RE: Best options for polling a file

Hi Pascal,

Depending upon what you're trying to accomplish, a trigger program would
probably have the most immediate reaction to new records being added to the
file.

If it has to be a separate job that processes the added records, you can
just override the file with an non-zero EOFDLY parm, in which case when the
processing programs gets to the end of the file, data management does not
tell it it is at EOF; instead, it checks every n seconds, and if no records
are available, does not wake up your application program. As soon as records
are added, and the EOFDLY seconds have passed, data management passes them
to your program.

hth,
Peter Dow
Dow Software Services, Inc.
www.dowsoftware.com
909 793-9050 voice
909 793-4480 fax

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of
pascal.jacquemain@xxxxxxxxxxxxxx
Sent: Monday, May 23, 2005 9:57 AM
Subject: Best options for polling a file

Imagine a file where records are created by jobs and are processed by other
jobs. The processing jobs do not access all records but only those with the
right key field. There are several solutions to get data from the file and
to "wake up" the processing job.

- Use of data queue or message queue to tell the processing job to "wake
up". While not a bad idea, it means programs that create records in the file
must also call a program to generate the data queue message or the message.
This may be done via a trigger but this adds processing time every time a
record is created.

- Use a delay wait method (in this case, waiting 0.1 second each time) and
check with SETLL or CHAIN that at least 1 record is awaiting processing.
This is a "lighter" option than the above on the jobs that create data but
can lead to unnecessary use of CPU or I/O (although while running on our
system, the CPU and I/O of jobs that have nothing to process are very low if
not negligible).

Can you make comments or are there other more desirable methods? (We do not
want to use either data queues or MQ queues or message queues to store the
temporary data).

Thanks

Pascal