MVS Jan 2005.p65 - CBT Tape

Java execution environment. This article aims to provide a
brief overview of zAAP and what the potential benefits are.
HOW DOES zAAP WORK?
zAAP can be configured so that it operates within the CPs
within the logical partitions running z/OS. zAAPs operate
asynchronously with the general processors to execute Java
programming under the control of the IBM Java Virtual Machine
(JVM), thereby reducing the demands and capacity
requirements on the general purpose CPs.
Execution of the JVM processing cycles on a zAAP is handled
as a function of the IBM Software Developer’s Kit (SDK) 1.4
product, z/OS 1.6, and the Processor Resource/Systems
Manager (PR/SM).
The JVM instructs z/OS to redirect its Java processing cycles
to the zAAP. On completion of the Java processing cycle or
when a non-Java function is to be executed by the application,
control is redirected back to the general CP.
The key point to be noted is that the Java application(s)
doesn’t have to be modified to exploit this benefit of running
the JVM processing cycles in zAAPs. The switch to a zAAP
from general purpose CP for zAAP-qualifying work and the
switch back from a zAAP to a general-purpose processor
when non-qualifying work is encountered are completely
transparent to the application.
Another point to be noted is that this Java processor, or zAAP,
does not run z/OS, z/VM, or Linux, so it cannot be used to do
any other work. Hence unlike other processors (CP, ICF, IFL)
zAAP can do nothing on its own and cannot be IPLed.
zAAP AND COST REDUCTION
zAAPs cost (at around US$125K per zAAP) significantly less
than the general CPs, and provide an attractive option for
customers who want to run their Java load on a mainframe.
© 2005. Reproduction prohibited. Please inform Xephon of any infringement.
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