Gopher (protocol)

  From Wikipedia, the free encyclopedia

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  The Gopher protocol ( play  /|goUf@r/) is a TCP/IP application layer protocol designed for distributing, searching, and retrieving documents over the Internet.
  Strongly oriented towards a menu-document design, the Gopher protocol presented an alternative to the World Wide Web in its early stages, but ultimately HTTP
  became the dominant protocol. The Gopher ecosystem is often regarded as the effective predecessor of the World Wide Web.

  Invented by a team led by Mark P. McCahill at the University of Minnesota, the protocol offers some features not natively supported by the Web and imposes a
  much stronger hierarchy on information stored on it. Its text menu interface is easy to use,^[1] and well-suited to computing environments that rely heavily on
  remote text-oriented computer terminals, which were still common at the time of its creation in 1991, and the simplicity of its protocol facilitated a wide
  variety of client implementations. More recent Gopher revisions and graphical clients added support for multimedia.^[1] Gopher was preferred by many network
  administrators for using fewer network resources than Web services.^[2]

  With its hierarchical structure, Gopher provided a useful platform for the first large-scale electronic library connections.^[3] Gopher users remember the
  system as being "faster and more efficient and so much more organised" than today's Web services.^[4] Although largely supplanted by the Web in the years
  following, the Gopher protocol is still in use by enthusiasts, and a small population of actively maintained servers remains.

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[edit] Origins

  The original Gopher system was released in late spring of 1991 by Mark McCahill, Farhad Anklesaria, Paul Lindner, Daniel Torrey, and Bob Alberti of the
  University of Minnesota.^[5] Its central goals were, as stated in RFC 1436:
    * A file-like hierarchical arrangement that would be familiar to users.
    * A simple syntax.
    * A system that can be created quickly and inexpensively.
    * Extending the file system metaphor, such as searches.

  Gopher combines document hierarchies with collections of services, including WAIS, the Archie and Veronica search engines, and gateways to other information
  systems such as FTP and Usenet.

  The general interest in Campus-Wide Information Systems (CWISs)^[6] in higher education at the time, and the ease with which a Gopher server could be set up to
  create an instant CWIS with links to other sites' online directories and resources were the factors contributing to Gopher's rapid adoption. By 1992, the
  standard method of locating someone's e-mail address was to find their organization's CCSO nameserver entry in Gopher, and query the nameserver.^[7]

  The name was coined by Anklesaria^[8] as a play off of several meanings of the word "gopher." The University of Minnesota mascot is the gopher,^[9] a gofer
  (same sound) is an assistant who "goes for" things, and a gopher burrows through the ground to reach a desired location.

[edit] Stagnation

  The World Wide Web was in its infancy in 1991, and Gopher services quickly became established. By the late 1990s, Gopher had largely ceased expanding. Several
  factors contributed to Gopher's stagnation:
    * In February 1993, the University of Minnesota announced that it would charge licensing fees for the use of its implementation of the Gopher server.^[10] As
      a consequence of this, some users were concerned that a licensing fee would also be charged for independent implementations.^[11]^[12] Users were scared
      away from Gopher technology, to the advantage of the Web, which CERN disclaimed ownership of.^[13] In September 2000, the University of Minnesota
      re-licensed its Gopher software under the GNU GPL.^[14]^[15]
    * Gopher client functionality was quickly duplicated by early Web browsers, such as Mosaic, which subsumed the protocol as part of their functions.
    * Gopher has a more rigid structure compared to the free-form HTML of the Web. With Gopher, every document has a defined format and type, and the typical
      user navigates through a single server-defined menu system to get to a particular document. This can be quite different from the way a typical user might
      traverse documents on the Web.

  Gopher remains in active use by its enthusiasts, and there have been attempts to revive the use of Gopher on modern platforms and mobile devices. One such
  attempt is The Overbite Project, which hosts various browser extensions and modern clients.

  As of 2012^[update], there are approximately 160 gopher servers indexed by Veronica-2,^[16] reflecting a slow growth from 2007 when there were fewer than
  100,^[17] although many are infrequently updated. Within these servers Veronica indexed approximately 2.5 million unique selectors. A handful of new servers
  are set up every year by hobbyists - over 50 have been set up and added to Floodgap's list since 1999.^[18] A snapshot of Gopherspace as it was in 2007 was
  circulated on BitTorrent and is still available.^[19] Due to the simplicity of the Gopher protocol, setting up new servers or adding Gopher support to browsers
  is often done in a tongue in cheek manner, principally on April Fools' Day.^[20]^[21]

[edit] Native Gopher support

  Browser Currently Supported Supported from Supported until Notes
  Camino Yes 1.0 current Always uses port 70.
  Classilla Yes 9.0 current Hardcoded to port 70 from 9.0-9.2; whitelisted ports from 9.2.1.
  cURL Yes 7.21.2 (October 2010) current cURL is a command-line file transfer utility
  ELinks Beta^[22] Build option
  Epiphany No 2.26.3 Disabled after switch to WebKit
  Galeon Yes current
  Google Chrome No^[23] never An extension to automatically forward to Gopher proxies is available.
  Internet Explorer No 1 6.0 RTM IE 6 requires registry patch to re-enable.^[24] Always uses port 70.
  Internet Explorer for Mac (discontinued) No 5.2.3 PowerPC-only
  K-Meleon Yes current
  Konqueror Plugin kio_gopher
  lftp Yes ? current lftp is a command-line file transfer program
  libwww Yes 1.0c (December 1992) current libwww is an API for internet applications
  Line Mode Browser Yes 1.1 (January 1992) current
  Lynx Yes current Complete support
  Mozilla Firefox Addon 0 3.6 Always uses port 70. Built-in support dropped from Firefox 4.0 onwards;^[25] can be added back with OverbiteFF.
  Netscape Navigator (discontinued) Yes  ? 9.0.0.6
  NetSurf No Under development, based on the cURL fetcher.
  OmniWeb Yes 5.9.2 (April 2009) current First WebKit Browser to support Gopher^[26]^[27]
  Opera No never Opera 9.0 includes a proxy capability
  Pavuk Yes ? current Pavuk is a web mirror (recursive download) software
  Safari No never
  SeaMonkey Addon 1.0 2.0.14 Always uses port 70. Built-in support dropped from SeaMonkey 2.1 onwards; compatible with OverbiteFF.

  Browsers that do not natively support Gopher can still access servers using one of the available Gopher to HTTP gateways.

  Gopher support was disabled in Internet Explorer versions 5 and 6 for Windows in June 2002 by a patch meant to fix a security vulnerability in the browser's
  Gopher protocol handler; however, it can be re-enabled by editing the Windows registry. In Internet Explorer 7, Gopher support was removed on the WinINET
  level.^[28]

[edit] Gopher browser plugins

  For Mozilla Firefox and SeaMonkey, OverbiteFF extends Gopher browsing and supports Firefox 4. It includes support for accessing Gopher servers not on port 70
  using a whitelist and for CSO/ph queries, and allows versions of Firefox and SeaMonkey that do not support Gopher natively to access Gopher servers. Plugins
  are also available for Konqueror^[29] and a proxy-based extension for Google Chrome.^[30]

[edit] Gopher clients for mobile devices

  Some have suggested that the bandwidth-sparing simple interface of Gopher would be a good match for mobile phones and personal digital assistants (PDAs),^[31]
  but so far, mobile adaptations of HTML and XML and other simplified content have proven more popular. The PyGopherd server provides a built-in WML front-end to
  Gopher sites served with it.

  The early 2010s have seen a renewed interest in native Gopher clients for popular Smartphones. Overbite, an open source client for Android 1.5+ was released in
  alpha stage in 2010.^[32] PocketGopher was also released in 2010, along with its source code, for several Java ME compatible devices. iGopher was released in
  2011 as a proprietary client for iPhone and iPad devices.

[edit] Other Gopher clients

  Gopher was at its height of popularity during a time when there were still many equally competing computer architectures and operating systems. As such, there
  are several Gopher clients available for Acorn RISC OS, AmigaOS, Atari MiNT, CMS, DOS, classic Mac OS, MVS, NeXT, OS/2 Warp, most UNIX-like operating systems,
  VMS, Windows 3.x, and Windows 9x. GopherVR was a client designed for 3D visualization, and there is even a Gopher client MOO object. The majority of these
  clients are hard coded to work on TCP port 70.

[edit] Gopher to HTTP gateways

  Users of Web browsers that have incomplete or no support for Gopher can access content on Gopher servers via a server gateway or proxy server that converts
  Gopher menus into HTML; known proxies are the Floodgap Public Gopher proxy, Gopher Proxy, and the WikkaGopher proxy. Similarly, certain server packages such as
  GN and PyGopherd have built-in Gopher to HTTP interfaces. Squid Proxy software gateways any gopher:// URL to HTTP content, enabling any browser or web agent to
  access gopher content easily.

[edit] Gopher characteristics

  As part of its design goals, Gopher functions and appears much like a mountable read-only global network file system (and software, such as gopherfs, is
  available that can actually mount a Gopher server as a FUSE resource). At a minimum, whatever a person can do with data files on a CD-ROM, they can do on
  Gopher.

  A Gopher system consists of a series of hierarchical hyperlinkable menus. The choice of menu items and titles is controlled by the administrator of the server.
  The top level menu of a Gopher server. Selecting the "Fun and Games" menu item...
                                                                                   ...takes the user to the "Fun and Games" menu.

  Similar to a file on a Web server, a file on a Gopher server can be linked to as a menu item from any other Gopher server. Many servers take advantage of this
  inter-server linking to provide a directory of other servers that the user can access.

[edit] Technical details

[edit] Protocol

  The Gopher protocol was first described in RFC 1436. IANA has assigned TCP port 70 to the Gopher protocol.

  The protocol is simple to negotiate, making it possible to browse without using a client. A standard gopher session may therefore appear as follows:
/Reference
1CIA World Factbook     /Archives/mirrors/textfiles.com/politics/CIA    gopher.quux.org 70
0Jargon 4.2.0   /Reference/Jargon 4.2.0 gopher.quux.org 70      +
1Online Libraries       /Reference/Online Libraries     gopher.quux.org 70     +
1RFCs: Internet Standards       /Computers/Standards and Specs/RFC      gopher.quux.org 70
1U.S. Gazetteer /Reference/U.S. Gazetteer       gopher.quux.org 70      +
iThis file contains information on United States        fake    (NULL)  0
icities, counties, and geographical areas.  It has      fake    (NULL)  0
ilatitude/longitude, population, land and water area,   fake    (NULL)  0
iand ZIP codes. fake    (NULL)  0
i       fake    (NULL)  0
iTo search for a city, enter the city's name.  To search        fake    (NULL) 0
ifor a county, use the name plus County -- for instance,        fake    (NULL) 0
iDallas County. fake    (NULL)  0

  Here, the client has established a TCP connection with the server on port 70, the standard gopher port. The client then sends a string followed by a carriage
  return followed by a line feed (a "CR + LF" sequence). This is the selector, which identifies the document to be retrieved. If the item selector were an empty
  line, the default directory would be selected. The server then replies with the requested item and closes the connection. According to the protocol, before the
  connection is closed, the server should send a full-stop (i.e., a period character) on a line by itself. However, as is the case here, not all servers conform
  to this part of the protocol and the server may close the connection without returning the final full-stop.

  In this example, the item sent back is a gopher menu, a directory consisting of a sequence of lines each of which describes an item that can be retrieved. Most
  clients will display these as hypertext links, and so allow the user to navigate through gopherspace by following the links.^[5]

  All lines in a gopher menu are terminated by "CR + LF", and consist of five fields: the item type as the very first character (see below), the display string
  (i.e., the description text to display), a selector (i.e., a file-system pathname), host name (i.e., the domain name of the server on which the item resides),
  and port (i.e., the port number used by that server). The item type and display string are joined without a space; the other fields are separated by the tab
  character.

  Because of the simplicity of the Gopher protocol, tools such as netcat make it possible to download Gopher content easily from the command line:
echo jacks/jack.exe | nc gopher.example.org 70 > jack.exe

  The protocol is also supported by cURL as of 7.21.2-DEV.^[33]

[edit] Gopher item types

  Item types are described in gopher menus by a single number or (case specific) letter and act as hints to the client to tell it how to handle a specific media
  type in a menu, analogous to a MIME type. Every client necessarily must understand itemtypes 0 and 1. All known clients understand item types 0 through 9, g,
  and s, and all but the very oldest also understand file-types h and i.
    * 0 = plain text file
    * 1 = directory menu listing
    * 2 = CSO search query
    * 3 = error message
    * 4 = BinHex encoded text file
    * 5 = binary archive file
    * 6 = UUEncoded text file
    * 7 = search engine query
    * 8 = telnet session pointer
    * 9 = binary file
    * g = GIF image
    * h = HTML file
    * i = informational message
    * I = Image file of unspecified format. Client decides how to display. Often used for JPEG images.
    * s = Audio file format, primarily a WAV file
    * T = tn3270 session pointer

  A list of additional file-type definitions has continued to evolve over time, with some clients supporting them and others not. As such, many servers assign
  the generic 9 to every binary file, hoping that the client's computer will be able to correctly process the file.

[edit] URL links

  Historically, to create a link to a Web server, "GET /" was used as a pseudo-selector to simulate an HTTP client request. John Goerzen created an addition^[34]
  to the Gopher protocol, commonly referred to as "URL links", that allows links to any protocol that supports URLs. For example, to create a link to
  http://gopher.quux.org/, the item type is "h", the display string is the title of the link, the item selector is "URL:http://gopher.quux.org/", and the domain
  and port are that of the originating Gopher server (so that clients that do not support URL links will query the server and receive an HTML redirection page).

[edit] Related technology

  The master Gopherspace search engine is Veronica. Veronica offers a keyword search of all the public Internet Gopher server menu titles. A Veronica search
  produces a menu of Gopher items, each of which is a direct pointer to a Gopher data source. Individual Gopher servers may also use localized search engines
  specific to their content such as Jughead and Jugtail.

  GopherVR is a 3D virtual reality variant of the original Gopher system.

[edit] Gopher server software

  Because the protocol is trivial to implement in a basic fashion, there are many server packages still available, and some are still maintained.
    * Aftershock - written in Java.
    * Bucktooth - modern gopher server written in Perl.
    * Geomyidae - written in C. MIT X Consortium License.
    * GN
    * GoFish
    * Gophernicus - Linux, BSD License.
    * gophrier - An open source gopher server written in C
    * GOPHSERV - cross-platform, GPLv3, FreeBASIC.
    * Gopher Cannon - Windows (Win32/Win64), freeware, written in .NET 3.5
    * Goscher - written in Scheme.
    * Grumpy - Linux, GPLv3, written in FreeBASIC.
    * mgod
    * PyGopherd - modern gopher+ server written in Python.
    * PyGS
    * Motsognir open-source gopher server

    * gopherfs - a gopher filesystem FUSE abstraction

[edit] See also

  Portal icon Computer Science portal
    * Veronica - the search engine system for the Gopher protocol, an acronym for "Very Easy Rodent-Oriented Net-wide Index to Computer Archives"
    * Gopher+ - early proposed extensions to the Gopher protocol
    * GopherVR
    * Jugtail - an alternative search engine system for the Gopher protocol. Jugtail was formerly known as Jughead.
    * SDF Public Access Unix System - a non-profit organization which provides free Gopher hosting
    * Phlog - The gopher version of a weblog
    * Wide area information server - a search engine whose popularity was contemporary with Gopher

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[edit] Standards

    * IANA Port Number allocations
    * RFC 1436 - The Internet Gopher Protocol (a distributed document search and retrieval protocol)
    * RFC 1580 - Guide to Network Resource Tools
    * RFC 1689 - Networked Information Retrieval: Tools and Groups
    * RFC 1727 - A Vision of an Integrated Internet Information Service
    * RFC 1738 - Uniform Resource Locators (URL)
    * RFC 1808 - Relative Uniform Resource Locators
    * RFC 2396 - Uniform Resource Identifiers (URI): Generic Syntax
    * RFC 4266 - The gopher URI Scheme

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  Early web browsers (up to 1996)
    * Comparison
    * History
    * List
         + for Unix
    * Timeline
    * Usage share

    1990
             * WorldWideWeb (Nexus)

    1991
             * Line Mode Browser (libwww)

    1992
             * ViolaWWW
             * Erwise
             * MidasWWW
             * MacWWW (Samba)
             * tkWWW

    1993
             * NCSA Mosaic
             * AMosaic
             * VMS Mosaic
             * Cello
             * Lynx (2.0)
             * Arena
             * Emacs/W3

    1994
             * IBM WebExplorer
             * Netscape Navigator
             * MicroMind SlipKnot (1.0)
             * TradeWave MacWeb
             * IBrowse
             * Navipress
             * Argo
             * Minuet
             * AIR Mosaic (Internet in a Box)
             * Spyglass Mosaic
             * TCP/Connect II
             * ANT Fresco

    1995
             * Internet Explorer 1
             * Netscape Navigator 2.0
             * OmniWeb
             * Sun WebRunner (HotJava)
             * Grail
             * Internet Explorer 2
             * Delrina Cyberjack
             * AOL Web Browser for Macintosh
             * eWorld Web Browser for Macintosh
             * NetShark
             * WebShark
             * Opera
             * AMSD Ariadna
             * UdiWWW
             * ALynx
             * Agora

    1996
             * Arachne 1.0
             * Internet Explorer 3
             * Netscape Navigator 3.0
             * Oracle PowerBrowser
             * Apple Cyberdog
             * INRIA Amaya (.9)
             * AWeb
             * VaporWare Voyager
             * tcpCONNECT4

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  Gopher
     Active clients

                       Free/open source
                                          * Amaya
                                          * Arachne
                                          * Camino
                                          * Classilla
                                          * Conkeror
                                          * ELinks
                                          * Gnuzilla
                                          * K-Meleon
                                          * K-Ninja
                                          * Kazehakase
                                          * Line Mode Browser
                                          * Lynx
                                          * Songbird
                                          * Mothra
                                          * W3m
                                          * xB Browser

                         Proprietary
                                          * Mosaic-CK
                                          * OmniWeb
                                          * Sleipnir
                                          * VMS Mosaic

  Discontinued clients
                         * Agora
                         * Arena
                         * AT&T Pogo
                         * Beonex Communicator
                         * Cello
                         * Cyberjack
                         * Galeon
                         * IBrowse
                         * Internet Explorer for Mac
                         * Minimo
                         * Minuet
                         * Mosaic
                         * Mozilla Application Suite
                         * Netscape Browser
                         * Netscape Communicator
                         * Netscape Navigator 9
                         * SlipKnot
                         * tkWWW
                         * UdiWWW

  Previously supported
                         * Epiphany
                         * Mozilla Firefox
                         * Flock
                         * Internet Explorer
                         * SeaMonkey

    Server software
                         * Bucktooth
                         * PyGopherd
                         * Squid

        Persons
                         * Mark P. McCahill

        See also
                         * Gopher+
                         * GopherVR
                         * Jughead
                         * Libwww
                         * Phlog
                         * SDF Public Access Unix System
                         * Veronica
                         * CCSO Nameserver
                         * Wide area information server

  Retrieved from "http://en.wikipedia.org/w/index.php?title=Gopher_(protocol)&oldid=515846584"

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