RE: Encapsulating file access in Service Programs

I would rely on the composite key of the file.  Being that you are not
locking the record there is the chance there will be a different record
there when you go back.  Now if you allow them to change the unique key
values then you might have issues with that approach.

Aaron Bartell 

-----Original Message-----
From: rpgnext-bounces@xxxxxxxxxxxx [mailto:rpgnext-bounces@xxxxxxxxxxxx]

Sent: Tuesday, September 07, 2004 12:45 PM
To: RPGNext Discussion and Information
Subject: RE: [RPGNext] Encapsulating file access in Service Programs

How about using RRN.....save it on the first read and then update/delete
using the RRN ?

-----Original Message-----
From: Joel Cochran [mailto:jrc@xxxxxxxxxx]
Sent: Tuesday, September 07, 2004 8:43 AM
To: RPGNext Discussion and Information
Subject: RE: [RPGNext] Encapsulating file access in Service Programs


On Tue, 2004-09-07 at 16:43, Richard Rothe wrote:
> I don't have the luxury of using embedded SQL since we don't have SQL 
> DevKit.  So, I must use native RPG I/O in my encapsulation endeavors.
> 
> What should I do to prevent record-locking ?  Should I code every 
> operation no-update (N) and read the record for update when I need to 
> ? Or, do I need to not worry about record locks and be more concerned 
> about whether the record was updated by another user since the last 
> read ?

Richard,

You could have multiple files, a logical for reading, and one for
updating, writing, and deleting.  Then you just chain to the update
logical right before the update or delete.  You could also do a ton of
open-chain-close operations, but I'm pretty sure you'd take a big
performance hit, so I wouldn't recommend it.

If you wanted to verify that the record was the same as when you
initially read it, you could save the original return values into a DS,
chain again before the update, and then compare the two DS's.  In fact,
this may be a handy way to prevent unnecessary updates as well (where
none of the fields have changed).  We have an application (written when
I was still in middle school) that updates any time you hit enter on the
maintenance screen.  As such, the change dates and users are not very
useful.

BTW, I think the SQL DevKit is only about $800.  It might be worth
looking into.

Joel
http://www.rpgnext.com

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