Date: Mon, 11 Dec 89 19:15:07 EST
>From: Christine M Gianone <cmg@watsun.cc.columbia.edu>
Subject: Proposal for REMOTE SET Extension to the Kermit Protocol
Keywords: Kermit Protocol, REMOTE SET Command

PROBLEM:

Certain Kermit programs (including MS-Kermit 3.0, C-Kermit 4F) include
information about whether a file is text or binary in the File Attribute
packet, so the receiver can put itself into the right mode automatically.  But
when talking to a server there is no way for the client program, before
issuing a GET command, to tell the server whether to send the file in text or
binary mode.  This problem extends to various other protocol and file-related
parameters.

NOTE:

The Kermit protocol definition includes a REMOTE KERMIT command, and the
associated packet format and protocol.  It lets the user of the client program
issue a command to the server in its own interactive-mode command language.
But this is not a totally satisfactory answer because the syntax of Kermit
programs can and does vary and, perhaps more to the point, some Kermit
programs do not have an interactive command mode at all (Macintosh Kermit is
one example).  What is needed is a standard mechanism and syntax that can
apply to all Kermit programs uniformly.

SOLUTION:

A new addition to the Kermit protocol: REMOTE SET.

REMOTE SET would be a Generic Kermit Server command.  A generic command looks
like this:

    +-----+---------------------------------+
    |  G  | x <len1> <op1> <len2> <op2> ... |
    +-----+---------------------------------+
     Type   Data

where "x" is the generic command, a single letter.  The letter S is not yet in
use, so let's define S to mean SET.  The S is followed by a single operand,
which includes a single-character length field, similar to other generic
command packets.

The parameters which may be SET remotely are the ones having to do with file
transfer and Kermit protocol in general, not system-dependent or
communications-dependent parameters, since these must already have been set
prior to making the initial connection, and must be set correctly in any event
BEFORE you can successfully send a REMOTE SET (or any other) packet to the
server.

The most needed REMOTE SET command is REMOTE SET FILE TYPE {TEXT,BINARY}, but
the others should be specified in the protocol too.  Numeric codes are
assigned to the parameters and values, so that the mechanism for conveying
this information is system- and language-independent and reasonably compact.
The REMOTE SET command does exactly what the corresponding SET command would
do if it had been given to the remote server as an interactive command before
it entered server mode.

  Command                                Code   Values

  REMOTE SET ATTRIBUTES IN ALL            132   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN LENGTH         133   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN TYPE           134   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN DATE           135   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN CREATOR        136   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN ACCOUNT        137   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN AREA           138   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN BLOCK-SIZE     139   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN ACCESS         140   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN ENCODING       141   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN DISPOSITION    142   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN PROTECTION     143   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN GPROTECTION    144   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN SYSTEM-ID      145   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN FORMAT         146   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN SYS-INFO       147   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES IN BYTE-COUNT     148   0 = OFF, 1 = ON

  REMOTE SET ATTRIBUTES OUT ALL           232   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT LENGTH        233   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT TYPE          234   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT DATE          235   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT CREATOR       236   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT ACCOUNT       237   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT AREA          238   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT BLOCK-SIZE    239   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT ACCESS        240   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT ENCODING      241   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT DISPOSITION   242   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT PROTECTION    243   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT GPROTECTION   244   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT SYSTEM-ID     245   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT FORMAT        246   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT SYS-INFO      247   0 = OFF, 1 = ON
  REMOTE SET ATTRIBUTES OUT BYTE-COUNT    248   0 = OFF, 1 = ON

  REMOTE SET FILE TYPE                    300   0 = TEXT, 1 = BINARY
  REMOTE SET FILE NAMES                   301   0 = CONVERTED, 1 = LITERAL
  REMOTE SET FILE COLLISION               302   0 = RENAME,  1 = REPLACE,
                                                2 = BACKUP,  3 = APPEND,
                                                4 = DISCARD, 4 = ASK
  REMOTE SET FILE REPLACE                 303   0 = PRESERVE, 1 = DEFAULT
  REMOTE SET FILE INCOMPLETE              310   0 = DISCARD, 1 = KEEP
  REMOTE SET INCOMPLETE (same as above)

*** Added Later ***

  REMOTE SET FILE BLOCKSIZE               311   number
  REMOTE SET FILE RECORD-LENGTH           312   number
  REMOTE SET FILE RECORD-FORMAT           313   number
  REMOTE SET FILE ORGANIZATION            314   number
  REMOTE SET FILE CARRIAGE-CONTROL        315   number

*** End Added Later ***

  REMOTE SET BLOCK-CHECK                  400   number (1, 2, 3, 4, or B)
  REMOTE SET RECEIVE PACKET-LENGTH        401   number (10-9024)
  REMOTE SET RECEIVE TIMEOUT              402   number (any, 0 = no timeout)
  REMOTE SET RETRY                        403   number (any, 0 = no limit)
  REMOTE SET SERVER TIMEOUT               404   number (any, 0 = no timeout)
  REMOTE SET TRANSFER CHARACTER-SET       405   Character Set Designator
  REMOTE SET WINDOW-SLOTS                 406   number (1-31)

*** Added Later ***

  REMOTE SET TRANSFER MODE                410   0 = automatic, 1 = manual

*** End Added Later ***

One Kermit program should not have knowledge of another Kermit program's local
character sets, therefore REMOTE SET FILE CHARACTER-SET is not included.  The
Transfer Character Set Designator is the one described in the "ISO/Kermit"
proposal.  For example "I2/100" (ISO Latin Alphabet 1), "I2/144" (ISO
Latin/Cyrillic), or "I14/13" (Japanese Roman/Katakana).  The command would
use the name (for example REMOTE SET TRANSFER CHARACTER-SET LATIN1) and the
generic server command packet would use the corresponding designator.

REMOTE SET LANGUAGE is omitted for the present, but can be added later.  The
problem here is assigning a unique code to each of the world's languages.

The numbers shown for the codes and values are expressed as character
strings composed of ASCII digits, 0-9.  Here are examples, showing the TYPE
and DATA fields of the Kermit packet:

  GS#101!0      = REMOTE SET ATTRIBUTE LENGTH OFF
  GS#202!0      = REMOTE SET ATTRIBUTE TYPE OFF
  GS#300!1      = REMOTE SET FILE TYPE BINARY
  GS#400!2      = REMOTE SET BLOCK CHECK 2
  GS#401$1000   = REMOTE SET RECEIVE PACKET-LENGTH 1000
  GS#405&I2/100 = REMOTE SET TRANSFER CHARACTER-SET LATIN-1

ORGANIZATION AND EXPANSION:

The codes are numeric strings, with the hundred's place assigned roughly
according to "topic": 100's for Incoming Attributes, 200's for Outbound
Attributes, 300's for file-related items, and 400's for packet-related items.
Note that the SET ATTRIBUTE codes are equal to 100 or 200 plus the value of
the corresponding attribute designator.  There is plenty of room for expansion
within each category, and new categories can be added as required.

PROTOCOL:

The person using the client Kermit program issues a REMOTE SET command for
a single parameter, such as REMOTE SET FILE TYPE BINARY.  The program forms
the corresponding G packet and sends it to the server.

The server program can respond in any of the following ways, and the client
program should be prepared for each kind of response:

  E-packet:  An Error packet.  The server does not understand REMOTE SET
             packets, or it is not able to perform the specific SET that was
             requested.  Therefore the client must not assume that the SET has
             been done, and if it is in local mode, it must give a message to
             the user, as described below.

  Y-packet:  An Acknowledgement.  The server accepted the command, and
             performed the requested SET.  The data field of the Y-packet can
             be empty, to indicate that the requested value was accepted.  Or
             it can contain the value which the server actually set.  For
             example, the user types REMOTE SET RECEIVE PACKET-LENGTH 5000 but
             the server only supports lengths up to 1000:

		To server -->  GS#400$5000
			       Y1000        <-- To client

CLIENT IMPLEMENTATION:

A client can include support for any number of the REMOTE SET commands, or
none at all.  A minimal implementation might include only REMOTE SET FILE
TYPE.  This would include addition of the command to the program's command
tables, code to send the generic packet, and code to interpret the response
and issue any appropriate messages to the user, like the contents of the
error packet data field, or any altered value that the server sent back in
the data field of an acknowledgement.  Examples:

    REMOTE SET command succeeded
    REMOTE SET value changed to 1000
    REMOTE SET command failed: <reason from data field of E-packet>

SERVER IMPLEMENTATION:

A server can also include support for any number of the REMOTE SET commands,
or none at all.  If it supports none at all, then it will automatically
respond to a REMOTE SET packet with an error packet containing a message
like "Unimplemented REMOTE command".

If the server receives a REMOTE SET packet for a parameter it does not support
the REMOTE SETting of, then it should respond with an error packet containing
the message "Unknown REMOTE SET parameter".

If the server gets a REMOTE SET packet for a parameter which is known to it,
then it should:

(a) Set the parameter to the requested value and respond with an empty Y
    packet, or:

(b) If the requested value exceeds the server's maximum value for the
    parameter, set it to its own maximum value and respond with a Y packet
    containing the new value in its data field, as in the packet-length
    example above.

If the server is a "permanent" Kermit server which cannot be terminated using
BYE or FINISH, then when the user disengages from it using BYE, FINISH, or
LOGOUT, then when the server receives a BYE, FINISH, or LOGOUT command, it
should revert any parameters that were changed by REMOTE SET back to the
values that were in use when server mode was entered.

Thanks to Joe Doupnik and John Chandler for their assistance in the design
of this protocol extension.

From: Christine M Gianone <cmg@watsun.cc.columbia.edu>
Subject: Kermit Protocol Additions
Keywords: Kermit Protocol

This issue of the Info-Kermit Digest contains several proposals for extending
the Kermit protocol in certain minor ways, all of them related.  These
discussions are for Kermit developers.  They assume familiarity with the
Kermit protocol, as described in "Kermit, A File Transfer Protocol", by Frank
da Cruz, Digital Press (1987).

------------------------------

Date: Mon, 22 Jan 90 12:51:21 EST
From: Christine M Gianone <cmg@watsun.cc.columbia.edu>
Subject: Additions to REMOTE SET Proposal
Keywords: Kermit Protocol, REMOTE SET Command

REMOTE SET FILE BLOCKSIZE       311  number
REMOTE SET FILE RECORD-LENGTH   312  number
REMOTE SET FILE RECORD-FORMAT   313  ???

This is just for the record, to assign these numbers to these commands
for somebody who needed them.  Details to be filled in later.

------------------------------
Date: Tue Jul 21 15:50:16 1998
From: fdc
Subject: Additions to REMOTE SET Proposal

Client/Server settings, 420 series.

  REMOTE SET SERVER CD-MESSAGE            420   0 = OFF, 1 = ON

------------------------------
Date: Thu Oct 14 13:46:17 1999
From: fdc
Subject: REMOTE SET FILE CHARACTER-SET

Here we have two choices: just pass the keywords and hope for the best
(requires the client know the server's syntax) or assign codes to every
possible file character-set, which would be silly since that would make
us a registration authority for private charsets.  Or use MIME tags, but
I hate MIME.  In any case, using any kind of codes means the user can't
choose a set that might be supported but is not codified.  So names are
the lesser of two evils.

  REMOTE SET FILE CHARACTER-SET         320   string

------------------------------