RE: [WEB400] New System Development

["Wills, Mike N. (TC)" <MNWills@xxxxxxxxxxxxxx>]

I am just starting to understand it now, and I have been taking it at school
for the last year. I haven't jumped into it too much myself yet though.

-----Original Message-----
From: David Morris [mailto:David.Morris@plumcreek.com]
Sent: Friday, May 10, 2002 11:00 AM
To: web400@midrange.com
Subject: RE: [WEB400] New System Development


Joe,

I agree with your consumer/creator description. I would also point out
that
you can rely on open source for most of your creator needs. It is still

necessary for the consumer to understand what is going on. That means
understanding HTTP, Servlets, and JSP. That is similar to understanding

how an RPG program passes parameters, the cycle, how external file
definition come into a program etc. You can work without the background
--
you point out that you can help someone build an application in a
matter
of hours -- but it is still a real good idea to understand the
underlying
technology. That would take closer to a few months.

David Morris

>>> joepluta@PlutaBrothers.com 05/10/02 08:16AM >>>
> From: Justin Houchin
>
>     We made this same decision about a month ago. We chose CGI
because of
> the time frame. I have not programmed in JAVA before and all of
> the articles
> I have read said there is a steep learning curve. We did not have the
time
> to learn a new language.

Let me say up front that I am very biased towards servlets and
JavaServer
Pages, for a number of reasons, not the least of which is that I sell
a
product that makes heavy use of servlet/JSP technology.

That being said, I want to point out that Justin's opinion is one
shared by
many people, but that it's not 100% accurate.  Yes, there is a
learning
curve to learning Java, and yes you need at least some Java to be able
to
use servlets and JSPs.  However, it's not as bad as you might think.

This is because there are really two types of Java programmers: class
creators and class consumers.  Class consumers are more like
application
programmers; they use classes created by other people to develop
applications.  Class creators, on the other hand, are more like
compiler
developers.  They need to know the very technical details of OO
programming
and Java syntax.  However, most well-designed business applications
don't
need very much in the way of class creation - most of the classes you
will
use have already been created!

If your business logic is written in RPG, the amount of Java you need
to
write for your applications is very small.  Basically, your servlets
read
data from your application, put that data into beans (think of beans as
Java
data structures) and send these beans to the JSP.  The JSP displays the
data
to the user.  The user hits a button.  The servlet then reads the data
from
the user and passes it back to an RPG program.  There is very little
code
involved.

I give labs on this at COMMON and at iSeries DevCon, and somebody with
just
a little Java knowledge can usually create a successful servlet/JSP
combination in an hour or two.  I also teach onsite seminars, where
RPG
programmers with zero Java knowledge learn Visual Age for Java, basic
Java
syntax, servlets, JSPs and AS/400 communications.  Most programmers
learn
how to create a fully functional business application in a week.

The beauty of this approach is, as David pointed out, if your business
logic
changes, your RPG programmers take care of it, and if your UI needs
change,
your JSP programmers take care of it, and they can often work
independently.
With CGI, your RPG programmers need to know a bit more about the
interface,
unless you use a tool like CGIDEV.  And once you do that, you're stuck
with
whatever functionality is supported by the tool.

With the servlet/JSP approach, your JSP programmer can use any of the
most
advanced features of HTML without having to worry about whether the
RPG
business logic is affected.

Joe
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