Re: RPG redbook

[Nathan Andelin <nandelin@xxxxxxxxx>]

Justin,

Regarding externalizing I/O, it may not be a panacea but I think the
premise is valid. If an f-spec is defined in only one service program
(which exports a procedural interface), that will have advantages over
defining the f-spec in 800-900 programs. It gives you options for solving
or mitigating the effects of changes to record formats.

It may not solve certain issues, but others it will. Nothing will address
all issues. For example, SQL I/O wouldn't solve numeric overflows in
program host variables after increasing numeric field lengths in DB tables.
It wouldn't solve orphaned fields, if I understand what you mean by that.

Externalizing I/O is congruent with the principle of creating software
components which have high cohesion in and of themselves, and loose
coupling with the DBMS. That's a valid architectural premise.













On Sat, Oct 22, 2016 at 12:03 PM, Justin Taylor <JUSTIN@xxxxxxxxxxxxx>
wrote:

> I just finished the Externalizing I/O section, and I'm not really sure it
> helps with the "hack the DB one more time" mentioned at the start.
>
> We're just finishing up what I imagine is a typical DB change issue.  We
> have a table with several columns that need to be lengthened.  The table is
> used in 800-900 programs, some still using I-specs.  We of course had no
> practical choice but to add new columns at the end and orphan the old ones.
>
> The sample app exposes (via EXPORT/IMPORT) data structures defined off PF
> record formats.  How does that help with DB changes?  If you change the
> table and service program, the service program will be exposing a different
> layout of the DS than calling programs expect which will cause errors.
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