RE: Are level checks still useful? -- RPG400-L

The purpose of level checks is to safeguard against a program
unwittingly accessing a different version of a file from that it was
compiled against. If you are only adding new fields to the end of a
file, the question is, how much impact on your system will it have if
records are written to this file without data in these new fields? If
the answer is none, then go ahead and turn level checking off. At least
with RPG you had this option, evidently PHP programs could corrupt your
database whatever your level check setting was!

Trevor Briggs
Analyst/Programmer
Lincare, Inc.
(727) 431-1246
TBriggs2@xxxxxxxxxxx

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of dale janus
Sent: Thursday, November 01, 2012 9:18 AM
To: rpg400-l@xxxxxxxxxxxx
Subject: Are level checks still useful?

We are in the slow, gradual process of changing from DDS to DDL.
Actually, we are creating new files with ops navigator and usually not
keeping the create specs. We just use navigator to change the file when

needed. Mostly we need record ID and timestamp, or date fields added.

But we have lots of old files. Yesterday, we needed to add 2 fields to
a
file (a timestamp and a record id, both added with DDL in ops nav.)
Since we are adding the fields to the end of the files, we figured this
would be a good time to remove level check from the file. But it did
not
work.

Here is our process for adding new fields to a file. We have a library
that contains all our RPG, DDL, CL etc. but no data. We add the new
fields to the file (called DIRECT). We change to level check *no. This

creates an empty file with the new fields.

We write a CL program to copy the data from production library to empty
library using CPYF with *nochk. Then in the production library we
delete
all the logicals, rename the existing file to DIRECTOLD. Next CPYF from

the empty library file (now filled with production data and new fields)
to the production library, CRTFILE(*YES) then recreate the logicals.

When checking with DSPFD, both the file in the empty library and
production library say:
Record format level check . . . . . . . . . : LVLCHK *NO

Yet when I run programs against the file DIRECT or its logicals, I get
level check CPF4131errors.

So I had to recompile all the programs anyway.

We are a small shop with just 2 of us. We write all our own code, so we

are quite sure that adding fields to the end of a record will not affect

old programs.

I am RPG guy, my associate is PHP/WEB guy. He just kind of rolls his
eyes at me when I jump through all these hoops to add fields. His PHP
programs just keep on rolling, no matter what the file looks like.

So this long discourse asks two questions.

Why do my RPG programs (some RPG III, some ILE) insist on level check
when the file says LVLCHK *NO?

And

Is level check still useful? The ability to quickly add fields to files

seems to outweigh the comfort of your rpg programs knowing exactly what
the file looks like. Especially when half (uhh, maybe not half but lots

of them) of your programs are PHP.

---Dale