GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc1436

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.

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 1] 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
 reasons:
    (a) A hierarchical arrangement of information is familiar to many
    users.  Hierarchical directories containing items (such as
    documents, servers, and subdirectories) are widely used in
    electronic bulletin boards and other campus-wide information
    systems. People who access a campus-wide information server will
    expect some sort of hierarchical organization to the information
    presented.

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 2] RFC 1436 Gopher March 1993

    (b) A file-system style hierarchy can be expressed in a simple
    syntax.  The syntax used for the internet Gopher protocol is
    easily understandable, and was designed to make debugging servers
    and clients easy.  You can use Telnet to simulate an internet
    Gopher client's requests and observe the responses from a server.
    Special purpose software tools are not required.  By keeping the
    syntax of the pseudo-file system client/server protocol simple, we
    can also achieve better performance for a very common user
    activity: browsing through the directory hierarchy.
    (c) Since Gopher originated in a University setting, one of the
    goals was for departments to have the option of publishing
    information from their inexpensive desktop machines, and since
    much of the information can be presented as simple text files
    arranged in directories, a protocol modeled after a file system
    has immediate utility.  Because there can be a direct mapping from
    the file system on the user's desktop machine to the directory
    structure published via the Gopher protocol, the problem of
    writing server software for slow desktop systems is minimized.
    (d) A file system metaphor is extensible.  By giving a "type"
    attribute to items in the pseudo-file system, it is possible to
    accommodate documents other than simple text documents.  Complex
    database services can be handled as a separate type of item.  A
    file-system metaphor does not rule out search or database-style
    queries for access to documents.  A search-server type is also
    defined in this pseudo-file system.  Such servers return "virtual
    directories" or list of documents matching user specified
    criteria.

2. The internet Gopher Model

 A detailed BNF rendering of the internet Gopher syntax is available
 in the appendix...but a close reading of the appendix may not be
 necessary to understand the internet Gopher protocol.
 In essence, the Gopher protocol consists of a client connecting to a
 server and sending the server a selector (a line of text, which may
 be empty) via a TCP connection.  The server responds with a block of
 text terminated with a period on a line by itself, and closes the
 connection.  No state is retained by the server between transactions
 with a client. The simple nature of the protocol stems from the need
 to implement servers and clients for the slow, smaller desktop
 computers (1 MB Macs and DOS machines), quickly, and efficiently.
 Below is a simple example of a client/server interaction; more
 complex interactions are dealt with later.  Assume that a "well-
 known" Gopher server (this may be duplicated, details are discussed

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 3] RFC 1436 Gopher March 1993

 later) listens at a well known port for the campus (much like a
 domain-name server).  The only configuration information the client
 software retains is this server's name and port number (in this
 example that machine is rawBits.micro.umn.edu and the port 70). In
 the example below the F character denotes the TAB character.

Client: {Opens connection to rawBits.micro.umn.edu at port 70}

Server: {Accepts connection but says nothing}

Client: <CR><LF> {Sends an empty line: Meaning "list what you have"}

Server: {Sends a series of lines, each ending with CR LF} 0About internet GopherFStuff:About usFrawBits.micro.umn.eduF70 1Around University of MinnesotaFZ,5692,AUMFunderdog.micro.umn.eduF70 1Microcomputer News & PricesFPrices/Fpserver.bookstore.umn.eduF70 1Courses, Schedules, CalendarsFFevents.ais.umn.eduF9120 1Student-Staff DirectoriesFFuinfo.ais.umn.eduF70 1Departmental PublicationsFStuff:DP:FrawBits.micro.umn.eduF70

                  {.....etc.....}

. {Period on a line by itself}

                  {Server closes connection}
 The first character on each line tells whether the line describes a
 document, directory, or search service (characters '0', '1', '7';
 there are a handful more of these characters described later).  The
 succeeding characters up to the tab form a user display string to be
 shown to the user for use in selecting this document (or directory)
 for retrieval.  The first character of the line is really defining
 the type of item described on this line. In nearly every case, the
 Gopher client software will give the users some sort of idea about
 what type of item this is (by displaying an icon, a short text tag,
 or the like).
 The characters following the tab, up to the next tab form a selector
 string that the client software must send to the server to retrieve
 the document (or directory listing).  The selector string should mean
 nothing to the client software; it should never be modified by the
 client.  In practice, the selector string is often a pathname or
 other file selector used by the server to locate the item desired.
 The next two tab delimited fields denote the domain-name of the host
 that has this document (or directory), and the port at which to
 connect.  If there are yet other tab delimited fields, the basic
 Gopher client should ignore them.  A CR LF denotes the end of the
 item.

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 4] RFC 1436 Gopher March 1993

 In the example, line 1 describes a document the user will see as
 "About internet Gopher".  To retrieve this document, the client
 software must send the retrieval string: "Stuff:About us" to
 rawBits.micro.umn.edu at port 70.  If the client does this, the
 server will respond with the contents of the document, terminated by
 a period on a line by itself.  A client might present the user with a
 view of the world something like the following list of items:
    About Internet Gopher
    Around the University of Minnesota...
    Microcomputer News & Prices...
    Courses, Schedules, Calendars...
    Student-Staff Directories...
    Departmental Publications...
 In this case, directories are displayed with an ellipsis and files
 are displayed without any.  However, depending on the platform the
 client is written for and the author's taste, item types could be
 denoted by other text tags or by icons.  For example, the UNIX
 curses-based client displays directories with a slash (/) following
 the name; Macintosh clients display directories alongside an icon of
 a folder.
 The user does not know or care that the items up for selection may
 reside on many different machines anywhere on the Internet.
 Suppose the user selects the line "Microcomputer News & Prices...".
 This appears to be a directory, and so the user expects to see
 contents of the directory upon request that it be fetched.  The
 following lines illustrate the ensuing client-server interaction:
  Client:           (Connects to pserver.bookstore.umn.edu at port 70)
  Server:           (Accepts connection but says nothing)
  Client: Prices/   (Sends the magic string terminated by CRLF)
  Server:           (Sends a series of lines, each ending with CR LF)
  0About PricesFPrices/AboutusFpserver.bookstore.umn.eduF70
  0Macintosh PricesFPrices/MacFpserver.bookstore.umn.eduF70
  0IBM PricesFPrices/IckFpserver.bookstore.umn.eduF70
  0Printer & Peripheral PricesFPrices/PPPFpserver.bookstore.umn.eduF70
                    (.....etc.....)
  .                 (Period on a line by itself)
                    (Server closes connection)

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 5] RFC 1436 Gopher March 1993

3. More details

3.1 Locating services

 Documents (or other services that may be viewed ultimately as
 documents, such as a student-staff phonebook) are linked to the
 machine they are on by the trio of selector string, machine domain-
 name, and IP port.  It is assumed that there will be one well-known
 top-level or root server for an institution or campus.  The
 information on this server may be duplicated by one or more other
 servers to avoid a single point of failure and to spread the load
 over several servers.  Departments that wish to put up their own
 departmental servers need to register the machine name and port with
 the administrators of the top-level Gopher server, much the same way
 as they register a machine name with the campus domain-name server.
 An entry which points to the departmental server will then be made at
 the top level server.  This ensures that users will be able to
 navigate their way down what amounts to a virtual hierarchical file
 system with a well known root to any campus server if they desire.
 Note that there is no requirement that a department register
 secondary servers with the central top-level server; they may just
 place a link to the secondary servers in their own primary servers.
 They may indeed place links to any servers they desire in their own
 server, thus creating a customized view of thethe Gopher information
 universe; links can of course point back at the top-level server.
 The virtual (networked) file system is therefore an arbitrary graph
 structure and not necessarily a rooted tree.  The top-level node is
 merely one convenient, well-known point of entry.  A set of Gopher
 servers linked in this manner may function as a campus-wide
 information system.
 Servers may of course point links at other than secondary servers.
 Indeed servers may point at other servers offering useful services
 anywhere on the internet.  Viewed in this manner, Gopher can be seen
 as an Internet-wide information system.

3.2 Server portability and naming

 It is recommended that all registered servers have alias names
 (domain name system CNAME) that are used by Gopher clients to locate
 them.  Links to these servers should use these alias names rather
 than the primary names.  If information needs to be moved from one
 machine to another, a simple change of domain name system alias
 (CNAME) allows this to occur without any reconfiguration of clients
 in the field.  In short, the domain name system may be used to re-map
 a server to a new address.  There is nothing to prevent secondary
 servers or services from running on otherwise named servers or ports

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 6] RFC 1436 Gopher March 1993

 other than 70, however these should be reachable via a primary
 server.

3.3 Contacting server administrators

 It is recommended that every server administrator have a document
 called something like: "About Bogus University's Gopher server" as
 the first item in their server's top level directory.  In this
 document should be a short description of what the server holds, as
 well as name, address, phone, and an e-mail address of the person who
 administers the server.  This provides a way for users to get word to
 the administrator of a server that has inaccurate information or is
 not running correctly.  It is also recommended that administrators
 place the date of last update in files for which such information
 matters to the users.

3.4 Modular addition of services

 The first character of each line in a server-supplied directory
 listing indicates whether the item is a file (character '0'), a
 directory (character '1'), or a search (character '7').  This is the
 base set of item types in the Gopher protocol.  It is desirable for
 clients to be able to use different services and speak different
 protocols (simple ones such as finger; others such as CSO phonebook
 service, or Telnet, or X.500 directory service) as needs dictate.
 CSO phonebook service is a client/server phonebook system typically
 used at Universities to publish names, e-mail addresses, and so on.
 The CSO phonebook software was developed at the University of
 Illinois and is also sometimes refered to as ph or qi.  For example,
 if a server-supplied directory listing marks a certain item with type
 character '2', then it means that to use this item, the client must
 speak the CSO protocol.  This removes the need to be able to
 anticipate all future needs and hard-wire them in the basic Internet
 Gopher protocol; it keeps the basic protocol extremely simple.  In
 spite of this simplicity, the scheme has the capability to expand and
 change with the times by adding an agreed upon type-character for a
 new service.  This also allows the client implementations to evolve
 in a modular fashion, simply by dropping in a module (or launching a
 new process) for some new service.  The servers for the new service
 of course have to know nothing about Internet Gopher; they can just
 be off-the shelf CSO, X.500, or other servers.  We do not however,
 encourage arbitrary or machine-specific proliferation of service
 types in the basic Gopher protocol.
 On the other hand, subsets of other document retrieval schemes may be
 mapped onto the Gopher protocol by means of "gateway-servers".
 Examples of such servers include Gopher-to-FTP gateways, Gopher-to-
 archie gateways, Gopher-to-WAIS gateways, etc.  There are a number of

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 7] RFC 1436 Gopher March 1993

 advantages of such mechanisms. First, a relatively powerful server
 machine inherits both the intelligence and work, rather than the more
 modest, inexpensive desktop system that typically runs client
 software or basic server software.  Equally important, clients do not
 have to be modified to take advantage of a new resource.

3.5 Building clients

 A client simply sends the retrieval string to a server if it wants to
 retrieve a document or view the contents of a directory.  Of course,
 each host may have pointers to other hosts, resulting in a "graph"
 (not necessarily a rooted tree) of hosts.  The client software may
 save (or rather "stack") the locations that it has visited in search
 of a document.  The user could therefore back out of the current
 location by unwinding the stack.  Alternatively, a client with
 multiple-window capability might just be able to display more than
 one directory or document at the same time.
 A smart client could cache the contents of visited directories
 (rather than just the directory's item descriptor), thus avoiding
 network transactions if the information has been previously
 retrieved.
 If a client does not understand what a say, type 'B' item (not a core
 item) is, then it may simply ignore the item in the directory
 listing; the user never even has to see it.  Alternatively, the item
 could be displayed as an unknown type.
 Top-level or primary servers for a campus are likely to get more
 traffic than secondary servers, and it would be less tolerable for
 such primary servers to be down for any long time.  So it makes sense
 to "clone" such important servers and construct clients that can
 randomly choose between two such equivalent primary servers when they
 first connect (to balance server load), moving to one if the other
 seems to be down.  In fact, smart client implementations do this
 clone server and load balancing.  Alternatively, it may make sense to
 have the domain name system return one of a set of redundant of
 server's IP address to load balance betwen redundant sets of
 important servers.

3.6 Building ordinary internet Gopher servers

 The retrieval string sent to the server might be a path to a file or
 directory.  It might be the name of a script, an application or even
 a query that generates the document or directory returned.  The basic
 server uses the string it gets up to but not including a CR-LF or a
 TAB, whichever comes first.

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 8] RFC 1436 Gopher March 1993

 All intelligence is carried by the server implementation rather than
 the protocol.  What you build into more exotic servers is up to you.
 Server implementations may grow as needs dictate and time allows.

3.7 Special purpose servers

 There are two special server types (beyond the normal Gopher server)
 also discussed below:
    1.  A server directory listing can point at a CSO nameserver (the
    server returns a type character of '2') to allow a campus
    student-staff phonebook lookup service.  This may show up on the
    user's list of choices, perhaps preceded by the icon of a phone-
    book.  If this item is selected, the client software must resort
    to a pure CSO nameserver protocol when it connects to the
    appropriate host.
    2.  A server can also point at a "search server" (returns a first
    character of '7').  Such servers may implement campus network (or
    subnet) wide searching capability.  The most common search servers
    maintain full-text indexes on the contents of text documents held
    by some subset of Gopher servers.  Such a "full-text search
    server" responds to client requests with a list of all documents
    that contain one or more words (the search criteria).  The client
    sends the server the selector string, a tab, and the search string
    (words to search for). If the selector string is empty, the client
    merely sends the search string.  The server returns the equivalent
    of a directory listing for documents matching the search criteria.
    Spaces between words are usually implied Boolean ANDs (although in
    different implementations or search types, this may not
    necessarily be true).
 The CSO addition exists for historical reasons: at time of design,
 the campus phone-book servers at the University of Minnesota used the
 CSO protocol and it seemed simplest to just engulf them.  The index-
 server is however very much a Gopher in spirit, albeit with a slight
 twist in the meaning of the selector-string.  Index servers are a
 natural place to incorperate gateways to WAIS and WHOIS services.

3.7.1 Building CSO-servers

 A CSO Nameserver implementation for UNIX and associated documentation
 is available by anonymous ftp from uxa.cso.uiuc.edu.  We do not
 anticipate implementing it on other machines.

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 9] RFC 1436 Gopher March 1993

3.7.2 Building full-text search servers

 A full-text search server is a special-purpose server that knows
 about the Gopher scheme for retrieving documents.  These servers
 maintain a full-text index of the contents of plain text documents on
 Gopher servers in some specified domain.  A Gopher full-text search
 server was implemented using several NeXTstations because it was easy
 to take advantage of the full-text index/search engine built into the
 NeXT system software.  A search server for generic UNIX systems based
 on the public domain WAIS search engine, is also available and
 currently an optional part of the UNIX gopher server.  In addition,
 at least one implementation of the gopher server incorperates a
 gateway to WAIS servers by presenting the WAIS servers to gopherspace
 as full-text search servers.  The gopher<->WAIS gateway servers does
 the work of translating from gopher protocol to WAIS so unmodified
 gopher clients can access WAIS servers via the gateway server.
 By using several index servers (rather than a monolithic index
 server) indexes may be searched in parallel (although the client
 software is not aware of this).  While maintaining full-text indexes
 of documents distributed over many machines may seem a daunting task,
 the task can be broken into smaller pieces (update only a portion of
 the indexes, search several partial indexes in parallel) so that it
 is manageable.  By spreading this task over several small, cheap (and
 fast) workstations it is possible to take advantage of fine-grain
 parallelism.  Again, the client software is not aware of this. Client
 software only needs to know that it can send a search string to an
 index server and will receive a list of documents that contain the
 words in the search string.

3.8 Item type characters

 The client software decides what items are available by looking at
 the first character of each line in a directory listing.  Augmenting
 this list can extend the protocol.  A list of defined item-type
 characters follows:
 0   Item is a file
 1   Item is a directory
 2   Item is a CSO phone-book server
 3   Error
 4   Item is a BinHexed Macintosh file.
 5   Item is DOS binary archive of some sort.
     Client must read until the TCP connection closes.  Beware.
 6   Item is a UNIX uuencoded file.
 7   Item is an Index-Search server.
 8   Item points to a text-based telnet session.
 9   Item is a binary file!

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 10] RFC 1436 Gopher March 1993

     Client must read until the TCP connection closes.  Beware.
 +   Item is a redundant server
 T   Item points to a text-based tn3270 session.
 g   Item is a GIF format graphics file.
 I   Item is some kind of image file.  Client decides how to display.
 Characters '0' through 'Z' are reserved.  Local experiments should
 use other characters.  Machine-specific extensions are not
 encouraged.  Note that for type 5 or type 9 the client must be
 prepared to read until the connection closes.  There will be no
 period at the end of the file; the contents of these files are binary
 and the client must decide what to do with them based perhaps on the
 .xxx extension.

3.9 User display strings and server selector strings

 User display strings are intended to be displayed on a line on a
 typical screen for a user's viewing pleasure.  While many screens can
 accommodate 80 character lines, some space is needed to display a tag
 of some sort to tell the user what sort of item this is.  Because of
 this, the user display string should be kept under 70 characters in
 length.  Clients may truncate to a length convenient to them.

4. Simplicity is intentional

 As far as possible we desire any new features to be carried as new
 protocols that will be hidden behind new document-types.  The
 internet Gopher philosophy is:
    (a) Intelligence is held by the server.  Clients have the option
    of being able to access new document types (different, other types
    of servers) by simply recognizing the document-type character.
    Further intelligence to be borne by the protocol should be
    minimized.
    (b) The well-tempered server ought to send "text" (unless a file
    must be transferred as raw binary).  Should this text include
    tabs, formfeeds, frufru?  Probably not, but rude servers will
    probably send them anyway.  Publishers of documents should be
    given simple tools (filters) that will alert them if there are any
    funny characters in the documents they wish to publish, and give
    them the opportunity to strip the questionable characters out; the
    publisher may well refuse.
    (c) The well-tempered client should do something reasonable with
    funny characters received in text; filter them out, leave them in,
    whatever.

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 11] RFC 1436 Gopher March 1993

Appendix

 Paul's NQBNF (Not Quite BNF) for the Gopher Protocol.
 Note:  This is modified BNF (as used by the Pascal people) with a few
        English modifiers thrown in.  Stuff enclosed in '{}' can be
        repeated zero or more times.  Stuff in '[]' denotes a set of
        items.  The '-' operator denotes set subtraction.

Directory Entity

CR-LF ::= ASCII Carriage Return Character followed by Line Feed

            character.

Tab ::= ASCII Tab character.

NUL ::= ASCII NUL character.

UNASCII ::= ASCII - [Tab CR-LF NUL].

Lastline ::= '.'CR-LF.

TextBlock ::= Block of ASCII text not containing Lastline pattern.

Type ::= UNASCII.

RedType ::= '+'.

User_Name ::= {UNASCII}.

Selector ::= {UNASCII}.

Host ::= {{UNASCII - ['.']} '.'} {UNASCII - ['.']}.

Note: This is a Fully Qualified Domain Name as defined in RFC 1034.

    (e.g., gopher.micro.umn.edu)  Hosts that have a CR-LF
    TAB or NUL in their name get what they deserve.

Digit ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' .

DigitSeq ::= digit {digit}.

Port ::= DigitSeq.

Note: Port corresponds the the TCP Port Number, its value should

    be in the range [0..65535]; port 70 is officially assigned
    to gopher.

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 12] RFC 1436 Gopher March 1993

DirEntity ::= Type User_Name Tab Selector Tab Host Tab Port CR-LF

        {RedType User_Name Tab Selector Tab Host Tab Port CR-LF}

Notes:

 It is *highly* recommended that the User_Name field contain only
 printable characters, since many different clients will be using
 it.  However if eight bit characters are used, the characters
 should conform with the ISO Latin1 Character Set.  The length of
 the User displayable line should be less than 70 Characters; longer
 lines may not fit across some screens.
 The Selector string should be no longer than 255 characters.

Menu Entity

Menu ::= {DirEntity} Lastline.

Menu Transaction (Type 1 item)

C: Opens Connection S: Accepts Connection C: Sends Selector String S: Sends Menu Entity

 Connection is closed by either client or server (typically server).

Textfile Entity

TextFile ::= {TextBlock} Lastline

Note: Lines beginning with periods must be prepended with an extra

   period to ensure that the transmission is not terminated early.
   The client should strip extra periods at the beginning of the line.

TextFile Transaction (Type 0 item)

C: Opens Connection. S: Accepts connection C: Sends Selector String. S: Sends TextFile Entity.

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 13] RFC 1436 Gopher March 1993

 Connection is closed by either client or server (typically server).

Note: The client should be prepared for the server closing the

     connection without sending the Lastline.  This allows the
     client to use fingerd servers.

Full-Text Search Transaction (Type 7 item)

Word ::= {UNASCII - ' '} BoolOp ::= 'and' | 'or' | 'not' | SPACE SearchStr ::= Word {{SPACE BoolOp} SPACE Word}

C: Opens Connection. C: Sends Selector String, Tab, Search String. S: Sends Menu Entity.

Note: In absence of 'and', 'or', or 'not' operators, a SPACE is

     regarded as an implied 'and' operator.  Expression is evaluated
     left to right.  Further, not all search engines or search
     gateways currently implemented have the boolean operators
     implemented.

Binary file Transaction (Type 9 or 5 item)

C: Opens Connection. S: Accepts connection C: Sends Selector String. S: Sends a binary file and closes connection when done.

Syntactic Meaning for Directory Entities

The client should interpret the type field as follows:

0 The item is a TextFile Entity.

  Client should use a TextFile Transaction.

1 The item is a Menu Entity.

  Client should use a Menu Transaction.

2 The information applies to a CSO phone book entity.

  Client should talk CSO protocol.

3 Signals an error condition.

4 Item is a Macintosh file encoded in BINHEX format

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 14] RFC 1436 Gopher March 1993

5 Item is PC-DOS binary file of some sort. Client gets to decide.

6 Item is a uuencoded file.

7 The information applies to a Index Server.

  Client should use a FullText Search transaction.

8 The information applies to a Telnet session.

  Connect to given host at given port. The name to login as at this
  host is in the selector string.

9 Item is a binary file. Client must decide what to do with it.

+ The information applies to a duplicated server. The information

  contained within is a duplicate of the primary server.  The primary
  server is defined as the last DirEntity that is has a non-plus
  "Type" field.  The client should use the transaction as defined by
  the primary server Type field.

g Item is a GIF graphic file.

I Item is some kind of image file. Client gets to decide.

T The information applies to a tn3270 based telnet session.

  Connect to given host at given port. The name to login as at this
  host is in the selector string.

Security Considerations

 Security issues are not discussed in this memo.

Authors' Addresses

 Farhad Anklesaria
 Computer and Information Services, University of Minnesota
 Room 152 Shepherd Labs
 100 Union Street SE
 Minneapolis, MN 55455
 Phone: (612) 625 1300
 EMail: fxa@boombox.micro.umn.edu

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 15] RFC 1436 Gopher March 1993

 Mark McCahill
 Computer and Information Services, University of Minnesota
 Room 152 Shepherd Labs
 100 Union Street SE
 Minneapolis, MN 55455
 Phone: (612) 625 1300
 EMail: mpm@boombox.micro.umn.edu
 Paul Lindner
 Computer and Information Services, University of Minnesota
 Room 152 Shepherd Labs
 100 Union Street SE
 Minneapolis, MN 55455
 Phone: (612) 625 1300
 EMail: lindner@boombox.micro.umn.edu
 David Johnson
 Computer and Information Services, University of Minnesota
 Room 152 Shepherd Labs
 100 Union Street SE
 Minneapolis, MN 55455
 Phone: (612) 625 1300
 EMail: dmj@boombox.micro.umn.edu
 Daniel Torrey
 Computer and Information Services, University of Minnesota
 Room 152 Shepherd Labs
 100 Union Street SE
 Minneapolis, MN 55455
 Phone: (612) 625 1300
 EMail: daniel@boombox.micro.umn.edu
 Bob Alberti
 Computer and Information Services, University of Minnesota
 Room 152 Shepherd Labs
 100 Union Street SE
 Minneapolis, MN 55455
 Phone: (612) 625 1300
 EMail: alberti@boombox.micro.umn.edu

Anklesari, McCahill, Lindner, Johnson, Torrey & Alberti [Page 16]

/data/webs/external/dokuwiki/data/pages/rfc/rfc1436.txt · Last modified: 1993/03/17 22:27 (external edit)