Introduction

There are several Java virtual machine (jvm) flavors that have their advantages. Those that work with sipX are described here, along with instructions on how to install them. If you do not have any special java related requirements then there's nothing you need to do, the correct java virtual machine and jdk will be installed for you automatically.

Managing multiple JVMs on a single system

If you need to have several jvm versions on the same system, the easiest way to use them is by using the alternatives command. Any jvm that is installed using the instructions on this page will be available to be configured via alternatives. Note that when switching from one jvm to another, you will also want to switch the verion of javac you are using, if you are building from source.

OpenJDK

sipXecs is now compatible with OpenJDK and used as the default JVM. In the past Sun's JVM was the default JVM but OpenJDK now ships on CentOS 5.5 and has proved to be a adequate replacement as the default JVM.

Sun Java

You want to find the RPMs that are built using JPackage specifications. These rpms will have a "jpp" somewhere in the file name. JPackage is compatible with the "alternatives" setup described above and generally puts files in more standard places.

IBM Java

The easiest way to get IBM's jvm/jdk installed is to use IBM's jpackage installer. This consists of a .tar.gz archive containing the necessary RPMs. Installing these RPMs will result in a IBM jvm that is ready to be managed by alternatives.

The first step is to go to the IBM developerWorks Java download page: http://www.ibm.com/developerworks/java/jdk/linux/download.html

Click the link for the appropriate architecture. At this point you will be asked to login with your IBM ID and agree to a license. You will then be directed to the download page. The easiest way to proceed from here is to choose the "Download using HTTP" tab and then select the "Download Now" link in the Jpackage section of the page.

When the download is complete, unpack the archive and install all the RPMs using the rpm command.