RE: AS/400

> -----Original Message-----
> From: Lou Forlini
> Sent: Monday, July 30, 2001 1:08 PM
> To: MIDRANGE-L@midrange.com
> Subject: Re: AS/400
>
>     Take a proposal for making this kind of change to one of our local
> clients (10-15 person shops).  They would either laugh you out of the
> room (for the cost), or look at you as if you were insane.  Which, of
> course, you would be for proposing to alter the mass of application
> systems that are currently working in order to avoid some artificial
> limit that IBM has imposed.

If they're already running fine, why do they need to upgrade at all?  I'm
not advocating my techniques for existing, happy clients.  I advocate my
solution for people who wish to:

A. Take advantage of a browser or thick-client interface
B. Reduce the interactive tax
-or-
C. Start moving to client/server

If your 10-15 man shop doesn't need any of those, it doesn't need my
approach.  If it DOES need one of those, what is your alternative?


>     Uh no, that is the opposite of what I said.  The implementation
> technique is not applicable to other platforms, not the design.

The beauty of an object-oriented implementation of a message-based
architecture is that it is indeed applicable to any platform.  In fact, I
can move my middleware to another platform and still execute the RPG
programs on the AS/400.  The only platform dependence is the legacy systems
themselves, which is where it belongs.


>     Do you contend that writing client-server apps is just as easy as
> using a traditional DDS display file?  If so, why isn't everybody
> doing it that way?  I can point you to 2 shops full of people who
> have done absolutely *zero* coding this way.

Again, that's one of the primary driving forces behind my design.  Not only
does it avoid the interactive tax, but it also allows you encapsulate your
existing legacy systems AS IF THEY WERE SERVERS.  For example, you can write
an agent that takes an XML document and then interfaces with the existing
order entry system to enter an order, all in batch, without changing any of
your business logic.  Once you've wrappered your legacy systems in this
manner, you can then rewrite them at your leisure into true servers.  If any
of your clients are looking to move to client/server, you would be doing
them a disservice not to at least look at the techniques.


>     To me it seems like a losing proposition either way.  You can pay
> IBM's tax, or you can put all of your existing plans on hold and pay
> your programmers to change everything.  These shops are finally
> recovering from Y2K, they're not going to drop everything again just
> to run in place.

This is most definitely NOT running in place.  It is simply the first step
in a staged, progressive re-engineering existing systems.  The first step is
to separate the UI and the business logic.  Once you've done that, you can
begin the rest of the work that needs to be done to move all or part of your
existing systems to a true n-tier design.

This is not for everyone.  You need to be open to new ideas, willing to
learn new concepts, and above all, be willing to rethink how you design
applications.  But the good news is that by using a technique like mine, you
can do this in a gradual manner.  No massive rewrite like Y2K; instead, you
can modify programs one at a time or all at once, you can leave some
programs green screen, revitalize some, and reengineer others.  It's up to
you.

Joe Pluta
www.plutabrothers.com

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