Exchange/RJE Manual

CONTROL Procedure
Exchange/RJE System Procedure Calls
104698 Tandem Computers Incorporated 5–13
If your program has no more than one outstanding nowait I/O operation against a
single file at one time, you can omit this parameter. In this case, the file number
returned by AWAITIO uniquely identifies the I/O operation that was completed.
If you opened the line server for wait I/O operations, omit this parameter.
Line Activity The line activity depends on the value of operation . Each of the allowed values and
the resulting line activity is discussed below:
operation =2 This operation sends an end-of-text block to the remote system. If
one or more records are in the line server’s buffer waiting to be
sent to the remote system, the line server sends those records as a
block and terminates the block with an ETX character. If no
records are waiting to be sent, the line server sends a block of the
form STX ETX.
operation =13 This operation sends an EOT (end-of-transmission) character to the
remote system and relinquishes control of the data
communications line, which allows the remote system to bid for
the line. To accept a bid for the line by the remote system, your
program must call READ. See the READ procedure later in this
section for more information.
operation =19 This operation sends a DLE EOT (disconnect sequence) to the
remote system. Disconnect is used with switched lines and tells
the remote system to physically disconnect the data
communications line (to go “on hook” or, in other words, to hang
up the telephone).
Considerations The CONTROL procedure transmits an end-of-text (ETX), end-of-transmission (EOT),
or disconnect (DLE EOT) message to the remote system. If the Exchange/RJE line
server was opened for nowait I/O, you must call AWAITIO to complete the
CONTROL I/O operation.
End of Text
The end-of-text operation ( operation = 2) signals an end of file to the remote system
and is usually performed at the end of each file sent to the remote system.
Additionally, the end-of-text operation transmits any records in the line server’s
buffers waiting for transmission to the remote system. If you do not end the last
transmission to the remote system with an end-of-text operation, any records in the
line server waiting for transmission will not be transmitted and the file received by the
remote system may be incomplete.