• Subject: Re: Some experience - as400 server side java
  • From: nimrod@xxxxxxx
  • Date: Wed, 9 Jun 1999 07:12:12 +0200




> Nimrod wrote:
>
> >> <shahar mor wrote:>
> >>
> >> Just wondered if someone out there did some server side java on the
> >> as400 and tell some stories about it. mainly how can you:
> >>
> >> 1. interact with legacy programs
.....
> Or you could skip all that and simply use Jacada Connects (I hope
> I'm not breaking any list regulations by inserting this shameless
> plug).
.....
> Nimrod, I don't mind the shameless plugs TOO terribly much provided they
match
> one of the two following guidelines:
>
> 1. They promote FREE software (limited-function is OK, time-bombs are
not, to my
> way of thinking)
> -or-
> 2. They provide a specific solution to a specific problem
>
> Unfortunately, your reply was a bit incomplete.  Jacada Connects is a
one-way
> solution, allowing Java to execute legacy programs, which is actually
quite easy
> with the (FREE) JT400 ProgramCall class or by using PCML (for more
information
> on PCML, see Don Denoncourt's article in AS/400 NetJava Expert,
> www.midrangecomputing.com/anje/99/04).  However, executing a Java class
FROM a
> legacy program is still a problem, and Jacada Connect doesn't do anything
at all
> there.  To quote Jacada's website:
>
> "Any tool or application capable of communicating with a Java class can
use
> Jacada Connects."
>
> So Jacada Connects allows Java applications to execute legacy programs,
but not
> vice versa.  As I pointed out, this functionality is available for FREE
from the
> IBM Toolbox.  If Jacada provided a way for RPG program to execute a Java
class,
> well, THEN I'd be impressed.  Until such a package is available, you'll
still
> need to use data queues or data areas or something to allow bidirectional
calls
> to Java from a legacy application.

Well, we don't (at least not yet :) Give Jacada Connects away, although
it does sell for a lot less than the GUI-generating Jacada products.

As for solving the specific problem, it depends on how you interpret
the question, or rather the words "interact" and "legacy programs".

Jacada Connects allows you not only to execute legacy programs, but also
to interact with them via the "green-screens" in a high-level manner.
The two important points here are the interaction (by emulating a user)
and the fact that there's no need to rewrite the legacy program (which
is almost always the first requirement about reusing legacy systems).
[Note - I certainly mean "legacy" not as "RPG", but as an existing
system which is in use and cannot be discarded.  A newly written RPG
program is no more legacy than a newly written Java program]

While it's certainly possible to do all that with other technologies,
some of which may be free, the main difference is the level of
abstraction you get.  It's like saying that you can code object-
oriented GUI-based programs in assembly language.  It's certainly
possible, but would anyone do that knowing there's Java (or even
C++), even if the assembler was free but Java wasn't?

Given all of that, I think Jacada Connects does solve a specific
problem, and I don't view executing a Java class from RPG as Java
interacting with a legacy program, although if RPG can execute
any other program it can certainly execute Java programs in the
same manner (not to mention JNI).

Final comment - My initial reply was brief and incomplete because
I didn't want to turn it into a marketing pitch - I opted to
point you to our Web site instead.  I think you can see now that
my plug has merit, but if not, then I sincerely apologize for
wasting your bandwidth.

Nimrod


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