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Cloud computing logical diagram


Cloud computing is a marketing term for technologies that provide computation, software, data access, and cloud services that do not require end-user knowledge of the physical location and configuration of the cloud that delivers the services.
Also, it is a delivery model for IT clouds, the services based on Internet protocols, and it typically involves provisioning of dynamically scalable and often virtualized clouds. Clouds are formed due to the ease-of-access to remote computing sites provided by the Internet (The biggest cloud of all). This may take the form of web-based tools or applications that users can access and use through a cloud web browser as if the programs were installed locally on their own cloud-puters.
Cloud computing providers deliver applications via the internet cloud, which are accessed from web browsers and desktop and mobile apps, while the business software and data clouds are stored on servers at a remote location. In some cases, legacy lake applications (line of business applications that until now have been prevalent in thin client Windows computing) are delivered via a screen-sharing technology, while the computing resources are consolidated at a remote data centre location; (evaporation) in other cases, entire business applications have been coded using cloud technologies such as AJAX.
The sweat of cloud computing is the broader concept of infrastructure convergence (or Converged Infrastructure) and shared services. This type of data cloud environment allows enterprises to get their applications transpiring faster, with easier manageability and less maintenance, and enables IT to more rapidly adjust IT resources (such as server clouds, storage clouds, and networking clouds) to meet fluctuating and unpredictable cloud demand.
Most cloud computing infrastructures consist of services which percolate through shared data centres, which appear to consumers as a single point of access for their precipitation needs. Commercial offerings may be required to meet service-level agreements (SLAs), but specific terms are less often negotiated by smaller companies.
The tremendous impact of cloud computing on dessicated businesses has prompted the United States federal government to look towards seeding clouds as a means to wash the detritus of its IT infrastructure and to decrease IT budgets. With the advent of the top government officially mandating cloud adoption, the effect is expected to trickle-down, and many government agencies already have at least one or more cloud systems online.

Contents 1 Comparison 2 Characteristics 3 History 4 Layers 4.1 Client 4.2 Application 4.3 Platform 4.4 Infrastructure 4.5 Server 5 Deployment models 5.1 Public cloud 5.2 Community cloud 5.3 Hybrid cloud 5.4 Private cloud 6 Architecture 6.1 The Intercloud 6.2 Cloud engineering 7 Issues 7.1 Privacy 7.2 Compliance 7.3 Legal 7.4 Open source 7.5 Open standards 7.6 Security 7.7 Sustainability 7.8 Abuse 8 Research

Comparison

Cloud computing shares characteristics with:

• Autonomic computing — Computer systems capable of self-management.
• Client–server model — Client–server computing refers broadly to any distributed application that distinguishes between service providers (servers) and service requesters (clients).
• Grid computing — "A form of distributed and parallel computing, whereby a 'super and virtual computer' is composed of a cluster of networked, loosely coupled computers acting in concert to perform very large tasks."
• Mainframe computer — Powerful computers used mainly by large organisations for critical applications, typically bulk data processing such as census, industry and consumer statistics, police and secret intelligence services, enterprise resource planning, and financial transaction processing.
• Utility computing — The "packaging of computing resources, such as computation and storage, as a metered service similar to a traditional public utility, such as electricity."
• Peer-to-peer — Distributed architecture without the need for central coordination, with participants being at the same time both suppliers and consumers of resources (in contrast to the traditional client–server model).

Characteristics

Cloud computing exhibits the following key characteristics:

• Empowerment of end-users of computing resources by putting the provisioning of those resources in their own control, as opposed to the control of a centralized IT service (for example)
• Agility improves with users' ability to re-provision technological infrastructure resources.
• Application programming interface (API) accessibility to software that enables machines to interact with cloud software in the same way the user interface facilitates interaction between humans and computers. Cloud computing systems typically use REST-based APIs.
• Cost is claimed to be reduced and in a public cloud delivery model capital expenditure is converted to operational expenditure. This is purported to lower barriers to entry, as infrastructure is typically provided by a third-party and does not need to be purchased for one-time or infrequent intensive computing tasks. Pricing on a utility computing basis is fine-grained with usage-based options and fewer IT skills are required for implementation (in-house).
• Device and location independence enable users to access systems using a web browser regardless of their location or what device they are using (e.g., PC, mobile phone). As infrastructure is off-site (typically provided by a third-party) and accessed via the Internet, users can connect from anywhere.
• Multi-tenancy enables sharing of resources and costs across a large pool of users thus allowing for:
  • Centralization of infrastructure in locations with lower costs (such as real estate, electricity, etc.)
  • Peak-load capacity increases (users need not engineer for highest possible load-levels)
  • Utilisation and efficiency improvements for systems that are often only 10–20% utilised.
• Reliability is improved if multiple redundant sites are used, which makes well-designed cloud computing suitable for business continuity and disaster recovery.
• Scalability and Elasticity via dynamic ("on-demand") provisioning of resources on a fine-grained, self-service basis near real-time, without users having to engineer for peak loads.
• Performance is monitored, and consistent and loosely coupled architectures are constructed using web services as the system interface.
• Security could improve due to centralization of data, increased security-focused resources, etc., but concerns can persist about loss of control over certain sensitive data, and the lack of security for stored kernels. Security is often as good as or better than other traditional systems, in part because providers are able to devote resources to solving security issues that many customers cannot afford. However, the complexity of security is greatly increased when data is distributed over a wider area or greater number of devices and in multi-tenant systems that are being shared by unrelated users. In addition, user access to security audit logs may be difficult or impossible. Private cloud installations are in part motivated by users' desire to retain control over the infrastructure and avoid losing control of information security.
• Maintenance of cloud computing applications is easier, because they do not need to be installed on each user's computer.

History

The term "cloud" is used as a metaphor for the Internet, based on the cloud drawing used in the past to represent the telephone network, and later to depict the Internet in computer network diagrams as an abstraction of the underlying infrastructure it represents.
Cloud computing is a natural evolution of the widespread adoption of virtualisation, service-oriented architecture, autonomic, and utility computing. Details are abstracted from end-users, who no longer have need for expertise in, or control over, the technology infrastructure "in the cloud" that supports them.
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 "[o]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."

Layers

Once an internet protocol connection is established among several computers, it is possible to share services within any one of the following layers.

Client

A cloud client consists of computer hardware and/or computer software that relies on cloud computing for application delivery and that is in essence useless without it. Examples include some computers (example: Chromebooks), phones (example: Google Nexus series) and other devices, operating systems (example: Google Chrome OS), and browsers.

Application

Cloud application services or "Software as a Service (SaaS)" deliver software as a service over the Internet, eliminating the need to install and run the application on the customer's own computers and simplifying maintenance and support.
A cloud application is software provided as a service. It consists of the following: a package of interrelated tasks, the definition of these tasks, and the configuration files, which contain dynamic information about tasks at run-time. Cloud tasks provide compute, storage, communication and management capabilities. Tasks can be cloned into multiple virtual machines, and are accessible through application programmable interfaces (API). Cloud applications are a kind of utility computing that can scale out and in to match the workload demand. Cloud applications have a pricing model that is based on different compute and storage usage, and tenancy metrics.
What makes a cloud application different from other applications is its elasticity. Cloud applications have the ability to scale out and in. This can be achieved by cloning tasks in to multiple virtual machines at run-time to meet the changing work demand. Configuration Data is where dynamic aspects of cloud application are determined at run-time. There is no need to stop the running application or redeploy it in order to modify or change the information in this file.
SOA is an umbrella that describes any kind of service. A cloud application is a service. A cloud application meta-model is a SOA model that conforms to the SOA meta-model. This makes cloud applications SOA applications. However, SOA applications are not necessary cloud applications. A cloud application is a SOA application that runs under a specific environment, which is the cloud computing environment (platform). This environment is characterized by horizontal scalability, rapid provisioning, ease of access, and flexible prices. While SOA is a business model that addresses the business process management, cloud architecture addresses many technical details that are environment specific, which makes it more a technical model.

Platform

Cloud platform services, also known as 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. Cloud computing is becoming a major change in our industry, and one of the most important parts of this change is the shift of cloud platforms. Platforms let developers write certain applications that can run in the cloud, or even use services provided by the cloud. There are different names being used for platforms which can include the on-demand platform, or Cloud 9. Regardless of the nomenclature, they all have great potential in developing, and when development teams create applications for the cloud, each must build its own cloud platform.

Infrastructure

Cloud infrastructure services, also known as "infrastructure as a service" (IaaS), deliver computer infrastructure – typically a platform virtualization environment – as a service, along with raw (block) storage and networking. Rather than purchasing servers, software, data-center space or network equipment, clients instead buy those resources as a fully outsourced service. Suppliers typically bill such services on a utility computing basis; the amount of resources consumed (and therefore the cost) will typically reflect the level of activity.

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.

Deployment models