Re: Calling Java from RPG/COBOL -- JAVA400-L

The KeyedDataQueue page of the Toolbox pub has a producer/consumer example
using Data Queues.  In the example both the producer and consumer are
written in Java, but once you have the example working you can switch the
producer to be COBOL or RPG.  It also shows using the record format classes
to describe the data put on the queue.  That is probably working to hard to
format the data (the example was also trying to show the record format
classes).  Be sure to look on the keyed data queue page.  I could not find
a reference to the examples from the base data queue or sequential data
queue pages.

David Wall
Toolbox for Java
iSeries ODBC Driver for Linux




                      MEovino@estes-exp
                      ress.com                 To:       java400-l@midrange.com
                      Sent by:                 cc:
                      java400-l-admin@m        Subject:  Re: Calling Java from 
RPG/COBOL
                      idrange.com


                      05/30/2002 10:18
                      AM
                      Please respond to
                      java400-l






David/David,

I am currently having fits with calling a Java program from RPG (it works
when I call it from the QSHELL command line, but not when I call it from
the RPG program).

Can you forward on any links with examples of how to use a Java program as
a daemon to monitor a data queue?

Thanks in advance!
Mike E.





                    "David Morris"
                    <David.Morris@plum       To:
<java400-l@midrange.com>
                    creek.com>               cc:
                    Sent by:                 Subject:     Re: Calling Java
from RPG/COBOL
                    java400-l-admin@mi
                    drange.com


                    05/30/2002 10:39
                    AM
                    Please respond to
                    java400-l






Jon,

I would second the recommendation of a queue for any call intensive
operation.
I have used several techniques and one that works pretty well is a data
queue
that notifies of an action and passes a key (offset into a user space).
You can
go either direction with this technique and it is reasonably fast. One
advantage
is that you can easily multi thread your applications by using more
than one
listener on your data queue(s).

David Morris

>>> dawall@us.ibm.com 05/30/02 07:59AM >>>

To throw out one more idea, have you thought about using some sort of
program-to-program data passing instead of a direct call?  For example,
use
a data queue, a user space, or a data area.  Take data queues.  The
Java
program becomes a daemon job waiting for work by listening to the
queue.
When the RPG/COBOL program has work, it puts an entry on the queue
then
waits for a reply.  Maybe the worst consideration with this setup is
managing the Java daemon process.  How do you start it, how do you know
if
it is still active, what authority does it have, etc.  On the other
hand, a
benefit is you can move your Java app to a different machine if you
ever
need to distribute the work.  Toolbox has a DataQueue object that lets
you
access a queue on the same or a remote box.

David Wall
Toolbox for Java
iSeries ODBC Driver for Linux




                      "Jon Paris"
                      <Jon.Paris@Partne        To:
<java400-l@midrange.com>
                      r400.com>                cc:
                      Sent by:                 Subject:  Calling Java
from RPG/COBOL
                      java400-l-admin@m
                      idrange.com


                      05/29/2002 05:16
                      PM
                      Please respond to
                      java400-l





I'd like to hear from those of you with more "real world" experience
than
me
of the pros and cons of different methods of invoking a Java app from
RPG
and/or COBOL.  One specific item that I'm interested in is parameter
passing - and returning results from the Java code.  I've used the new
RPG
method call support and am aware of the pitfalls there, but that is
not
applicable to COBOL and JNI is just to darned ugly to want to consider
unless the alternative is a lobotomy!

Jon Paris
Partner400


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