In computing Computing, also known as computer science, is usually defined as the activity of using and improving computer technology, computer hardware and software. It is the computer-specific part of information technology. Computer science is the study and the science of the theoretical foundations of information and computation and their implementation, a mirror is an exact copy of a data The term data refers to groups of information that represent the qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which information and set. On the Internet The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks of local to global scope that are linked by a broad array of electronic and, a mirror site is an exact copy of another Internet site. Mirror sites are most commonly used to provide multiple sources of the same information, and are of particular value as a way of providing reliable access to large downloads. Mirroring is a type of file synchronization File synchronization in computing is the process of making sure that files in two or more locations are updated through certain rules.[citation needed].
A live mirror is automatically updated as soon as the original is changed.
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Reasons
Mirroring of sites occurs for a variety of reasons.
- To preserve a website or page, especially when it is closed or is about to be closed.
- To allow faster downloads for users at a specific geographical location. For example, a U.S. ^ b. English is the de facto language of American government and the sole language spoken at home by 80% of Americans age five and older. Spanish is the second most commonly spoken language server could be mirrored in Japan Japan is an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south. The characters that make up Japan's name mean "sun-origin", which is why Japan is, allowing Japanese Internet users to download content faster from the local Japanese server than from the original American one. This may be viewed as caching In computer science, a cache is a component that improves performance by transparently storing data such that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere. If requested data is contained in the on a worldwide scale.
- To counteract censorship Strict censorship existed in the Eastern Bloc. Throughout the bloc, the various ministries of culture held a tight rein on their writers. Cultural products there reflected the propaganda needs of the state. Party-approved censors exercised strict control in the early years. In the Stalinist period, even the weather forecasts were changed if they and promote freedom of information Freedom of information refers to the protection of the right to freedom of expression with regards to the Internet and information technology (see also, digital rights). Freedom of information may also concern censorship in an information technology context, i.e. the ability to access Web content, without censorship or restrictions. For example, an activist Activism consists of intentional action to bring about social, political, economic, or environmental change. This action is in support of, or opposition to, one side of an often controversial argument. In contemporary use, "activism" tends to be a word associated with the actions and ideologies of those on the political left might post pictures on a website of a company conducting illegal activities or make available information on secret government activity and be litigated A lawsuit, or "suit in law", is a civil action brought before a court of law in which a plaintiff, a party who claims to have received damages from a defendant's actions, seeks a legal or equitable remedy. The defendant is required to respond to the plaintiff's complaint. If the plaintiff is successful, judgment will be given in the for such. Other internet users will make the content in question available on other servers when the legal action results in the cancellation of ISP An Internet service provider , also sometimes referred to as an Internet access provider (IAP), is a company that offers its customers access to the Internet[citation needed]. The ISP connects to its customers using a data transmission technology appropriate for delivering Internet Protocol Paradigm, such as dial-up, DSL, cable modem, wireless or or DNS The Domain Name System is a hierarchical naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participants. Most importantly, it translates domain names meaningful to humans into the numerical (binary) identifiers services for the original activist.
- To provide access to otherwise unavailable information. For example, when the popular Google Google Inc. is a multinational public cloud computing, Internet search, and advertising technologies corporation. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program. The company was founded by Larry Page and Sergey Brin, often dubbed the " search engine was banned in 2002 by the People's Republic of China b. ^ Simple characterizations of the political structure since the 1980s are no longer possible, the mirror elgooG elgooG is the literal mirror image of the Google search engine; that is, elgooG displays all text on all web pages cached by Google in reverse. Though originally created "for fun", it has found practical use in mainland China after the domestic banning of Google was used as a way of effectively circumventing the ban.
- To preserve historic content. Financial constraints and/or bandwidth prevent the maintainers of a server from keeping older and unsupported content available to users who still may desire them - a mirror may be made to prevent this content from disappearing.
- To balance load. If one server is extremely popular a mirror may help relieve this load: for example if a Linux Linux refers to the family of Unix-like computer operating systems using the Linux kernel. Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2009 it held a server market share distribution is released as an ISO image An ISO image is an archive file of an optical disc in a format defined by the International Organization for Standardization (ISO). This format is supported by many software vendors. ISO image files typically have a file extension of .ISO. The name ISO is taken from the ISO 9660 file system used with CD-ROM media, but an ISO image can also contain onto the distribution developer's own server, this server may become overloaded with demand. Alternative download points allow the total number of download requests to be spread among several servers, maintaining the availability of the distribution. Metalink Metalink is a cross-platform and cross-application Internet standard/framework/file format for programs that download, including download managers, BitTorrent clients, Web browsers, FTP clients, and P2P programs. For increased convenience, it stores the multiple download locations for a file and other metadata in an XML file with the extension is frequently used for automatic load balancing by listing all mirrors.
- As a temporary measure to counterbalance a sudden, temporary increase in traffic Web traffic is the amount of data sent and received by visitors to a web site. It is a large portion of Internet traffic. This is determined by the number of visitors and the number of pages they visit. Sites monitor the incoming and outgoing traffic to see which parts or pages of their site are popular and if there are any apparent trends, such. For example, Slashdotted The Slashdot effect, also known as slashdotting, occurs when a popular website links to a smaller site, causing a massive increase in traffic. This overloads the smaller site, causing it to slow down or even temporarily close. The name stems from the huge influx of web traffic that results from the technology news site Slashdot linking to websites websites will often be mirrored by a few slashdot Slashdot is a technology-related news website owned by Geeknet, Inc. The site, which bills itself as "News for Nerds. Stuff that Matters", features user-submitted and ‑evaluated current affairs news stories about science- and technology-related topics. Each story has a comments section attached to it. Slashdot was founded in 1997 as a posters until the article is pushed off the front page.
- To increase a site's ranking in a search engine A web search engine is designed to search for information on the World Wide Web. The search results are generally presented in a list of results and are often called hits. The information may consist of web pages, images, information and other types of files. Some search engines also mine data available in databases or open directories. Unlike Web by placing hyperlinks In computing, a hyperlink is a reference to a document that the reader can directly follow, or that is followed automatically[citation needed]. The reference points to a whole document or to a specific element within a document. Hypertext is text with hyperlinks. Such text is usually viewed with a computer. A software system for viewing and from each mirror to every other mirror (a technique known as link farming On the World Wide Web, a link farm is any group of web sites that all hyperlink to every other site in the group. Although some link farms can be created by hand, most are created through automated programs and services. A link farm is a form of spamming the index of a search engine . Other link exchange systems are designed to allow individual). This is viewed as unethical Ethics is a branch of philosophy that addresses questions about morality — that is, concepts such as good and evil, right and wrong, justice, virtue, etc by most search engine administrators and websurfers.
- Rarely, as a form of plagiarism The 18th century new morals have been institutionalized and enforced prominently in the sectors of academia and journalism, where plagiarism is now considered academic dishonesty and a breach of journalistic ethics, subject to sanctions like expulsion and othere severe career damages. Not so in the arts, which have resisted in their long-; this is, however, usually pointless, as a website popular enough to be worth plagiarizing will quickly discover the copy as soon as one of their many readers stumbles onto the plagiarized site.
- As a form of raising advertising revenue. Wikipedia Wikipedia is a free, web-based, collaborative, multilingual encyclopedia project supported by the non-profit Wikimedia Foundation. Its 16 million articles have been written collaboratively by volunteers around the world, and almost all of its articles can be edited by anyone with access to the site. Wikipedia was launched in 2001 by Jimmy Wales is probably the best example of material released under the GNU Free Documentation License The GNU Free Documentation License is a copyleft license for free documentation, designed by the Free Software Foundation (FSF) for the GNU Project. It is similar to the GNU General Public License, giving readers the rights to copy, redistribute, and modify a work and requires all copies and derivatives to be available under the same license which is then duplicated by other companies which, unlike Wikipedia, then attempt to generate money from advertising, etc. See Wikipedia:Mirrors and forks.
- To serve as a method of circumventing firewalls.
Examples
A good example of mirroring is the well-known SOURCEFORGE.NET website. The basis of the Sourceforge SourceForge is a web-based source code repository. It acts as a centralized location for software developers to control and manage open source software development. The website is operated by Geeknet and runs a version of SourceForge Enterprise Edition, forked from the last open-source version available. As of February 2009[update], the concept is, primarily, the hosting of open-source software Open-source software is computer software that is available in source code form for which the source code and certain other rights normally reserved for copyright holders are provided under a software license that permits users to study, change, and improve the software. Open source licenses often meet the requirements of the Open Source projects, but secondarily the use of many different locations to achieve one goal: to maintain download availability to the user. Many innovative computer A computer is a programmable machine that receives input, stores and manipulates data//information, and provides output in a useful format projects host their sites and software on SourceForge, which provides mirrors in several countries A country is a geographical region considered to be the physical territory of a sovereign state, or of a smaller, or former, political division within a geographical region. Usually, but not always, a country coincides with a sovereign territory and is associated with a state, nation or government, from Dublin Dublin is the primate and capital city of Ireland. It is officially known in Irish as Baile Átha Cliath [bˠalʲə aːha klʲiəh] or Áth Cliath [aːh cliə(ɸ)]. The English name comes from the Irish Dubh Linn meaning "black pool". It is located near the midpoint of Ireland's east coast, at the mouth of the River Liffey and at the, Ireland Ireland (pronounced [ˈaɾlənd],; Irish: Éire, pronounced [ˈeːɾʲə] ( listen); Ulster Scots: Airlann) is the third-largest island in Europe and the twentieth-largest island in the world. It lies to the northwest of continental Europe and is surrounded by hundreds of islands and islets. To the east of Ireland is Great Britain, separated from to Tokyo Tokyo , officially Tokyo Metropolis (東京都, Tōkyō-to?), is one of the 47 prefectures of Japan. It is located on the eastern side of the main island Honshū and includes the Izu Islands and Ogasawara Islands. Tokyo Metropolis was formed in 1943 from the merger of the former Tokyo Prefecture (Tokyo-fu) and the city of Tokyo. Tokyo is the, Japan Japan is an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south. The characters that make up Japan's name mean "sun-origin", which is why Japan is.
Examples of even larger mirrored networks include those of the Debian Debian is a computer operating system composed of software packages released as free and open source software especially under the GNU General Public License and other free software licenses. The primary form, Debian GNU/Linux, which uses the Linux kernel and GNU OS tools, is a popular and influential GNU/Linux distribution. It is distributed with[1], Ubuntu Ubuntu , is a computer operating system based on the Debian GNU/Linux distribution[2] and FreeBSD FreeBSD is a free Unix-like operating system descended from AT&T UNIX via the Berkeley Software Distribution . It has been characterized as "the unknown giant among free operating systems". It is not a clone of UNIX, but works like UNIX, with UNIX-compliant internals and system APIs. FreeBSD is generally regarded as reliable and software projects. The encyclopedia Wikipedia Wikipedia is a free, web-based, collaborative, multilingual encyclopedia project supported by the non-profit Wikimedia Foundation. Its 16 million articles have been written collaboratively by volunteers around the world, and almost all of its articles can be edited by anyone with access to the site. Wikipedia was launched in 2001 by Jimmy Wales is mirrored at numerous locations.
Software
There are numerous offline browsers The terms "online" and "offline" have specific meanings in regards to computer technology and telecommunications. In general, "online" indicates a state of connectivity, while "offline" indicates a disconnected state. In common usage, "online" often refers to the Internet or the World Wide Web that provide automated mirroring of entire sites. Some are oriented towards personal use, which allows browsing from a local copy — this means an initial waiting time but much improved load time for those pages once they're mirrored.
Other programs are intended to be used by public mirror maintainers.
- CVSup CVSup is a computer program written for Unix/Linux based systems that synchronizes files and directories from one location to another while minimizing data transfer using file-type specific delta encoding when appropriate. CVSup was designed for keeping source code repositories - such as CVS - synchronized, but has been extended to support
- rsync rsync is a software application for Unix systems which synchronizes files and directories from one location to another while minimizing data transfer using delta encoding when appropriate. An important feature of rsync not found in most similar programs/protocols is that the mirroring takes place with only one transmission in each direction. rsync
Free file mirroring software includes MMup by MassMirror and wget GNU Wget is a computer program that retrieves content from web servers, and is part of the GNU Project. Its name is derived from World Wide Web and get, connotative of its primary function (See also HTTP GET). It currently supports downloading via HTTP, HTTPS, and FTP protocols, the most popular TCP/IP-based protocols used for web browsing, mirror and mirrordir available as add ons for many Linux Linux refers to the family of Unix-like computer operating systems using the Linux kernel. Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2009 it held a server market share distributions.
See also
- Coral CDN The Coral Content Distribution Network, sometimes called Coral Cache or Coral, is a free peer-to-peer content distribution network. Coral uses the bandwidth of volunteers to mirror web content, often to avoid the Slashdot Effect or to reduce the load on websites in general
- Disk mirroring In data storage, disk mirroring or RAID1 is the replication of logical disk volumes onto separate physical hard disks in real time to ensure continuous availability. A mirrored volume is a complete logical representation of separate volume copies. File:Wikimedia.org/wikipedia/commons/0/05/Raid1 Version for Wiki.jpg
- Offline browsing The terms "online" and "offline" have specific meanings in regards to computer technology and telecommunications. In general, "online" indicates a state of connectivity, while "offline" indicates a disconnected state. In common usage, "online" often refers to the Internet or the World Wide Web
- Website mirroring software Website mirroring software is software that allows one to download a copy of an entire website to the local hard disk for offline browsing. In effect, the downloaded copy serves as a mirror of the original site
References
- ^ "Debian mirrors". Debian. http://www.debian.org/mirror/. Retrieved 2010-02-19.
- ^ "Mirrors - Ubuntu Wiki". Ubuntu. https://wiki.ubuntu.com/Mirrors. Retrieved 2010-02-19.
Categories: Data management | Web technology | Black hat search engine optimization
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It was all a smoke and mirror , bait and switch play to get something they wanted forced on the parties that were really interested in the spectrums. ...
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