Guardian Application Conversion Guide

Being Opened by and Communicating With a High-PIN Requester
Converting Pascal Applications
096047 Tandem Computers Incorporated 6–29
Replying to System Message -103 (Process Open). The D-series system supports returning a
label value in the reply to a system message -103 (Process open). Typically, an opener-
table index gets sent in this way. This label then appears in the open_label field of
future FILE_GETRECEIVEINFO_ procedure calls that provide information about
messages received from the same requester. To support this feature, the file system
expects a reply buffer with a length of 0 to 4 bytes; otherwise, the open in the requester
returns an error.
Your server might reply to an Open message as follows:
write_count := any_valid_integer;
CALL REPLYX(reply_buffer,
write_count,
! count_written ! ,
! message_tag ! ,
error_return);
To make use of the open_label field in the FILE_GETRECEIVEINFO_ procedure,
you must convert your code to reply to the Open message as follows:
reply_buffer[0] := -103;
reply_buffer[1] := open_label_value;
write_count := 4;
CALL REPLYX (reply_buffer,
write_count,
{ count_written } ,
{ message_tag } ,
error_return);
If you do not want to use the open_label field, you still need to be sure that the
reply buffer has a length of 0 to 4 bytes. Convert your server as follows:
write_count := 0;
CALL REPLYX (reply_buffer,
write_count,
{ count_written } ,
{ message_tag } ,
error_return);
Replying to an Unknown System Message. Your server should be able to handle an
unknown system message. If the first word of a message contains an unknown
message number, call the REPLY[X] procedure with an error indication of 2 (invalid
operation):
status := REPLYX ({ reply_buffer } ,
{ write_count } ,
{ count_written } ,
{ message_tag } ,
invalid_operation); /* Value is 2 */