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Network Working Group                                          R. BradenRequest for Comments: 88                                        S. WolfeNIC: 5668                                                       UCLA/CCN                                                         13 January 1971NETRJS - A THIRD LEVEL PROTOCOL FOR REMOTE JOB ENTRY   A.  Introduction   NETRJS is the name for a message protocol and set of control   conventions which will allow users at remote Hosts to access the RJS   ("Remote Job Service") remote batch subsystem of CCN.  RJS[1] was   written at CCN to support remote batch (car reader/line printer)   terminals over communications lines.   RJS makes a remote batch terminal's unit record devices operate as if   they were at the central site; thus, a remote user enters OS/360   jobs, complete with JCL, into the remote reader.  The jobs are   spooled into the operating system and run in their turn, and the   printed and/or punched output is returned to the remote terminal from   which the jobs originated (unless the user or operator re-routes the   output).  The remote terminal may also include a console typewriter   to be used by the remote operator to receive and send messages and to   exert control over his terminal [2].   When RJS is used via the ARPA Network, the "remote terminal" is   expected to be a multiprogrammed user process in a remote Host.  We   will use the RJS term "remote site" for such a user process, which   presumably simulates unit record devices by file I/O.  Furthermore,   several users at the same remote Host may simultaneously use NETRJS,   acting as independent "remote sites" distinguished by 8-character   names called _terminal-ids_ (because each remote site appears to RJS   as a separate physical terminal).  Valid terminal-ids will be   assigned to individual users or user groups at remote Hosts who wish   to use NETRJS.   Under NETRJS, a separate ARPA network connection is opened from this   remote site to CCN for each (simulated) unit record device.  Each   such connection will be called a _channel_ and be designated _input_   or _output_ with reference to CCN.  We define a _standard_ remote   site in NETRJS to have the following five channels (See Figure 1):      1._Operator Input Channel_ - Commands and messages entered by         remote "operator" console.      2 _Operator Output Channel_ - Message stream which would normally         be directed to remote operator.Braden, et. al.                                                 [Page 1]

RFC 88              NETRJS - A THIRD LEVEL PROTOCOL      13 January 1971      3._Input Stream_ - One simulated Hollerith card reader for job         submission.      4._Printer Stream_ - One simulated line printer to record printed         output (system messages and SYSOUT data sets) from jobs.      5._Punch Stream_ - One simulated card punch, capable of recording         arbitrary (i.e., transparent) binary text.   RJS actually will support more than one reader, printer, and punch at   each remote terminal, so the NETRJS protocol could easily be expanded   to allow multiple simultaneous I/O streams to each Network user.   However, this does not presently appear useful, as the ARPA Network   bandwidth will normally be the limitation on the transmission speed   under NETRJS.   Under NETRJS, the text of a single network message is called a   _block_.  A block is of variable length, up to 900 bytes (except   operator input and output blocks, which may not exceed 130 bytes).   Here the term _byte_ refers to the set of 8 bits representing one   character; each byte is to be aligned on an 8-bit boundary within the   message (and block).  Thus we may consider a block to be a string of   bytes.  The detailed format of a block will be defined in Sections E,   F, and G, using essentially the formalism suggested by Bobrow and   Sutherland in RFC #31.   Since the central site Host (CCN) is an IBM 360, NETRJS uses the IBM   EBCDIC character code to avoid redundant code conversion at both   hosts in those cases when the remote host also uses EBCDIC   internally.  However, the message formats make no assumption about   the code, and in fact, "object decks" sent to the (simulated) card   punch will normally contain arbitrary binary text.   To maximize the use of the available Network bandwidth, we strongly   recommend transmitting input blocks as large as possible; CCN will   always fully block NETRJS output.  Furthermore, to avoid excessive   overhead, we urge that all NETRJS users make their marking _a   multiple of 8 bits_, so the messages received at CCN arrive on a byte   boundary.   B.  Starting a Session[3]   The initial connection protocol for NETRJS is essentially that of   Crocker in RFC #66 (as restated by Harslem and Heafner in RFC #80),   with some extensions.  User U at a remote Host presumably requests   his outgoing logger to make a NETRJS connection to CCN.  ThisBraden, et. al.                                                 [Page 2]

RFC 88              NETRJS - A THIRD LEVEL PROTOCOL      13 January 1971   logger does so by first sending an initial RFC to connect socket   (user,aen) = (U,s) to CCN socket (0,5).  User 0 at CCN is the   incoming logger, and aen = 5 signifies NETRJS.   The CCN incoming logger will allocate a set of (six) consecutive aen   numbers A, A+1,......A+5, for user U, return a message containing the   socket number (U,A) as specified in RFC #66, and close the initial   connection.  The remote and central sites will then open an input   channel between CCN socket (U,A) (socket f in Figure 1) and remote   socket (U, s+1).  This is the remote operator input channel.  The   other devices have fixed aen's at CCN assigned relative to A, in   particular:                                 CCN Socket         Channel                 (User,aen)         Operator Input          (U,A)         Operator Output         (U,A+1)         Card Reader (No. 1)     (U,A+2)         Printer (No. 1)         (U,A+3)         Punch (No. 1)           (U,A+5)   Once the operator input channel is open, the remote site must   transmit a valid RJS signon message [2].  This message is free-format   and consists of the command verb "SIGNON" followed by the user's   terminal-id.  If RJS does not recognize the terminal-id or has no   available Line Handler for the Network, it will indicate refusal by   closing the operator input channel.  Central site issues subsequent   RFC's for the other channels listed above only in response to   corresponding RFC's from the remote site   To terminate the session, the remote site may close the console input   channel (socket "a" in figure 1).  Alternatively, the user can enter   a SIGNOFF command through the operator input channel; in this case,   RJS will wait until the current job output streams are complete and   then terminate the session.  RJS terminates the session by closing   the console output channel (socket g).  Also, if RJS should abend   then socket g will close.  If either site terminates the session, all   other connections for this remote site should be closed.  Note that a   user can submit a number of jobs, sign off, and later receive his   output when he signs on again.C.  Channel Control   Flow control in NETRJS is handled by the Network protocol ALL   mechanism.  Before transmission of a stream of records can begin on a   particular channel, the remote site must issue an RFC and Central   must reply.  This allows the central site to determine the remoteBraden, et. al.                                                 [Page 3]

RFC 88              NETRJS - A THIRD LEVEL PROTOCOL      13 January 1971   configuration dynamically.  A particular card reader, printer, or   punch channel is open only while it is active, so the receiver need   not tie up buffer space needlessly.  Each of these channels, when   open, assumes a buffer allocation of at least 900 bytes at the   receiver.   The operator input and output channels, on the other hand, are open   throughout the session.  On these channels the receiver must provide   an allocation of at least 130 bytes.   After sending the SIGNON command over the operator input channel, the   remote site should send RFC's for all output channels which are ready   to receive data.  When output is available for that site, Central   returns an RFC and begins transmission.  Central closes an output   channel (socket i and j) at the end of the output for each complete   batch job.[4]  The remote site must then send a new RFC and Central   must reply with an RFC to start output for another job to that   device.  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[2] on the   operator input channel.   When the remote site is ready to submit a job (or stack of   consecutive jobs), it issues an RFC for the card reader input   channel.  The remote site is not required to close the channel   (socket c) after each job in a "stack" of jobs, but he must close it   following the last job in the stack to initiate its processing.   It may be necessary for the receiver site to abort a particular   channel, perhaps due to a transmission error (see Section D below on   checking) or a disk I/O error.  The receiver may abort a channel   (other than console output) by closing it (sockets d, e, f, and h).   This action signals the transmitter to re-transmit the information   after the channel has been reopened (initiated by the remote site, as   always).  The transmitter, on the other hand, aborts a channel by   sending a block with a particular bit combination (e = 2 in BCBYTE;   see Section E).   If either site aborts card reader (input) channel, RJS will discard   the text of the last partially-spooled job; the remote site should   re-transmit this job.  Note that repeating an entire stack will enter   duplicate jobs into the system, but the second copy of a job will   "flush" due to its duplicate job name.   If a printer or punch (output) channel is aborted, Central will re-   transmit from the beginning of the current SYSOUT data set; the   effect is the same as a RESTART command.[2]Braden, et. al.                                                 [Page 4]

RFC 88              NETRJS - A THIRD LEVEL PROTOCOL      13 January 1971   If the operator input channel is aborted, the remote site must re-   transmit the last _block_.  Finally, the operator output channel has   no abort condition defined.  Central will never send Channel Abort   message on this channel; if the remote site closes its socket (socket   b), Central will not re-transmit, but simply cease sending messages   until the channel is reopened.  Therefore a remote site can operate   without an operator output channel; however we do not recommend this,   as the user will then miss operator advisory messages such as a   warning of an impending IPL.D.  Checking   The nature of remote job entry service is such that a low rate of   undetected errors is mandatory.  The IMP's use CRC's and sequence   numbers over the communication lines, so the effective IMP-IMP error   rate should be negligible.  Although there is no checking provided   for the IMP-Host interface, it seems likely that these interfaces   will either be reliable or fail catastrophically; it seems unlikely   that "drop-outs" or other random failures will occur.  Therefore only   the following simple checks are provided:   1. Each block will (at least initially) contain a fixed bit check      pattern using both on and off states of each bit path in the 16      bit PDA interface at CCN.      It is anticipated that even this crude check on IMP-Host      transmission will be useful both during the initial checkout of      hardware and software and also later if the interface becomes      marginal.  However, either site can omit the check pattern if it      sets a bit in the Block Control Byte (BCBYTE); see Section F.   2. Each block contains a sequence number.  Again this is intended for      initial checkout and to signal catastrophic hardware or software      problems.  If the receiver detects an incorrect check pattern or      block sequence number, he aborts the channel by closing the      corresponding network connection; the remote site should then      issue an RFC to re-establish the network connection.  The sequence      number of the first block after an RFC is 0.  The  numbers are      never reset while the connection is open.Braden, et. al.                                                 [Page 5]

RFC 88              NETRJS - A THIRD LEVEL PROTOCOL      13 January 1971E.  Block Format      BLOCK <---- BLOCKHEAD + (RECORD = r) + ENDOFBLOCK                  Here r > 0                         =   BLOCKHEAD <--  BCBYTE + [e=0=>CHECK] + DEVBYTE                  The Blockhead field consists of a Block Control Byte,                  a 32-bit check field CHECK, and a Device Byte.   BCBYTE <----   '1'BIT + e:ERRORCONTROL + b:BLKSEQ                  Here BLKSEQ contains a 5-bit modulo 32 block sequence                  number b.  ERRORCONTROL is a 2 bit field with the                  following meanings:                  e=0 :  Normal block.  Contains a (presumably valid)                         check field CHECK.                  e=1 :  Block contains no check field CHECK.                  e=2 :  Abort channel, initiated by transmitter.                         Channels is not closed, transmission restarts                         on job-related boundary.   DEVBYTE <----  '1'BIT + n:DEVNO + t:DEVTYPE                  This byte identifies a particular remote device, i.e.,                  it identifies a stream.  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 is a 3-bit integer which identifies the                  particular device type of type t at this remote site.   CHECK <---     '10101111'BYTE + 01010000'BYTE + '11111010'BYTE +                                                   '00000101'BYTE   ENDOFBLOCK<----'0'BYTEBraden, et. al.                                                 [Page 6]

RFC 88              NETRJS - A THIRD LEVEL PROTOCOL      13 January 1971Record Format      RECORD <------ DATA RECORD | JOBNAMERECORD   The first record sent on a printer or punch output channel will be a   JOBNAMERECORD, identifying the OS/360 jobname of the job which   produced the following output.   DATARECORD <---   '10'BIT2 + DEVCNTRL + (STRING=p) + ENDOFRECORD   JOBNAMERECORD <-- '11000000'BYTE + '11001000'BYTE + JOBNAME +                     ENDOFRECORD   JOBNAME <----     (TEXTBYTE = 8)                     This is the 8-character OS/360 jobname for the                     following job.   DEVCNTRL <-----    d:BIT2 + k:BIT4                     DEVCNTRL specifies carriage control for a printer,                     so if the device is not a printer then DEVCNTRL                     should be '000000'.  For a printer:                     d=0     : Space k lines after printing; 0 < k < 3                                                               =   =                               is allowed                     d=2     : Immediately space k lines.                     d=1, k=1: Skip to top of new page after printing.                     d=3, k=1: Immediately skip to top of new page.   STRING <---         ('100' + i:DUPCOUNT)| This is a string of i                     consecutive blanks.                     ('101' + i:DUPCOUNT + TEXTBYTE)|                     This is a string of i consecutive duplicates of                     TEXTBYTE.                     ('11' + j:LENGTH + (TEXTBYTE=j)| This is an                     uncompressed string of j characters.   ENDOFRECORD <----   '0'BYTEBraden, et. al.                                                 [Page 7]

RFC 88              NETRJS - A THIRD LEVEL PROTOCOL      13 January 1971G.  Field Definitions   Name*           Meaning                 Length (bits)   _____           _______                 _____________   BIT             1-bit field                  1   BIT2            2-bit field                  2   BIT4            4-bit field                  4   BLKSEQ          Block sequence number        5   BYTE            8-bit field aligned on 8-bit 8                   boundary   CHECK           Block check number          32   DEVNO           Device number of a given     3                   type   DEVTYPE         Device type                  4   DUPCOUNT        Number of replications of    5                   duplicated character in                   compressed text.   ERRORCONTROL    Block transmission error     2                   control.   LENGTH          Length in bytes of the       6                   following string of text.   TEXTBYTE        An 8-bit byte of text        8   *Note:  All non-terminal fields whose names end in           "...BYTE" represent bytes in both length and           alignment.Braden, et. al.                                                 [Page 8]

RFC 88              NETRJS - A THIRD LEVEL PROTOCOL      13 January 1971   H.  NOTES AND REFERENCES   1. Martin, V.A. and Springer, T.W., "Implementation of A Remote Job      Service", Technical Report TR2, Campus Computing Network, UCLA,      Los Angeles, (undated).   2. The RJS operator commands and messages are described in detail in      Reference 1.   3. We use the phrase "starting a session" rather than "logging on"      because RJS has its own log on procedure, which is, we suppose, a      fourth-level protocol.   4. Note that NETRJS uses closing of connections as end-of-file      signals.           REMOTE SITE             CENTRAL SITE (CCN)      +---------------------+    +--------------------+      |                 a   |    |                    |      | Console Input  o----------->o f               |      |                 b   |    |                    |      | Console Output o<-----------o g               |      |                 c   |    |                    |      | Card Reader    o------------o h               |      |                 d   |    |                    |      | Printer        o<-----------o i               |      |                 e   |    |                    |      | Card Punch     o<-----------o j               |      |                     |    |                    |      +---------------------+    +--------------------+                           FIGURE 1                ARPA Network Connections (Channels)              For a Standard Remote Site Under NETRJS      R.T. Braden/rb.      S.M. Wolfe           [This RFC was put into machine readable form for entry]            [into the online RFC archives by Lorrie Shiota, 10/01]Braden, et. al.                                                 [Page 9]