Tim,
This is probably best asked on RPG400-L, but in a nutshell, your goal is to externalize your business logic. ILE modules and/or service programs are the packages that contain your business logic, and your 5250 screen programs invoke the business logic as needed. Its not really difficult to do, but it does require a bit more thought and planning.
Once you have externalized your business logic, it may be reused anywhere you need, via a number of interfaces. SQL stored procedures, the new integrated web services server, Java toolkit procedure call/EGL/PHP/whatever.... Many options become available to you once you externalize your business logic. This is one of the most important aspects of any modernization strategy.
One of the issues that make this difficult is the lack of training in the midrange world. Its often difficult to understand how to design robust interfaces, for example. How are you going to manage feedback, when you cannot simply pop a screen on the users' 5250 terminal session? These are not show stoppers, but the quality and reusability of the code could be compromised if care is not taken.
I found the book "Code Complete 2nd ed." by Steve McConnell (Microsoft Press) to be very helpful when I was re-thinking my design strategies. It demonstrates quite nicely the difference between good and bad designs or implementations....
hth,
Eric DeLong
-----Original Message-----
From: wdsci-l-bounces@xxxxxxxxxxxx
[mailto:wdsci-l-bounces@xxxxxxxxxxxx]On Behalf Of Tim Gornall
Sent: Tuesday, July 15, 2008 10:41 AM
To: wdsci-l@xxxxxxxxxxxx
Subject: [WDSCI-L] Webfacing out, EGL in
How does one go about "application re-engineering"? I just realized I don't
know how to separate the presentation and business logic. We have programs
originally written in RPG, then converted to LE mostly just to take
advantage of the newer op codes. They are not bound to other modules, no
sub procedures, no prototyping, etc. I suspect there are many shops like
this one out there. So if I was to re-engineer one of these apps, what
would it look like? Would it me broken into multiple modules, programs,
service programs, etc? I guess I'm trying to get an idea of a best
practices approach.
Tim
message: 3
date: Tue, 15 Jul 2008 09:06:17 -0500
from: Joe Pluta <joepluta@xxxxxxxxxxxxxxxxx>
subject: Re: [WDSCI-L] Webfacing out, EGL in
Aaron Bartell wrote:
How can we as IBM i professionals make decisions for our organization's
longterm success when IBM is continually stabilizing their different
modernization strategies, and thus only allowing for short-term success?
I'm only going to do this once, because the tone of this conversation is
already way too far in the negative, but it still needs at least one
response.
Webfacing was never a modernization strategy. IBM has always pointed
you towards application re-engineering, primarily through rewriting to
Java. That's IBM's strategy, always has been. However, we in the
midrange industry have resisted that for years, primarily because RPG is
a better language than Java for business development.
Snip...
midrange.com
