Network Working Group                                     F. Anklesaria
Request for Comments: 1436                                  M. McCahill
                                                             P. Lindner
                                                             D. Johnson
                                                              D. Torrey
                                                             B. Alberti
                                                University of Minnesota
                                                             March 1993


                      The Internet Gopher Protocol
         (a distributed document search and retrieval protocol)

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is
   unlimited.

Abstract

   The Internet Gopher protocol is designed for distributed document
   search and retrieval.  This document describes the protocol, lists
   some of the implementations currently available, and has an overview
   of how to implement new client and server applications.  This
   document is adapted from the basic Internet Gopher protocol document
   first issued by the Microcomputer Center at the University of
   Minnesota in 1991.

Introduction

   gopher  n.  1. Any of various short tailed, burrowing mammals of the
   family Geomyidae, of North America.  2. (Amer. colloq.) Native or
   inhabitant of Minnesota: the Gopher State.  3. (Amer. colloq.) One
   who runs errands, does odd-jobs, fetches or delivers documents for
   office staff.  4. (computer tech.) software following a simple
   protocol for burrowing through a TCP/IP internet.

   The Internet Gopher protocol and software follow a client-server
   model.  This protocol assumes a reliable data stream; TCP is assumed.
   Gopher servers should listen on port 70 (port 70 is assigned to
   Internet Gopher by IANA).  Documents reside on many autonomous
   servers on the Internet.  Users run client software on their desktop
   systems, connecting to a server and sending the server a selector (a
   line of text, which may be empty) via a TCP connection at a well-
   known port.  The server responds with a block of text terminated by a
   period on a line by itself and closes the connection.  No state is
   retained by the server.




 
RFC 1436                         Gopher                       March 1993


   While documents (and services) reside on many servers, Gopher client
   software presents users with a hierarchy of items and directories
   much like a file system.  The Gopher interface is designed to
   resemble a file system since a file system is a good model for
   organizing documents and services; the user sees what amounts to one
   big networked information system containing primarily document items,
   directory items, and search items (the latter allowing searches for
   documents across subsets of the information base).

   Servers return either directory lists or documents.  Each item in a
   directory is identified by a type (the kind of object the item is),
   user-visible name (used to browse and select from listings), an
   opaque selector string (typically containing a pathname used by the
   destination host to locate the desired object), a host name (which
   host to contact to obtain this item), and an IP port number (the port
   at which the server process listens for connections). The user only
   sees the user-visible name.  The client software can locate and
   retrieve any item by the trio of selector, hostname, and port.

   To use a search item, the client submits a query to a special kind of
   Gopher server: a search server.  In this case, the client sends the
   selector string (if any) and the list of words to be matched. The
   response yields "virtual directory listings" that contain items
   matching the search criteria.

   Gopher servers and clients exist for all popular platforms.  Because
   the protocol is so sparse and simple, writing servers or clients is
   quick and straightforward.

1.  Introduction

   The Internet Gopher protocol is designed primarily to act as a
   distributed document delivery system.  While documents (and services)
   reside on many servers, Gopher client software presents users with a
   hierarchy of items and directories much like a file system.  In fact,
   the Gopher interface is designed to resemble a file system since a
   file system is a good model for locating documents and services.  Why
   model a campus-wide information system after a file system?  Several