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RFC 119 - Network Fortran Subprograms


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Network Working Group                                     M. Krilanovich
Request for Comments: 119                                           UCSB
NIC: 5831                                                 April 21, 1971

                      NETWORK FORTRAN SUBPROGRAMS

Preface

   The subroutines described in this document have been implemented at
   UCSB and make the Network (via the NCP) accessible to Fortran
   programs executing in the 360/75.  They are callable from within any
   Fortran main program or subroutine compiled at UCSB.

   A set of assembly-language written subprograms is provided to
   facilitate the sue of the Network by FORTRAN programmers.  They serve
   as an interface between the user and the Network Control Program
   (NCP), which supervises all Network operations at this site.

   A concept fundamental to FORTRAN Network operations is that of a
   completion code variable.  Associated with each socket that is not in
   the closed state is a unique variable, called a completion code
   variable.  This variable serves two purposes: it identifies the local
   socket referenced, and upon completion of the operation it contains a
   completion code to indicate the outcome of the operation to the
   programmer.  It may be used at any time for any purpose other than
   network operations.  Its value at the beginning of a Network
   operation is immaterial; rather it is the variable itself that is
   important.  In all Network operations, whenever a completion code
   variable is called for, the only acceptable type variable is
   INTERGER*4.

   In general, the subprograms will initiate the operation, and enter
   the WAIT state (consume no CPU time) until notified by the NCP of the
   completion of the operation.  For such operations, the programmer
   supplies a time limit, of type INTERGER*4, which specifies, in tenths
   of a second, the maximum length of time the subprogram is to wait for
   the operation to complete.  If this time limit is exceeded, a
   completion code is supplied to indicate the error; and control is
   returned to the calling program, with the operation still pending.

   In those operations requiring a socket to be specified by its socket
   identifier, the following format is used.  The identifier is
   specified as a INTEGER*4 array with at least two elements, or an
   element of such an array.  The first element specified is taken to be
   the site number, and the next element the socket number.  A socket
   number may have any value, positive, negative, or zero.  Since
   negative numbers are represented internally in two's complement form,
   for the purposes of the gender of a socket, a socket number is even
   for odd according to whether its absolute value is even or odd,
   respectively.

   Following is a description of each subprogram, its function and
   calling sequence.

   (1) OPEN

       By invoking this subprogram, the user requests that the specified
       local socket be removed from the closed state and thus be
       prepared to participate in data transfer.  There are three
       distinct operations that can be performed by this subprogram, and
       these are described below:

       (A) CONNECT

           By initiating this operation, the user requests that the
           specified local socket be logically connected to the
           specified foreign socket, and that data transfer between the
           two sockets be enabled.  The subprogram will wait until the
           foreign socket either accepts or rejects the connection
           attempt.  This operation is valid only when the local socket
           is in the closed state.

              The calling sequence is as follows:

                 CALL OPEN (cmpcd, time, lclsck, fgnsck, ws)

           where
                'cmpcd' is the completion code variable to be associated
                     with the local socket.

                'time' is the length of time the subprogram is to wait
                     for the completion of the operation.

                'lclsck' is the socket identifier of the local socket.

                'fgnsck' is the socket identifier of the foreign socket.

                'ws' is a workspace, which as the same attributes as a
                     socket identifier, and, if the operation is
                     successful, will become associated with the local
                     socket for the life of the connection.  In response
                     to certain future operations, information may be
                     returned to the programmer in this workspace.

                The following completion codes are possible for this
                operation:

                     0, The operation was successful and the connection
                        has been established

                     4, The specified completion code variable is
                        already assigned to a socket; the operation was
                        suppressed

                     8, The specified local socket is not in the closed
                        state; the operation was suppressed

                    12, All communication paths to the specified foreign
                        site are in use; the operation was suppressed

                    16, Local resources are insufficient to support
                        another connection; the operation was suppressed

                    20, The connection attempt was rejected by the
                        foreign process

                    24, The specified local socket is not local to UCSB;
                        the operation was suppressed

                    28, The specified foreign site is invalid; the
                        operation was suppressed

                    32, An addressing or protection exception was
                        encountered with respect to the specified
                        workspace; the operation was suppressed

                    36, Either hardware at the foreign site is
                        inoperative or the NCP's counterpart at the
                        foreign site does not exist or has failed

                    40, Local and foreign sockets are both either send
                        or receive sockets; the operation was suppressed

                    44, By operator command, all Network operations were
                        terminated; the socket will be closed

                    60, An NCP control transmission error occurred; the
                        operation was suppressed

                   252, The specified time limit was exceeded; the
                        operation was initiated but not completed

       (B) LISTEN

           This operation is a request for notification of any
           connection attempt directed toward the specified local
           socket.  The subprogram waits until such a call is received,
           at which time the calling processes' socket identifier is
           returned to the calling program.  This operation is valid
           only when the designated local socket is in the closed state.

              The calling sequence is as follows:

                 CALL OPEN (cmpcd, time, lclsck, ws)

           Where
                'cmpcd' is the completion code variable to be associated
                     with the local socket.

                'time' is the length of time the subprogram is to wait
                     for the completion of the operation.

                'lclsck' is the socket identifier of the local socket.

                'ws' is a workspace which, if the operation is
                     successful, will contain the socket identifier of
                     the calling socket, and will become associated with
                     the local socket for the life of the connection.
                     'ws' has the same attributes as a socket
                     identifier.

                The following completion codes are possible for this
                operation:

                     0, The operation was successful and a call has been
                        received

                     4, The specified completion code variable is
                        already assigned to a socket; the operation was
                        suppressed

                     8, The specified local socket is not in the closed
                        state; the operation was suppressed

                    12, Local resources are insufficient to support
                        another connection; the operation was suppressed

                    16, The specified local socket is not local to UCSB;
                        the operation was suppressed

                    20, An addressing or protection exception was
                        encountered with respect to the specified
                        workspace; the operation was suppressed

                    44, By operator command, all Network operations were
                        terminated; the socket will be closed

                   252, The specified time limit was exceeded; the
                        operation was initiated but not completed

       (C) ACCEPT

           This operation accepts connection with the foreign socket
           whose call caused successful completion of a previous LISTEN
           operation by the specified local socket.  After completion of
           this operation, data may be transferred to or from the local
           socket, depending on its gender.  This operation is valid

           only when the last operation referencing the local socket was
           a LISTEN operation.  The subprogram will wait until the
           operation is completed.

              The calling sequence is as follows:

                 CALL OPEN (cmpcd, time)

           Where
                'cmpcd' is the completion code variable associated with
                the local socket by a previous LISTEN operation.

                'time' is the length of time the subprogram is to wait
                for the completion of the operation

             The following completion codes are possible for this
             operation:

                     0, The operation was successful, and the connection
                        is established

                     4, The specified local socket is in the closed
                        state 9The NCP may have received an abort
                        notification from the foreign process); the
                        operation was suppressed

                     8, the previous operation specifying the designated
                        local socket was not a LISTEN; the operation was
                        suppressed

                    12, All communication paths to the specified foreign
                        site are in use; the socket has been returned to
                        the closed state

                   252, the specified time limit was exceeded; the
                        operation was initiated but not completed

   (2) CLOSE

       This operation is a request that the specified local socket be
       returned to the closed state.  If the last operation involving
       this socket was a LISTEN, this operation refuses the foreign
       process' connection attempt.  If the last operation was CONNECT,
       the attempt is aborted.  If a connection is established, any data
       in transit from the local socket is allowed to reach the foreign
       socket to be either received or flushed before the local socket
       is closed.  The subprogram will wait until the socket has been
       returned to the closed state.

          The calling sequence is as follows:

             CALL CLOSE (cmpcd, time)

       Where
                'cmpcd' is the completion code variable associated with
                     the local socket.

                'time' is the length of time the subprogram is to wait
                     for the completion of the operation.

         The following completion codes are possible for this operation:

                     0, the operation was successful, and the socket has
                        been returned to the closed state

                     8, The specified completion code variable is not
                        currently assigned to a socket; the operation
                        was suppressed

                    12, The specified local socket is in the process of
                        being closed; the operation was suppressed, but
                        the local socket will be closed

                    36, Either hardware at the foreign site is
                        inoperative, or the NCP's counterpart at the
                        foreign site does not exist or has failed

                    44, By operator command, all Network operations were
                        terminated; the socket will be closed

                    60, An NCP control transmission error occurred; the
                        operation was aborted

                    64, A transmission error occurred; the operation was
                        aborted, but the socket will be closed

                   252, The specified time limit was exceeded; the
                        operation was initiated but not completed

   3) SEND

       This program causes data to be sent to the foreign socket.  The
       subprogram will wait until the data has been received by the
       foreign socket, or until it has been queued locally by the NCP.

          The calling sequence is as follows:

             CALL WRITE (cmpcd, bfr, len, time [,offset])

       Where
                'cmpcd' is the completion code variable associated with
                     the local socket.

                'bfr' is the data to be sent, and can be of any type,
                     any length.

                'len' is the number of bits of data to be sent.  If
                     'len' is non-positive, no operation is performed.
                     'len' is of type INTEGER*4.

                'time' is the length of time the subprogram is to wait
                     for the completion of the operation.

                'offset' is the bit offset from the first bit of 'bfr'
                     at which data transmission is to begin, and is of
                     type INTEGER*4.  If not specified, 'offset'
                     defaults to zero.

         The following completion codes are possible for this operation:

                     0, The operation was successful, and the data has
                        been sent

                     4, The specified local socket is not a send socket;
                        the operation was suppressed

                     8, The specified completion code variable is not
                        assigned to a socket; the operation was
                        suppressed

                    12, A previous send operation is in progress; the
                        operation was suppressed

                    16, The connection is not fully open; the operation
                        was suppressed

                    20, The foreign socket terminated the connection
                        before completion of the send operation; not all
                        the data was transmitted

                    36, Either hardware at the foreign site is
                        inoperative, or the NCP's counterpart at the
                        foreign site does not exist or has failed

                    44, By operator command, all Network operations were
                        terminated; the socket will be closed

                    52, One or more interrupts were received from the
                        foreign socket; the operation was suppressed

                    56, An addressing exception was encountered with
                        respect to the data buffer; the operation was
                        suppressed

                    60, An NCP control transmission error occurred; the
                        operation was aborted and the socket will be
                        closed

                    64, A transmission error occurred; the operation was
                        aborted and the socket will be closed

                   252, The specified time limit was exceeded; the
                        operation was initiated but not completed

   4) RECEIVE

       This operation causes data to be received from the foreign
       socket.  The subprogram will wait until the reception of data is
       complete.

          The calling sequence is as follows:

             CALL READ (cmpcd, bfr, len, time [,offset])

       Where
                'cmpcd' is the completion code variable associated with
                     the local socket.

                'bfr' is the variable into which the data is to be
                     placed, and can be of any type, any length.

                'len' is the number of bits of data to be received.  If
                     'len' is non-positive, no operation is performed.
                     'len' is of type INTEGER*4.

                'time' is the length of time the subprogram is to wait
                     for the completion of the operation.

                'offset' is the bit offset from the first bit of 'bfr'
                     at which the first bit of data is to be placed, and
                     is of type INTEGER*4.  If not specified, the
                     'offset' defaults to zero.

         The following completion codes are possible for this operation:

                     0, The operation was successful and the data has
                        been received

                     4, The specified local socket is not a receive
                        socket; the operation was suppressed

                     8, The specified completion code variable is not
                        assigned to a socket; the operation was
                        suppressed

                    12, A previous receive operation is in process; the
                        operation was suppressed

                    16, The connection is not fully open; the operation
                        was suppressed

                    20, The foreign socket terminated the connection
                        before completion of the receive operation; data
                        is unpredictable

                    24, An addressing or protection exception was
                        encountered with respect to the data buffer; the
                        operation was suppressed

                    36, Either hardware at the foreign site is
                        inoperative, or the NCP's counterpart at the
                        foreign site does not exist or has failed

                    44, By operator command, all network operations were
                        terminated; the socket will be closed

                    52, One or more interrupts were received from the
                        foreign socket; the operation was suppressed

                    60, An NCP control transmission error occurred; the
                        operation was suppressed and the socket will be
                        closed

                   252, the specified time limit was exceeded; the
                        operation was initiated but not completed

   5) CHECK

       This operation causes the status of the specified local socket to
       be returned.  There is no completion code variable associated
       with this operation, since it is always successful and the socket
       is identified by its socket number.  This operation is valid at
       any time and is always completed immediately.

          The calling sequence is as follows:

          CALL CHECK (lclsck, stat, menu, fgnsck, deficit)

       Where
                'lclsck' is the socket identifier of the local socket.

                'stat' is a code for the status, and is of type
                     INTEGER*4.

                'mnem' is a mnemonic for the status, and can be of any
                     type, of any length greater than or equal to eight
                     bytes.

                'fgnsck' is the socket identifier of the foreign socket,
                     or zero.

                'deficit' is the send/receive deficit in bits, or zero,
                     and is to type INTEGER*4.

                'lclsck' is the only argument the programmer need
                     define; the others are output from the subprogram.

   'STAT'    'MNEM'         MEANING
   ------    ------         ---------
     0        OPEN         A connection is fully established. No
                           SEND/RECEIVE operation is in progress.
                          'fgnsck' is the socket identifier of the
                           connected socket.  'deficit' is the number of
                           bites queued locally at the socket by the NCP
                           and available to satisfy a future RECEIVE
                           operation, or awaiting output ads the results
                           of a previous SEND operation.

     1       LISTEN        A LISTEN has been issued.

     2       CONNECT       A CONNECT has been issued. 'fgnsck' is the
                           socket identifier of the foreign socket.

     3       DECISION      A LISTEN has been completed.  'fgnsck' is
                           the socket identifier of the calling socket.

     4       CALL(S)       One or more calls have been received for the
                           local socket. No LISTEN or CONNECT has been
                           issued.

     5       I/O           A connection is fully established. A
                           SEND/RECEIVE operation is in progress.
                          'fgnsck' is the socket identifier of the
                           connected socket.  'deficit' is the number
                           of bits yet to be sent or received.

     6       CLOSED        The socket is in the closed state.

     7      <--DRAIN       The foreign socket is attempting to close the
                           connection.  The NCP has data yet to be ready
                           by the local socket.  'fgnsck' is the socket
                           identifier of the connected socket.
                          'deficit' is the number of bits yet to be
                           received.

     8       DRAINED       The foreign socket is attempting to close the
                           connection.  The NCP is awaiting arrival at
                           the foreign site of data currently in
                           transit.  'fgnsck' is the socket identifier
                           of the connected socket.

     9       CLOSING       The local socket has issued a CLOSE. The NCP
                           is in the process of returning the local
                           socket to the closed state. 'fgnsck' is the
                           socket identifier of the connected socket.

    10       DRAIN-->      The local socket has issued a CLOSE.  The NCP
                           is completing the last SEND operation before
                           returning the local socket to the closed
                           state.  'fgnsck' is the socket identifier
                           of the connected socket. 'deficit' is the
                           number of bits the NCP has yet to transmit.

   (6) IDENTIFY

       This operation is used to identify a local socket by its
       completion code variable.  The operation is valid at any time,
       and is always completed immediately.  Since it is always
       successful, there are no completion codes for the operation, and
       the contents of the completion code variable are not changed.

          The calling sequence is as follows:

             CALL ID (cmpcd, lclsck)

       Where
                'cmpcd' is the completion code variable associated with
                     the local socket.

                'lclsck' is set to the socket identifier of the local
                     socket if the completion code variable is
                     associated with a socket, or to zero otherwise.

   (7) SIGNAL

       This operation is used to convey a signal to the foreign process.
       The significance of the signal is completely user-dependent.  The
       effect is that the next time the foreign socket attempts to
       initiate a RECEIVE or SEND operation, the operation will be
       suppressed, and a completion code supplied indicating that a
       signal had been received.  The subprogram will wait until the
       signal has been sent to the foreign NCP.  This operation is valid
       only when the socket is fully open.

          The calling sequence is as follows:

             CALL SIGNAL (cmpcd, time)

       Where
                'cmpcd' is the completion code variable associated with
                     the local socket.

                'time' is the length of time the subprogram is to wait
                     for completion of the operation.

         The following completion codes are possible for this operation:

                     0, The operation was successful, and the signal has
                        been sent

                     4, The specified completion code variable is not
                        assigned to a socket; the operation was
                        suppressed

                     8, The connection is not fully open; the operation
                        was suppressed

       Certain of the Network subprograms are intended for, although not
       restricted to, use with the Online System Network operators.  The
       following is a general description of these operators:

          In all Network operations involving the Online System Network
          operators, there are certain conventions concerning the format
          of the data sent and received.  The data is grouped in
          'messages' consisting of three fields, op code, length, and
          text, in that order. The op code is one byte in length and is
          a code which indicates how the text field is to be
          interpreted.  The length field is two bytes long, and gives
          the length, in bits, of the text fields, which contains the
          actual data. (The op code and length fields together are
          termed a header.)

       The following op codes are presently defined:

       Op Code   Meaning

         0       This op code is a NOP. No text field exists, and the
                 contents of the length field are unpredictable. (This
                 op code is used mainly as a delimiter.)

         1       The text field contains EBCDIC characters, one
                 character per byte.  The Online System operators
                 consider the characters as intended for display as soon
                 as the text field has been received.

         2       The text contains codes for keypushes, one byte per
                 key.  The Online operators consider the keys as
                 intended for execution as soon as the text field has
                 been received.

         3       The same as for an op code of 2, except that the Online
                 operators consider that the execution of the keys will
                 be delayed until all data for that receive operations
                 has been received.

       The standard format of data sent or received by the Online System
       operators is a string of messages, with the last message
       indicated by a header with a NOP op code, called a trailer.
       These conventions are the default situation; any of them may be
       overridden by appropriate programming.

       Following are descriptions of those subprograms intended for use
       the Online System operators.

   (8) WRITE TO ONLINE CONSOLE

       This subprogram causes data, assumed to be characters represented
       by their EBCDIC codes, to be sent from the specified local
       socket.  The characters are sent in a standard message, preceded
       by a header, and optionally followed by a trailer.  The
       subprogram waits for the data to be received by the foreign
       socket, or to be queued locally by the NCP.  This operation is
       valid only when the local socket is a send socket, and is fully
       open.

          The calling sequence is as follows:

             CALL WTOLC (cmpcd, bfr, len, level, across, down, time)

       Where
                'cmpcd' is the completion code variable associated with
                     the local socket.

                'bfr' is the character string to be sent, and can be of
                     any type, any length.

                'len' in absolute value, is the number of characters to
                     be sent.  If 'len' is positive or zero, the end of
                     the data is indicated by a trailer; if 'len' is
                     negative, no trailer is sent.  'len' is of type
                     INTEGER*4.

                'level' indicates the mode of typing.  The absolute
                     value of 'level', if non-zero, is the shift level
                     on which to type, and must be less than or equal to
                     nine.  If greater than nine, one is sued.  If
                     'level' is positive, 'across' and 'down' are
                     relative to the current typing location.  If
                     'level' is negative, the carriage is positioned to
                     the upper left-hand corner before typing begins,
                     thus making 'across' and 'down' absolute
                     coordinates.  If 'level' is zero, the tying is in
                     case one characters, and a carriage return precedes
                     the positioning for 'across' and 'sown.' If the
                     characters to be displayed are case one characters,
                     the header sent will have an op code which
                     indicates characters to be displayed as soon as
                     they are received; otherwise, the op code will
                     indicate buttons to be executed as soon as
                     received. 'level' is of type INTEGER*4.

                'across' is the number of spaces to be moved
                     horizontally across the display tube before
                     beginning to type.  'across' can have any value,
                     positive, negative, or zero, and is type INTEGER*4.

                'time' is the length of time the subprogram is to wait
                     for completion of the operation.

                     The completion codes for this operation are the
                     same as for SEND.

   (9) READ FROM ONLINE CONSOLE

       This subprogram receives data, assumed to be characters
       represented by their EBCDIC codes, from the foreign socket in one
       or more standard messages.  The subprogram will wait for the
       data, optionally followed by a trailer, to be received by the
       local socket.  This operation is valid only when the local socket
       is a receive socket and is fully open.

          The calling sequence is as follows:

             CALL RFOLC (cmpcd, bfr, len, time)

       Where
                'cmpcd' is the completion code variable associated with
                     the local socket.

                'bfr' is the variable into which the data is to be
                     placed, and can be of any type, any length.

                'len', in absolute value, is the maximum number of
                     characters to be placed in 'bfr'.  If the length
                     fields of the head(s) received total more data than
                     'len', the excess data will be received, but will
                     not placed into 'brf', and will not be accessible
                     to the program.  If 'len' is positive or zero, data
                     will be received until a trailer is encountered.
                     If 'len' is negative, a single message, exclusive
                     of trailer, will be received. 'len' is of type
                     INTEGER*4.

                'time' is the length of time the subprogram is to wait
                     for completion of the operation.

                     The completion codes for this operation are the
                     same as for RECEIVE.

   (10) WRITE TO ONLINE CONSOLE WITH REPLY

       This subprogram combines the functions of 'WRITE TO ONLINE
       CONSOLE' and 'READ FROM ONLINE CONSOLE'.  The subprogram first
       sends a string of data to the foreign socket form the specified
       send socket, waits for it to be received by the foreign socket
       (or queued locally by the NCP), and then waits for a reply
       directed toward the specified receive socket.  The operation is
       valid only when the sockets have the correct gender and both are
       fully open.

          The calling sequence is as follows:

             CALL WTOLCR (cmpcd, bfr, len, level, across, down, time,
             cmpcd2, bfr2, len2)

       Where
                'cmpcd' is the completion code variable associated with
                     the local send socket.

                'bfr' is as in 'WRITE TO ONLINE CONSOLE'.

                'len' is as in 'WRITE TO ONLINE CONSOLE'.

                'level' is an in 'WRITE TO ONLINE CONSOLE'.

                'across' as in 'WRITE TO ONLINE CONSOLE'.

                'down' is as in 'WRITE TO ONLINE CONSOLE'.

                'time' is the length of time the subprogram is to wait
                     for completion, individually, of the transmission
                     and reception of data.

                'cmpcd2' is the completion code variable associated with
                     the local receive socket.

                'brf2' is as 'bfr' in 'READ FROM ONLINE CONSOLE'.

                'len2' is as 'len' in 'READ FROM ONLINE CONSOLE'.

                     The completion codes for the send socket are the
                     same as for the SEND operation, and the completion
                     codes for the receive socket are the same as for
                     the RECEIVE operation.

   (11) ERASE

       This subprogram cause data constituting on Online System command
       to erase the display tube to be sent from the specified local
       socket.  The data is sent in a single standard message, including
       an op code indicating characters to be displayed as they are
       received, and optionally including a trailer.  The subprogram
       waits for the data to be received by the foreign socket, or to be
       queued locally by the NCP.  This operation is valid only when the
       local socket is a send socket, and is fully open.

          The calling sequence is as follows:

             CALL ERASE ('cmpcd', 'delay1', 'delay2', 'time')

       Where
                'cmpcd' is the completion code variable associated with
                     the local socket.

                'delay1', in absolute value, is the length of time, in
                     tenths of a second, the subprogram is to pause (in
                     the WAIT state) before sending the erase.  If
                     'delay1' is positive or zero, a trailer will be
                     sent after the erase; if negative, no trailer will
                     be sent.  'delay1' is of type INTEGER*4.

                'delay2' is the length of time, in tenths of a second,
                     the subprogram is to pause after sending the erase
                     and before returning control to the calling
                     program, and is of type INTEGER*4.

                'time' is the length of time the subprogram is to wait
                     for completion of the operation.

                     The completion codes for this operation are the
                     same as for SEND.

 

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