Installation Files

Writing Installation XML Files

What You Need

Your editor

In order to write your XML installation files, you just need a plain text editor. Of course it's always easier to work with color coded text, so you might rather want to work with a text editor having such a feature. Here is a list of free editors that work well :

If you are a developer and tend to write your own patches, extension or features to IzPack sources, or, if you wish to debug your compilation, installation and uninstallation, we recommend these IDE:

For the first one, JetBrains has granted us an Open Source License. All project members can ask the Licence Key to one of the project manager.

The other ones are well know open source projects (Just like us (smile) ). We provide a tutorial on how to develop/debug IzPack using Eclipse in the chapter Getting Started > How to develop and debug IpPack using Eclipse

Writing XML

Though you might not know much about XML, you have certainly heard about it. If you know XML you can skip this subsection as we will briefly present how to use XML.

XML is a markup language, really close to HTML. If you've ever worked with HTML the transition will be fast. However there are a few little things to know. The markups used in XML have the following form : <markup>. Each markup has to be closed somewhere with its ending tag : </markup>. Each tag can contain text and other markups. If a markup does not contain anything, it is just reported once : <markup/>. A markup can contain attributes like : <markup attr1="123" attr2="hello !"/>. Here is a sample of a valid XML structure :

<chapter title="Chapter 1">
  <section name="Introduction">
    This is the text of the paragraph number 1. It is available
    for the very low
    price of <price currency="dollar">1 000 000</price>.
  <section name="xxx">

You should be aware of the following common mistakes :

markups*are case sensitive : <markup> is different from <Markup>.
you*must close the markups in the same order as you create them : <m1><m2>(...)</m2></m1> is right but <m1><m2>(...)</m1></m2> is not.

Also, an XML file must start with the following header : <?xml version="1.0" encoding="iso-8859-1 standalone="yes" ?>. The only thing you should modify is the encoding (put here the one your text editor saves your files to). The standalone attribute is not very important for us.

This (brief !) introduction to XML was just meant to enable you to write your installation specification. For a better introduction there are plenty of books and articles/tutorials dealing with XML on the Internet, in book stores, in magazines and so on.

Variable Substitution

During the installation process IzPack can substitute variables in various places with real values. Obvious targets for variable substitution are resource files and launch scripts, however you will notice many more places where it is more powerful to use variables rather then hard coded values. Wherever variables can be used it will be explained in the documentation.

There are three types of variables:

  • Built-In variables. These are implemented in IzPack and are all dynamic in nature. This means that the value of each variable depends on local conditions on the target system.
  • Environment variables. These are provided by the operating system the installer is run on.
  • Variables that you can define. You also define the value, which is fixed for a given installation file.

You define your own variables in the installation XML file with the <variable> tag. How to do this is explained in detail later in this chapter.

Please note that when using variables they must always appear with a '$' sign as the first character, even though they are not defined this way.

The Built-In Variables

The following variables are built-in :

  • $INSTALL_PATH : the installation path on the target system, as chosen by the user
  • $INSTALL_DRIVE : the drive letter part of the installation path on the target system, set on Windows systems, only (for instance C:)
  • $APPLICATIONS_DEFAULT_ROOT : the default path for applications
  • $JAVA_HOME : the JavaTM virtual machine home path
  • $CLASS_PATH : the Class Path used mainly for Java Applications
  • $USER_HOME : the user's home directory path
  • $USER_NAME : the user name
  • $APP_NAME : the application name
  • $APP_URL : the application URL
  • $APP_VER : the application version
  • $ISO3_LANG : the ISO3 language code of the selected langpack.
  • $IP_ADDRESS : the IP Address of the local machine.
  • $HOST_NAME : the HostName of the local machine.
  • $FILE_SEPARATOR : the file separator on the installation system
  • $DesktopShortcutCheckboxEnabled : When set to true, it automatically checks the "Create Desktop Shortcuts" button. To see how to use it, go to `The Variables Element <variables> Be careful this variable is case sensitve !
  • $InstallerFrame.logfilePath : The path to the install log. This file contains the paths of all installed files. If set to "default" then the "$INSTALL_PATH/Uninstaller/install.log" path will be used. To see how to use it, go to `The Variables Element <variables>. If this variable is not set, no install.log will be created.

Environment Variables

Environment variables can be accessed via the syntax ${ENV[variable]}. The curly braces are mandatory. Note that variable names are case-sensitive and usually in UPPER CASE.

Example: To get the value of the OS environment variable "CATALINA_HOME", use ${ENV[CATALINA_HOME]}.

Dynamic Variables

Dynamic variables can be defined in the installation XML with the <variable> tag inside the <dynamicvariables> element. The value of dynamic variables will be evaluated every time a panel is switched, i.e. between the panels. Dynamic variables can have a condition which will be evaluated first. If it's true, the value would be assigned, otherwise nothing happens to the variable.

As and addition to normal variables, the value of a variable can either be defined by using the value attribute or by using a child element called value.

Example1: To change a certain directory based on user input, use the following <variable name="test" value="/test/${USER_INPUT}" condition="hasuserinput" /> The condition has userinput has to be specified in the condition section of installation XML.

Example2: To comment out something in a xml file if a certain pack with id mycoolfeature is not activated, you could use "two" dynamic variables to create a xml comment or not.

<variable name="XML_Comment_Start" condition="!izpack.selected.mycoolfeature">
<variable name="XML_Comment_End" condition="!izpack.selected.mycoolfeature">
<variable name="XML_Comment_Start" value="" condition="izpack.selected.mycoolfeature" />
<variable name="XML_Comment_End" value="" condition="izpack.selected.mycoolfeature" />

The condition izpack.selected.mycoolfeature is generated automatically when a pack with id mycoolfeature was specified. You would now use ${XML_Comment_Start} and ${XML_Comment_End} in a file which should be parsed.

Parse Types

Parse types apply only when replacing variables in text files. At places where it might be necessary to specify a parse type, the documentation will mention this. Depending on the parse type, IzPack will handle special cases such as escaping control characters correctly. The following parse types are available:

  • plain - use this type for plain text files, where no special substitution rules apply. All variables will be replaced with their respective values as is.
  • javaprop - use this type if the substitution happens in a Java properties file. Individual variables might be modified to function properly within the context of Java property files.
  • java - use this type for Java files.
  • xml - use this type if the substitution happens in a XML file. Individual variables might be modified to function properly within the context of XML files.
  • shell - use this type if the substitution happens in a shell script. Because shell scripts use $variable themselves, an alternative variable marker is used: %variable or %{variable}.
  • at - use this type if the substitution must occure on files where paramters are marked with leading AT characters. The example: @variable.
  • ant - use this type if the substitution must occure on files where parameters are surrounded with AT characters (similar to ANT filters, hence the type name). The example:  (variable).

Unless using braces to surround variable's name (${variable} or %{variable}}, the variable name can contain following characters: letters, digits, dots, dashes (minus) , underbars (_). Example: $

If you want to have two variables separated by character that is allowed to appear in variable name, for example: $major-version.$minor-version, then you must use braces, and the above example should look like: ${major-version}.${minor-version}.

The IzPack Elements

When writing your installer XML files, it's a good idea to have a look at the iZPACK installation DTD.

The Root Element <installation>

The root element of an installation is <installation>. It takes one required attribute : version. The attribute defines the version of the XML file layout and is used by the compiler to identify if it is compatible with the XML file. This should be set to 1.0 for the moment.

The Information Element <info>

This element is used to specify some general information for the installer. It contains the following elements :

  • <appname> : the application name
  • <appversion> : the application version
  • <appsubpath> : the subpath for the default of the installation path. A variable substitution and a maskable slash-backslash conversion will be done. If this tag is not defined, the application name will be used instead.
  • <url> : the application official website url
  • <authors> : specifies the author(s) of the application. It must contain at least one <author>element whose attributes are :
    • name : the author's name
    • email : the author's email
  • <uninstaller> : specifies whether to create an uninstaller after installation, and which name to use for it. This tag has the write attribute, with default value yes. If this tag is not specified, the uninstaller will still be written. The name attribute can be used to change the default name of the generated uninstaller, i.e. uninstaller.jar. The condition attribute can be used to specify a condition which has to be fullfilled for creating the uninstaller. The path attribute can be used to define the destination path where the uninstaller is written to, i.e. ${INSTALL_PATH}/Uninstaller.
  • <javaversion> : specifies the minimum version of Java required to install your program. Values can be 1.2, 1.2.2, 1.4, etc. The test is a lexical comparison against the java.version System property on the install machine.
  • <requiresjdk>: (yes or no) specifies wether a JDK is required for the software to be installed and executed. If not, then the user will be informed and given the option to still proceed with the installation process or not.
  • <webdir> : Causes a web installer to be created, and specifies the URL packages are retrieved from at install time. The content of the tag must be a properly formed URL.
  • <summarylogfilepath> : specifies the path for the logfile of the `SummaryLoggerInstallerListener`.
  • <writeinstallationinformation> : (yes or no) specifies if the file .installinformation should be written which includes the information about installed packs. The default if not specified is yes.
  • <pack200/>: adding this element will cause every JAR file that you will add to your packs to be compressed using Pack200 (see As a special exception, signed JARs are not compressed using Pack200, as it would invalidate the signatures. This makes the compilation process a little bit longer, but it usually results in drasticaly smaller installer files. The decompression is relatively fast. Please note that Pack200 compression is destructive, i.e., after decompression a JAR won't be identical to its original version (yet the code in the class files remains semantically equivalent).
  • <run-privileged/>: adding this element will make the installer attempt to launch itself with administrator permissions. Il also supports a condition attribute to reference a condition id so that the elevation is not always attempted (e.g., you may want to activate it only for Windows Vista). This is not supported on all platforms, in which case a message will be provided to the user before continuing the installation. You can disable this feature for the uninstaller by specifying uninstaller="yes" as an attribute. Only use this feature if you really need to be an administrator as part of your installation process.
  • <rebootaction>: defines what to do if there were pending file operations left which require a reboot; otherwise any of the options below will be ignored. Possible values are:
    • ignore (default): Doesn't reboot at all even if there are pending operations. Pending operations can be recognized only on the installer command line output (for all options).
    • notice: Doesn't reboot, but notices the user interactively at the end of an installation, which must be confirmed. Notification works only for interactive installation types (no auto-installation).
    • ask: Reboots only if the user confirms it interactively at the end of an installation.
    • always: Reboots always without any confirmation at the end of an installation.
    1. The usage of <rebootaction> is bound to using the attribute blockable_ with the values auto or force at least in one of the elements <file>, <singlefile> or <fileset>, for being able to recognize blocked files before IzPack tries to overwrite them (which would result in a failing installation of the file). See the documentation of these elements later.
    2. <rebootaction> works and makes sense only on Windows, where target files (as device drivers, EXE or DLL files) might be blocked during an installation. On other platforms than Windows the <rebootaction> element will be ignored.
    3. <rebootaction> supports the condition attribute to limit reboot processing on particular conditions.
    4. Without setting at least one attribute blockable = auto or blockable = force rebootaction will not have any effect.
      See also the description of the blockable_ attribute.
      For getting more information see the chapter Advanced features.

Here is an example of a typical <info> section :

  <appname>Super extractor</appname>
  <appversion>2.1 beta 6</appversion>
    <author name="John John Doo" email=""/>
    <author name="El Goyo" email=""/>

Here is one where the privileges elevation is attempted on Windows Vista and Mac OS X :

        <author email="" name="Julien Ponge (project founder)"/>
        <author email="" name="The fantastic IzPack developers and contributors"/>
    <run-privileged condition="|izpack.macinstall"/>

The Packaging Element <packaging>

This element allows to specify packaging options. If not specified, the default will be to create an all in one installer. This element will usually be used to create an installer which spans over multiple volumes, e.g. the output will be two CDs. The packaging-element contains the following elements:

  • <packager> : specifies options used by the packager. The packager tag has the class attribute, which specifys the class to use for packaging. Currently two implementations are available (com.izforge.izpack.compiler.packager.impl.Packager, com.izforge.izpack.compiler.packager.impl.MultiVolumePackager). The packager-element can contain the <options>element which can have different attributes for the different implementations of packagers. For the MultiVolumePackager, it can have the following attributes:
    • volumesize: the size of the volumes
    • firstvolumefreespace: free space on the first volume used for the installer jar and additional resources like readme-files etc.
  • <unpacker> : specifies which unpacker class should be used. Currently there are two unpacker implementations (com.izforge.izpack.compiler.UnPacker, com.izforge.izpack.compiler.MultiVolumeUnPacker).

Here's an example how to specify an installer which will create multiple volumes. In this example the volumes shall be CDs with 650 megabytes. There will be an additional free space of 150 megabytes on the first volume. This will result in the creation of an installer.jar and multiple installer.pak* files. The installer.jar plus installer.pak plus the additional resources have to be copied on the first volume, each installer.pak.<number> on several volumes.

  <packager class="com.izforge.izpack.compiler.packager.impl.MultiVolumePackager">
  <!-- 650 MB volumes, 150 MB space on the first volume -->
      <options volumesize="681574400" firstvolumefreespace="157286400"/>
  <unpacker class="com.izforge.izpack.installer.MultiVolumeUnpacker" />

The Variables Element <variables>

This element allows you to define variables for the variables substitution system. Some variables are built-in, such as $INSTALL_PATH (which is the installation path chosen by the user). When you define a set of variables, you just have to place as many <variable> tags in the file as needed. If you define a variable named VERSION you need to type $VERSION in the files to parse. The variable substitutor will then replace it with the correct value. One <variable> tag take the following attributes :

  • name : the variable name
  • value : the variable value

Here's a sample <variables> section :

  <variable name="app-version" value="1.4"/>
  <variable name="released-on" value="08/03/2002"/>

Here's a precise sample on how to use desktopshortcutcheckboxenabled and InstallerFrame.logfilePath variables:

  <variable name="InstallerFrame.logfilePath" value="$INSTALL_PATH
    <!-- This means that the log name will be My-install and that
  it will be stored at the root of the installation. -->
    <!-- Any path is fine. If value is set to "Default" then
  "$INSTALL_PATH/uninstall/install.log" is used. -->
    <!-- And if variable isn't defined then no log is written. -->
  <variable name="desktopshortcutcheckboxenabled" value="true"/>
    <!-- This automatically checks the "Create Desktop Shortcuts"
  button. Default value is "False". -->

The dynamic Variables Element <dynamicvariables>

This element allows you to define dynamic variables for the variables substitution system. In contrast to the static <variables, dynamic variables will be evaluated every time, a panel switch is done.

When you define a set of variables, you just have to place as many <variable> tags in the file as needed. Normally you would use the condition attribute to specify, when a certain value will be set.

One <variable> tag take the following attributes :

  • name : the variable name
  • value : the variable value
  • condition : a condition for this variable, which has to be true to set the value

Here's a sample <dynamicvariables> section :

  <variable name="app-version" value="1.4" condition="mycondition1" />
  <variable name="app-version" value="1.4b" condition="!mycondition1" />
  <variable name="released-on" value="08/03/2002" />

The Conditions Element <conditions>

This element allows you to define conditions which can be used to dynamically change the installer, e.g. the panels shown, the variables set, files parsed, files executed and much more. When you define a condition it will get a type and an id. The id has to be unique. Conditions can be referenced based on this id (e.g. with the RefCondition).

There are several built-in types of conditions. At the time of writing this, Izpack has the following built-in types:

  • VariableCondition: a condition based on the value of a certain variable
  • PackSelectionCondition: a condition based on a pack selected for installation
  • JavaCondition: a condition based on a static java field or method.
  • CompareNumericsCondition: a condition based on the comparison of a certain variable with a given value and operator.

There are also boolean types to combine more than one condition:

  • AndCondition: both conditions have to be true
  • OrCondition: only one of both conditions has to be true
  • XOrCondition: one condition has to be true, the other one has to be false
  • NotCondition: the condition has to be false

When you define a set of conditions, you just have to write as many <condition> tags as you like. A condition can take the following attributes:

**; type: the type of the condition. For built-in types, this is the lowercase portion of the condition class

  • : name without condition appended (variable,packselection,java, ...). Custom condition types should be referenced by the full qualified class name, e.g. de.dr.rules.MyCoolCondition.
  • id: the id of the condition. This will be used to refer to this conditions in other elements

The condition element can have several child elements depending on the type of this conditions. E.g. the VariableCondition has a name and value child element to specify, which variable should have a certain value to fullfil this condition.

This is an example which defines four conditions, two VariableConditions, a JavaCondition and a AndCondition which will refer to two of the first conditions.

   <condition type="variable" id="standardinstallation">
   <condition type="variable" id="expertinstallation">
   <condition type="java" id="installonwindows">
 <returnvalue type="boolean">true</returnvalue>
 <condition type="and" id="standardinstallation.onwindows">
   <condition type="ref" refid="standardinstallation"/>
   <condition type="ref" refid="installonwindows" />

Note, from IzPack 3.11 on normally, you don't have to define the compound conditions because you can use a simple expression language. The language has the following operators:

  • {+}: an operator for the Andcondition
  • |: an operator for the OrCondition
  • {{}}: an operator for the XOrCondition
  • !: an operator for the NotCondition

Neverthless if you define really complex conditions it's much easier to define them using the xml structure.

More types of conditions can be defined by inheriting com.izforge.izpack.Condition class.

Built-in conditions

A number of built-in condition IDs are available for you.




The OS is Windows (any variant)


The OS is Windows XP


The OS is Windows Server 2003

The OS is Windows Vista


The OS is Windows 7


The OS is Linux (any variant)


The OS is Solaris (any variant)


The OS is Solaris (any x86 variant)


The OS is Solaris (any Sparc variant)

The Installer Requirements Element <installerrequirements>

This element allows to specify requirements for running the installation. This will be done based on conditions defined in the conditions section.

An installer requirement consists of a condition and a message which will be shown if the condition is not fulfilled. If so, the installer will show the message and exit after that.

  • installerrequirement: specifies a single installer requirement. You can define an unlimited number of them.

Installerrequirements have the following attributes: - condition: an id of a condition defined in the conditions section - message: a message text or a langpack key defining which message should be shown before exiting the installer in case of a missing requirement.

   <installerrequirement condition="izpack.windowsinstall" message="This installer could only be run on Windows operating systems."/>

The GUI Preferences Element <guiprefs>

This element allows you to set the behavior of your installer GUI. This information will not have any effect on the command-line installers that will be available in future versions of IzPack. The arguments to specify are :

  • resizable : takes yes or no and indicates whether the window size can be changed or not.
  • width : sets the initial window width
  • height : sets the initial window height.

Here's a sample :

<guiprefs resizable="no" width="800" height="600"/>

Starting from IzPack 3.6, the look and feel can be specified in this section on a per-OS basis. For instance you can use the native look and feels on Win32 and OS X but use a third-party one on Unix-like platforms. To do that, you have to add some children to the guiprefs tag:

  • laf: the tag that specifies a look and feel. It has a name parameter that defines the look and feel name.
  • Each laf element needs at least one os tag, specified like in the other parts of the specification that support this tag.
  • Like you can add os elements, you can add any number of param elements to customize a look and feel. A param elements has two attribues: name and value.

The available look and feels are:

  • Kunststoff: kunststoff
  • Liquid: liquid
  • Metouia: metouia
  • JGoodies Looks: looks
  • Substance: substance

If you don't specify a look and feel for a particular operating system, then the default native one will be used: Windows on Windows, Aqua on Mac OS X and Metal on the Unix-like variants.

The Liquid Look and Feel supports the following parameters:

  • decorate.frames: yes means that it will render the frames in Liquid style
  • decorate.dialogs: yes means that it will render the dialogs in Liquid style

The JGoodies Looks look and feel can be specified by using the variant parameters. The values can be one of:

  • windows: use the Windows look
  • plastic: use the basic Plastic look
  • plastic3D: use the Plastic 3D look
  • plasticXP: use the Plastic XP look (default).

Here is a small sample:

<guiprefs height="600" resizable="yes" width="800">
    <laf name="metouia">
        <os family="unix" />
    <laf name="looks">
        <os family="windows" />
        <param name="variant" value="extwin" />

The Substance look and feel toned-down themes can be specified using the variant parameter, with the value being one of: business, business- blue, business-black, creme, sahara, moderate, officesilver. We have reduced the choice to the toned-down themes since they are the only ones to actually look decent (the other families colors are way too saturated). Please consult for a gallery of the different toned-down themes.

Starting from IzPack 3.7, some characteristics can be customized with the <modifier> tag. There is a separate description in the `Advanced Features` chapter paragraph `Modifying the GUI`.

The Localization Element <locale>

This element is used to specify the language packs (langpacks) that you want to use for your installer. You must set one <langpack> markup per language. This markup takes the iso3 parameter which specifies the iso3 language code.

Here's a sample :

  <langpack iso3="eng"/>
  <langpack iso3="fra"/>
  <langpack iso3="spa"/>

The supported ISO3 codes are:

porPortuguese (Brazilian)
prtPortuguese (European)

Several panels, such as the license panel and the shortcut panel, require additional data to perform their task. This data is supplied in the form of resources. This section describes how to specify them. Take a look at each panel description to see if it might need any resources. Currently, no checks are made to ensure resources needed by any panel have been included. The <resources> element is not required, and no <res> elements are required within. The <resources> element is the only element besides the <packs> element that is taken into consideration in referenced pack-files (see `<packs> element`_ for more info)

You have to set one <res> markup for each resource. Here are the attributes to specify :

  • src : the path to the resource file which can be named freely of course (for instance my-picture.jpg).
  • id : the resource id, depending on the needs of a particular panel
  • parse : takes yes or no (default is no) - used to specify whether the resource must be parsed at the installer compilation time. For instance you could set the application version in a readme file used by InfoPanel.
  • type : specifies the parse type. This makes sense only for a text resource - the default is plain, other values are javaprop, xml, plain, java, shell, at, ant (Java properties file and XML files)
  • encoding : specifies the resource encoding if the receiver needs to know. This makes sense only for a text resource.

Here's a sample :

  <res id="" src="doc/readme.txt" parse="yes"/>
  <res id="LicencePanel.licence" src="legal/License.txt"/>

Please note that in general a resource id is unique. Thus if you define multiple resources with the same id the later definition (e.g. a resource defined in a referenced pack-file) will overwrite the previous definition. However there is an exception for packsLang.xml_xyz files (see `Internationalization of the PacksPanel`). If multiple packsLang-files were defined, all files will be merged into a single temporary file. This allows refpack files to provide their own internationalization-information.

You can define bundles of resources by using <bundle> You have to set a unique id for the bundle id. One bundle can be marked to be default: default="true"

You need to define a variable to set the name of the SystemProperty:

Here's a sample:

; <variables>

... <variable name="" value="BUNDLE_NAME" />

</variables> ... <resources> <

!-- bundle 1 -->