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<appendix
id="jdk-installing_configuring_and_running">
<title>Java Development Kit (<acronym>JDK</acronym>): Installing, Configuring and Running</title>
<para>
The <application>&THIS.PLATFORM; Platform</application> is written in Java; therefore, before running any <application>&THIS.PLATFORM;</application> server, you must have a working Java Runtime Environment (<acronym>JRE</acronym>) or Java Development Kit (<acronym>JDK</acronym>) installed on your system. In addition, the JRE or JDK you are using to run <application>&THIS.PLATFORM;</application> must be version 5 or higher<footnote>
<para>
At this point in time, it is possible to run most <application>&THIS.PLATFORM;</application> servers, such as the JAIN SLEE, using a Java 6 JRE or JDK. Be aware, however, that presently the XML Document Management Server does not run on Java 6. We suggest checking the &THIS.PLATFORM; web site, forums or discussion pages if you need to inquire about the status of running the XML Document Management Server with Java 6.
</para>
</footnote>.
</para>
<formalpara>
<title>Should I Install the JRE or JDK?</title>
<para>
Although you can run <application>&THIS.PLATFORM;</application> servers using the Java Runtime Environment, we assume that most users are developers interested in developing Java-based, <application>&THIS.PLATFORM;</application>-driven solutions. Therefore, in this guide we take the tact of showing how to install the full Java Development Kit.
</para>
</formalpara>
<formalpara>
<title>Should I Install the 32-Bit or the 64-Bit JDK, and Does It Matter?</title>
<para>
Briefly stated: if you are running on a 64-Bit Linux or Windows platform, you should consider installing and running the 64-bit JDK over the 32-bit one. Here are some heuristics for determining whether you would rather run the 64-bit Java Virtual Machine (JVM) over its 32-bit cousin for your application:
</para>
</formalpara>
<itemizedlist>
<listitem>
<para>
Wider datapath: the pipe between RAM and CPU is doubled, which improves the performance of memory-bound applications when using a 64-bit JVM.
</para>
</listitem>
<listitem>
<para>
64-bit memory addressing gives virtually unlimited (1 exabyte) heap allocation. However large heaps affect garbage collection.
</para>
</listitem>
<listitem>
<para>
Applications that run with more than 1.5 GB of RAM (including free space for garbage collection optimization) should utilize the 64-bit JVM.
</para>
</listitem>
<listitem>
<para>
Applications that run on a 32-bit JVM and do not require more than minimal heap sizes will gain nothing from a 64-bit JVM. Barring memory issues, 64-bit hardware with the same relative clock speed and architecture is not likely to run Java applications faster than their 32-bit cousin.
</para>
</listitem>
</itemizedlist>
<para>
Note that the following instructions detail how to download and install the 32-bit JDK, although the steps are nearly identical for installing the 64-bit version.
</para>
<!-- <formalpara
id="jdkicar-binary-Java_Development_Kit-Pre-Install Requirements and Prerequisites">
<title>Pre-Install Requirements and Prerequisites</title>
<para></para>
</formalpara> --><!-- <variablelist
condition="jdkicar-binary-Java_Development_Kit-Hardware_Requirements">
<title>Hardware Requirements</title>
<varlistentry>
<term>Sufficient Disk Space</term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist> --><!-- <variablelist
condition="jdkicar-binary-Java_Development_Kit-Software_Prerequisites">
<title>Software Prerequisites</title>
<varlistentry>
<term></term>
<listitem>
<para></para>
</listitem>
</varlistentry>
</variablelist> -->
<formalpara>
<!-- id="jdkicar-binary-Java_Development_Kit-Downloading"> -->
<title>Downloading</title>
<para>
You can download the Sun JDK 5.0 (Java 2 Development Kit) from Sun's website: <ulink
url="http://java.sun.com/javase/downloads/index_jdk5.jsp"></ulink>. Click on the <guilabel>Download</guilabel> link next to "JDK 5.0 Update <replaceable><x></replaceable>" (where <replaceable><x></replaceable> is the latest minor version release number). On the next page, select your language and platform (both architecture—whether 32- or 64-bit—and operating system), read and agree to the <literal>Java Development Kit 5.0 License Agreement</literal>, and proceed to the download page.
</para>
</formalpara>
<para>
The Sun website will present two download alternatives to you: one is an RPM inside a self-extracting file (for example, <filename>jdk-1_5_0_16-linux-i586-rpm.bin</filename>), and the other is merely a self-extracting file (e.g. <filename>jdk-1_5_0_16-linux-i586.bin</filename>). If you are installing the JDK on Red Hat Enterprise Linux, Fedora, or another RPM-based Linux system, we suggest that you download the self-extracting file containing the RPM package, which will set up and use the SysV service scripts in addition to installing the JDK. We also suggest installing the self-extracting RPM file if you will be running <application>&THIS.PLATFORM;</application> in a production environment.
</para>
<formalpara>
<!-- id="jdkicar-binary-Java_Development_Kit-Installing"> -->
<title>Installing</title>
<para>
The following procedures detail how to install the Java Development Kit on both Linux and Windows.
</para>
</formalpara>
<procedure>
<title>Installing the JDK on Linux</title>
<step>
<para>
Regardless of which file you downloaded, you can install it on Linux by simply making sure the file is executable and then running it:
</para>
<!-- ~]$ chmod +x "jdk-1_5_0_<minor_version>-linux-<architecture>-rpm.bin"
~]$ ./"jdk-1_5_0_<minor_version>-linux-<architecture>-rpm.bin" -->
<screen>~]$ chmod +x "jdk-1_5_0_<minor_version>-linux-<architecture>-rpm.bin"
~]$ ./"jdk-1_5_0_<minor_version>-linux-<architecture>-rpm.bin"</screen>
</step>
</procedure>
<note>
<title>You Installed Using the Non-RPM Installer, but Want the SysV Service Scripts</title>
<para>
If you download the non-RPM self-extracting file (and installed it), and you are running on an RPM-based system, you can still set up the SysV service scripts by downloading and installing one of the <literal>-compat</literal> packages from the JPackage project. Remember to download the <literal>-compat</literal> package which corresponds correctly to the minor release number of the JDK you installed. The compat packages are available from <ulink
url="ftp://jpackage.hmdc.harvard.edu/JPackage/1.7/generic/RPMS.non-free/"></ulink>.
</para>
</note>
<important>
<para>
You do not need to install a <literal>-compat</literal> package in addition to the JDK if you installed the self-extracting RPM file! The <literal>-compat</literal> package merely performs the same SysV service script set up that the RPM version of the JDK installer does.
</para>
</important>
<procedure>
<title>Installing the JDK on Windows</title>
<step>
<para>
Using Explorer, simply double-click the downloaded self-extracting installer and follow the instructions to install the JDK.
</para>
</step>
</procedure>
<formalpara>
<!-- id="jdkicar-binary-Java_Development_Kit-Configuring"> -->
<title>Configuring</title>
<para>
Configuring your system for the JDK consists in two tasks: setting the <envar>JAVA_HOME</envar> environment variable, and ensuring that the system is using the proper JDK (or JRE) using the <command>alternatives</command> command. Setting <envar>JAVA_HOME</envar> usually overrides the values for <command>java</command>, <command>javac</command> and <command>java_sdk_1.5.0</command> in <command>alternatives</command>, but we will set them all just to be safe and consistent.
</para>
</formalpara>
<variablelist>
<varlistentry>
<term>Setting the <envar>JAVA_HOME</envar> Environment Variable on Generic Linux</term>
<listitem>
<para>
After installing the JDK, you must ensure that the <envar>JAVA_HOME</envar> environment variable exists and points to the location of your JDK installation.
</para>
<formalpara>
<title>Setting the <envar>JAVA_HOME</envar> Environment Variable on Linux</title>
<para>
You can determine whether <envar>JAVA_HOME</envar> is set on your system by <command>echo</command>ing it on the command line:
</para>
</formalpara>
<!-- ~]$ echo $JAVA_HOME -->
<screen>~]$ echo $JAVA_HOME</screen>
<para>
If <envar>JAVA_HOME</envar> is not set already, then you must set its value to the location of the JDK installation on your system. You can do this by adding two lines to your personal <filename>~/.bashrc</filename> configuration file. Open <filename>~/.bashrc</filename> (or create it if it doesn't exist) and add a line similar to the following one anywhere inside the file:
</para>
<programlisting>export JAVA_HOME="/usr/lib/jvm/jdk1.5.0_<version>"
</programlisting>
<para>
You should also set this environment variable for any other users who will be running <application>&THIS.PLATFORM;</application> (any environment variables <command>export</command>ed from <filename>~/.bashrc</filename> files are local to that user).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Setting <envar>java</envar>, <envar>javac</envar> and <envar>java_sdk_1.5.0</envar> Using the <command>alternatives</command> command </term>
<listitem>
<formalpara>
<title>Selecting the Correct System JVM on Linux using <command>alternatives</command>
</title>
<para>
On systems with the <command>alternatives</command> command, including Red Hat Enterprise Linux and Fedora, you can easily choose which JDK (or JRE) installation you wish to use, as well as which <command>java</command> and <command>javac</command> executables should be run when called.
</para>
</formalpara>
<para>
<emphasis>As the root user</emphasis>, call <command>/usr/sbin/alternatives</command> with the <option>--config java</option> option to select between JDKs and JREs installed on your system:
</para>
<programlisting>root@localhost ~]$ /usr/sbin/alternatives --config java
There are 3 programs which provide 'java'.
Selection Command
-----------------------------------------------
1 /usr/lib/jvm/jre-1.5.0-gcj/bin/java
2 /usr/lib/jvm/jre-1.6.0-sun/bin/java
*+ 3 /usr/lib/jvm/jre-1.5.0-sun/bin/java
Enter to keep the current selection[+], or type selection number:
</programlisting>
<para>
In our case, we want to use the Sun JDK, version 5, that we downloaded and installed, to run the <command>java</command> executable. In the <command>alternatives</command> information printout above, a plus (<literal>+</literal>) next to a number indicates the one currently being used. As per <command>alternatives</command>' instructions, pressing <keycap>Enter</keycap> will simply keep the current JVM, or you can enter the number corresponding to the JVM you would prefer to use.
</para>
<para>
Repeat the procedure above for the <command>javac</command> command and the <literal>java_sdk_1.5.0</literal> environment variable, <emphasis>as the root user</emphasis>:
</para>
<screen>~]$ /usr/sbin/alternatives --config javac</screen>
<screen>~]$ /usr/sbin/alternatives --config java_sdk_1.5.0</screen>
</listitem>
</varlistentry>
<varlistentry>
<term>Setting the <envar>JAVA_HOME</envar> Environment Variable on Windows</term>
<listitem>
<para>
For information on how to set environment variables in Windows, refer to <ulink
url="http://support.microsoft.com/kb/931715"></ulink>.
</para>
</listitem>
</varlistentry>
</variablelist>
<formalpara>
<!-- id="jdkicar-binary-Java_Development_Kit-Testing"> -->
<title>Testing</title>
<para>
Finally, to make sure that you are using the correct JDK or Java version (5 or higher), and that the java executable is in your <envar>PATH</envar>, run the <command>java <option>-version</option>
</command> command in the terminal from your home directory:
</para>
</formalpara>
<screen>~]$ java -version
java version "1.5.0_16"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_16-b03)
Java HotSpot(TM) Client VM (build 1.5.0_16-b03, mixed mode, sharing)</screen>
<!-- <formalpara
id="jdkicar-binary-Java_Development_Kit-Running">
<title>Running</title>
<para></para>
</formalpara> --><!-- <formalpara
id="jdkicar-binary-Java_Development_Kit-Stopping">
<title>Stopping</title>
<para></para>
</formalpara> -->
<formalpara>
<!-- id="jdkicar-binary-Java_Development_Kit-Uninstalling"> -->
<title>Uninstalling</title>
<para>
There is usually no reason (other than space concerns) to remove a particular JDK from your system, given that you can switch between JDKs and JREs easily using <command>alternatives</command>, and/or by setting <envar>JAVA_HOME</envar>.
</para>
</formalpara>
<formalpara>
<title>Uninstalling the JDK on Linux</title>
<para>
On RPM-based systems, you can uninstall the JDK using the <command>yum <option>remove <jdk_rpm_name></option>
</command> command.
</para>
</formalpara>
<formalpara>
<title>Uninstalling the JDK on Windows</title>
<para>
On Windows systems, check the JDK entry in the <literal>Start</literal> menu for an uninstall command, or use <literal>Add/Remove Programs</literal>.
</para>
</formalpara>
</appendix>
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