Application: gvSIG desktop

% IzPack - Documentation

% Shortcut definition

\chapter{Desktop Shortcuts} (by Elmar \textsc{Grom} and Marc \textsc{Eppelmann})\\

\section{Defining Shortcuts}

\subsection{Introduction}

On todays GUI oriented operating systems, users are used to launching

applications, view web sites, look at documentation and perform a

variety of other tasks, by simply clicking on an icon on the desktop or

in a menu system located on the desktop. Depending on the operating

system these icons have different names. In this context we will refer to

them collectively as shortcuts.\\

Apart from actually placing an application on the target system, users

routinely expect an installer to create the necessary shortcuts for the

application as well. For you as application developer, this means that

for a professional appearance of your product you should also

consider creating shortcuts.\\

In contrast to the general specification of an IzPack installer, the

specification of shortcuts in IzPack requires a little more effort. In

addition, some of the concepts are a bit more complex and there are some

operating system specific issues to observe. Fortunately, you only need

to worry about operating system specifics if you want to deploy your

application to multiple different operating systems. In any case, it

will pay off to spend some time to study this documentation and the

example spec files before you start to implement your own shortcuts.\\

At the time of writing this Chapter the current IzPack Version 3.7.0-M3 is only

capable to creating shortcuts on

\begin{enumerate}

\item Microsoft Windows\\

 and

\item Unix and Unix-based operating systems (like Linux), which use the \href{http://www.x11.org/}{X11} GUI-System and \href{http://www.freedesktop.org/}{FreeDesktop.org}

based shortcut handling (such as \href{http://www.kde.org/}{KDE} and \href{http://www.gnome.org/}{Gnome}).

\end{enumerate}

Other operating or GUI systems, such as MacOS \texttt{<} MacOS-X are

not supported. However, there is a special UI-variant that automatically pops up

on unsupported systems. It informs the user about the intended targets of your shortcuts and allows

the user to save this information to a text file. While this is not an

elegant solution, at least it aids the user in the manual creation of

the shortcuts.\\

If you would like to review what an end user would see if the target

operating system is not supported, you can do the following. Simply

place the tag \texttt{<notSupported/>} in the spec file. This tag requires no

attributes or other data. It must be placed under \texttt{<shortcuts>}, just like

the individual shortcut specifications. Be sure to remove this tag

before getting your application ready for shipment.\\

We expect other operating systems to be supported in the near future and

as always, contributions are very welcome. At present someone is

actively working on Mac support.

\subsection{What to Add to the Installer}

There are some things that you have to add to your installer to enable

shortcut creation. Obviously you need to add the panel

responsible for creating shortcuts. This panel is aptly enough called

ShortcutPanel. However, in order for the ShortcutPanel to work

properly a number of additional items are required. These must be added

manually to the installer, as all other resourcs, since the front-end will be rewritten.

In this chapter we will explain which of these items are

required and for what reason.\\

First, we would like to discuss items that are supplied with IzPack and

only need to be added to the installer. After that, we move on to the

things you have to prepare yourself before you can add them. The way in

which shortcuts are created varies widely among operating systems. In

some cases it is possible to do this with pure Java code, while

other systems -such as MS-Windows- require native code to accomplish

this task. On the other side, the current implementation, which creates shortcuts on

Unix based systems needs no native library at all, since it works with 'these' pure Java code.

The native library required for the Windows operating

systems are supplied with IzPack is called \texttt{ShellLink.dll}.

Note: They will not be automatically added to your installer file.

You need to list them yourself in the XML file for

the installer. A describtion how to do this follows in the next section.\\

Native libraries can be added to the installer by using the

\texttt{<native>} tag. To add the \texttt{ShellLink.dll}, you just

have to add the following line to the installer XML file:\\

\texttt{<native type="izpack" name="ShellLink.dll"/>}\\

For more details about the use of the \texttt{<native>} tag see the

chapter about the format of the XML file.\\

You have also to add an extra specification file for each platform family to enable shortcut creation on these platforms.

At least one (the default file) is required by the shortcut panel. The format of all spec files is XML and they must be

added to the installer as a resource. The source name of this

specification does not matter, however its resource name (also called id or alias) when added to the

installer must be \texttt{(prefix)+shortcutSpec.xml}.\\

At this release, there are only two prefixes supported: "Win\_" for the Windows family and "Unix\_" for all Unixes.

If the prefix is ommited the shortcut panel searches for a named resource: \texttt{shortcutSpec.xml}. This is the default resource name.

As the default resource name will be used on Windows platforms, the \texttt{"Win\_shortcutSpec.xml"} can be ommited.\\

Hint: If the shortcut panel does not find one of these named resources, it will never appears.

So, do not use different resource names and do not add a path to these.\\

\textbf{Example}\\

\footnotesize

\begin{verbatim}

<res src="C:\MyDocuments\Installer\default_shortcut_specification.xml"

     id="shortcutSpec.xml"/>

<res src="C:\MyDocuments\Installer\unix_shortcut_specification.xml"

     id="Unix_shortcutSpec.xml"/>

\end{verbatim}

\normalsize

Why use different shortcut spec files?\\

\begin{enumerate}

\item The Target filenames are most different.(batch files on Windows vs. shell scripts on Unix.)

\item The Icon file formats are different. ICOs on Windows-, PNGs on Unix-platforms.

\item The Target locations can be different.

\end{enumerate}

This is the simple reason.\\

\subsection{Why Native Code to do the Job on Windows?}

by Elmar\\

This little chapter is not strictly part of the documentation but I have

been asked this question sufficiently often that I think it's worth

explaining right here. It is certainly a natural question to ask. After

all IzPack is an application completely written in Java and primarily

targeted for the installation of Java based programs. So why wouldn't we

try to keep everything pure Java and avoid the use of native code

altogether? There must be some personal preference of the developer

hidden behind this approach you might think. Well, not really, but I

admit at first it seems quite feasible to write it all in Java. On

virtually any operating system or GUI surface around, Shortcuts are

simply files on the local file system. Files can be created and accessed

directly from within Java, so why should there be a need for using

native code?\\

Well, it turns out that just creating a file is not good enough, it also

needs to have the right content. Shell Links as they are called in

Windows land are binary files. I actually managed to find documentation

on the format. Naturally this was hacker data, you won't get this sort

of thing from Microsoft (by the way: thanks a lot to Jesse Hager for a

smash job!). Armed with this information I tried to create these files

myself in Java. The problem was that the documentation was not entirely

accurate and had some gaps as well. I tried for over a month to get this

to work but finally I had to give up. Even if I would have succeeded, it

would have been a hack, since a shell link requires some information that

is impossible to obtain from within Java. Usually you can successfully

create a shell link by only filling in the bare minimum information and

then ask Windows to resolve the link. Windows then repairs the shell

link. Unfortunately this was only the beginning, soon I encountered a

host of other problems. For one thing, the installer needs to know the

correct directories for placing the links and it turns out they are

named differently in different countries. In addition, there are ways of

manually modifying them, which some people might actually have done. The

only way to place the shortcut files reliably is through accessing the

Windows Registry. Naturally, this operation also required native code.

Same thing with asking Windows to resolve the link... On the bottom

line, at every step and turn you run into an issue where you just need

to use native code to do the trick. So I decided that I would do it the

proper way all the way through. That is in a nutshell the reason why I

used native code to create shortcuts on MS-Windows.\\

As I am writing this I am at work with a friend to replicate this work

for the Mac and it looks very much like we need to take the same

approach there as well. On the various Unix GUIs on the other hand, we are lucky that we

can do the job without native libraries.\\

\subsection{The Shortcut Specification}

As we say above, the specification for shortcuts is provided to the ShortcutPanel in the

XML fileformat. At the time of this writing (for IzPack version 3.7.0-M3)

the front-end will be rewritten. Until these work is in progress

you have to write the specification files manually. For your convenience, there are two annotated sample

specification files in the sample subdirectory of your IzPack installation. At the beginning you might want to experiment with these files.\\

Both specification files have one root element called \texttt{<shortcuts>}.

This root elements recognizes 3 different child elements:\\

\texttt{<programGroup>}, \texttt{<skipIfNotSupported/>} and \texttt{<shortcut>}.\\

\texttt{<skipIfNotSupported/>} can be used to avoid the panel to show the alternative UI which shows the shortcut information

that would have been created on a system that supports it. In other words,

using this tag will make the panel be silent on non-supported systems. The

default is to show the alternative UI.\\

The \texttt{<programGroup>} tag allows you to specify the name of the

menu, or more precise, the folder in which the shortcuts will be grouped. The exact location and

appearance of the program group depends on the specific target system on

which the application will be installed, however you can partially control it.

Please note that \texttt{<programGroup>} may only appear once

in the specification. If more than one instance occurs, only the first

one will be used. This tag requires two attributes: \texttt{defaultName}

and \texttt{location}. \texttt{defaultName} specifies the name that the

group menu should have on the target system. You should be aware that

the ShortcutPanel will present this name to the user as a choice. The

user can then edit this name or select a group that already exists. As a

result, there is no guarantee that the actual name of the program group

on the target system is identical with your specification.

\texttt{location} specifies where the group menu should show up. There

are two choices: \texttt{applications} and \texttt{startMenu}. If you

use \texttt{applications}, then the menu will be placed in the menu that

is ordinarily used for application shortcuts. \texttt{applications} is recommended for Unix shortcuts.

If you use \texttt{startMenu}, the group menu will be placed at the top most menu

level available on the target system. Depending on the target system, it

might not be possible to honor this specification exactly. In such

cases, the ShortcutPanel will map the choice to the location that most

closely resembles your choice. Unix shortcuts do not need to support the \texttt{startMenu}, because the \texttt{applications} menu is already on the highest level. This means this has no affect on thess platform.\\

For each shortcut you want to create, you have to add one \texttt{<shortcut>} tag.

Most details about the shortcut are listed as attributes with this tag.

The following sections describe what each attribute does, which

attributes are optional and which ones are required and what the values

are that are accepted for each of the attributes. Note that all

attributes that have a yes/no choice can also be omitted. Doing so has

the same effect as using a value of no. The shortcut attributes can be

divided into two groups\\

\begin{itemize}

\item attributes that describe properties of the shortcut

\item attributes that define the location(s) at which a copy of the

      shortcut should be placed.

\end{itemize}\

The following attributes are used to define location:

\begin{itemize}

\item \texttt{programGroup}

\item \texttt{desktop}

\item \texttt{applications}

\item \texttt{startMenu}

\item \texttt{startup}

\end{itemize}\

\subsection{Shortcut Attributes}

There are three classes of attributes. Some are required, most are

completely optional and some are semi-optional. The set of semi-optional

attributes are all the attributes used to define the location of a

shortcut. These are semi-optional because for any individual one it is

your choice if you want to include it or not. However they are not

completely optional. You must specify at least one location. If all were

omitted, the instruction would essentially tell the panel that a copy of

this shortcut is to be placed at no location. In other words no copy is

to be placed anywhere.

\textbf{name} \texttt{- required}\\

The value of this attribute defines the name that the shortcut will

have. This is the text that makes up the menu name if the shortcut is

placed in a menu or the caption that is displayed with the shortcut if

it is placed on the desktop.\\

\textbf{target} \texttt{- required}\\

The value of this attribute points to the application that should be

launched when the shortcut is clicked. The value is translated through

the variable substitutor. Therefore variables such as

\texttt{\$INSTALL\_PATH} can be used to describe the location.

\textbf{You should be aware that the use of this tag is likely to change

once other operating systems are supported}.\\

\textbf{commandLine} \texttt{- optional}\\

The value of this attribute will be passed to the application as command

line. I recommend to work without command line arguments, since these are

not supported by all operating systems. As a result, your applications

will not be portable if they depend on command line arguments. Instead,

consider using system properties or configuration files.\\

\textbf{workingDirectory} \texttt{- optional}\\

This attribute defines the working directory for the application at the

time it is launched. I would recommend some caution in relying on this

too heavily if your application should be portable, since this might not

be supported by all operating systems. At this time I don't have enough

information to make a definite statement one way or the other. The value

is translated through the variable substitutor. Therefore variables such

as \texttt{\$INSTALL\_PATH} can be used to describe the directory.\\

\textbf{description} \texttt{- optional}\\

The value of this attribute will be visible to the user when a brief

description about associated application is requested. The form of the

request and the way in which this description is displayed varies

between operating systems. On MS-Windows the description is shown as a

tool tip when the mouse cursor hovers over the icon for a few seconds.

On some operating systems this feature might not be supported but I

think it is always a good idea to include a brief description.\\

\textbf{iconFile} \texttt{- optional}\\

The value of this attribute points to the file that holds the icon that

should be displayed as a symbol for this shortcut. This value is also

translated through the variable substitutor and consequently can contain

variables such as \$INSTALL\_PATH. If this attribute is omitted, no icon

will be specified for the shortcut. Usually this causes the OS to

display an OS supplied default icon. \textbf{The use of this attribute

is also likely to change once other operating systems are supported.

Read the Section about Icons below, for more information.}\\

\textbf{iconIndex} \texttt{- optional}\\

If the file type for the icon supports multiple icons in one file, then

this attribute may be used to specify the correct index for the icon. I

would also advise against using this feature, because of operating

system incompatibilities in this area. In file formats that do not

support multiple icons, this values is ignored.\\

\textbf{initialState} \texttt{- optional}\\

There are four values accepted for this attribute: \texttt{noShow},

\texttt{normal}, \texttt{maximized} and \texttt{minimized}. If the

target operating system supports this feature, then this value will have

the appropriate influence on the initial window state of the

application. \texttt{noShow} is particularly useful when launch scripts

are used that cause a command window to open, because the command window

will not be visible with this option. For instance on MS-Windows

starting a batch file that launches a Java application has the less than

pretty side effect that two windows show: the DOS command prompt and the

Java application window. Even if the shortcut is configured to show

minimized, there are buttons for both windows in the task bar. Using

\texttt{noShow} will completely eliminate this effect, only the Java

application window will be visible.  \textit{On Unix use } \texttt{normal}

\textit{, because this is not supported}.\\

\textbf{programGroup} \texttt{- semi-optional}\\

The value for this attribute can be either yes or no. Any other value

will be interpreted as no. If the value is yes, then a copy of this

shortcut will be placed in the group menu.

\textit{On Unix (KDE) this will always be placed on the top level.}\\

\textbf{desktop} \texttt{- semi-optional}\\

For this attribute the value should also be yes or no. If the value is

yes, then a copy of the shortcut is placed on the desktop.

\textit{On Unix the shortcuts will only be placed on the (KDE-) desktop

of the user, who currently runs the installer. For Gnome the user can

simply copy the *.desktop files from } \texttt{\~/Desktop} \textit{ to }

\texttt{\~/gnome-desktop}.

(This is already a TODO for the Unix-shortcut implementation.)\\

\textbf{applications} \texttt{- semi-optional}\\

This is also a yes/no attribute. If the value is yes, then a copy of the

shortcut is placed in the applications menu (if the target operating

system supports this). This is the same location as the applications

choice for the program group.

\textit{This makes no sense on Unix.}\\

\textbf{startMenu} \texttt{- semi-optional}\\

This is a yes/no attribute as well. If the value is yes, then a copy of

the shortcut is placed directly in the top most menu that is available

for placing application shortcuts.

\textit{This is not supported on Unix. see above.}\\

\textbf{startup} \texttt{- semi-optional}\\

This is also a yes/no attribute. If the value is yes, then a copy of the

shortcut is placed in a location where all applications get automatically

started at OS launch time, if this is available on the target OS.

\textit{This is also not supported on Unix.}\\

\subsubsection{Unix specific shortcut attributes }

This extension was programmed by \textsc{Marc Eppelmann}.

This is still in development and may be changed in

one of the next releases of IzPack.\\

\textbf{type} \texttt{- required}\\

This must be one of \texttt{Application} or \texttt{Link}\\

\begin{itemize}

\item Application: To start any application, native, Java or shell-script based,

the \textbf{type} has to be \texttt{Application}. The GUI-System will launch

this Application, so as is, thru their native shell or application launcher.

In this case, note that the right \texttt{workingDirectory}

is always important on Unix platforms. If the users PATH environment

variable does not contain the path, where the application is located,

this can never be run, until the \texttt{workingDirectory} does not contain

these path. The needed current path: ".", this is the case on most

systems, should be in the users PATH environment variable.

Consult the Unix manuals for more details.

\item Link: If you want to open a URL in the users default Webbrowser,

you have to set the \textbf{type} to \texttt{Link}. Note: The \texttt{url} attribute

must be set to work properly.

\item Other: There are more supported types on KDE, like FSDevice,

but these types makes no sense for IzPack, in my opinion.

\end{itemize}

Without the type the Unix shortcut does not work.\\

\textbf{url} \texttt{- semi-optional}\\

If you want to create a shortcut as type \textit{Link}, then you have

to set the \texttt{url} attribute. The value can be a locally installed

html or another document, with a known MIME type, like plain text,

or a WWW Url i.e. 'http://www.izforge.com/izpack'.\\

A local document can be referenced by i.e. "\$INSTALL\_PATH/doc/index.html".\\

The IzPack variable substitution system is supported by the \textbf{url}.\\

\textbf{encoding} \texttt{- required}\\

This should always set to \textbf{UTF-8}.\\

\textbf{terminal} \texttt{- optional}\\

If you want, the user can see the console output of a program

(in Java applications "System.outs"), set the \texttt{terminal} attribute to \textbf{true}.\\

\textbf{KdeSubstUID} \texttt{- unused}\\

This is not fully implemented by IzPack.

I the future this is the sudo option for a shortcut.\\

\subsection{Selective Creation of Shortcuts}

Usually all shortcuts that are listed will be created when the user

clicks the 'Next' button. However it is possible to

control to some degree if specific shortcuts should be created or

not. This is based on install conditions. By including one or more

\texttt{<createForPack name=''a pack name'' />} tags in the

specification for a shortcut, you can direct the ShortcutPanel to

create the shortcut only if any of the listed packs are actually

installed. The 'name' attribute is used to define the name of one of

the packs for which the shortcut should be created. You do not need to

list all packs if a shortcut should always be created. In this case

simply omit this tag altogether.\\

\textbf{A word of caution}\\

For any shortcut that is always created, I would recommend to omit this

tag, since I have seen a number of problems related to changing pack

names. You can save yourself some troubleshooting and some Aspirin by

not using this feature if it's not required. On the other hand if you

need it I would advise to be very careful about changing pack names.\\

\subsection{Summary}

\textbf{Native Libraries}

\begin{itemize}

\item ShellLink.dll \texttt{- required by Microsoft Windows}

\item 'Nothing' \texttt{- for KDE/Gnome shortcuts}

\end{itemize}\

\textbf{Names of the Specification Files}\\

\texttt{shortcutSpec.xml} for Windows and as default.\\

\texttt{Unix\_shortcutSpec.xml} for Unix.\\

\textbf{Specification File Layout - Windows}

\footnotesize

\begin{verbatim}

<shortcuts>

  <skipIfNotSupported/>

  <programGroup defaultName="MyOrganization\MyApplication"

                location="applications||startMenu"/>

  <shortcut

    name="Start MyApplication"

    target="$INSTALL_PATH\Path\to\MyApplication\launcher.bat"

    commandLine=""

    workingDirectory="$INSTALL_PATH\Path\to\MyApplication"

    description="This starts MyApplication"

    iconFile="$INSTALL_PATH\Path\to\MyApplication\Icons\start.ico"

    iconIndex="0"

    initialState="noShow||normal||maximized||minimized"

    programGroup="yes||no"

    desktop="yes||no"

    applications="yes||no"

    startMenu="yes||no"

    startup="yes||no">

    <createForPack name="MyApplication Binaries"/>

    <createForPack name="MyApplication Batchfiles"/>

  </shortcut>

</shortcuts>

\end{verbatim}

\normalsize

\textbf{A sample Specification File for Unix is at the end of this chapter}

\section{Shortcut Tips}

I wrote this section to provide additional information about issues

surrounding the creation of shortcuts. Reading this section is not

necessary to successfully create shortcuts, but it might help you

creating an installation that works more smoothly. In addition, it might

give you some knowledge about operating systems that you don't know so

well. In fact most of the issues described in this section are focused

on differences in operating system specifics.\\

\subsection{The Desktop}

You should recognize that the desktop is precious real estate for many

people. They like to keep it uncluttered and keep only the things there

that they use on a regular basis. This is not true for everybody and you

might personally think different about this. Still, the fact remains

that a lot of people might have different feelings about it, so you

should not automatically assume that it is ok to place all of your

shortcuts on the desktop proper. While your application is certainly one

of the most important things for you, for your customers it is probably

one of many applications they use and maybe not even the most important

one. Accordingly, placing more shortcut icons there than they feel they

will use on a regular basis and especially doing this without asking for

permission might trigger some bad temper.\\

Annotation: But even the experienced user should be able to organize their Desktop.

On Linux the users desktop is the only place, which supports any kind of shortcuts.\\

It is common practice to create a program group in the application menu

system of the OS and place all shortcuts that go with an application in

that program group. In addition, only one shortcut to the key access

point of the application is placed directly on the desktop. Many

installers first ask for permission to do so, as does the ShortcutPanel

in IzPack.\\

I would like to recommend that you always create a shortcut in the menu

system, even if your application has only one access point and you are

placing this on the desktop. Note that shortcuts can also be placed directly

in the menu, they don't need to be in a program group. There are two

reasons for doing so.\\

\begin{itemize}

\item If the user elects not to create shortcuts on the desktop, they

      will end up with no access point to your application

\item Even if this works fine, occasionally people 'clean up' their

      desktop. They might later find that they accidentally deleted the

      only access point to your application. For the less technology

      savvy users, recreating the shortcut might be a rough experience.

\end{itemize}

\subsection{Icons}

Icons are supplied in image files, usually in some kind of bitmap

format. Unfortunately there is no format that is universally recognized

by all operating systems. If you would like to create shortcuts on a

variety of operating systems that use your own icons, you must supply

each icon in a number of different formats. This chapter discusses icon

file formats used on various operating systems. Fortunately there are

good programs available that allow you to convert between these formats,

so that creating the different files is not much of a problem once the

icons themselves are created.\\

\textbf{Microsoft Windows}\\

Windows prefers to use its native icon file format. Files of this type

usually use the extension *.ico. These so called ICO files can hold

multiple icons in one file, which can be useful if the same icon is

to be provided in a number of sizes and color-depths.

Windows itself selects the icon with the most matching dimensions and displays it.

While the Start menu displays the icon with 16x16 pixel if available, the desktop displays

the 32x32 pixel resolution of the same ICO if this is in.

In other words, a ICO file has embedded one or more dimensions of the same Icon.

We recommend to play with \href{http://www.microangelo.us}{microangelo}.

Dlls and Exe files on the other side, can store, amongst other things, a collection of different Icons.

You can select your desired Icon by its index. The lowest index is 0.

Use the iconIndex attribute in the spec file to specify this index.\\

As a sample look into

\begin{verbatim}

%SystemRoot%\system32\shell32.dll

\end{verbatim}

These contains a lot of Windows own icons.

You can use the \href{http://www.heaventools.com}{PE Explorer}

or another Resource Editor to extract or modify

Icons in dlls or exe  files. But be warned. You can also destroy a working

application with these kind of tools.

At least Windows also supports the use of bitmap files in the *.bmp format as

icons. Note that this format does not support multiple icons.\\

We might have overlooked other file formats that are supported by Windows.

However, we suggest to test other formats for compatibility as they

might not work all the way back to Windows 95 or on the NT/non-NT strain.

Sticking with one of these two formats should keep you out of trouble.\\

\textbf{Apple}\\

Apple Macintosh systems use the Macintosh PICT format, extension *.pct.

If you are working with an apple system you know a whole lot more about

this format than I do. If you don't but would like to be able to install

your application on a Mac, simply start with any bitmap format that you

feel comfortable to work with. Then find an application that is capable

of converting this format into a *.pct file. I like to use Paint Shop

Pro (PC based), because it provides conversion capabilities among

several dozen different file formats.\\

\textbf{UNIX flavors}\\

by Marc Eppelmann\\

As my knowledge, all X based Unix Window systems supports

the (ASCII-) XBM (X-Bitmap ) and the better XPM (X-PixMap) format.

The modern GUI systems like KDE and Gnome can display additionally

a lot of other ImageIcon formats, such as GIF, JPG, and PNG.\\

I suggest to use PNG, because this can lossless compress like the GIF format,

however this format is absolutely free. And not least, this can store true

transparency informations (It has an alpha channel).

\subsection{Targets}

So, you thought you could escape the ugly mess of operating system

dependencies at least with the way how your Java application is started?

Sorry but I have just another bad message. The one positive thing is

that here you have a way of escaping, even if doing so has a few less

pretty side effects. At first, I would like to discuss various launching

options you have available on different operating systems. At the end of

the chapter I write about a way to make launching your application OS

independent.\\

\textbf{Microsoft Windows}\\

On Microsoft Windows you have a variety of options for launching your

application. Probably the most simple case is directly starting the Java

VM from the command line and typing out all parameters, such as class

path, the class name etc. In principle, this can be placed right in a

shortcut and should work.\\

A little more elegant solution is to place this in a batch file and have

the shortcut point to this batch file. This will also make it more

likely that users can repair or recreate shortcuts. Recreating shortcuts

with sophisticated command lines is practically impossible.\\

Another method is less commonly used but just as possible. Implement a

native executable that launches the VM with your Java application. The

VM comes as DLL and is used by java.exe in just the same way.

As a sample look at the exlipse.exe provided by the \href{http://www.eclipse.org}{Eclipse-IDE}\\

Clearly, even though the first option is a bit ugly and has some

restrictionss, it is the most portable solution among the three.\\

\textbf{Apple}\\

We hope, there is a IzPack developer currently researching

for the details for the Mac environment. We expect

an updated chapter in one of the next releases.\\

\textbf{UNIX}\\

UNIX provides essentially the same options as Windows. You can simply

use the command line option, you can write a shell script and you can

write a native launcher. Naturally this stuff is in no way compatible

with the equivalent Windows implementations. The native option is even

more problematic in this environment, since the code can not even be

moved from one UNIX platform to another, without recompilation.\\

\textbf{OS Independent Launching}\\

So, after all this rather discouraging news, there is actually a

portable way to launch Java applications? You bet! although I have to

admit that it is not necessarily the most pretty way of doing things.\\

This approach is currently used by IzPack. Package your application in a

*.jar file if you don't already do so and make it executable by including the

necessary METAINF/MANIFEST.MF information file. I am not

going into all the details on how exactly to do this, the Java

documentation will have to do. You might have noticed that even though

the instructions to install IzPack say to type :

\begin{verbatim}

java -jar IzPack-install.jar

\end{verbatim}

You can just as well double click on IzPack-install.jar and it will

start up. This procedure will work on all GUI based Java supported operating

systems -though you might have to replace double clicking with dropping

the file on the VM. In just the same way, you can make the *.jar file

itself the target of a shortcut. Note: This works only, if jars are registered

as files, which have to launch by the installed JRE (with: javaw.exe -jar *)\\

The one restriction with this approach is that a *.jar file can only have

one main file. So, if you have multiple targets, they need to be

packaged each into a different *.jar file. They can be in one *.jar file

but then you have to start them explicitly, which gets you back to the

problems that I mentioned before. This brings me to the ugly part. If

you have just one target, then you are all set. If you have multiple

targets, you need to create a *.jar file for each of them. In addition,

you have a much harder time setting the classpath, because each of the

*.jar files that contain supporting code must be listed. In fact, at

present there is no way of setting this during the installation, because

IzPack does not yet (version 3.0) support the setting and modification

of environment variables.\\

\subsection{Command Line}

Before I start to write a lot about the use of command line arguments

let me state this: If you can avoid using them, do it! Not that there

is anything wrong with command line arguments as such. The issue is

simply that if you want your application to be usable cross platform

(the big Java promise) you should shy away from using command line

arguments. The problem here is that not all operating systems actually

support command line arguments. To be more precise, to my knowledge only

Apple operating systems do not support command line parameters. If you

don't care for running your application on a Mac, then you might not

worry about his at all. If you are interested to support the Mac as

well, read on.\\

In fact the Mac lower than MacOSX supports command line parameters in a way.

More to the point, it supports a single parameter that your application should

interpret as the name of a data file to open. You have no way of

supplying this to your application through the command line attribute.

The operating system generates this when the user drops the file on your

application and then passes it as command line argument. That's it. This

same behavior will probably fly well on pretty much any system and

should therefore be an ok implementation.\\

So what to do if you want to modify program behavior based on runtime

switches? For one thing, you could set system properties accordingly.

The disadvantage here is the same as with the command line parameters: the

way of setting these might vary between operating systems. The best way

seems to be using a property file that contains the configuration

data.\\

\section{Trouble Shooting}

by Elmar

It has been some time since I wrote this chapter during which a good

number of users had a chance to gather experience. Unfortunately I

never know how many have used it successfully without much difficulty. I

only hear from those that have encountered one problem or another. The

type of problems that I have seen prompted me to write this section,

because I think it will help you in locating most problems that you might

encounter or at least give you some idea where the problem might be

located.\\

\subsection{Problems You Can Solve}

If you see an exception that essentially says that a library can not be

loaded (ShellLink.dll) you have an easy problem to deal with. Your

installer file is probably missing the native tag that adds the Windows

dll to the installer or something with this tag is no quite right. Read

'What to Add to the Installer' for all details on this topic.\\

Most other problems cause the ShortcutPanel not to show at all during

the installation process. The reason is simply that the ShortcutPanel

skips if it does not know what to do or if it has nothing to do (no

point showing then and confusing the user). The problem is that this is

not always what you intended. The most simple but not so uncommon

case is, that the ShortcutPanel cannot find their spec file. This can be caused by

a number of reasons. The associated resource tag might be missing in the

installer specification file, the target file name might be misspelled (the

name you specify for the \texttt{id} attribute) or the target file name

has a path or package name pre-pended. You have only to use

\texttt{shortcutSpec.xml} or \texttt{Unix\_shortcutSpec.xml} and nothing else,

just as described in 'What to Add to the Installer'.

You can always verify if this part is ok by

inspecting the content of the installer *.jar file. The file

shortcutSpec.xml should be located in the directory \texttt{res}. This

inspection can be performed with any zip tool. If the file is not there,

first correct this before proceeding.\\

If the file is there and the panel does not appear, you have a problem

within the specification file. In most cases that I have seen, it comes

down to a spelling mistake of an attribute or tag name. You just have to

carefully make sure that everything is spelled correctly. Don't forget

that all names are case sensitive! In a few cases it is also happend,

that required or semi-optional attributes are omitted, so you might want

to verify if all attributes that you need are actually supplied.\\

If everything is correct up to this point the problem becomes more

elusive.  Most likely the panel will not be displayed, because it is instructed

not to show. There are be several reasons for this. The simple

case is that no location has been specified for the shortcuts in your

installation. This can happen if all five location attributes are

omitted or if all the ones that are listed are set to \texttt{no}.

Remember, you have to specify at least one location for every shortcut. If

this is also correct, you might have used the \texttt{<createForPack>} tag. Review

the details in 'Selective Creation of Shortcuts'. One possibility for

the panel not to show is that based on the packs that are currently

selected for installation no shortcut qualifies for creation. In this

case the panel will not show, this is perfectly normal behavior. More

likely this condition is true because of some accident and not because

it's intended. Make sure the packs that you list for the shortcut are

actually defined in your installation and verify that they are all

spelled correctly. Remember: case matters! Did the ShortcutPanel use to

work in your installation and all of a sudden stopped working? Very

likely you are dealing with the last problem. A package name might have

been modified and the shortcut spec was not adjusted to stay in sync.\\

\subsection{Problems That Have No Solution (yet)}

Unfortunately one problem has been very persistent and only recently one

user found the reason. The problem occurs when installing on some target

systems where non-English characters are used in the storage path for

the shortcuts. The problem is that these characters don't seem to be

properly translated across the Java Native Interface. This leads to a

situation where the proper path can not be located and the shortcut

creation fails. I write 'some target systems' because it does not fail

everywhere. After much agonizing over this problem, one user found the

solution: The shortcut creation works fine if a Sun virtual machine is

installed, but fails if a version from IBM happens to be installed. So

far I have no solution for this problem but I am trying to find a

workaround the problem.\\

\subsection{A sample shortcut specification file for Unix}

\footnotesize

\begin{verbatim}

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>

<shortcuts>

  <programGroup defaultName="IzForge/IzPack" location="applications"/>

    <!-- Disabled since there is no Frontend

  shortcut

     name="IzPack"

     programGroup="yes"

     desktop="yes"

     applications="no"

     startMenu="yes"

     startup="no"

     target="$INSTALL_PATH/bin/izpack-fe.sh"

     commandLine=""

     workingDirectory="$INSTALL_PATH/bin"

     description="Front-End for IzPack installation tool"

     iconFile="$INSTALL_PATH/bin/icons/izpack.png"

     iconIndex="0"

     type="Application"

     encoding="UTF-8"

     terminal="true"

     KdeSubstUID="false"

     initialState="normal">

     <createForPack name="Core"/>

   </shortcut -->

   <shortcut

     name="IzPack Documentation"

     programGroup="yes"

     desktop="yes"

     applications="no"

     startMenu="yes"

     startup="no"

     target="konqueror"

     workingDirectory=""

     commandLine=""

     initialState="noShow"

     iconFile="help"

     iconIndex="0"

     url="$INSTALL_PATH/doc/izpack/html/izpack-doc.html"

     type="Link"

     encoding="UTF-8"

     description="IzPack user documentation (HTML format)">

     <createForPack name="Documentation-HTML"/>

   </shortcut>

   <shortcut

     name="Documentation"

     programGroup="yes"

     desktop="yes"

     applications="no"

     startMenu="yes"

     startup="no"

     target="acroread"

     workingDirectory=""

     commandLine="$INSTALL_PATH/doc/izpack/pdf/izpack-doc.pdf"

     initialState="noShow"

     iconFile="acroread"

     iconIndex="0"

     url="$INSTALL_PATH/doc/izpack/pdf/izpack-doc.pdf"

     type="Application"

     encoding="UTF-8"

     description="IzPack user documentation (PDF format)">

     <createForPack name="Documentation-PDF"/>

   </shortcut>

   <shortcut

     name="Uninstaller"

     programGroup="yes"

     desktop="yes"

     applications="no"

     startMenu="no"

     startup="no"

     target="/usr/lib/java/bin/java"

     commandLine="-jar "$INSTALL_PATH/Uninstaller/uninstaller.jar""

     initialState="noShow"

     iconFile="trashcan_full"

     iconIndex="0"

     workingDirectory=""

     type="Application"

     encoding="UTF-8"

     description="IzPack uninstaller">

     <createForPack name="Core" />

   </shortcut>

</shortcuts>

\end{verbatim}

\normalsize