| Rfc | 0189 |
|---|
| Title | Interim NETRJS specifications |
|---|
| Author | R.T. Braden |
|---|
| Date | July 1971 |
|---|
| Format: | TXT,
HTML |
|---|
| Obsoletes | RFC0088 |
|---|
| Obsoleted by | RFC0599 |
|---|
| Updated by | RFC0283 |
|---|
| Status: | UNKNOWN |
|---|
|
Network Working Group R. T. Braden
Request for Comments: 189 UCLA/CCN
Obsoletes: RFC 88 (NIC 5668) 15 July 1971
NIC 7133
Category: D
INTERIM NETRJS SPECIFICATIONS
The following document describes the operation and protocol of the
remote job entry service to CCN's 360 Model 91. The interim protocol
described here will be implemented as a production service before the
end of July. Two host sites (Rand and UCLA/NMC) have written user
processes for the interim NETRJS, based on the attached document.
Questions on it should be addressed to CCN's Technical Liaison.
It is anticipated that the interim protocol will be superseded in a
few months by a revised NETRJS, but the changes will be minor. The
revision will bring the data transfer protocol of NETRJS into
complete conformity with the proposed Data Transfer Protocol DTP (see
RFC #171). The present differences between the DTP and NETRJS
protocols are:
(a) The format (but not the contents) of the 72 bit transaction
header of NETRJS must be changed to conform with DTP.
(b) The End-of-Data marker must be changed from X'FE' to X'B40F'.
(c) The initial "modes available" transaction of DTP must be
added.
(d) Some of the DTP error codes will be implemented.
No other protocol changes are presently planned, although some may be
suggested by operating experience with the interim protocol. When
the revised protocol has been fully specified, it will be implemented
with different ICP sockets than the interim protocol. This will
allow a site which wants to start using CCN immediately to convert
his protocol at leisure.
Some possible future extensions to NETRJS which have been suggested
are:
(1) A 7-bit ASCII option of data transfer connections, for the
convenience of PDP-10s.
(2) A "transparency" mode for input from ASCII remote sites, to
allow the transmission of "binary decks" (object decks) in
the job stream from these sites.
(3) More than one simultaneous virtual card read, printer, and
punch stream to the same virtual terminal.
Comments on the utility of these proposals or others for your site
would be appreciated.
Robert T. Braden
Technical Liaison
UCLA/CCN
(213) 825-7518
REMOTE JOB ENTRY TO UCLA/CCN
FROM THE ARPA NETWORK
(Interim Protocol)
A. Introduction
NETRJS is the protocol for the remote job entry service to the 360
Model 91 at the UCLA Campus Computing Network (CCN). NETRJS allows
the user at a remote host to access CCN's RJS ("Remote Job Service")
sub-system, which provides remote job entry service to real remote
batch (card reader/line printer) terminals over direct communications
lines as well as to the ARPA Network.
To use NETRJS, a user at a remote host needs a NETRJS user process to
communicate with one of the NETRJS server processes at CCN. Each
active NETRJS user process appears to RJS as a separate (virtual)
remote batch terminal; we will refer to it as a VRBT.
A VRBT may have virtual card readers, printers, and punches. Through
a virtual card reader a Network user can transmit a stream of card
images comprising one or more OS/360 jobs, complete with Job Control
Language, to CCN. These jobs will be spooled into CCN's batch system
(OS/360 MVT) and run according to their priority. RJS will automati-
cally return the print and/or punch output images which are created
by these jobs to the virtual printer and/or card punch at the VRBT
from which the job came (or to a different destination specified in
the JCL). The remote user can wait for his output, or he can sign
off and sign back on later to receive it.
The VRBT is assumed to be under the control of the user's teletype or
other remote console; this serves the function of an RJS remote
operator console. To initiate a NETRJS session, the remote user must
execute the standard ICP (see RFC #165) to a fixed socket at CCN.
The result is to establish a duplex Telnet connection to his console,
allowing the user to sign into RJS. Once he is signed in, he can use
his console to issue commands to RJS and to receive status, confirma-
tion, and error messages from RJS. The most important RJS commands
are summarized in Appendix D.
Different VRBT's are distinguished by 8-character terminal id's.
There may be more than one VRBT using RJS simultaneously from the
same remote host. Terminal id's for new VRBT's will be assigned by
CCN to individual users or user groups who wish to run batch jobs at
CCN (contact the CCN Technical Liaison for details).
B. Connections and Protocols
Figure 1 shows conceptually the processes and protocols required to
use NETRJS. The operator console uses a duplex connection under the
Telnet third-level protocol (see RFC #158). The actual data transfer
streams for job input and output are handled over separate simplex
connections using a data transfer protocol.
We will use the term channel for one of these NETRJS connections, and
designate it input or output with reference to CCN. Each data
transfer channel is identified with a particular virtual remote dev-
ice -- card reader, printer, or punch. The data transfer channels
need be open only while they are in use, and different channels may
be used sequentially or simultaneously. NETRJS will presently sup-
port simultaneous operation of a virtual card reader, a virtual
printer, and a virtual punch (in addition to the operator console) on
the same VRBT process. RJS itself will support more than one reader,
printer, and punch at each remote terminal, so the NETRJS protocol
could easily be expanded in the future to allow more simultaneous I/O
streams to each Network user.
The remote user needs a local escape convention so he can send com-
mands directly to his VRBT process. These local VRBT commands would
allow selection of the files at his host which contain job streams to
be sent to the server, and files to receive job output from the
server. They would also allow the user to open data transfer chan-
nels to the NETRJS server process, and to close these connections to
free buffer space or abort a transmission.
When a VRBT starts a session, it has a choice of two ICP sockets,
depending upon whether it is an ASCII or an EBCDIC virtual terminal.
An EBCDIC virtual terminal transmits and receives its data as tran-
sparent streams of 8 bit bytes (since CCN is an EBCDIC installation).
It is expected that a user at an ASCII installation, however, will
want his VRBT declared ASCII; RJS will then translate the input
stream from ASCII to EBCDIC and translate the printer stream back to
ASCII. This will allow the user to employ his local text editor for
preparing input to CCN and for examining output. The punch stream
will always be transparent, for outputting "binary decks".
It should be noted that the choice of code for the operator console
connections is independent of declared terminal type; in particular,
they always use ASCII under Telnet protocol, even from an EBCDIC
VRBT.
NETRJS protocol provides data compression, replacing repeated blanks
or other characters by repeat counts. However, when the terminal id
is assigned by CCN, a particular network terminal may be specified as
using no data compression. In this case, NETRJS will simply truncate
trailing blanks and send records in a simple "op code-length-data"
form, called truncated format.
C. Starting and Terminating a Session
The remote user establishes a connection to RJS via the standard ICP
from his socket U to socket 11 [sub] 10 (EBCDIC) or socket 13 [sub]
10 (ASCII) at host 1, IMP 1. If successful, the ICP results in a
pair of connections which are in fact the NETRJS operator control
connections.
Once the user is connected, he must enter a valid RJS signon command
("SIGNON terminal-id") through his console. RJS will normally ack-
nowledge signon with a console message; however, if RJS does not
recognize the terminal-id or has no available Line Handler for the
Network, it will indicate refusal by closing both operator connec-
tions. If the user attempts to open data transfer connections before
his signon command is accepted, the data transfer connections will be
refused by CCN with an error message to his console.
Suppose the operator input connection is socket S at CCN; S is the
even number sent in the ICP. Then the other NETRJS channels have
sockets at CCN with fixed relation to S, as shown in the table below.
Until there is a suitable Network-wide solution to the problem of
identity control on sockets, NETRJS will also require that the VRBT
process use fixed socket offsets from his initial connection socket
U. These are shown in the following table:
Channel CCN Socket Remote Socket
(Server) (User)
Telnet / Remote Operator Console Input S U + 3 \
\ Remote Operator Console Output S + 1 U + 2 / Telnet
Data / Card Reader #1 S + 2 U + 5
Transfer < Printer #1 S + 3 U + 4
\ Punch #1 S + 5 U + 6
Once the user is signed on, he can open data transfer channels and
initiate input and output operations as explained in the following
sections. To terminate the session, the remote user may close all
connections. Alternatively, the user may enter a SIGNOFF command
through his console; in this case, RJS will wait until the current
job output streams are complete and then itself terminate the session
by closing all connections.
D. Input Operations
A job stream for submission to RJS at CCN is a series of logical
records, each of which is a card image. A card image may be at most
80 characters long, to match the requirements of OS/360 for job
input. The user can submit a "stack" of successive jobs through the
card reader channel with no end-of-job indication between jobs; RJS
recognizes the beginning of each new job by the appearance of a JOB
card.
To submit a job or stack of jobs for execution at CCN, the remote
user must first open the card reader channel. He signals his VRBT
process to issue Init (local = U + 5, foreign = S + 2, size = 8).
NETRJS, which is listening on socket S + 2, will normally return an
RTS command, opening the channel. If, however, it should happen that
all input buffer space within the CCN NCP is in use, the request will
be refused, and the user should try again later. If the problem per-
sists, call the Technical Liaison at CCN.
When the connection is open, the user can begin sending his job
stream using the protocol defined in Appendix A. For each job suc-
cessfully spooled, the user will receive a confirming message on his
console. At the end of the stack, he must send an End-of-Data tran-
saction to initiate processing of the last job. NETRJS will then
close the channel (to avoid holding buffer space unnecessarily). At
any time during the session, the user can re-open the card reader
channel and transmit another job stack. He can also terminate the
session and sign on later to get his output.
The user can abort the card reader channel at any time by closing the
channel (his socket S + 2). NETRJS will then discard the last par-
tially spooled job. If NETRJS finds an error (e.g., transaction
sequence number error or a dropped bit), it will abort the channel by
closing the connection prematurely, and also inform the user via his
console that his job was discarded (thus solving the race condition
between End-of-Data and aborting). The user needs to retransmit only
the last job. However, he could retransmit the entire stack
(although it would be somewhat wasteful) since the CCN operating sys-
tem enforces job name uniqueness by immediately "flushing" jobs with
names already in the system.
If the user's process, NCP, or host, or the Network itself fails dur-
ing input, RJS will discard the job being transmitted. A message
informing the user that this job was discarded will be generated and
sent to him the next time he signs on. On the other hand, those jobs
whose receipt have been acknowledged on the operator's console will
not be affected by the failure, but will be executed by CCN.
E. Output Operations
The user may wait to set up a virtual printer (or punch) and open its
channel until a STATUS message on his console indicates output is
ready; or he may leave the output channel(s) open during the entire
session, ready to receive output whenever it becomes available. He
can also control which one of several available jobs is to be
returned by entering appropriate operator commands.
To be prepared to receive printer (or punch) output from his jobs,
the user site issues Init (local = U + 4 (U + 6), foreign = S + 3 (S
+ 5), size = 8), respectively. NETRJS is listening on these sockets
and should immediately return an STR. However, it is possible that
because of software problems at CCN, RJS will refuse the connection
and a CLS will be returned; in this case, try again or call the
Technical Liaison.
When RJS has output to send to a particular (virtual) terminal and a
corresponding open output channel, it will send the output as a
series of logical records using the protocol in Appendix A. The
first record will consist of the job name (8 characters) followed by
a comma and then the ID string from the JOB card (if any). In the
printer stream, the first column of each record will be an ASA car-
riage control character (see Appendix C); the punch output stream
will never contain carriage control characters.
NETRJS will send an End-of-Data transaction and then close an output
channel at the end of the output for each complete batch job; the
remote site must then send a new RFC (and ALL) to start output for
another job. This gives the remote site a chance to allocate a new
file for each job without breaking the output within a job. If the
user at the remote site wants to cancel (or backspace or defer) the
output of a particular job, he enters appropriate RJS commands on the
operator input channel (see Appendix D).
A virtual printer in NETRJS has 254 columns, exclusive of carriage
control; RJS will send up to 255 characters of a logical record it
finds in a SYSOUT data set. If the user wishes to reject or fold
records longer than some smaller record size, he can do so in his
VRBT process.
If RJS encounters a permanent I/O error in reading the disk data set,
it will notify the user via his console, skip forward to the next set
of system messages or SYSOUT data set in the same job, and continue.
In the future, RJS may be changed to send a Lost Data marker within
the data stream as well as a console message to the user. In any
case, the user will receive notification of termination of output
data transfer for each job via messages on his console.
If the user detects an error in the stream, he can issue a Backspace
(BSP) command from his console to repeat the last "page" of output,
or a Restart (RST) command to repeat from last SYSOUT data set or the
beginning of the job, or he can abort the channel by closing his
socket. If he aborts the channel, RJS will simulate a Backspace com-
mand, and when the user re-opens the channel the job will begin
transmission again from an earlier point in the same data set. This
is true even if the user terminates the current session first, and
re-opens the channel in a later session; RJS saves the state of its
output streams. However, before re-opening the channel he can defer
this job for later output, restart it at the beginning, or cancel its
output (see Appendix D). Note that aborting the channel is only
effective if RJS has not yet sent the End-of-Data transaction.
If the user's process, NCP, or host, or the Network itself fails dur-
ing an output operation, RJS will act as if the channel had been
aborted and the user signed off. In no case should a user lose out-
put from NETRJS.
Appendix A
Data Transfer Protocol in NETRJS
1. Introduction
The records in the data transfer channels (for virtual card reader,
printer, and punch) are generally grouped into _transactions_ pre-
ceded by headers. The transaction header includes a sequence number
and the length of the transaction. Network byte size must be 8 bits
in these data streams.
A transaction is the unit of buffering within the Model 91 software.
Internal buffers are 880 bytes. Therefore, CCN cannot transmit or
receive a single transaction larger than 880 bytes. Transactions can
be as short as one record; however, those sites which are concerned
with efficiency should send transactions as close as possible to the
880 byte limit.
There is no necessary connection between physical message boundaries
and transactions ("logical messages"); the NCP can break the "logical
message" arbitrarily into physical messages. At CCN we will choose
to have each logical message start a new physical message, so the NCP
can send the last part of each message without waiting for an expli-
cit request, but a remote site is not required to follow this conven-
tion.
Each logical record within a transaction begins with an "op code"
byte which contains the channel identification, so its value is
unique to each channel but constant within a channel. This choice
provides a convenient way to verify bit synchronization at the
receiver, and also allows an extension in the future to true "multi-
leaving" (i.e., multiplexing all channels within one connection in
each direction).
The only provisions for transmission error detection in the current
NETRJS protocol are (1) this "op code" byte to verify bit synchroni-
zation and (2) the transaction sequence number. At the urging of
Crowther, we favor putting an optional 16 bit check sum in the unused
bytes of the second-level header. It is currently assumed that if an
error is detected then the channel is to be aborted and the entire
transmission repeated. To provide automatic retransmission we would
have to put in reverse channels for ACK/NAK messages.
2. Character Sets
For an ASCII VRBT, NETRJS will map ASCII in the card reader stream
into EBCDIC, and re-map the printer stream to ASCII, by the following
rules:
1. One-to-one mapping between the three ASCII characters | ~ \
which are not in EBCDIC, and the three EBCDIC characters
[vertical bar, not-sign and cent-sign] (respectively) which
are not in ASCII.
2. The other six ASCII graphics not in EBCDIC will be
translated on input to an EBCDIC question mark (?).
3. The ASCII control DC3 (the only one not in EBCDIC) will be
mapped into and from the EBCDIC control TM.
4. The EBCDIC characters not in ASCII will be mapped in the
printer stream into the ASCII question mark.
3. Meta-Notation
The following description of the NETRJS data transfer protocol uses a
formal notation derived from that proposed in RFC #31 by Bobrow and
Sutherland. (The NETRJS format is also shown diagramatically in
Figure 2.)
The derived notation is both concise and easily readable, and we
recommend its use for Network documentation. The notation consists
of a series of productions for bit string variables whose names are
capitalized. Each variable name which represents a fixed length
field is followed by the length in bits (e.g., SEQNUMB(16)). Numbers
enclosed in quotes are decimal, unless qualified by a leading X
meaning hex. Since each hex digit is 4 bits, the length is not shown
explicitly in hex numbers. For example, '1'(8) and X'FF' both
represent a string of 8 one bits. The meta-syntactic operators are:
| :alternative string
[ ] :optional string
( ) :grouping
+ :catenation of bit strings
The numerical value of a bit string (interpreted as an integer) is
symbolized by a lower case identifier preceding the string expression
and separated by a colon. For example, in "i:FIELD(8)", i symbolizes
the numeric value of the 8 bit string FIELD.
Finally, we use Bobrow and Sutherland's symbolism for iteration of a
sub-string: (STRING-EXPRESSION = n); denotes n occurrences of STRING
EXPRESSION, implicitly catenated together. Here any n >= 0 is
assumed unless n is explicitly restricted.
4. Protocol Definition
STREAM <-- (TRANSACTION = n) + [END-OF-DATA]
That is, STREAM, the entire sequence of data on a particular open
channel, is a sequence of n TRANSACTIONS followed by an END-OF-DATA
marker (omitted if the sender aborts the channel).
TRANSACTION <-- THEAD(72) + (RECORD = r) + ('0'(1) = f)
That is, a transaction consists of a 72 bit header, r records, and f
filler bits.
THEAD <-- X'FF' + f:FILLER(8) + SEQNUMB(16) + LENGTH(32) + X'00'
Transactions are to be consecutively numbered in the SEQNUMB field,
starting with 0 in the first transaction after the channel is (re-)
opened. The 32 bit LENGTH field gives the total length in bits of
the r RECORD's which follow. For convenience, the using site may add
f additional filler bits at the end of the transaction to reach a
convenient word boundary on his machine; the value f is also
transmitted in the FILLER field of THEAD.
RECORD <-- COMPRESSED | TRUNCATED
RJS will accept intermixed RECORD's which are COMPRESSED or TRUNCATED
in an input stream. RJS will send one or the other format in the
printer and punch streams to a given VRBT; the choice is determined
when CCN establishes a terminal id.
COMPRESSED <-- '2'(2) + DEVID(6) + (STRING = p) + '0'(8)
STRING <-- ('6'(3) + i:DUPCOUNT(5))
This form represents a string of i
consecutive blanks
('7'(3) + i:DUPCOUNT(5) + TEXTBYTE(8))
This form represents string of i consecutive
duplicated of TEXTBYTE.
('2'(2) + j:LENGTH(6) + (TEXTBYTE(8) = j))
This form represents a string of j
characters.
The first two alternatives above in the STRING production begin with
count bytes chosen to be distinguishable from the (currently defined)
Telnet control characters. In a Telnet stream, the third count byte
would not be needed. This is irrelevant to the current NETRJS, but
it would allow the use of compression within a Telnet data stream.
TRUNCATED <-- '3'(2) + DEVID(6) + n:COUNT(8) + (TEXTBYTE(8) = n)
DEVID(6) <-- DEVNO(3) + t:DEVTYPE(3)
DEVID identifies a particular virtual device, i.e.,
it identifies a channel. DEVTYPE specifies the type
of device, as follows:
t = 1: Output to remote operator console
2: Input from remote operator console
3: Input from card reader
4: Output to printer
5: Output to card punch
6,7: Unused
DEVNO(3) identifies the particular device of type t
at this remote site; at present only DEVNO = 0 is
possible.
END-OF-DATA <-- X'FE'
Signals end of job (output) or job stack (input).
APPENDIX B
Telnet for VRBT Operator Console
The remote operator console connections use the ASCII Telnet
protocol as in RFC #158. Specifically:
1) The following one-to-one character mappings are used for the
three EBCDIC graphics not in ASCII:
ASCII
in Telnet NETRJS
| [vertical bar]
~ [not-sign]
\ [cent-sign]
2) Initially all Telnet control characters will be ignored. In the
future we will implement the Telnet Break facility to allow a
remote user to terminate extensive console output from a
command.
3) An operator console input line which exceeds 133 characters
(exclusive of CR LF) will be truncated by NETRJS.
4) NETRJS will accept BS to delete a character, and CAN to delete
the current line. The sequence CR LF terminates each input and
output line. HT will be translated to a single space in RJS.
All other ASCII control characters will be ignored. NETRJS will
translate the six ASCII graphics with no equivalent in EBCDIC
into the character question mark ("?") on input.
APPENDIX C
Carriage Control
The carriage control characters sent in a printer channel by NETRJS
conform to IBM's extended USASI code, defined by the following table:
CODE ACTION BEFORE WRITING RECORD
blank Space one line before printing
0 Space two lines before printing
- Space three lines before printing
+ Suppress space before printing
1 Skip to channel 1
2 Skip to channel 2
3 Skip to channel 3
4 Skip to channel 4
5 Skip to channel 5
6 Skip to channel 6
7 Skip to channel 7
8 Skip to channel 8
9 Skip to channel 9
A Skip to channel 10
B Skip to channel 11
C Skip to channel 12
APPENDIX D
Network/RJS Command Summary
Terminal Control and Information Command
SIGNON First command of a session; identifies VRBT by giving
its terminal id.
SIGNOFF Last command of a session; RJS waits for any data
transfer in progress to complete and then closes all
connections.
STATUS Outputs on the remote operator console a complete
list, or a summary, of all jobs in the system for
this VRBT, with an indication of their processing
status in the Model 91.
ALERT Outputs on the operator console the special "Alert"
message, if any, from CCN computer operator. The
Alert message is also automatically sent when the
user does a SIGNON, or whenever the message changes.
MSG Sends a message to CCN computer operator or to any
other RJS terminal (real or virtual). A message from
the computer operator or another RJS terminal will
automatically appear on the remote operator console.
Job Control and Routing Commands
Under CCN's job management system, the default destination for output
is the input source. Thus, a job submitted under a given VRBT will
be returned to that VRBT (i.e., the same terminal id), unless the
user's JCL overrides the default destination.
RJS places print and punch output described for a particular remote
terminal into either an Active Queue or a Deferred Queue. When the
user opens his print or punch output channel, RJS immediately starts
sending job output from the Active Queue, and continues this queue is
empty. Job output in the Deferred Queue, on the other hand, must be
called for by job name, (via a RESET command from the remote opera-
tor) before RJS will send it. The Active/Deferred choice for output
from a job is determined by the deferral status of the VRBT when the
job is entered; the deferral status, which is set to the Active
option when the user signs on, may be changed by the SET command.
SET Allows the remote user to change certain properties
of his VRBT for the duration of the current session;
(a) May change the default output destination to be
another (real or virtual) RJS terminal or the central
facility.
(b) May change the deferral status of the VRBT.
DEFER Moves the print and punch output for a specified job
or set of jobs from the Active Queue to the Deferred
queue. If the job's output is in the process of
being transmitted over a channel, RJS aborts the
channel and saves the current output location before
moving the job to the Deferred Queue. A subsequent
RESET command will return it to the Active Queue with
an implied Backspace (BSP).
RESET Moves specified job(s) from Deferred to Active Queue
so they may be sent to user. A specific list of job
names or all jobs can be moved with one RESET
command.
ROUTE Re-routes output of specified jobs (or all jobs)
waiting in the Active and Deferred Queues for this
VRBT. The new destination may be any other RJS
terminal or the central facility.
ABORT Cancels a job which was successfully submitted and
awaiting execution or is current executing in the
Model 91. If he cancelled job was in execution, all
output it produced ill be returned.
Output Stream Control Commands
BSP (BACKSPACE) "Backspaces" output stream within current sysout data
set. Actual amount backspaced depends upon sysout
blocking but is typically equivalent to a page on the
line printer.
CAN (CANCEL) (a) On an output channel, CAN causes the rest of the
output in the sysout data set currently being
transmitted to be omitted. Alternatively, may
omit the rest of the sysout data sets for the job
currently being transmitted; however, the remain-
ing system and accounting messages will be sent.
(b) On an input channel, CAN causes RJS to ignore the
job currently being read. However, the channel
is not aborted as a result, and RJS will continue
reading in jobs on the channel.
(c) CAN can delete all sysout data sets for specified
job(s) waiting in Active or Deferred Queue.
RST (RESTART) (a) Restarts a specified output stream at the begin-
ning of the current sysout data set or, option-
ally, at the beginning of the job.
(b) Marks as restarted specified job(s) whose
transmission was earlier interrupted by system
failure or user action (e.g., DEFER command or
aborting the channel). When RJS transmits these
jobs again it will start at the beginning of the
partially transmitted sysout data set or, option-
ally, at the beginning of the job. This function
may be applied to jobs in either the Active or
the Deferred Queue; however, if the job was in
the Deferred Queue then RST also moves it to the
Active Queue. If the job was never transmitted,
RST has no effect other than this queue movement.
REPEAT Sends additional copies of the output of specified
jobs.
EAM Echoes the card reader stream back in the printer or
punch stream, or both.
+---------------------------------+
| RJS |
+---------------------------------+
^ | ^ | |
| v | v v
+------------------------------+
CCN -- Server | |
| NETRJS |
+------------------------------+
^ | ^ | |
| v | v v
+----------+ +---------------+
| TELNET | | Data Xfer | (server)
| Server | | 3rd Level |
+----------+ +---------------+
^ | ^ | |
---------------------|-----|----------|-----|-----|-----------------
O | O | | | |
p | p | C| C| C|
e I | e O| I h| O h| P h|
ARPA r n | r u| n a| u a| u a|
a p | a t| p n| t n| n n|
Network t u | t p| u n| p n| c n|
o t | o u| t e| u e| h e|
r | r t| l| t l| l|
---------------------|-----|----------|-----|-----|-----------------
| | | | |
| V | V V
+----------+ +---------------+
| TELNET | | Data Xfer | (user)
| Server | | 3rd Level |
+----------+ +---------------+
Remote ^ ^ | |
/ "Virtual | | |
User / Remote Batch | V V
/ Terminal" +------------------+
/ | |
V | NETRJS |
+---------+ | User |
/ |<------------->| Process |
/ Console | | |
+____________| +------------------+
^ | |
| V V
(file) (file) (file)
FIGURE 1. SCHEMATIC OF NETRJS OPERATION
+------+ +------+ +-----------+ +---------------------+
TRANSACTION <--> | X'FF'| |Filler| |Sequence | | Data Length |
| | | Count| | Number | | in bits |
+------+ +------+ +-----------+ +---------------------+
+------+
| X'00'| { RECORD } *
| |
+------+
<---- n text bytes ------>
+--+-----+ +--------+ +--------+ +--------+
TRUNCATED <--> |11|Devid| | n (8) | | Text | . . . | Text |
RECORD | | (6) | | | | (8) | | (8) |
+--+-----+ +--------+ +--------+ +--------+
/ \
| +---+----+ | *
| |110| n | (n blanks) |
| | |(5) | |
| +---+----+ |
| |
+--+-----+ / +---+----+ +--------+ |
COMPRESSED<--> |10|Devid|< |111| n | |Char- | (n replications |
RECORD | | (6) | \ | |(5) | | acter | of "Character") |
+--+-----+ | +---+----+ +--------+ |
| |
| +--+-----+ +--------+ +--------+ |
| |10| n | | Text | . . .| Text | |
| | | (6) | | (8) | | (8) | |
| +--+-----+ +--------+ +--------+ |
\ /
+------+
| X'00'|
| |
+------+
FIGURE 2. DATA TRANSFER PROTOCOL IN NETRJS
[ This RFC was put into machine readable form for entry ]
[ into the online RFC archives by Tony Hansen 11/98 ]