Re: N-tier design

I'm ba-a-a-a-a--ack!

Hello everyone!  Good to see that the forum is alive and pumping.  Now that
I've returned from my sojourn to COMMON (which went quite well - Java/400
and web enabling technologies are beginning to flourish!) and now that the
book is finished, I can return to active participation here.

Andrew, I have specifically done just what you want to do, using data
queues.  Jon has used my same logic and incorporated sockets into the
design (the beauty of my approach is that it is implementation-neutral just
about everywhere).

If you'd like to take a look at what I did, drop by the Revitalization site
at:

http://www.zappie.net/revitalization

You'll find a complete demonstratable application there, along with all the
source code.  It's relatively trivial, but it demonstrates the concept.
What it does is replace each I/O statement in your HLL program with a call
to an API.  This API communicates with a Java display file emulation
object, which then further communicates with a UI server.  The UI server
can be either a thick (Swing) client or a thin (JSP/servlet) client.  In
fact, it can be ANY client, but those are the only two I've written so far.

A further version will be out in the summer which will provide more
support, and about that time my book will be out as well, which provides a
step-by-step procedure for implementing the example.  Until then, feel free
to download the example and see how it flies for your requirements.

Joe Pluta
www.java400.net (the ONLY open source Java/400 site)
www.plutabrothers.com

-----------
There are a lot of facets to n-tier design, and I am interested and happy
to
discuss any of them (I think).  I assume (with no particular evidence) that
somebody, if not lots of people, have worked on separating the UI from the
business logic (BL) on the AS/400 in some similar fashion, and I am looking
for
ideas and reference material to achieve the best design for this
implementation.

I am thinking along the lines of having a naming service that is accessed
over a
data queue that invokes requested services as needed, and returns to the
requester a data queue over which to access the requested service.  It
doesn't
have to be too smart, but it has the potential to be made as smart as
needed.
-----------



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