Summary

Synopsis

This article explains how one can determine the bitness of the JVM used to run the installer in Windows.

Discussion

In Windows, the rule ?Check System Architecture? can be used to determine the system architecture (32 bit or 64 bit) regardless of the bitness of the JVM used to run the installer. This is not the case in non-Windows platforms, since the rule checks the value of the Java System property ?os.arch? in order to determine the system architecture and thus relies on the bitness of the JVM used to run the installer. So if a 32 bit JVM is bundled with an installer that runs on a non-Windows platform, the rule will always return the system architecture as 32 bit regardless of whether the machine is 64 bit or 32 bit.

In Windows, the rule makes a call to native API to determine the system architecture. Thus it is independent of bitness of the JVM used to run the installer. Regardless of what bitness of JVM is used to run the installer, the rule always returns 64 for a 64 bit machine and 32 for a 32 bit machine on Windows platform.

On non-Windows platforms, to determine the bitness of the JVM used to run the installer, one can simply make use of the Check System Architecture rule. In Windows, to determine the JVM bitness used to run the installer, one can use one of the following Java System Properties:

os.arch

Or,

sun.arch.data.model, if using Sun JVM

com.ibm.vm.bitmode, if using IBM JVM

The above java system properties can be accessed through InstallAnywhere variables by prepending ?prop? to them such as shown below:

$prop.os.arch$

$prop.sun.arch.data.model$

$prop.com.ibm.vm.bitmode$

The IA variables $prop.sun.arch.data.model$ and $prop.com.ibm.vm.bitmode$ return 32 if the JVM used to run the installer is a 32 bit JVM and return 64 if the JVM used to run the installer is a 64 bit JVM.