Re: File Encapsulation Quandary

Kurt,

I assume the problem with #1 is that sometimes you have a file with
read-only data that you don't want to have to copy into a test library
(since you know you won't be updating it) - is that correct? If so, when
does the file open fail - immediately on the OPEN (or implicit open if
you're not using USROPN)? I see that the UPDPROD keyword to the STRDBG
command specifies this:

"...The exception to this is starting debug mode after a production library
is already opened..."

Not sure whether it's possible to bypass this problem by 'opening' the
production library (or whether this would simply potentially open you up to
other problems.

An option might be to make your *PROD library into a *TEST library (so
avoiding the UPDPROD issue altogether) and then include a trigger on your
updateable files in that library which prompts the user before attempting
any update/add?

As far as #2 goes, would it work to simply have two F-spec definitions of
the file, both specifying USROPN and EXTFILE, where one is U/A and one is
input-only, and then open and use the correct one depending on the
requirements (reading or writing)? A bit of a hassle, but it should work.

Just some top-of-the-head thoughts.....

Rory


On Tue, Apr 3, 2012 at 2:35 PM, Kurt Anderson
<kurt.anderson@xxxxxxxxxxxxxx>wrote:

Being a big fan of file encapsulation (essentially centralizing business
logic relating to a file), I've created a fair number of file encapsulated
service programs. They use native I/O. Since the service program is a
one-stop shop, the file is defined as Update/Add. This causes a couple
issues:

1. File needs to be copied into a test library.
In our environment we don't have separate test and production
environments. In fact, most testing references a client's production
library. This has actually worked fine without consequence. We always
run STRDBG UPDPROD(*NO) for testing. What this means is that any file that
is encapsulated needs to be copied into a test library otherwise the
service program won't open the file. This is a minor pain (however has on
occasion caused issues in testing b/c a file had pre-existed in a test
library and it wasn't updated).

2. Files opened for update don't block read.
One of our main files I really wanted encapsulated couldn't be because
it's a transaction file with millions of records. No blocking on read
loops hurts. A lot.

3. Using SQL bloats job log in test mode. Slows single-record access.
IBM has really been pushing using SQL to access data, so I thought this
might be a good occasion to follow that path they've laid out. Doing so
addresses issues #1 & #2 above. I've modified one of our file encapsulated
service programs to use SQL. I think it works pretty slick. Although one
not-so-slick aspect is the "chain." Presumably Closing an existing cursor,
Preparing a cursor, Declaring the cursor, then Fetching the cursor is going
to be a lot slower than a simple chain. I'm willing to live with that,
although I'm getting some beef about over-complicating it. In addition,
using SQL and running the program with STRDBG UPDPROD(*NO) balloons the job
log. Maybe I shouldn't care about the size of the job log in test,
although in one of my tests of 100,000 records (~80k chains), the job
wrapped twice and then I killed it. In this situation I may be able to
load the file into an array or something, but I know that won't always be
the case. (I do realize this is only
an issue in testing, but I can also foresee concerns about this slowing
down testing since it's writing out to the job log so much.)

This had me wondering how other shops handle file encapsulation. I know
my last job had a completely separate test environment. That's not likely
going to happen here anytime soon.

We also don't have change management software. Files being encapsulated
had made some of our file changes quite a bit easier.

Here is a sample of the code. If you have the time, I'd appreciate
comments.
http://code.midrange.com/f5aa843519.html

Thanks,
Kurt Anderson
Sr. Programmer/Analyst
CustomCall Data Systems
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