Re: Modernizing Green Screen Was: Re: IBM HATS vs. ?

[Nathan Andelin <nandelin@xxxxxxxxx>]

> From: Joe Pluta
> I disagree a bit with Nathan about throwing out your existing RPG
> code.

Let me qualify that a bit.  You make a good point about shops that may have already moved to writing ILE procedures - I get the impression that most RPG shops haven't, but I failed to make that point.

If you categorize existing code for interactive applications as follows:

1. User interface definition. 
2. User Interface I/O. 
3. Flow control - how programs respond to user events. 
4. Navigation and state transitions from one screen to the next (or whatever).
--
5. Database definition. 
6. Database I/O. 
--
7. Data validation & business rules. 


I suspect that categories 1-4 contain the majority of existing code, which is what I'd tend to replace outright because it would be very unlikely for any of it to fit within my Web 2.0 UI & RPG models.  We also see the problem where so much of it is mixed in a monolith - so that it's too hard to work with.

Regarding categories 5-6, I tend to generate most of that code from metadata, and encapsulate it into modules.  Extracting it from a monolith may not be worth the time.

Regarding category 7, that's the kind of stuff I'd like to keep, particularly if it were encapsulated in procedures.

-Nathan.