Gopher protocol

Gopher is a distributed document search and retrieval network protocol designed for the Internet. Its goal was similar to that of the World Wide Web, and it has been almost completely displaced by the Web.

The Gopher protocol offers some features not natively supported by the Web and imposes a much stronger hierarchy on information stored in it. Its text menu interface is well-suited to computing environments that rely heavily on remote computer terminals, common in universities at the time of its creation. Some consider it to be the superior protocol for storing and searching large repositories of information.

History

Origins

The original Gopher system was released in late spring of 1991 by Mark McCahill, Farhad Anklesaria, Paul Lindner, Dan Torrey, and Bob Alberti of the University of Minnesota. Its central goals were:
* 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 to include things like searches

The source of the name "Gopher" is claimed to be three-fold:# Users instruct it to "go for" information# It does so through a web of menu items analogous to gopher holes# The sports team of the University of Minnesota is the Golden Gophers

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) Google Groups archive of bit.listserv.cwis-l discussion 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 CSO nameserver entry in Gopher, and query the nameserver Google Groups archive of comp.infosystems.gopher discussion.

The exponential scaling of utility in social networked systems (Reed's law) seen in Gopher, and then the web, is a common feature of networked hypermedia systems with distributed authoring. In 1993–1994, Web pages commonly contained large numbers of links to Gopher-delivered resources, as the Web continued Gopher's embrace and extend tradition of providing gateways to other services.

Decline

The World Wide Web was in its infancy in 1991, and Gopher services quickly became established. However, by the late 1990s, Gopher had almost disappeared. Insofar as information management is concerned, the progress from gopher to the web as a standard can be seen simply as a natural progression from text-based to graphical interfaces . Several other factors contributed to the acceleration of Gopher's decline:
*In February of 1993, the University of Minnesota announced that they would charge licensing fees for the use of their implementation of the Gopher server. http://www.funet.fi/pub/vms/networking/gopher/gopher-software-licensing-policy.ancient As a consequence of this some users suspected that a licensing fee would be also charged for independent implementations. http://groups.google.com/groups?selm=1mj6cb$6gm@pith.uoregon.edu http://groups.google.com/groups?selm=36e4c2f1.10244576@nntp.best.ix.netcom.com In contrast, there was no such limitation on the World Wide Web. The University of Minnesota eventually re-licensed their Gopher software under the GNU GPL ftp://boombox.micro.umn.edu/pub/gopher/gopher-software-licensing-policy.new.
*Gopher's functionality was quickly duplicated by early Web browsers, such as Mosaic. Furthermore, the greater flexibility of the Web's HTML, and particularly its integration of text and graphics, encouraged the migration of content from Gopher to the World Wide Web .
*Gopher has an inflexible structure when compared to the free-form HTML of the Web. With Gopher, every document has a defined format and type, and the typical user must navigate through a single server-defined menu system to get to a particular document. Many people did not like the artificial distinction between menu and fixed document in the Gopher system, and found the Web's open-ended flexibility much more useful for constructing interrelated sets of documents and interactive applications.

Availability of Gopher today

As of 2006, there are still a few Gopher servers present on the net, in organizations such as the Smithsonian Institution and the US government; a few are also being maintained by enthusiasts of the protocol, where almost all growth is occurring.

Some have suggested that the bandwidth-sparing simple interface of Gopher would be a good match for mobile phones and Personal digital assistants (PDAs), but so far, the market prefers Wireless Markup Language (WML)/Wireless Application Protocol (WAP), DoCoMo i-mode, XHTML Basic or other adaptations of HTML and XML. The PyGopherd server, however, provides a built-in WML front-end to Gopher sites served with it.

Gopher characteristics

A Gopher system consists of a series of hierarchical menus. The choice of menu items and titles is set 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.

A Gopher menu listing other accessible servers.

Gopher menu from a terminal client.

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.

Technical details

Protocol

The Gopher protocol is documented in RFC 1436. It is traditionally served on TCP port 70.

After the client has established a TCP connection with the server, it sends a line that contains the item selector, a string that identifies the document to be retrieved. The line is ended with a carriage return followed by a line feed (a "CR + LF" sequence). An empty line will select the default directory. The server then replies with the requested item and closes the connection.

A directory consists of a sequence of lines, each of which describes an item that can be retrieved. These lines are ended with "CR + LF". They consist of five fields, separated by TAB characters:
* item type character, which can be any one of the following:
** 0 = Plain text file
** 1 = Directory
** 2 = CSO phone book server
** 3 = Error condition
** 4 = BinHex encoded Mac file
** 5 = ZIP archive
** 6 = uuencoded file
** 7 = Search server (returns a directory)
** 8 = Telnet link
** 9 = Generic binary file
** + = Redundant server
** c = Calendar
** e = Event
** g = GIF-format graphic
** h = HTML file
** i = Informational text that does not link to any actual file
** I = Any kind of graphic file other than GIF
** M = MIME multipart/mixed file
** s = Any kind of sound file
** T = tn3270 link
* description text
* item selector (typically a file-system pathname)
* domain name of the server on which the item resides
* port number of that server

URL links

Historically, to create a link to a Web server, "GET /" was used as the file to simulate an HTTP client request. John Goerzen created an addition http://gopher.quux.org/Archives/Mailing%20Lists/gopher/gopher.2002-02|/MBOX-MESSAGE/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 description is arbitrary, the item selector is "URL:http://gopher.quux.org", and the domain and port are that of the originating Gopher server. For clients that do not support URL links, the server creates an HTML redirection page.

Gopher support in Web browsers

Mozilla Firefox 1.5 displaying the top-level menu of the Floodgap gopher server

Gopher support was disabled in Internet Explorer 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 This is achieved by adding the following registry entry: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\EnableGopher = dword:00000001.

Other browsers, including Mozilla and AOL, still support the protocol, but incompletely — the most obvious deficiency is that they cannot display the informational text found on many Gopher menus. Konqueror needs a pluginThe kgopher KIO plugin can be downloaded from http://kgopher.berlios.de/. to be installed for full Gopher support. Mozilla Firefox has full Gopher support as of release 1.5, and partial support in previous versions. The SeaMonkey Internet suite, successor of the Mozilla all-in-one suite, also supports Gopher fully, as does Camino, an open source browser based on Mozilla's engine. However, the most extensive gopher support is offered in Lynx, a text based browser.

The Safari Web browser does not support Gopher at all while Opera requires the use of a proxy such as Squid.

Gopher to HTTP gateways

Users of Web browsers that have incomplete or no support for GopherTo determine whether a Web browser supports Gopher, compare the display of [gopher://gopher.floodgap.com/ this gopher menu] with the same menu produced by a Gopher to HTML gateway in the browser. can access content on Gopher servers via a server gateway that converts Gopher menus into HTML. One such server is at Floodgap.com.

Some Gopher servers, like PyGopherd, also have built-in Gopher to HTTP interfaces.

Related technology

The main Gopher search engine is Veronica. Veronica offers a keyword search of most Gopher server menu titles in the gopher web. A Veronica search produces a menu of Gopher items, each of which is a direct pointer to a Gopher data source. Currently, there is only one Veronica-2 server.

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

References and footnotes

External links

*[gopher://gopher.quux.org/1/Software/Gopher The Gopher Project] (gopher link)
*The Gopher Project (web link)
*The state of Gopher support for common Web browsers

Standards

*The Gopher Protocol (RFC1436)
*Gopher+ Extensions
*URL links

Gopher protocol: Encyclopedia BETA

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