| RFC : | rfc283 |
| Title: | |
| Date: | December 1971 |
| Status: | UNKNOWN |
| Updates: | 189 |
NETWORK WORKING GROUP R. T. BRADEN
REQUEST FOR COMMENTS #283 UCLA/CCN
NIC #8165 DECEMBER 20, 1971
CATEGORIES: D
OBSOLETES: NONE
UPDATES: RFC #189
NETRJT -- Remote Job Service Protocol for TIPS
----------------------------------------------
A. INTRODUCTION
------------
TIP's have very limited processing capability; their function is
mainly limited to interfacing printer-keyboard devices to the Network
using TELNET protocol. It will also be possible to have a tape drive
on a TIP, using a subset of the count form of DTP (see RFC #264).
However, TIP's cannot and will not support either DTP or FTP (see RFC
#265) in general. Therefore, TIP users are excluded from using any
existing remote job entry protocol (e.g. CCN's NETRJS - see RFC #189).
It appears, however, that it may be feasible in the future to use
TIP's for remote job entry in one or more of the following three ways:
(a) Attach local card readers, line printers, and card punches
directly to TIP ports. These devices would use a TELNET-like*
format and frame their characters with Start/Stop bits. BBN
can now supply a suitable 200 LPM printer, and is searching for
suitable readers and punches.
(b) Connect a remote batch terminal to a full-duplex TIP port via
a communication line. BBN is looking into this.
(c) Use the tape drive, and do card-to-tape and/or tape-to-print
on another computer.
BBN hopes to make case (b) look exactly like (a) to the server host.
That is, the remote batch terminal will send to and receive from the
server in a TELNET-like format*; the printer, card reader, punch, and
operator console connections will all use different sockets but one
hardware port at the TIP, which will map multiple sockets into the one
port.
NOTE: By "TELNET-like format", we mean: (a) _CR_LF_ used to delimit
logical records (lines or cards), and (b) the ASCII or EBCDIC
format effector control characters used for carriage control
in the printer stream. It does _not_ necessarily imply ASCII
character codes.
[Page 1]
[ This RFC was put into machine readable form for entry ]
[ into the online RFC archives by BBN Corp. under the ]
[ direction of Alex McKenzie. 12/96 ]
This document describes NETRJT, a modification of CCN's NETRJS
protocol specifically to provide remote job entry service to TIP's
using one of the methods (a), (b), or (c). NETRJT follows the general
model of NETRJS: use TELNET protocol over a primary or "operator"
connection pair, and open simplex secondary connections for data
transfer of job stream input and output. (We also considered the
possibility of using the Divert Output mechanism of the TIP for
sending remote job output over the operator connection, and an
analogous mechanism for input. However, in discussion with Alex
McKenzie, it was agreed that sharing the operator connections has
little merit and causes lots of problems).
NETRJT differs in two principal ways from NETRJS:
1. The NETRJT server process initiates the data transfer
connections, under control of commands from the remote
operator console. On the other hand, under NETRJS the
remote user process has responsibility for initiating
the opening of secondary data transfer connections; the
NETRJS server simply listens on these sockets.
2. NETRJT provides the TELNET-like format defined above for
data transfer, as well as the TIP-tape DTP format. NETRJS,
on the other hand, is restricted to counts to delimit logical
records within DTP-like transactions, and ASA carriage control.
There are some other minor differences. For example, (1) the NETRJT
server takes responsibility for folding output records when they
exceed a size specified by a user command; under NETRJS, this was the
user process' responsibility. (2) There are NETRJT operator commands
to set the record format, record size, and code for each data transfer
connection. NETRJS made the first two fixed properties of a particular
terminal id, and deter- mined the last by the choice of ICP socket.
These differences imply remote operator commands in NETRJT in addition
to those of NETRJS. The operator must be able to (1) cause NETRJT to
open a secondary connection to a TIP socket, and (2) specify the data
transfer protocol, maximum logical record length, and/or transmission
code. These NETRJT commands are discussed in the following section.
CCN plans to proceed with implementation of a NETRJT server with the
goal of completing an initial version by March 15, 1972. This initial
version may support only DTP=BS or TT, and RECFM=TELNET or RECORDS;
other options will be added as the need arises. We welcome comments
and suggestions.
[Page 2]
In the longer term, we believe that the NETRJT protocol described
here should be considered as the first draft of a Network standard for
remote job entry via TIP's. In its present form, NETRJT owes much to
the ideas and comments of Alex McKenzie (BBN), Jon Postel (NMC), Jim
White (UCSB), and Steve Wolfe (CCN).
B. NETRJT COMMANDS
---------------
NETRJT provides the following commands over the remote operator
connection, in addition to the NETRJS operator commands (see Appendix
D of RFC #189). The symbol "#" denotes one or more spaces. We will
use the IBM meta-language to describe the command syntax. The literal
text shown here in upper case may, in fact, be entered in either upper
or lower case.
1. Opening a Stream
----------------
/ \
| PR [INTER] | _ _
| | | |
O [PEN] # < PU [NCH] >| (jobname) | [ =socket-number[ /host-name ]]
| | | |
| R [EADER] | | (*) |
\ / |_ _|
If the specified device does not already have an open connection, the
NETRJT server will request connection to the specified socket. The
optional "(jobname)" para- meter is used to specify a particular job
by name; for more information on the semantics of this parameter, see
the discussion of input and output operations below. The "/host-name"
parameter, to be implemented later, is intended to allow the file to
be at a host different from both user and server hosts. We include it
here only to suggest a syntax.
The socket number may have a one-letter suffix D, H, or O to mean
decimal, hex, or octal. Octal is the default, so the O suffix may be
omitted. If BBN establishes standardized TIP sockets for specific
unit record devices, the socket number parameter could be omitted when
the standard socket number is intended.
[Page 3]
2. Closing a Stream
----------------
_ _
| # PR [INTER] |
| |
CL [OSE] | # PU [NCH] | [,A [CCEPT]]
| |
| # R [EADER] |
|_ _|
This command closes the specified data transfer connection. The
ACCEPT option is used to signal the server that it may discard output
it has transmitted, or that it has received a complete stack of job
input. See discussion in next section. The device specification (PR,
PU, or R) may be omitted if only one device stream is currently open.
3. Setting Format and Device Characteristics
-----------------------------------------
In each of the following variants of the RJT commands, the parameter
"device" is one of "PR [INTER]", "PU [NCH]", or "R [EADER]".
/ \
RJT # D [TP] (device) = < B [S] >
| T [T] |
| D [TP] |
\ /
BS: an unstructured byte stream.
TT: the TIP-tape transfer protocol (essentially
the count form of Network DTP).
DTP: the Network standard DTP, complete with a modes-
available handshake. This form is not useful
for TIP's but is included here in anticipation
of the general Network standard RJE protocol.
/ \
RJT # R [ECFM] (device) = < T [ELNET] >
| A [SA] |
| R [ECORDS] |
| C [OMPRESSED] |
\ /
[Page 4]
The following choice of options is tentative, as it is presently
unclear just what record formats will be useful for TIP tapes or
remote batch terminals connected to TIP's.
TELNET: the "TELNET-like format": _CR_LF_ used to delimit
logical records in all streams, and format effector
control characters (_CR_, _LF_, _FF_) for printer
carriage control.
ASA: CRLF used to delimit logical records, but an ASA
carriage control character is sent as the first
character of each printer record. (This option
may be useful for remote batch terminals which
expect ASA carriage control).
RECORDS: the "truncated" format of NETRJS: an id byte, a
count byte, and then the string, with ASA carriage
control in each printer record.
COMPRESSED: the "compressed" format of NETRJS (see RFC #189 for
details). (Compression will be useful for batch
terminals connected remotely to Tip's) .
RJT # SIZE (device) = integer
This command sets the maximum logical record length for the specified
device. NETRJT will automatically fold any records exceeding this
size. Default sizes are:
PR: 120
PU: 80
R : 80
/ \
RJT # CODE (device) = < A [SCII] >
| E [BCDIC] |
\ /
This command sets the code to be used.
[Page 5]
C. USING NETRJT AT CCN
-------------------
1. Getting Started
---------------
a. Perform ICP to server TELNET (socket 1).
b. Execute command "RJT", yielding ready message from NETRJT.
c. Issue RJS SIGNON command.
d. These steps result in a standard full-duplex TELNET connection
for an RJS remote operator console. The user can issue commands
to learn the status of his jobs, send messages, reroute and abort
jobs, etc.
2. Retrieving Output
-----------------
a. The TIP user captures a local output device and then executes
the NETRJT OPEN command for the PRINTER or PUNCH. For example,
if the connection is not yet open, then either of:
O PR=socket
O PR(*)=socket
opens a printer connection and selects the first job in the
printer queue for this terminal id.
O PR(jobname)=socket
similarly opens a connection but selects a specified job's
output. In either case, if output is not yet available the
connection remains open but idle, and the output is sent when
it does appear. If the socket number is omitted and the
connection is not yet open, the server will prompt for a
socket number.
b. If the specified output device already has an open connection,
either of the open commands:
O PR
O PR(jobname)
[Page 6]
may be issued to _accept_ (see e. below) the last job's output
and select and send another job's output. If the connection
is already open, the open command may still specify "=socket",
but if the specified socket does not match that currently open
there will be an error message.
c. While the output stream is idle, the user can issue RJT
commands with DTP, RECFM, CODE and/or SIZE parameters.
d. When the specified output is available, the server will
send a stream of print line (or punched card) images. The
user may issue the following RJS stream control commands
(see NIC 7182 and 7183 for more information on RJS commands).
1. BACKSPACE: repeats roughly the last page of printed output.
2. RESTART: restarts output at the beginning of the current
SYSOUT data set or ("JOB" option) at the beginning
of the job.
3. CANCEL: deletes rest of current SYSOUT data set, or
(",JOB" option) the entire job except account-
ing information.
4. DEFER: stops transmission of the current job and returns
it to the queue, marked "deferred". Can be
restarted later, with a "backspace" ("RESET
jobname" command) or from the beginning
("RESTART jobname" command).
e. The server does not discard job output until it is fully
transmitted to the TIP and the user has _accepted_ it. If the
user issues a "CLOSE device" or the connection breaks
accidentially (e.g. due to software or hardware failure in
either host) before the output is accepted, the server saves
the output with an implied BACKSPACE. When the user later reopens
the connection and again selects this job (either explicitly by
name or by calling for the next job), it will be retransmitted,
repeating the last page. The user can also defer or restart the
job output before reopening the connection. Note that CLOSE
without the ACCEPT option is generally a "panic" control to stop
the output stream if the printer paper jams, etc.
f. Transmitted output will be considered accepted by the user if:
1. The user issues a new OPEN command for that device.
[Page 7]
2. The user issues a "CLOSE device, ACCEPT" (e.g. "CL#PR,A")
command for that device. This command will be held pending
until job output in progress has completed. After the last
RFNM is received, the connection will be closed and the job
output discarded at the server end.
3. The original OPEN command specified "(*)", i.e. an asterisk
for jobname. This implies that the device stream is going
to be running continuously and that the user does not want
to explicitly request each output job or to accept each
one. Thus, if the stream is opened "(*)", then the server
assumes each job is accepted when the RFNM returns from the
last block.
3. Sending Input
-------------
(a) The user sends the following remote operator command to the server:
OPEN READER=socket
(This may be shortened to "O R=socket"). The server will send
an RFC to the user's card reader socket on which his TIP should
be listening. The server will issue an operator message when
the connection is open. The connection will be considered _idle_
until the first card image is received by the server. The OPEN
command will be ignored if the connection is already open, or
if an earlier open request is pending.
(b) Before or after the open, but while the connection is idle, the
user may issue RJT commands to set the record format, data trans-
fer protocol, code, and/or maximum record size to different values.
(c) The user sends in a stream of card images which constitute one
or more jobs. The server will discard the spooled images for a
job without processing them if the user issues a CANCEL READER
command or if the connection breaks (e.g. due to software or
hardware failures in either host) before the job is accepted
for processing. The stream then becomes idle again.
[Page 8]
(d) A spooled job will be accepted by the server only when one of
the following occurs:
1. A server-dependent end-of-job card (e.g. "//null" at CCN)
is received by the server. The last job is accepted, and
the stream becomes idle until another card is received.
2. A server-dependent beginning-of-job card (e.g. a "JOB" card
at CCN) is received by the server. The previous job is
accepted but the stream does not become idle at this time.
3. The user issues a CLOSE READER,ACCEPT (or "CL#R,A") com-
mand to the server. The stream is closed.
(e) The user can issue a CLOSE READER ("CL#R") command to close the
stream. However, this command will be held pending by the server
until the stream is idle, unless the form "CLOSE READER,ACCEPT"
is issued. A CLOSE will cancel a pending OPEN command, and vice
versa. The server will send the remote operator a message when
a connection opens or closes.
(f) Some servers (e.g. CCN) will extract the jobname for each input
job from the reader stream. However, the OPEN command may
specify a particular jobname, overriding that in the reader
stream. That is, the jobname from the OPEN command will replace
that appearing in the first job of the newly-opened stream. This
feature is merely a convenience, and was included mainly for
syntactic consistency between input and output. However, the use
of asterisk as a jobname has no meaning for the reader stream,
and will be ignored.
[Page 9]