Cloud computing can be confused with

Grid computing—”a form of distributed 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”;

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”;and

Autonomic computing—”computer systems capable of self-management”.

Indeed, many cloud computing deployments as of 2009 depend on grids, have autonomic characteristics, and bill like utilities—but cloud computing tends to expand what is provided by grids and utilities.me successful cloud architectures have little or no centralized infrastructure or billing systems whatsoever, including peer-to-peer networks such as BitTorrent and Skype, and volunteer computing such as SETI@home.

Furthermore, many analysts are keen to stress the evolutionary, incremental pathway between grid technology and cloud computing, tracing roots back to application service providers (ASPs) in the 1990s and the parallels to SaaS, often referred to as applications on the cloud. Some believe the true difference between these terms is marketing and branding; that the technology evolution was incremental and the marketing evolution discrete.

Characteristics

Cloud computing customers do not generally own the physical infrastructure serving as host to the software platform in question. Instead, they avoid capital expenditure by renting usage from a third-party provider. They consume resources as a service and pay only for resources that they use. Many cloud-computing offerings employ the utility computing model, which is analogous to how traditional utility services (such as electricity) are consumed, while others bill on a subscription basis. Sharing “perishable and intangible” computing power among multiple tenants can improve utilization rates, as servers are not unnecessarily left idle (which can reduce costs significantly while increasing the speed of application development). A side effect of this approach is that overall computer usage rises dramatically, as customers do not have to engineer for peak load limits. Additionally, “increased high-speed bandwidth” makes it possible to receive the same response times from centralized infrastructure at other sites.

Economics

Diagram showing economics of cloud computing versus traditional IT, including capital expenditure (CapEx) and operational expenditure (OpEx)

Cloud computing users can avoid capital expenditure (CapEx) on hardware, software, and services when they pay a provider only for what they use. Consumption is usually billed on a utility (e.g. resources consumed, like electricity) or subscription (e.g. time based, like a newspaper) basis with little or no upfront cost. A few cloud providers are now beginning to offer the service for a flat monthly fee as opposed to on a utility billing basis. Other benefits of this time sharing style approach are low barriers to entry, shared infrastructure and costs, low management overhead, and immediate access to a broad range of applications. Users can generally terminate the contract at any time (thereby avoiding return on investment risk and uncertainty) and the services are often covered by service level agreements (SLAs) with financial penalties.

According to Nicholas Carr, the strategic importance of information technology is diminishing as it becomes standardized and less expensive. He argues that the cloud computing paradigm shift is similar to the displacement of electricity generators by electricity grids early in the 20th century.Although companies might be able to save on upfront capital expenditures, they might not save much and might actually pay more for operating expenses. In situations where the capital expense would be relatively small, or where the organization has more flexibility in their capital budget than their operating budget, the cloud model might not make great fiscal sense. Other factors impacting the scale of any potential cost savings include the efficiency of a company’s data center as compared to the cloud vendor’s, the company’s existing operating costs, the level of adoption of cloud computing, and the type of functionality being hosted in the cloud.

Architecture

The majority of cloud computing infrastructure, as of 2009 consists of reliable services delivered through data centers and built on servers with different levels of virtualization technologies. The services are accessible anywhere that provides access to networking infrastructure. Clouds often appear as single points of access for all consumers’ computing needs. Commercial offerings are generally expected to meet quality of service (QoS) requirements of customers and typically offer SLAs. Open standards are critical to the growth of cloud computing, and open source software has provided the foundation for many cloud computing implementations

History

The Cloud is a term that borrows from telephony. Up to the 1990s, data circuits (including those that carried Internet traffic) were hard-wired between destinations. Subsequently, long-haul telephone companies began offering Virtual Private Network (VPN) service for data communications. Telephone companies were able to offer VPN-based services with the same guaranteed bandwidth as fixed circuits at a lower cost because they could switch traffic to balance utilization as they saw fit, thus utilizing their overall network bandwidth more effectively. As a result of this arrangement, it was impossible to determine in advance precisely which paths the traffic would be routed over. The term “telecom cloud” was used to describe this type of networking, and cloud computing is conceptually somewhat similar.

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. Ramnath K. Chellappa defined it as a computing paradigm where the boundaries of computing will be determined by economic rationale rather than technical limits.The term cloud had already come into commercial use in the early 1990s to refer to large Asynchronous Transfer Mode (ATM) networks. By the turn of the 21st century, the term “cloud computing” began to appear more widely, although most of the focus at that time was limited to SaaS.

In 1999, Salesforce.com was established by Marc Benioff, Parker Harris, and their associates. They applied many technologies developed by companies such as Google and Yahoo! to business applications. They also provided the concepts of “on demand” and SaaS with their real business and successful customers. The key for SaaS is that it is customizable by customers with limited technical support required. Business users have enthusiastically welcomed the resulting flexibility and speed.

In the early 2000s, Microsoft extended the concept of SaaS through the development of web services. IBM detailed these concepts in 2001 in the Autonomic Computing Manifesto, which described advanced automation techniques such as self-monitoring, self-healing, self-configuring, and self-optimizing in the management of complex IT systems with heterogeneous storage, servers, applications, networks, security mechanisms, and other system elements that can be virtualized across an enterprise.

Amazon played a key role in the development of cloud computing by modernizing their data centers after the dot-com bubble 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 easier, Amazon started providing access to their systems through Amazon Web Services on a utility computing basis in 2005.

In 2007, Google, IBM, and a number of universities embarked on a large scale cloud computing research project.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 in significant reductions in other areas.”

Political issues

The Cloud spans many borders and “may be the ultimate form of globalization.”As such, it becomes subject to complex geopolitical issues, and providers are pressed to satisfy myriad regulatory environments in order to deliver service to a global market. This dates back to the early days of the Internet, when libertarian thinkers felt that “cyberspace was a distinct place calling for laws and legal institutions of its own”.

Despite efforts (such as US-EU Safe Harbor) to harmonize the legal environment, as of 2009[update], providers such as Amazon Web Services cater to major markets (typically the United States and the European Union) by deploying local infrastructure and allowing customers to select “availability zones.”Nonetheless, concerns persist about security and privacy from individual through governmental levels (e.g., the USA PATRIOT Act, the use of national security letters, and the Electronic Communications Privacy Act’s Stored Communications Act.

Legal issues

In March 2007, Dell applied to trademark the term “cloud computing” (U.S. Trademark 77,139,082) in the United States. The “Notice of Allowance” the company received in July 2008 was cancelled in August, resulting in a formal rejection of the trademark application less than a week later.

In September 2008, the United States Patent and Trademark Office (USPTO) issued a “Notice of Allowance” to CGactive LLC (U.S. Trademark 77,355,287) for “CloudOS”. As defined under this notice, a cloud operating system is a generic operating system that “manage[s] the relationship between software inside the computer and on the Web”, such as Microsoft Azure[30].

In November 2007, the Free Software Foundation released the Affero General Public License, a version of GPLv3 intended to close a perceived legal loophole associated with Free software designed to be run over a network, particularly SaaS. An application service provider is required to release any changes they make to Affero GPL open source code.[citation needed]

Control issues

The founder and president of the Free Software Foundation Richard Stallman has warned people that cloud computing will force people to buy into locked, proprietary systems that will cost more and more over time.

Key characteristics

• Agility improves with users able to rapidly and inexpensively re-provision technological infrastructure resources. The cost of overall computing is unchanged, however, and the providers will merely absorb up-front costs and spread costs over a longer period..

• Cost is claimed to be greatly reduced and capital expenditure is converted to operational expenditure. This ostensibly lowers 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). Some would argue that given the low cost of computing resources, that the IT burden merely shifts the cost from in-house to outsourced providers. Furthermore, any cost reduction benefit must be weighed against a corresponding loss of control, access and security risks.

• 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). 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)

  • Utilization and efficiency improvements for systems that are often only 10–20% utilized.

• Reliability improves through the use of multiple redundant sites, which makes cloud computing suitable for business continuity and disaster recovery.Nonetheless, many major cloud computing services have suffered outages, and IT and business managers can at times do little when they are affected.

• Scalability 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 typically improves 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 under traditional systems, in part because providers are able to devote resources to solving security issues that many customers cannot afford. Providers typically log accesses, but accessing the audit logs themselves can be difficult or impossible.

• Sustainability comes about through improved resource utilization, more efficient systems, and carbon neutrality. Nonetheless, computers and associated infrastructure are major consumers of energy.

Layers

Clients

See also category: Cloud clients

A cloud client consists of computer hardware and/or computer software which relies on cloud computing for application delivery, or which is specifically designed for delivery of cloud services and which, in either case, is essentially useless without it.For example:

• Mobile (Android, iPhone, Windows Mobile)

• Thin client (CherryPal, Zonbu, gOS-based systems)

• Thick client / Web browser (Mozilla Firefox, Google Chrome, WebKit)

Application

See also category: Cloud applications

A cloud application leverages cloud computing in software architecture, often eliminating the need to install and run the application on the customer’s own computer, thus alleviating the burden of software maintenance, ongoing operation, and support. For example:

• Peer-to-peer / volunteer computing (BOINC, Skype)

• Web applications (Facebook, Twitter, YouTube)

• Security as a service (MessageLabs, Purewire, ScanSafe, Zscaler)

• Software as a service (Google Apps, Salesforce, Cool Life Systems, SpringCM)

• Software plus services (Microsoft Online Services)

• Storage [Distributed]

  • Content distribution (BitTorrent, Amazon CloudFront)

  • Synchronisation (Live Mesh)

[Platform

See also category: Cloud platforms

A cloud platform (PaaS) delivers a computing platform and/or solution stack as a service, generally consuming cloud infrastructure and supporting cloud applications. It facilitates deployment of applications without the cost and complexity of buying and managing the underlying hardware and software layers. For example:

• Services

  • Identity (OAuth, OpenID)

  • Payments (Amazon Flexible Payments Service, Google Checkout, PayPal)

  • Search (Alexa, Google Custom Search, Yahoo! BOSS)

  • Real-world (Amazon Mechanical Turk)

• Solution stacks

  • Java (Google App Engine)

  • PHP (Rackspace Cloud Sites)

  • Python Django (Google App Engine)

  • Ruby on Rails (Heroku)

  • .NET (Azure Services Platform, Rackspace Cloud Sites)

  • Proprietary (Force.com, WorkXpress, Wolf Frameworks)

• Storage [Structured]

  • Databases (Amazon SimpleDB, BigTable)

  • File storage (Amazon S3, Nirvanix, Rackspace Cloud Files)

  • Queues (Amazon SQS)

Infrastructure

See also category: Cloud infrastructure

Cloud infrastructure (IaaS) is the delivery of computer infrastructure, typically a platform virtualization environment, as a service. For example:

• Compute (Amazon CloudWatch, RightScale)

  • Physical machines (Softlayer)

  • Virtual machines (Amazon EC2, GoGrid, Rackspace Cloud Servers, Terremark Enterprise Cloud)

  • OS-level virtualisation

• Network (Amazon VPC)

• Storage [Raw] (Amazon EBS)

Servers

The servers layer consists of computer hardware and/or computer software products which are specifically and soley designed for the delivery of cloud services.For example:

• Fabric computing (Cisco UCS)

Architecture

Cloud computing sample architecture

Cloud architecture,the systems architecture of the software systems involved in the delivery of cloud computing, comprises hardware and software designed by a cloud architect who typically works for a cloud integrator. It typically involves multiple cloud components communicating with each other over application programming interfaces, usually web services.

This closely resembles the Unix philosophy of having multiple programs each doing one thing well and working together over universal interfaces. Complexity is controlled and the resulting systems are more manageable than their monolithic counterparts.

Cloud architecture extends to the client, where web browsers and/or software applications access cloud applications.

Cloud storage architecture is loosely coupled, where metadata operations are centralized enabling the data nodes to scale into the hundreds, each independently delivering data to applications or users.

Types

Cloud computing types

Public cloud

Public cloud or external cloud describes cloud computing in the traditional mainstream sense, whereby resources are dynamically provisioned on a fine-grained, self-service basis over the Internet, via web applications/web services, from an off-site third-party provider who shares resources and bills on a fine-grained utility computing basis.

Hybrid cloud

A hybrid cloud environment consisting of multiple internal and/or external providers “will be typical for most enterprises”.

Private cloud

Private cloud and internal cloud are neologisms that some vendors have recently used to describe offerings that emulate cloud computing on private networks. These (typically virtualisation automation) products claim to “deliver some benefits of cloud computing without the pitfalls”, capitalising 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, essentially “[lacking] the economic model that makes cloud computing such an intriguing concept”.

While an analyst predicted in 2008 that private cloud networks would be the future of corporate IT, there is some uncertainty whether they are a reality even within the same firm. Analysts also claim that within five years a “huge percentage” of small and medium enterprises will get most of their computing resources from external cloud computing providers as they “will not have economies of scale to make it worth staying in the IT business” or be able to afford private clouds.. Analysts have reported on Platform’s view that private clouds are a stepping stone to external clouds, particularly for the financial services, and that future datacenters will look like internal clouds.

The term has also been used in the logical rather than physical sense, for example in reference to platform as a service offerings, though such offerings including Microsoft’s Azure Services Platform are not available for on-premises deployment.

Source: wikipedia.org

Leave a Reply

Name (required)

Email (required) (not shown)

Website