Re: JVM version on 400

[pluta@xxxxxxxxxxxxxxxxxx]

Buck Calabro writes:

Hi!
  After lurking for many moons, I have a question about the JVM on the
AS400.  I poked through
http://publib.boulder.ibm.com/html/as400/infocenter.html and found that I
can determine the JVM version by issuing the java *version command.  It
tells me that I am at Version JVM V4R3M0 JDK 1.1.6. That's a bit old.  How
can I upgrade my 400 to the most recent version?  Is this going to be
another "maintain one set of objects for each version you intend to
support" nightmare?  How are others supporting server-side Java on the 400?

---------

Ah, Buck, you've happened upon the first stumbling block of server-side
Java/400, although it's not really that big of a deal right now.

JDK1.1.6 is indeed a bit long in the tooth, but it's still very reliable and
comprehensive.  Remember how Sun's numbering scheme works: Java versions 1.1.x
are all inter-compatible at the binary level.  This means that bytecode I create
with JDK1.1.8 will run on the JDK1.1.6 JVM, and vice versa.

However, JDK1.2 (or Java 2) is a different animal entirely.  Classes designed
for JDK1.2 won't run on JDK1.1.x JVMs.  But that's OK, there not that much in
the Java 2 specification that you probably need today.  Here's where you can
find the actual enhancements for Java 2:

     http://www.javasoft.com/products/jdk/1.2/docs/relnotes/features.html

I'll do a little more digging and see if I can't find the URL for Sun's release
numbering policy.

Anyway, my suggestion is to develop on your PC with JDK1.1.8 and Swing1.1.1 Beta
2.  With these to components, you have a very robust development environment.
You can go to my website to see how to download and install those pieces (along
with the IBM toolkit):

     http://www.zappie.net/java/javatorium/installi.htm

Joe


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