Re: Java as a batch language on System i

Jon,

Our shop uses Java in batch and RPG in batch extensively, with a little
COBOL. We have found that batch Java is viable. IMHO a single stream
Java application is slower than a single stream COBOL or RPG application
online or in batch, however, with threading you can close the gap
significantly. There is a JVM start-up cost - again this can be reduced
by compiling the Java or optimising it - all options on the JAVA
command. Setting the correct Garbage collection size for your
application can also make a significant difference. However, where
major gains can be made is in the methods employed for retrieving the
data. Consider compiled stored procedures for complex queries. Having
someone who knows there way around SQL is definitely a bonus: badly
written SQL can really bog down performance.

Once the Java is up and running, we find it comparable to other
languages for performance - it is the initial loading of classes that
can be slow. Therefore, where online speed is required, start
continuously running Java programs that communicate via Data queues -
these are quick.

Logically moving from COBOL to Java would seem to be moving to slower
batch processing, but so long as your server is correctly sized for Java
applications, I don't think you will notice that much difference. On
the server side, JAVA performs best with heaps of memory, and fast
processors (preferably more than one).

I guess the other advantage you have with Java, is you could leave the
database on the i, but move some of the processing off to other
platforms if that was desirable.

Regards
John
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date: Mon, 17 Mar 2008 15:18:14 -0400
from: Jon Paris <Jon.Paris@xxxxxxxxxxxxxx>
subject: Java as a batch language on System i ?

Have any of you had much experience using Java in a batch environment
on the System i?

Much of the customer's workload is batch - currently written in
COBOL. They are experiencing problems in getting experienced COBOL
programmers and this situation is likely to be exacerbated as their
in-house pool shrinks when their mainframe applications are replaced
during the 2008 - 2009 timeframe.

Everything else in the shop is Java WebSphere (but not on i). They
want to keep the data on the i but need to address the programmer
problem.

My gut tells me that the Java performance will be an issue - but I
have no experience to back that up one way or the other. COBOL
already outperforms RPG in batch and I've never seen a Java program
beat out RPG performance wise so ... but if somebody has some
experience that suggests that Java is viable as an option in this
arena I'm more that happy to be wrong.

No religious wars please.

Jon Paris

www.Partner400.com
www.SystemiDeveloper.com