Guardian Application Conversion Guide

Opening and Communicating With a High-PIN Server
Converting Pascal Applications
096047 Tandem Computers Incorporated 6–21
Reading System Messages From $RECEIVE
Your requester might read system messages from $RECEIVE using the Guardian
READ[X] or READUPDATE[X] procedure:
{ Message buffer (200 bytes) }
VAR message_buffer : ARRAY[1..200] OF CHAR;
...
read_count := 200;
status := READX (receive_file_number,
message_buffer,
read_count,
bytes_read);
The lengths shown for each system message are subject to change. In a future release,
Tandem might add new fields to the end of a system message (while maintaining the
layout of the existing fields). Therefore, use a Guardian READ[X] or
READUPDATE[X] message buffer at least 250 bytes in length. Also, use a
read_count parameter of 250 bytes.
If you use the ZSYSPAS file, use the ZSYS_VAL_SMSG_LEN constant declaration to
specify the system message length in bytes. If you work in words you can use the
ZSYS_VAL_SMSG_WLEN constant declaration instead.
VAR message_buffer : ARRAY [1..ZSYS_VAL_SMSG_LEN] OF CHAR;
...
read_count := ZSYS_VAL_SMSG_LEN;
status := READX (receive_file_number,
message_buffer,
read_count,
bytes_read);
The ZSYSPAS file also contains structures that you can use when your requester reads
system messages.
Reading Process-Deletion System Messages. Your requester might monitor a server
process by reading these process-deletion system messages from $RECEIVE:
-2 CPU down: named process deletion
-5 Process normal deletion: stop
-6 Process abnormal deletion: abend
Convert your requester to read and process the D-series system message -101 (Process
deletion), which supersedes all the above messages.