An undocumented command - GENMSG

Maybe I'm inattentive* but it seems that I never noticed until a few days ago that there are two son forms to the 'step query' form (that in itself is a son form of Procedure Steps that is a son form of the procedure generator): 'Procedure Messages' and 'General error messages'. Maybe the son form has always been there.

Anyway, today my curiosity was piqued and I started to investigate what data this form displays and how it can be used. Both son forms are based on the EXTMSG table whose primary key is based on two fields, EXEC (the name of the form) and NUM (the message number). It turns out that there are only two general messages, both of which say something like 'An error has occurred; please contact the system manager'. I can't remember at the moment how to get the English version of these messages but that's not too important.

How does one display these messages? Here a little ingenuity is called for. I fired up the WINDBI program, chose 'Queries' then 'Find string' and wrote 'GENMSG' (that's the name of the form) before pressing enter. This useful functionality displays wherever the search string is used, be it a form trigger or a procedure. Unfortunately it doesn't work too well with strings composed of more than one word so one often gets the message back that there are too many results for all to be displayed. Of course normally the results that one wants are those that aren't displayed. Fortunately GENMSG doesn't return that many results. Here's an example of the output

ORDERITEMS           BUF69                GENMSG 1 WHERE :RETVAL <= 0;   

Obviously one uses the GENMSG command instead of WRNMSG (or ERRMSG) when one wants to display one of these messages. To be honest, this isn't very useful as I prefer the error message like 'An error has occurred' to show the name of the procedure or trigger where the error occurred so that I can immediately find the source. Otherwise one has to depend on users giving an accurate answer.

This GENMSG functionality would be useful if one could define one's own general messages instead of having to define them in every procedure. For example, I could define a message with the value 599 and the text '<P1> <P2> <P3>' so that I wouldn't have to define this string every time but simply write GENMSG 599 whenever I want some debugging information. This isn't such a good idea as I suspect that GENMSG is equivalent to ERRMSG, not WRNMSG. But I could use it for my version of error 1 that includes the procedure name. 

The value of EXEC for these strings is 208799, and getting that was slightly different from the usual method. The GENMSG form has a pre-form trigger that I copied into WINDBI in order to get the number.

:GENMSGEXEC = 0;
SELECT EXEC INTO :GENMSGEXEC
FROM EXEC
WHERE ENAME = 'GENMSG'
AND TYPE = 'C'
;

I would have expected the EXEC type to be F, not C (curiously enough, there is an EXEC number where TYPE = 'F' but it doesn't lead to the correct error messages). *As a side effect, knowing the EXEC number allows me to discover when this form was added: during the upgrade to version 23.1. It may or may not be in version 22, as we went straight from v21.1 to v23.1. I do know that my first addition with an EXEC higher than 208,799 was added on 18 April this year, after the upgrade. So I wasn't as unobservant as I thought at the beginning of this blog entry.