QMHLSTM API and QSYSOPR potential issues

[Dave Murvin <davem@xxxxxxxx>]

Hi,

I am using the QMHLSTM  API (List Nonprogram Messages) to retrieve only 
messages needing a reply (selection *MNR) from the QSYSOPR message 
queue.  The API documentation lists a warning about this API locking the 
message queues:

"New messages are prevented from being added to or removed from the message 
queues being listed during the use of this API. The maximum messages 
requested field and the number of fields to return field for each listed 
message increases the time that the queues are unavailable. Users of this 
API should use caution when listing many messages or many fields. Try to 
avoid causing lock-out situations on highly used message queues. "

I am basically trying to emulate option 7=Display message on the WRKSBMJOB 
command and I need to retrieve all the messages waiting for a reply from 
the QSYSOPR message queue to find the message related to a particular job 
so I can supply the reply using the message key.  Since I don't know when 
the original message was issued, how long the message has been waiting, or 
how many other messages may be waiting for a reply, I am using a value of 
25 for the Maximum messages requested parm to the API.

What is the downside, if any, of  using 25 as the Maximum messages 
requested?  I would hope that most users do not have that many outstanding 
messages in  QSYSOPR, but I am trying to cover all the bases.

If I am only looking for unanswered messages, how long would the QSYSOPR 
message queue be locked when/if it is almost full?

Is there a better way to get the message key for the message I am 
interested in?  (I have be able to find the message in the joblog, but this 
is the sender's copy and does not have the same message key as the message 
on the QSYSOPR message queue.)

Thanks.



Dave Murvin
DRM Enterprises, Inc.