Remote Write Protocol - Version 1.0
RFC 1756

Document Type RFC - Experimental (January 1995; No errata)
Last updated 2013-03-02
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Network Working Group                                          T. Rinne
Request for Comments: 1756                                          HUT
Category: Experimental                                     January 1995

                  REMOTE WRITE PROTOCOL - VERSION 1.0

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  This memo does not specify an Internet standard of any
   kind.  Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

1. Background

   It is often convenient to use electronic communication somewhat
   lighter than electronic mail.  Sometimes even the use of the talk(1)
   *) program seems like overkill.  We like to offer to user something
   like UNIX **) command write(1) ***) except that it can also pass
   messages through the network instead of the single host.

   There have been few programs offering this kind of service, but they
   have either based on SUN-RPC protocol or used a strictly undocumented

   This document describes a simple Remote Write Protocol (RWP) that
   should have been documented at least 10 years ago.  But late is
   better than never.  Version number of the RWP protocol in this
   document is 1.0.

2. Overview

   RWP is a simple protocol that can be used to relay short messages
   through the network to other users.  RWP looks pretty much like
   Simple Mail Transfer Protocol (SMTP) ****) though it is a bit more
   complicated due to the interactive nature of the RWP session.

   The idea behind the RWP session is that client program that is
   relaying message to the host in which the target user is logged in
   opens the tcp or udp connection to the server program running in the
   target machine  Then the client gives the sender's and recipient's
   identification (usually login ids), actual message body and tells the
   server to deliver a message to the user.  On tcp-connection server
   returns a status from each action taken.  On udp-connection no
   responses are sent.  RWP sessions through udp are implemented to
   support message broadcasting.

Rinne                                                           [Page 1]
RFC 1756                 Remote Write Protocol              January 1995

   Message delivering methods are not defined within this document, but
   the basic method could be a simple write to users terminal.  This is
   basically what UNIX command write(1) does.  Depending on server
   implementation, the delivery method could be configurable personally
   by each user.

3. Description

   Server program answers to each command submitted by a response.  All
   responses have two parts: three number unique response code and a
   short textual explanation of the response.  Also whenever the server
   is ready to accept new commands a notification is submitted to the

   There are three kinds of commands in RWP.  The first group is for
   querying a status of the server.  The second group is actual message
   handling commands and the last set of commands are for RWP session

   When the server is ready to receive a command from the client, it
   sends a message code 100 to the client.  This message is for example
   as follows:

                    100 Ready.

    Server commands are as follows:

    Status Query

        HELP    Gives a short help message that contains legal
                RWP commands.  Help lines have code 510.  Example RWP
                implementation *****) gives a following response to
                HELP command:

                    510 Valid commands are:
                    510     BYE,    DATA,   HELP,   HELO,
                    510     RSET,   SEND,   PROT,   QUIT,
                    510     VRFY,   VER
                    510     FROM senderlogin
                    510     FHST senderhost
                    510     TO   recipentlogin [tty]
                    510     FWDS current_hop_count

        HELO    Says hello to the server.  Server response to HELO
                command has code 500.  For example:

                    500 Hello  This is speaking.

Rinne                                                           [Page 2]
RFC 1756                 Remote Write Protocol              January 1995

        PROT    Asks the RWP protocol version from the server.
                Response code to PROT command is 502.  Protocol
                version described in this document is RWP 1.0 and the
                response is as follows:

                    502 RWP version 1.0.

        VRFY    After the recipient of the message is set by to command
                described later, the possibility of message delivery
                can be queried by VRFY command.  If message can be
                delivered the response code is 108.  If message is
                about to be forwarded the response code is 110 and
                message is either form:
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