A dedicated hosting service, dedicated server, or managed hosting service is a type of Internet hosting in which the client leases an entire server not shared with anyone. This is more flexible than shared hosting, as organizations have full control over the server(s), including choice of operating system.
Managed dedicated server
To date, no industry standards have been set to clearly define the management role of dedicated server providers. What this means is that each provider will use industry standard terms, but each provider will define them differently. For some dedicated server providers.
The compact edition is an embedded database engine. Unlike the other editions of SQL Server, the SQL CE engine is based on SQL Mobile (initially designed for use with hand-held devices) and does not share the same binaries.
When writing code for SQL CLR, data stored in SQL Server databases can be accessed using the ADO.NET APIs like any other managed application that accesses SQL Server data.
Bandwidth refers to the data transfer rate or the amount of data that can be carried from one point to another in a given time period (usually a second) and is often represented in bits (of data) per second (bit/s).
Clustered hosting is a type of web hosting that spreads the load of hosting across multiple physical machines ("nodes"), increasing availability and decreasing the chances of one service (e.g., FTP or email) affecting another (e.g., MySQL). Many large websites run on clustered hosting solutions, for example, large discussion forums will tend to run using multiple front-end webservers with multiple back-end database servers.
Typically, most hosting infrastructures are based on the paradigm of using a single physical machine to host multiple hosted services, including web, database, email, FTP and others. A single physical machine is not only a single point of failure, but also has finite capacity for traffic, that in practice can be troublesome for a busy website or for a website that is experiencing transient bursts in traffic.
By clustering services across multiple hardware machines, and using load balancing you can eliminate single points of failure increasing availability of your website and other web services beyond that of ordinary single server hosting. A single server can require periodic reboots for software upgrades and the like, whereas in a clustered platform you can stagger the restarts such that the service is still available whilst still upgrading all necessary machines in the cluster.
Clustered hosting is similar to cloud hosting, in that the resources of many machines are available for a website to utilize on demand, making scalability a large advantage to a clustered hosting solution.
Cloud computing
Cloud computing refers to the provision of computational resources on demand via a computer network. Because the cloud is an underlying delivery mechanism, cloud based applications and services may support any type of software application or service in use today. Before the advent of computer networks, both data and software were stored and processed on or near the computer. The development of Local Area Networks LAN allowed for a tiered architecture in which multiple CPUs and storage devices may be organized to increase the performance of the entire system. LANs were widely deployed in corporate environments in the 1990's, and are notable for vendor specific connectivity limitations. These limitations gave rise to the marketing term "Islands of Information" which was widely used within the computing industry. The widespread implementation of the TCP/IP protocol stack and the subsequent popularization of the web has lead to multi-vendor networks that are no longer limited by company walls.
Cloud computing fundamentally allows for a functional separation between the resources used and the user's computer. The computing resources may or may not reside outside the local network, for example in an internet connected datacenter. What is important to the individual user is that they 'simply work'. This separation between the resources used and the user's computer also has allowed for the development of new business models. All of the development and maintenance tasks involved in provisioning the application are performed by the service provider. The user's computer may contain very little software or data (perhaps a minimal operating system and web browser only), serving as little more than a display terminal for processes occurring on a network of computers far away. Consumers now routinely use data intensive applications driven by cloud technology which were previously unavailable due to cost and deployment complexity. In many companies employees and company departments are bringing a flood of consumer technology into the workplace and this raises legal compliance and security concerns for the corporation.
A common shorthand for a provided cloud computing service (or even an aggregation of all existing cloud services) is "The Cloud". The most common analogy to explain cloud computing is that of public utilities such as electricity, gas, and water. Just as centralized and standardized utilities free individuals from the difficulties of generating electricity or pumping water, cloud computing frees users from certain hardware and software installation and maintenance tasks through the use of simpler hardware that accesses a vast network of computing resources (processors, hard drives, etc.). The sharing of resources reduces the cost to individuals.
The phrase “cloud computing” originated from the cloud symbol that is usually used by flow charts and diagrams to symbolize the internet. The principle behind the cloud is that any computer connected to the internet is connected to the same pool of computing power, applications, and files. Users can store and access personal files such as music, pictures, videos, and bookmarks or play games or use productivity applications on a remote server rather than physically carrying around a storage medium such as a DVD or thumb drive. Almost all users of the internet may be using a form of cloud computing though few realize it. Those who use web-based email such as Gmail, Hotmail, Yahoo, a Company owned email, or even an e-mail client program such as Outlook, Evolution, Mozilla Thunderbird or Entourage are making use of cloud email servers. Hence, desktop applications which connect to cloud email would be considered cloud applications.
How it works
Cloud computing utilizes the network as a means to connect user end point devices (end points) to resources that are centralized in a data center. The data center may be accessed via the internet or a company network, or both. In many cases a cloud service may allow access from a variety of end points such as a mobile phone, a PC or a tablet. Cloud services may be designed to be vendor agnostic, working equally well with Linux, Mac and PC platforms. They also can allow access from any internet connected location, allowing mobile workers to access business systems remotely as in Telecommuting, and extending the reach of business services provided by Outsourcing.
A user endpoint with minimal software requirements may submit a task for processing. The service provider may pool the processing power of multiple remote computers in "the cloud" to achieve the task, such as data warehousing of hundreds of terabytes, managing and synchronizing multiple documents online, or computationally intensive work. These tasks would normally be difficult, time consuming, or expensive for an individual user or a small company to accomplish. The outcome of the processing task is returned to the client over the network. In essence, the heavy lifting of a task is outsourced to an external entity with more resources and expertise.
The services - such as data storage and processing - and software are provided by the company hosting the remote computers. The clients are only responsible for having a simple computer with a connection to the Internet, or a company network, in order to make requests to and receive data from the cloud. Computation and storage is divided among the remote computers in order to handle large volumes of both, thus the client need not purchase expensive hardware to handle the task.
Technical description
The National Institute of Standards and Technology (NIST) provides a concise and specific
Definition:
Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.
Cloud computing provides computation, software, data access, and storage services that do not require end-user knowledge of the physical location and configuration of the system that delivers the services. Parallels to this concept can be drawn with the electricity grid, where end-users consume power without needing to understand the component devices or infrastructure required to provide the service.
Cloud computing describes a new supplement, consumption, and delivery model for IT services based on Internet protocols, and it typically involves provisioning of dynamically scalable and often virtualized resources. It is a byproduct and consequence of the ease-of-access to remote computing sites provided by the Internet. This may take the form of web-based tools or applications that users can access and use through a web browser as if they were programs installed locally on their own computers.
Cloud computing providers deliver applications via the internet, which are accessed from a Web browser, while the business software and data are stored on servers at a remote location. In some cases, legacy applications (line of business applications which until now have been prevalent in thick client Windows computing) are delivered via a screen sharing technology such as Citrix XenApp, while the compute resources are consolidated at a remote data center location; in other cases entire business applications have been coded using web based technologies such as AJAX.
Most cloud computing infrastructures consist of services delivered through shared data-centers. The Cloud may appear as a single point of access for consumers' computing needs, notable examples include the iTunes Store, and the iPhone App Store. Commercial offerings may be required to meet service level agreements (SLAs), but specific terms are less often negotiated by smaller companies.
Overview Comparisons
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 computing 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 organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, 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).
Service-oriented computing – Cloud computing provides services related to computing while, in a reciprocal manner, service-oriented computing consists of the computing techniques that operate on software-as-a-service.
Characteristics
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). This is in contrast to a model in which the processing takes place in one or more specific servers that are known. All the other concepts mentioned are supplementary or complementary to this concept.
Architecture
Cloud computing sample architecture
Cloud architecture, the systems architecture of the software systems involved in the delivery of cloud computing, typically involves multiple cloud components communicating with each other over application programming interfaces, usually web services and 3-tier architecture. This 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.
The two most significant components of cloud computing architecture are known as the front end and the back end. The front end is the part seen by the client, i.e. the computer user. This includes the client’s network (or computer) and the applications used to access the cloud via a user interface such as a web browser. The back end of the cloud computing architecture is the ‘cloud’ itself, comprising various computers, servers and data storage devices.
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 virtualization, 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 organized 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.
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 Virtual Private Network (VPN) services with comparable quality of service but at a much lower cost. By switching traffic to balance utilization as they saw fit, they were able to utilize 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. The first scholarly use of the term “cloud computing” was in a 1997 lecture by Ramnath Chellappa.
After the dot-com bubble, Amazon played a key role in the development of cloud computing by modernizing 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. The first exposure of the term Cloud Computing to public media is by GoogleEx CEO Eric Schmidt at SES San Jose 2006. It was reported in 2011 that Amazon has thousands of corporate customers, from large ones like Pfizer and Netflix to start-ups, Amongst them also include many corporations that live on Amazon's web services, including Foursquare, a location-based social networking site; Quora, a question-and-answer service; Reddit, a site for news-sharing and BigDoor, a maker of game tools for Web publishers.
In 2007, Google, IBM and a number of universities embarked on a large-scale cloud computing research project. 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. 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."
Key characteristics
This section appears to contain a large number of buzzwords. Specific concerns can be found on the Talk page. Please improve this section if you can. (May 2011)
Agility improves with users' ability to rapidly and inexpensively 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 greatly reduced and in a public cloud delivery model 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).
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:
o Centralization of infrastructure in locations with lower costs (such as real estate, electricity, etc.)
o Peak-load capacity increases (users need not engineer for highest possible load-levels)
o Utilization and efficiency improvements for systems that are often only 10–20% utilized.
Reliability is improved if multiple redundant sites are used, which makes well designed cloud computing suitable for business continuity and disaster recovery.
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 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 under 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 which 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. They are easier to support and to improve, as the changes reach the clients instantly.
Layers
Once an Internet Protocol connection is established among several computers, it is possible to share services within any one of the following layers.
Cloud Computing Stack.svg
Cloud clients
A cloud client consists of computer hardware and/or computer software that relies on cloud computing for application delivery, or that is specifically designed for delivery of cloud services and that, in either case, is essentially useless without it. Examples include some computers, phones and other devices, operating systems and browsers.
Cloud applications
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. People tend to use the terms "SaaS" and "cloud" interchangeably, when in fact they are two different things.[citation needed] Key characteristics include:[40][clarification needed]
Network-based access to, and management of, commercially available (i.e., not custom) software
Activities that are managed from central locations rather than at each customer's site, enabling customers to access applications remotely via the Web
Application delivery that typically is closer to a one-to-many model (single instance, multi-tenant architecture) than to a one-to-one model, including architecture, pricing, partnering, and management characteristics
Centralized feature updating, which obviates the need for downloadable patches and upgrades
Cloud platforms
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.
Cloud infrastructure
Cloud infrastructure services, also known as "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. 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. IaaS evolved from virtual private server offerings.
Cloud infrastructure often takes the form of a tier 3 data center with many tier 4 attributes, assembled from hundreds of virtual machines.
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
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 bills on a fine-grained utility computing basis.
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. The costs are spread over fewer users than a public cloud (but more than a single tenant). This option may offer a higher level of privacy, security and/or policy compliance. In addition it can be economically attractive as the resources (storage, workstations) utilized and shared in the community are already exploited and have reached their return of investment. Examples of community clouds include Google's "Gov Cloud".
Hybrid cloud and hybrid IT delivery
The main responsibility of the IT department is to deliver services to the business. With the proliferation of cloud computing (both private and public) and the fact that IT departments must also deliver services via traditional, in-house methods, the newest catch-phrase has become “hybrid cloud computing.” Hybrid cloud is also called hybrid delivery by the major vendors including HP, IBM, Oracle and VMware who offer technology to manage the complexity in managing the performance, security and privacy concerns that results from the mixed delivery methods of IT services.
A hybrid storage cloud uses a combination of public and private storage clouds. Hybrid storage clouds are often useful for archiving and backup functions, allowing local data to be replicated to a public cloud.
Another perspective on deploying a web application in the cloud is using Hybrid Web Hosting, where the hosting infrastructure is a mix between cloud hosting and managed dedicated servers – this is most commonly achieved as part of a web cluster in which some of the nodes are running on real physical hardware and some are running on cloud server instances.[citation needed]
Combined cloud
Two clouds that have been joined together are more correctly called a "combined cloud". A combined cloud environment consisting of multiple internal and/or external providers "will be typical for most enterprises".[53] By integrating multiple cloud services users may be able to ease the transition to public cloud services while avoiding issues such as PCI compliance.
Private cloud
Douglas Parkhill first described the concept of a "private computer utility" in his 1966 book The Challenge of the Computer Utility. The idea was based upon direct comparison with other industries (e.g. the electricity industry) and the extensive use of hybrid supply models to balance and mitigate risks.
"Private cloud" and "internal cloud" have been described as neologisms, but the concepts themselves pre-date the term cloud by 40 years. Even within modern utility industries, hybrid models still exist despite the formation of reasonably well-functioning markets and the ability to combine multiple providers.
Some vendors have used the terms to describe offerings that emulate cloud computing on private networks. These (typically virtualization automation) products offer the ability to host applications or virtual machines in a company's own set of hosts. These provide the benefits of utility computing – shared hardware costs, the ability to recover from failure, and the ability to scale up or down depending upon demand.
Private clouds have attracted criticism because users "still have to buy, build, and manage them" and thus 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". Enterprise IT organizations use their own private cloud(s) for mission critical and other operational systems to protect critical infrastructures. Therefore, for all intents and purposes, "private clouds" are not an implementation of cloud computing at all, but are in fact an implementation of a technology subset: the basic concept of virtualized computing.
Cloud engineering
Cloud engineering is the application of a systematic, disciplined, quantifiable, and interdisciplinary approach to the ideation, conceptualization, development, operation, and maintenance of cloud computing, as well as the study and applied research of the approach, i.e., the application of engineering to cloud. It is a maturing and evolving discipline to facilitate the adoption, strategization, operationalization, industrialization, standardization, productization, commoditization, and governance of cloud solutions, leading towards a cloud ecosystem[further explanation needed]. Cloud engineering is also known as cloud service engineering.
Cloud storage gateway
Cloud storage is a model of networked computer data storage where data is stored on multiple virtual servers, generally hosted by third parties, rather than being hosted on dedicated servers. Hosting companies operate large data centers; and people who require their data to be hosted buy or lease storage capacity from them and use it for their storage needs. The data center operators, in the background, virtualize the resources according to the requirements of the customer and expose them as virtual servers, which the customers can themselves manage. Physically, the resource may span across multiple servers.
The Intercloud
The Intercloud is an interconnected global "cloud of clouds" and an extension of the Internet "network of networks" on which it is based. The term was first used in the context of cloud computing in 2007 when Kevin Kelly stated that "eventually we'll have the intercloud, the cloud of clouds. This Intercloud will have the dimensions of one machine comprising all servers and attendant cloudbooks on the planet.". It became popular in 2009 and has also been used to describe the datacenter of the future.
The Intercloud scenario is based on the key concept that each single cloud does not have infinite physical resources. If a cloud saturates the computational and storage resources of its virtualization infrastructure, it could not be able to satisfy further requests for service allocations sent from its clients. The Intercloud scenario aims to address such situation, and in theory, each cloud can use the computational and storage resources of the virtualization infrastructures of other clouds. Such form of pay-for-use may introduce new business opportunities among cloud providers if they manage to go beyond theoretical framework. Nevertheless, the Intercloud raises many more challenges than solutions concerning cloud federation, security, interoperability, quality of service, vendor's lock-ins, trust, legal issues, monitoring and billing.[citation needed]
The concept of a competitive utility computing market which combined many computer utilities together was originally described by Douglas Parkhill in his 1966 book, the "Challenge of the Computer Utility". This concept has been subsequently used many times over the last 40 years and is identical to the Intercloud.
Issues
Privacy
The cloud model has been criticized by privacy advocates for the greater ease in which the companies hosting the cloud services control, and thus, can monitor at will, lawfully or unlawfully, the communication and data stored between the user and the host company. Instances such as the secret NSA program, working with AT&T, and Verizon, which recorded over 10 million phone calls between American citizens, causes uncertainty among privacy advocates, and the greater powers it gives to telecommunication companies to monitor user activity. While there have been efforts (such as US-EU Safe Harbor) to "harmonize" the legal environment, providers such as Amazon still cater to major markets (typically the United States and the European Union) by deploying local infrastructure and allowing customers to select "availability zones."
Compliance
In order to obtain compliance with regulations including FISMA, HIPAA and SOX in the United States, the Data Protection Directive in the EU and the credit card industry's PCI DSS, users may have to adopt community or hybrid deployment modes which are typically more expensive and may offer restricted benefits. This is how Google is able to "manage and meet additional government policy requirements beyond FISMA" and Rackspace Cloud are able to claim PCI compliance. Customers in the EU contracting with cloud providers established outside the EU/EEA have to adhere to the EU regulations on export of personal data.
Many providers also obtain SAS 70 Type II certification (e.g. Amazon, Salesforce.com, Google and Microsoft), but this has been criticised on the grounds that the hand-picked set of goals and standards determined by the auditor and the auditee are often not disclosed and can vary widely. Providers typically make this information available on request, under non-disclosure agreement.
Legal
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 canceled in August, resulting in a formal rejection of the trademark application less than a week later. Since 2007, the number of trademark filings covering cloud computing brands, goods and services has increased at an almost exponential rate. As companies sought to better position themselves for cloud computing branding and marketing efforts, cloud computing trademark filings increased by 483% between 2008 and 2009. In 2009, 116 cloud computing trademarks were filed, and trademark analysts predict that over 500 such marks could be filed during 2010.
Other legal cases may shape the use of cloud computing by the public sector. On October 29, 2010, Google filed a lawsuit against the U.S. Department of Interior, which opened up a bid for software that required that bidders use Microsoft's Business Productivity Online Suite. Google sued, calling the requirement "unduly restrictive of competition." Scholars have pointed out that, beginning in 2005, the prevalence of open standards and open source may have an impact on the way that public entities choose to select vendors.
Open source
Open source software has provided the foundation for many cloud computing implementations. 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.
Cloud standards
Most cloud providers expose APIs which are typically well-documented (often under a Creative Commons license) but also unique to their implementation and thus not interoperable. Some vendors have adopted others' APIs and there are a number of open standards under development, including the OGF's Open Cloud Computing Interface. The Open Cloud Consortium (OCC) is working to develop consensus on early cloud computing standards and practices.
Cloud computing security
The relative security of cloud computing services is a contentious issue which may be delaying its adoption. Issues barring the adoption of cloud computing are due in large part to the private and public sectors unease surrounding the external management of security based services. It is the very nature of cloud computing based services, private or public, that promote external management of provided services. This delivers great incentive amongst cloud computing service providers in producing a priority in building and maintaining strong management of secure services.
Organizations have been formed in order to provide standards for a better future in cloud computing services. One organization in particular, the Cloud Security Alliance is a non-profit organization formed to promote the use of best practices for providing security assurance within cloud computing.
Availability and performance
In addition to concerns about security, businesses are also worried about acceptable levels of availability and performance of applications hosted in the cloud.
There are also concerns about a cloud provider shutting down for financial or legal reasons, which has happened in a number of cases.
Sustainability and siting
Although cloud computing is often assumed to be a form of "green computing", there is as of yet no published study to substantiate this assumption. Siting the servers affects the environmental effects of cloud computing. In areas where climate favors natural cooling and renewable electricity is readily available, the environmental effects will be more moderate. Thus countries with favorable conditions, such as Finland,Sweden and Switzerland, are trying to attract cloud computing data centers.
SmartBay, marine research infrastructure of sensors and computational technology, is being developed using cloud computing, an emerging approach to shared infrastructure in which large pools of systems are linked together to provide IT services.
Research
A number of universities, vendors and government organizations are investing in research around the topic of cloud computing. Academic institutions include University of Melbourne (Australia), Georgia Tech, Yale, Wayne State, Virginia Tech, University of Wisconsin–Madison, Carnegie Mellon, MIT, Indiana University, University of Massachusetts, University of Maryland, IIT Bombay, North Carolina State University, Purdue University, University of California, University of Washington, University of Virginia, University of Utah, University of Minnesota, among others.
Joint government, academic and vendor collaborative research projects include the IBM/Google Academic Cloud Computing Initiative (ACCI). In October 2007 IBM and Google announced the multi- university project designed to enhance students' technical knowledge to address the challenges of cloud computing.[95] In April 2009, the National Science Foundation joined the ACCI and awarded approximately million in grants to 14 academic institutions.
In July 2008, HP, Intel Corporation and Yahoo! announced the creation of a global, multi-data center, open source test bed, called Open Cirrus, designed to encourage research into all aspects of cloud computing, service and data center management. Open Cirrus partners include the NSF, the University of Illinois (UIUC), Karlsruhe Institute of Technology, the Infocomm Development Authority (IDA) of Singapore, the Electronics and Telecommunications Research Institute (ETRI) in Korea, the Malaysian Institute for Microelectronic Systems(MIMOS), and the Institute for System Programming at the Russian Academy of Sciences (ISPRAS). In Sept. 2010, more researchers joined the HP/Intel/Yahoo Open Cirrus project for cloud computing research. The new researchers are China Mobile Research Institute (CMRI), Spain's Supercomputing Center of Galicia (CESGA by its Spanish acronym), Georgia Tech's Center for Experimental Research in Computer Systems (CERCS) and China Telecom.
In July 2010, HP Labs India announced a new cloud-based technology designed to simplify taking content and making it mobile-enabled, even from low-end devices. Called SiteonMobile, the new technology is designed for emerging markets where people are more likely to access the internet via mobile phones rather than computers[citation needed]. In November 2010, HP formally opened its Government Cloud Theatre, located at the HP Labs site in Bristol, England. The demonstration facility highlights high-security, highly flexible cloud computing based on intellectual property developed at HP Labs. The aim of the facility is to lessen fears about the security of the cloud. HP Labs Bristol is HP’s second-largest central research location and currently is responsible for researching cloud computing and security.
The IEEE Technical Committee on Services Computing in IEEE Computer Society sponsors the IEEE International Conference on Cloud Computing (CLOUD). CLOUD 2010 was held on July 5–10, 2010 in Miami, Florida
On March 23, 2011, Google, Microsoft, HP, Yahoo, Verizon, Deutsche Telekom and 17 other companies formed a nonprofit organization called Open Networking Foundation, focused on providing support for a new cloud initiative called Software-Defined Networking. The initiative is meant to speed innovation through simple software changes in telecommunications networks, wireless networks, data centers and other networking areas.
Criticism of the term
Some have come to criticize the term as being either too unspecific or even misleading. CEO Larry Ellison of Oracle Corporation asserts that cloud computing is "everything that we already do", claiming that the company could simply "change the wording on some of our ads" to deploy their cloud-based services. Forrester Research VP Frank Gillett questions the very nature of and motivation behind the push for cloud computing, describing what he calls "cloud washing"—companies simply relabeling their products as "cloud computing", resulting in mere marketing innovation instead of "real" innovation.GNU's Richard Stallman insists that the industry will only use the model to deliver services at ever increasing rates over proprietary systems, otherwise likening it to a "marketing hype campaign".
Virtual private server
Virtual private server (VPS) is a marketing term used by Internet hosting services to refer to a virtual machine for use exclusively by an individual customer of the service. The term is used to emphasize that the virtual machine, although running in software on the same physical computer as other customers' virtual machines, is functionally equivalent to a separate physical computer, is dedicated to the individual customer's needs, has the privacy of a separate physical computer, and can be configured to run as a server computer (i.e. to run server software). The term Virtual Dedicated Server or VDS is used less often for the same concept.
Each virtual server can run its own full-fledged operating system and can be independently rebooted.
The practice of partitioning a single server so that it appears as multiple servers has long been common practice on mainframe computers and mid-range computers such as the IBM AS/400. It has become more prevalent with the development of virtualization software and technologies for microcomputers.
Overview
The physical server typically runs a hypervisor which is tasked with creating, destroying, and managing the resources of "guest" operating systems, or virtual machines. These guest operating systems are allocated a share of resources of the physical server, typically in a manner in which the guest is not aware of any other physical resources save for those allocated to it by the hypervisor.
The Guest system may be fully virtualized, paravirtualized, or a hybrid of the two.
In a fully virtualized environment, the guest is presented with an emulated or virtualized set of hardware and is unaware that this hardware is not strictly physical. The hypervisor in this case must translate, map, and convert requests from the guest system into the appropriate resource requests on the host, resulting in significant overhead. Almost all systems can be virtualized using this method, as it requires no modification of the operating system, however a CPU supporting virtualization is required for most hypervisors that perform full virtualization.
In a paravirtualized environment, the guest is aware of the hypervisor and interfaces directly with the host system's resources, with the hypervisor implementing real-time access control and resource allocation. This results in near-native performance since the guest sees the same hardware as the host and can thus communicate with it natively. UNIX-like systems, such as Linux, some variants of BSD, Plan9, and OpenSolaris are currently known to support this method of virtualization. However, installing operating systems as paravirtualized guests tends to require more knowledge about the operating system in order to have it use special hypervisor-aware kernels and devices.
Some examples of paravirtualization-capable hypervisors are Xen, Virtuozzo, Vserver, and OpenVZ (which is the open source and development version of Parallels Virtuozzo Containers).
Hybrid or partial paravirtualization, is full virtualization, but in which the guest uses paravirtualized drivers for key components such as Networking and Disk I/O, resulting in greatly increased I/O performance. As such, it is a common solution for operating systems which cannot be modified (for various reasons) to support paravirtualiztion.
One example of a hybrid hypervisor is Kernel-based Virtual Machine.
Uses
Virtual private servers bridge the gap between shared web hosting services and dedicated hosting services, giving independence from other customers of the VPS service in software terms but at less cost than a physical dedicated server. As a VPS runs its own copy of its operating system, customers have superuser-level access to that operating system instance, and can install almost any software that runs on the OS. Certain software does not run well in a virtualized environment, such as virtualizers themselves; some VPS providers place further restrictions, but they are generally lax compared to those in shared hosting environments. Due to the number of virtualization clients typically running on a single machine, a VPS generally has limited processor time, RAM, and disk space.
Virtual private server hosting
A growing number of companies offer virtual private server hosting, or virtual dedicated server hosting as an extension for web hosting services. There are several challenges to consider when licensing proprietary software in multi-tenant virtual environments.
Unmanaged Hosting
The customer is left to monitor and administer their own server.
This type of service is generally offered with no limit on the amount of data-transferred on a fixed bandwidth line. Usually, unmetered hosting is offered with 10 Mbit/s, 100 Mbit/s or 1000 Mbit/s. This means that the customer is theoretically able to use 3.33~ TB on 10 Mbit/s, 33~ TB on 100 Mbit/s and 333~ TB on a 1000 Mbit/s line per month (although in practice the values will be significantly less).
Virtualization software
For some of the software packages commonly used to provide platform virtualization, see comparison of platform virtual machines
Cloud server
A VPS which is dynamic (that is, it can be changed at runtime) is often referred to as a cloud server. Key attributes for this are:
Additional hardware resources can be added at runtime (CPU, RAM)
Server can be moved to other hardware while the server is running (automatically according to load in some cases)
Reseller hosting is a form of web hosting wherein the account owner has the ability to use his/her allotted hard drive space and bandwidth to host websites on behalf of third parties. The reseller purchases the host's services wholesale and then sells them to customers, possibly for a profit. A certain portion of hard drive and bandwidth is allocated to the reseller account. The reseller may rent a dedicated server from a hosting company, or resell shared hosting services. In the latter case, the reseller is simply given the permission to sell a certain amount of disk space and bandwidth to his own customers without renting a server from a web hosting company he signed for a reseller account with.
The typical web hosting reseller might be a web design firm, web developer or systems integrator who offers web hosting as an add-on service. Reseller hosting is also an inexpensive way for web hosting entrepreneurs to start a company. Most reseller hosting plans allow resellers to create their own service plans and choose their own pricing structure. In many cases, resellers are able to establish their own branding via customized control panels and name servers.
Reseller hosting does not require extensive knowledge of the technical aspects of web hosting. Usually, the data center operator is responsible for maintaining network infrastructure and hardware, and the dedicated server owner configures, secures, and updates the server. A reseller is responsible for interfacing with his/her own customer base, but any hardware, software and connectivity problems are typically forwarded to the server provider from whom the reseller plan was purchased. Being a profitable reseller firm usually involves extensive advertising to get customers. While the monthly fees with major hosts are only a few dollars a month, it's a low margin business, and resellers must devote large advertising budgets to compete with established competitors. However, web hosting is one of the biggest online businesses, because every website needs hosting.
Resellers can set up and manage customer accounts via a web interface, usually point and click "Control Panels."
Shared web hosting service
A shared web hosting service or virtual hosting service or derive host refers to a web hosting service where many websites reside on one web server connected to the Internet. Each site "sits" on its own partition, or section/place on the server, to keep it separate from other sites. This is generally the most economical option for hosting, as many people share the overall cost of server maintenance.
Description
The hosting service must include system administration since it is shared by many users; this is a benefit for users who do not want to deal with it, but a hindrance to power users who want more control. In general shared hosting will be inappropriate for users who require extensive software development outside what the hosting provider supports. Almost all applications intended to be on a standard web server work fine with a shared web hosting service. But on the other hand, shared hosting is cheaper than other types of hosting such as dedicated server hosting. Shared hosting usually has usage limits and most hosting providers have extensive reliability features in place.
Shared hosting typically uses a web-based control panel system, such as cPanel, DirectAdmin, Plesk, InterWorx, H-Sphere or one of many other control panel products. Most of the large hosting companies use their own custom developed control panel. Control panels and web interfaces can cause controversy however, since web hosting companies sometimes sell the right to use their control panel system to others. Attempting to recreate the functionality of a specific control panel is common, which leads to many lawsuits over patent infringement.
In shared hosting, the provider is generally responsible for managing servers, installing server software, security updates, technical support, and other aspects of the service. Most servers are based on the Linux operating system and LAMP (software bundle), which is driven by the low cost of open source software. But some providers offer Microsoft Windows-based or FreeBSD-based solutions. For example, the Plesk control panel is available for two operating systems, Linux and Windows. Versions for either OS have very similar interfaces and functionality, with the exception of OS-specific differences (for example: ASP.NET, SQL Server and Access support under Windows; MySQL under Linux).
There are thousands of shared hosting providers in the United States alone. They range from mom-and-pop shops and small design firms to multi-million-dollar providers with hundreds of thousands of customers. A large portion of the shared web hosting market is driven through pay per click (PPC) advertising or Affiliate programs.
Shared web hosting can also be done privately by sharing the cost of running a server in a colocation centre; this is called cooperative hosting.
Implementation
Shared web hosting can be accomplished in two ways: name-based and IP-based, although some control panels allow a mix of name-based and IP-based on the one server.
IP-based
In IP-based virtual hosting, also called dedicated IP hosting, each virtual host has a different IP address. The web server is configured with multiple physical network interfaces, or virtual network interfaces on the same physical interface. The web server software uses the IP address the client connects to in order to determine which web site to show the user. The issue of IPv4 address exhaustion means that IP addresses are an increasingly scarce resource, so the the primary justification for a site to use a dedicated IP is to be able to use its own SSL certificate rather than a shared certificate.
Name-based
In name-based virtual hosting, also called shared IP hosting, the virtual hosts serve multiple hostnames on a single machine with a single IP address. This is possible because when a web browser requests a resource from a web server using HTTP/1.1 it includes the requested hostname as part of the request. The server uses this information to determine which web site to show the user.
Disadvantages
Name-based virtual hosts have some disadvantages:
They will not work with very old HTTP/1.0 browsers that do not send the hostname as part of requests. Since the "Host" header is mandatory in HTTP/1.1, which was issued in 1999 as RFC 2616, this is not a common issue.
They do not properly support secure websites using HTTPS. All name-based virtual hosts using the same IP address must share the same digital certificate because the SSL/TLS handshake takes place before the hostname is sent to the server. RFC 3546 - Transport Layer Security (TLS) Extensions, is a potential solution but it is not yet widely implemented.
If the Domain Name System is malfunctioning, it is not possible to fall back to using the IP address to contact the system, Some web hosting companies may offer an alternative access method like http://192.0.2.0/~virtualhostname to provide access in such cases.
If file permissions have been improperly configured, then shared file systems might give other (compromised) users or processes system-wide access to these files.
Internet hosting services can run Web servers; see Internet hosting services.
Many large companies who are not internet service providers also need a computer permanently connected to the web so they can send email, files, etc. to other sites. They may also use the computer as a website host so they can provide details of their goods and services to anyone interested. Additionally these people may decide to place online orders.
Free web hosting service: offered by different companies with limited services, sometimes supported by advertisements, and often limited when compared to paid hosting.
Shared web hosting service: one's website is placed on the same server as many other sites, ranging from a few to hundreds or thousands. Typically, all domains may share a common pool of server resources, such as RAM and the CPU. The features available with this type of service can be quite extensive. A shared website may be hosted with a reseller.
Reseller web hosting: allows clients to become web hosts themselves. Resellers could function, for individual domains, under any combination of these listed types of hosting, depending on who they are affiliated with as a reseller. Resellers' accounts may vary tremendously in size: they may have their own virtual dedicated server to a collocated server. Many resellers provide a nearly identical service to their provider's shared hosting plan and provide the technical support themselves.
Virtual Dedicated Server: also known as a Virtual Private Server (VPS), divides server resources into virtual servers, where resources can be allocated in a way that does not directly reflect the underlying hardware. VPS will often be allocated resources based on a one server to many VPSs relationship, however virtualisation may be done for a number of reasons, including the ability to move a VPS container between servers. The users may have root access to their own virtual space. Customers are sometimes responsible for patching and maintaining the server.
Dedicated hosting service: the user gets his or her own Web server and gains full control over it (root access for Linux/administrator access for Windows); however, the user typically does not own the server. Another type of Dedicated hosting is Self-Managed or Unmanaged. This is usually the least expensive for Dedicated plans. The user has full administrative access to the box, which means the client is responsible for the security and maintenance of his own dedicated box.
Managed hosting service: the user gets his or her own Web server but is not allowed full control over it (root access for Linux/administrator access for Windows); however, they are allowed to manage their data via FTP or other remote management tools. The user is disallowed full control so that the provider can guarantee quality of service by not allowing the user to modify the server or potentially create configuration problems. The user typically does not own the server. The server is leased to the client.
Colocation web hosting service: similar to the dedicated web hosting service, but the user owns the colo server; the hosting company provides physical space that the server takes up and takes care of the server. This is the most powerful and expensive type of web hosting service. In most cases, the colocation provider may provide little to no support directly for their client's machine, providing only the electrical, Internet access, and storage facilities for the server. In most cases for colo, the client would have his own administrator visit the data center on site to do any hardware upgrades or changes.
Cloud Hosting: is a new type of hosting platform that allows customers powerful, scalable and reliable hosting based on clustered load-balanced servers and utility billing. Removing single-point of failures and allowing customers to pay for only what they use versus what they could use.
Clustered hosting: having multiple servers hosting the same content for better resource utilization. Clustered Servers are a perfect solution for high-availability dedicated hosting, or creating a scalable web hosting solution. A cluster may separate web serving from database hosting capability. (Usually Web hosts use Clustered Hosting for their Shared hosting plans, as there are multiple benefits to the mass managing of clients)
Grid hosting: this form of distributed hosting is when a server cluster acts like a grid and is composed of multiple nodes.
Home server: usually a single machine placed in a private residence can be used to host one or more web sites from a usually consumer-grade broadband connection. These can be purpose-built machines or more commonly old PCs. Some ISPs actively attempt to block home servers by disallowing incoming requests to TCP port 80 of the user's connection and by refusing to provide static IP addresses. A common way to attain a reliable DNS hostname is by creating an account with a dynamic DNS service. A dynamic DNS service will automatically change the IP address that a URL points to when the IP address changes.
Some specific types of hosting provided by web host service providers:
File hosting service: hosts files, not web pagesImage hosting service
A web hosting service is a type of Internet hosting service that allows individuals and organizations to make their own website accessible via the World Wide Web. Web hosts are companies that provide space on a server they own or lease for use by their clients as well as providing Internet connectivity, typically in a data center. Web hosts can also provide data center space and connectivity to the Internet for servers they do not own to be located in their data center, called colocation or Housing as it is commonly called in Latin America or France.
The scope of hosting services varies widely. The most basic is web page and small-scale file hosting, where files can be uploaded via File Transfer Protocol (FTP) or a Web interface. The files are usually delivered to the Web "as is" or with little processing. Many Internet service providers (ISPs) offer this service free to their subscribers. People can also obtain Web page hosting from other, alternative service providers. Personal web site hosting is typically free, advertisement-sponsored, or inexpensive. Business web site hosting often has a higher expense.
Single page hosting is generally sufficient only for personal web pages. A complex site calls for a more comprehensive package that provides database support and application development platforms (e.g. PHP, Java, Ruby on Rails, ColdFusion, and ASP.NET). These facilities allow the customers to write or install scripts for applications like forums and content management. For e-commerce, SSL is also highly recommended.
The host may also provide an interface or control panel for managing the Web server and installing scripts as well as other services like e-mail. Some hosts specialize in certain software or services (e.g. e-commerce). They are commonly used by larger companies to outsource network infrastructure to a hosting company.
