspects of their applications and sites.

     Numerous underlying technologies can be incorporated into the basic architecture of the Cloud. The Internet, of course, is a common thread. And in most cases, clouds are built upon virtualization technologies, like VMware and Xen, or scalable architectures based on semi-dedicated managed hosting models or grids. Usually, public clouds (not in-house environments) utilize control panels and configuration management applications, much like Software-as-a-Service (SaaS). These facilitate application development activities and make raw technology readily consumable. Cloud computing environments typically provide access to LAMP and Windows stacks, web hosting and database technologies.

     A cloud can be private or public. A public cloud sells services to anyone on the Internet. (Currently, Amazon Web Services is the largest public cloud provider.) A private cloud is a proprietary network or a data center that supplies hosted services to a limited number of people. When a service provider uses public cloud resources to create their private cloud, the result is called a virtual private cloud. Private or public, the goal of cloud computing is to provide easy, scalable access to computing resources and IT services.

     Cloud computing providers offer their services according to three fundamental models: Infrastructure as a service (IaaS), platform as a service (PaaS), and software as a service (SaaS) where IaaS is the most basic and each higher model abstracts from the details of the lower models.

     Infrastructure-as-a-Service like Amazon Web Services provides virtual server instanceAPI) to start, stop, access and configure their virtual servers and storage. In the enterprise, cloud computing allows a company to pay for only as much capacity as is needed, and bring more online as soon as required. Because this pay-for-what-you-use model resembles the way electricity, fuel and water are consumed, it's sometimes referred to as utility computing.

     Platform-as-a-service in the cloud is defined as a set of software and product development tools hosted on the provider's infrastructure. Developers create applications on the provider's platform over the Internet. PaaS providers may use APIs, website portals or gateway software installed on the customer's computer. Force.com, (an outgrowth of Salesforce.com) and GoogleApps are examples of PaaS. Developers need to know that currently, there are not standards for interoperability or data portability in the cloud. Some providers will not allow software created by their customers to be moved off the provider's platform.

     In the software-as-a-service cloud model, the vendor supplies the hardware infrastructure, the software product and interacts with the user through a front-end portal. SaaS is a very broad market. Services can be anything from Web-based email to inventory control and database processing. Because the service provider hosts both the application and the data, the end user is free to use the service from anywhere.

The cloud computing have five defining characteristics:

     Characteristic 1: Dynamic computing infrastructure Cloud computing requires a dynamic computing infrastructure. The foundation for the dynamic infrastructure is a standardized, scalable, and secure physical infrastructure. There should be levels of redundancy to ensure high levels of availability, but mostly it must be easy to extend as usage growth demands it, without requiring architecture rework. Next, it must be virtualized.

     Today, virtualized environments leverage server virtualization (typically from VMware, Microsoft, or Xen) as the basis for running services. These services need to be easily provisioned and de-provisioned via software automation. These service workloads need to be moved from one physical server to another as capacity demands increase or decrease. Finally, this infrastructure should be highly utilized, whether provided by an external cloud provider or an internal IT department. The infrastructure must deliver business value over and above the investment.

     A dynamic computing infrastructure is critical to effectively supporting the elastic nature of service provisioning and de-provisioning as requested by users while maintaining high levels of reliability and security. The consolidation provided by virtualization, coupled with provisioning automation, creates a high level of utilization and reuse, ultimately yielding a very effective use of capital equipment.

     Characteristic 2: IT service-centric approach Cloud computing is IT (or business) service-centric. This is in stark contrast to more traditional system- or server- centric models. In most cases, users of the cloud generally want to run some business service or application for a specific, timely purpose; they don’t want to get bogged down in the system and network administration of the environment. They would prefer to quickly and easily access a dedicated instance of an application or service. By abstracting away the server-centric view of the infrastructure, system users can easily access powerful pre-defined computing environments designed specifically around their service.

     An IT Service Centric approach enables user adoption and business agility – the easier and faster a user can perform an administrative task the more expedient the business moves, reducing costs or driving revenue.

     Characteristic 3: Self-service based usage model Interacting with the cloud requires some level of user self-service. Best of breed self-service provides users the ability to upload, build, deploy, schedule, manage, and report on their business services on demand. Self-service cloud offerings must provide easy-to-use, intuitive user interfaces that equip users to productively manage the service delivery lifecycle.

     The benefit of self service from the users’ perspective is a level of empowerment and independence that yields significant business agility. One benefit often overlooked from the service provider’s or IT team’s perspective is that the more self service that can be delegated to users, the less administrative involvement is necessary. This saves time and money and allows administrative staff to focus on more strategic, high-valued responsibilities.

     Characteristic 4: Minimally or self-managed platform In order for an IT team or a service provider to efficiently provide a cloud for its constituents, they must leverage a technology platform that is self managed. Best-of-breed clouds enable self-management via software automation, leveraging the following capabilities:

     A provisioning engine for deploying services and tearing them down recovering resources for high levels of reuse Mechanisms for scheduling and reserving resource capacity Capabilities for configuring, managing, and reporting to ensure resources can be allocated and reallocated to multiple groups of users Tools for controlling access to resources and policies for how resources can be used or operations can be performed

     All of these capabilities enable business agility while simultaneously enacting critical and necessary administrative control. This balance of control and delegation maintains security and uptime, minimizes the level of IT administrative effort, and keeps operating expenses low, freeing up resources to focus on higher value projects.

     Characteristic 5: Consumption-based billing Finally, cloud computing is usage-driven. Consumers pay for only what resources they use and therefore are charged or billed on a consumption-based model. Cloud computing platforms must provide mechanisms to capture usage information that enables chargeback reporting and/or integration with billing systems.

     The value here from a user’s perspective is the ability for them to pay only for the resources they use, ultimately helping them keep their costs down. From a provider’s perspective, it allows them to track usage for charge back and billing purposes.

     In summary, all of these defining characteristics are necessary in producing an enterprise private cloud capable of achieving compelling business value which includes savings on capital equipment and operating costs, reduced support costs, and significantly increased business agility. All of these enable corporations to improve their profit margins and competitiveness in the markets they serve.