NET/MASTER Network Control Language (NCL) Reference Manual

INTREAD
Verbs
106126 Tandem Computers Incorporated 3–113
nnnn
specifies the number of seconds that the NCL process is to be suspended for,
while waiting for a message to arrive. After this time interval, control is
returned to the NCL process. WAIT=0 (zero) has the same effect as WAIT=NO.
The &SYS.FDBK system variable is set to 4 if the wait time has expired and no
message is received.
Considerations
NCL sets the &SYS.LOOPCTL system variable to 1000 each time the INTREAD
verb is executed, unless the user explicitly sets it to 0 (zero).
On completion of the INTREAD verb, the &SYS.VARCNT system variable is set to
the count of variables created or modified by the operation.
The &SYS.INT.REQ# and &SYS.INT.RSP# system variables are set to indicate the
number of messages queued to the request and response queues respectively.
If an NCL process is suspended while waiting on an INTREAD, the FLUSH
command can be used to force termination. The GO command cannot be used to
communicate with a procedure that is waiting on an INTREAD verb.
The INTQ command (like the WRITE verb) can be used to send messages to either
the dependent response queue or the dependent request queue. However, the
INTQ verb can be used to communicate directly from one NCL process to another,
or from an OCS window to any NCL process. If you want to use INTQ to
communicate with an NCL process, you must have sufficient authority. Note,
however, that INTQ cannot be used to send MDOs. See the WRITE verb in this
section, if this is what you want to do.
The INTCLEAR verb can be used to clear any outstanding messages queued to the
dependent queues.
If the &SYS.FDBK system variable is set to a value of 4 on the completion of the
INTREAD verb, it means that the wait time has expired without a message being
received.
If the &SYS.FDBK system variable is set to a value of 8 on the completion of the
INTREAD verb, it means that the request and response queues were congested
with unprocessed messages that exceeded the SYSPARMS NMIQLIM command
value (default is 1000). One or more messages can be lost.
If a new MDO is created by using the operand MDO=& mdo-name , &SYS.VARCNT
is set to 1.
INTREAD automatically creates an MDO variable (mapped by $MSG) of the form
&$INT., which the user can then access.
See EMSREAD, LOGREAD, and MSGREAD, which also create MDO variables
mapped by $MSG. For more information on MDO variables, refer to the NonStop
NET/MASTER NCL Programmer's Guide.