Re: Which JVM's are available for which OS400 versions?

["Larry Loen" <lwloen@xxxxxxxxxx>]

There is, of course, only the IBM JVM for OS/400.

What varies, by OS/400 release, is what "level" of Java is offered by that
JVM.  After the first or second release, the JVM began supporting two or
three levels with each release (1.1.7 versus 1.1.8, 1.2 versus 1.3, etc.
would vary).  As I recall, you can even install only "some" of these levels
as you install JV1.

This is included in the Java documentation for each release.  Which
versions are offered, and the defaults, are all in the manual.  Just go to
the on-line manuals and you can find it.  It is a little bit harder to
find, but the manual also documents a property you can set when invoking
Java to override the default value if some of your applications require a
different level from most everything else.

I should point out that the level of Java matters less in OS/400 than some
JVMs.  Most other JVMs tie things like performance improvements (i.e. a new
JIT) much more closely to the "level" of Java released.  The OS/400 JVM, by
contrast, has a common "core" provided with each release and then supports
the required differences to deal with each level it supports.

One rough-and-ready thing you can try is GO LICPGM and then begin (but
don't complete!) the install of individual new products (this is option 11
if I recall rightly).  Just scroll down until you find JV1 (the Java
virtual machine product) and see what it offers to install besides the
"base".  For JV1, this should be the various levels available.  Then,
_cancel_ the install.  That should show you what is available for your own
current release.  The reason to do "install" instead of "display" is that
display will only show what you've actually installed, whereas the aborted
install will show everything you _could_ install.


Larry W. Loen  -   Senior Linux, Java, and iSeries Performance Analyst
                          Dept HP4, Rochester MN

. . .speaking on his own