MVS Jan 2005.p65 - CBT Tape
MVS Jan 2005.p65 - CBT Tape
MVS Jan 2005.p65 - CBT Tape
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Java execution environment. This article aims to provide a<br />
brief overview of zAAP and what the potential benefits are.<br />
HOW DOES zAAP WORK?<br />
zAAP can be configured so that it operates within the CPs<br />
within the logical partitions running z/OS. zAAPs operate<br />
asynchronously with the general processors to execute Java<br />
programming under the control of the IBM Java Virtual Machine<br />
(JVM), thereby reducing the demands and capacity<br />
requirements on the general purpose CPs.<br />
Execution of the JVM processing cycles on a zAAP is handled<br />
as a function of the IBM Software Developer’s Kit (SDK) 1.4<br />
product, z/OS 1.6, and the Processor Resource/Systems<br />
Manager (PR/SM).<br />
The JVM instructs z/OS to redirect its Java processing cycles<br />
to the zAAP. On completion of the Java processing cycle or<br />
when a non-Java function is to be executed by the application,<br />
control is redirected back to the general CP.<br />
The key point to be noted is that the Java application(s)<br />
doesn’t have to be modified to exploit this benefit of running<br />
the JVM processing cycles in zAAPs. The switch to a zAAP<br />
from general purpose CP for zAAP-qualifying work and the<br />
switch back from a zAAP to a general-purpose processor<br />
when non-qualifying work is encountered are completely<br />
transparent to the application.<br />
Another point to be noted is that this Java processor, or zAAP,<br />
does not run z/OS, z/VM, or Linux, so it cannot be used to do<br />
any other work. Hence unlike other processors (CP, ICF, IFL)<br />
zAAP can do nothing on its own and cannot be IPLed.<br />
zAAP AND COST REDUCTION<br />
zAAPs cost (at around US$125K per zAAP) significantly less<br />
than the general CPs, and provide an attractive option for<br />
customers who want to run their Java load on a mainframe.<br />
© 2005. Reproduction prohibited. Please inform Xephon of any infringement.<br />
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