RE: JVM and activation groups in OS/400

About 2 years ago I was running into a similar situation.  I opened a
support call to IBM... The guy who spoke with me explained the entire
process very well.  Now -- lets see exactly how much I remember....  The
interface between RPG and JAVA is using JNI -- I think that
implementation would be within the activation group.  If you destroy (or
free up) the final jni pointer reference for the object, the jvm is
destroyed.  Once the jvm is destroyed, it can not be created again --
there is only one jvm instance per RPG program.  

Mike 

-----Original Message-----
From: java400-l-bounces@xxxxxxxxxxxx
[mailto:java400-l-bounces@xxxxxxxxxxxx] On Behalf Of Joe Sam Shirah
Sent: Wednesday, August 03, 2005 3:57 PM
To: Java Programming on and around the iSeries / AS400
Subject: Re: JVM and activation groups in OS/400


    I'm in agreement with Shane.  Java is not an ILE language or
participant.


                                                         Joe Sam

Joe Sam Shirah -        http://www.conceptgo.com
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----- Original Message ----- 
From: <Shane_Cessna@xxxxxxx>
To: "Java Programming on and around the iSeries / AS400"
<java400-l@xxxxxxxxxxxx>
Sent: Wednesday, August 03, 2005 3:17 PM
Subject: Re: JVM and activation groups in OS/400


> Larry,
>
> I'd imagine that each activation group has it's own instance of a
> JVM...when you reclaim the activation group, all resources to that are
> freed up by the system...including JVMs...
>
> Shane
>
>
>
> Larry Gorlin <LGorlin@xxxxxxxxxxxxxxxxx>
> Sent by: java400-l-bounces@xxxxxxxxxxxx
> 08/03/2005 01:56 PM
> Please respond to
> Java Programming on and around the iSeries / AS400
> <java400-l@xxxxxxxxxxxx>
>
>
> To
> "java400-l@xxxxxxxxxxxx" <java400-l@xxxxxxxxxxxx>
> cc
>
> Subject
> JVM and activation groups in OS/400
>
>
>
>
>
>
> I seem to have an odd issue going on when accessing Java from RPG
> programs within a single interactive job.
>
> Our company uses two activation groups (we'll call them
ActivationGroup1
> and ActivationGroup2).  All standard ILE RPG programs are compiled
under
> ActivationGroup1 and Service Programs are compiled under
> ActivationGroup2.
>
> We have a main menu program which regularly does a RCLACTGRP for each
of
> these two activation groups.
>
> The problem is when accessing Java methods inside an RPG Program.  The
> first time in, there's no issue.  The JVM creates itself and all
methods
> run fine.
>
> The issue happens after the user returns to the menu and the
RCLACTGRP's
> are run.  When the user then returns to one of the procedures that
call
> java methods, the program crashes with a "Attempting to access a
> destroyed object" message.  Occasionally, I've also seen the message
> "The Java Virtual Machine has ended".
>
> After some experimentation, it seems that the RCLACTGRP for the
Service
> Program activation group is the one that causes the problem.  If at
any
> time I do a RCLACTGRP ActivationGroup2, all attempts to access Java
from
> within my RPG will fail.
>
> I don't see the link between the JVM and the activation group.
>
> Any ideas?
>
> Thanks,
> Larry (lgorlin@xxxxxxxxxxxxxxxxx)
>