Couple questions:
1 - What is your criteria as to whether or not a file gets an RPG *SRVPGM IO
layer put in front of it? Or should all files potentially have a wrapper in
your approach?
2 - How do you relay record not found?
3 - How do you return information back to your program?
4 - How would you do a SETLL, READE, DOW not %EOF loop?
5 - How do you do a READ/CHAIN for lock vs. no-lock?
6 - How do you WRITE records to a file?
Some of the above are semi-rhetorical, simply because I have already been
down the road of what you are proposing. But I would be interested to know
if somebody came up with a solid and reasoned implementation of *SRVPGM IO -
I have yet to see one that is well reasoned other than going on a
case-by-case (read file-by-file) basis.
Aaron Bartell
http://mowyourlawn.com
-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Cassidy, Alan
Sent: Tuesday, September 25, 2007 4:40 PM
To: RPG programming on the AS400 / iSeries
Subject: RE: MVC in RPG?
-----Original Message-----
On Behalf Of albartell
Could you post an sample of your approach for review? I am curious to know
how you address partial key chains/setlls/reades/etc, and how you address
PF's with multiple logicals.
__I didn't do it full-blown but have done a little bit of "offloading"
some I/O to a service program, like for validating screen selections and
other things.
I *think* I like the idea for building new applications or application
"suites" from "scratch", since this would make it easier to do things with
the apps. If not for the limitation of the deadline, for example, it
certainly would have made Y2K a lot easier for a bunch of shops (like mine).
(And the way some shops did it, 2040 will bring Round 2)
For partial key lists to get at a logical, I just used %parms inside the
procedure to count them and do a select list to separate a CHAIN (or
SETLL) for example.
Select
When %parms >= 3 ;
Chain(e) (key1: key2: key3) OrdFile ; When %parms >= 2 ;
Chain(e) (key1: key2 ) OrdFile ;
When %parms >= 1 ;
Chain(e) (key1 ) OrdFile ;
When %parms < 1 ;
Read OrdFile ; // (Didn't use this one, but you could...) EndSL ;
I would suppose you could use %KLST from a DS, and calculate how many fields
from the %parms, but you'd need to load the KLST fields.
You could even set up a STATIC field to track whether it's the first time
in, to determine whether to do a SETLL/READE or just a READE.
I've thought that this might be useful in the stead of using triggers, IF
->ALL<- your DB access to a file was through this method, because among
other things, it would save the maintenance baggage. That's one reason they
haven't used triggers where I work, where it would complicate administration
for HA with journaling, for example. (Don't ask; too many files, libraries,
environments, etc).
--Alan
midrange.com
