Re: Problems using api's qmhsndpm amd qmhrcvpm

[Joep Beckeringh <joep@xxxxxxxxxxxxxxxxxxx>]

Scott Klement wrote:

> Are you sure that escape messages will even work for this task?
>
> Sending an escape message is intended for when a program calls another
> program.  If the second program ends abnormally, it uses an escape message
> to trigger an exception to the caller.  If the caller doesn't catch that
> exception, then it will also crash, and the cycle continues until either a
> program handles the error, or you get back to the command line.
>
> However, in your case, what you've got is the operating system running a
> routine to update/insert a record in your database.  You see, when you
> tell your RPG program to update or write a record, it calls a DB2/400
> routine in order to do the actual work. That DB2/400 routine will,
> eventually, call your trigger program.
>
> So, your program stack at the time that the trigger runs will look
> something like this:
>
> 1  P_PEP_CSUPDT  <-- ILE program entry procedure for CSUPDT
> 2  CSUPDT        <-- ILE procedure CSUPDT
> 3  _DB_UPDATE    <-- database update routine
> 4  QDBUDR        <-- routine called by database update
> 5  _TRGCSDELR    <-- entry procedure for trigger
> 6  TRGCSDELR     <-- the trigger's main procedure

So if you want to prevent the update, you should send the escape message to the 
database routine (SMMsgQ '*PGMBDY', SMStack# 1). The database will refuse the 
update and send an escape message to the requesting program (CSUPDT). The trick 
then, as Scott pointed out, is finding the useful information in the messages 
that are sent to you.

Joep Beckeringh