Re: EGL and RPG - The Fastest Path to the Future

Joe wrote:

You can create wonderful modal applications just as
quickly as you can with SDA, even quicker. The hard part of this whole
process is not the user interface, it's rewriting the business logic so
that it is server-based.

Thats what I mean. You have to rewrite the business logic. If i had the choice
i would throw away all monolithic RPG code. Point is, and i'm just practical here,
it's simply not going to happen. EGL is going to be used only for new apps or
existing apps which are such a maintenance nightmare that they simply have
to be rebuilt.

But i get the feeling you don't understand what i mean. I dont WANT to write
modal dialogs. But the way RPG apps work now (with 5250) is that each screen
is MODAL, like a windows dialog box. This means that the app on the server
displays a screen, waits for the user for input, and then continues it's program
flow. With a browser you always have a C/S app, meaning the main procedure of
the app is always a loop handling events. This is completely different from the way
RPG/5250 currently works. You can't do modal apps with a browser. A program or
procedure outputs some HTML which is displayed in a browser. And thats it. The
program/proc just ends and the server then waits for the next request to be
processed. With modal i mean that a program executes e.g. a EXDIALOG (or whatever)
and then waits for input, and then CONTINUES WITH THE NEXT INSTRUCTION. You
can do this with a browser but it's a big ugly hack.

I don;t mean screen scraping which simply translates 5250 to HTML. This just
gives the app a pretty face but is not practical for many reasons. I mean something
completely different than a browser.

Suppose IBM would introduce "5251", which would have the same functionality as 5250
but has a much richer interface (a GUI) and supports event driven programming?
What is the problem with that? And i mean in the context of local business apps
transaction oriented apps like current RPG/5250 apps. I don't mean public apps
because thats were browser based apps are goods for.

Point is, changes (especially in a business environment) are always evolutionary and
not revolutionary. It should be possible to EXTEND the current RPG apps instead of
completely rewriting them.

Date: Wed, 18 Jun 2008 11:55:02 -0500
From: joepluta@xxxxxxxxxxxxxxxxx
To: egl-i@xxxxxxxxxxxx
Subject: Re: [EGL-i] EGL and RPG - The Fastest Path to the Future

john e wrote:

Because EGL (and browser apps in general) is client/server. That means it can only be used for new apps. Our existing apps are all monolithic, and in fact are the client (where the terminal is the server). It is too much of an investment to re-build these apps because we have to factor out all business logic so that it can be called from the server. In practice, this is impossible. Not impossible, but very expensive and risky. So it's not going to happen. Because if this was an option it already happened with for example the ASNA products or whatever.

This will be my last comment on this, because once again we wander into
the land of opinions. But to me, the thing that is most holding
companies back from the future is the desire to hold on to monolithic
application design. Things like screen scrapers are horrible solutions,
because they neither provide a good interface nor move you towards a
proper architecture. Even my own tool, PSC/400, was designed to be a
stepping stone to the next level.

What we REALLY need is a technology so we can put a nice GUI on our EXISTING apps. And this is possible, but we need a new technlogy for this. One which merges the event-driven approach of GUI with the host-driven approach we use today with 5250. So we can take our existing app, simple replace the EXFMT with a EXDIALOG (which presents a nice looking windows MODAL screen). And so we can EXTEND our monolithic apps with event-driven functionality if that's what the user wants.

Have you tried EGL? You can create wonderful modal applications just as
quickly as you can with SDA, even quicker. The hard part of this whole
process is not the user interface, it's rewriting the business logic so
that it is server-based. If you do that, you immediately have access to
all manner of sophisticated architectures, from web services to rich
clients. If you don't, you will be forever doomed to trying to write
5250 in a browser.

But instead, IBM gives us..... EGL!

Yes!

Joe
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