Irrespective of whether you use DOS prompt or cygwin, Windows limits the length of environment variables. Though there are various options to overcome this problem using Java 6 wildcard classpath, mapping the path to some drive etc, they all look like workarounds to me as problem can recur again anytime.

After some amount of research, I found appassembler plugin resolves this issue with booter-windows and booter-unix daemons. From the outset it looked like daemon does something else as the name is a bit misleading but in reality it’s a generic way to start your Java applications. The booter-unix/booter-windows platforms were introduced for the sole purpose of resolving the long classpath issue (see MAPPASM-43) in appassembler maven plugin. Here’s how it looks like in the pom you are working with:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>appassembler-maven-plugin</artifactId>
    <configuration>
        <repositoryLayout>flat</repositoryLayout>
        <installArtifacts>false</installArtifacts>
        <target>${project.build.directory}/appassembler</target>
        <defaultJvmSettings>
            <initialMemorySize>512M</initialMemorySize>
            <maxMemorySize>1024M</maxMemorySize>
            <extraArguments>
                <extraArgument>-DconfigFile=../../etc/config.properties</extraArgument>
                <extraArgument>-Dlog4j.configuration=../../etc/log4j.properties</extraArgument>
            </extraArguments>
        </defaultJvmSettings>
        <configurationDirectory>etc</configurationDirectory>
        <daemons>
            <daemon>
                <id>applicationName</id>
                <mainClass>com.xebia.appassebler.sample.Main</mainClass>
                <platforms>
                    <platform>booter-unix</platform>
                    <platform>booter-windows</platform>
                </platforms>
                <environmentSetupFileName>app-env</environmentSetupFileName>
            </daemon>
        </daemons>
    </configuration>
    <executions>
        <execution>
            < phase>package</phase>
            <goals>
                 <goal>generate-daemons</goal>
                 <goal>create-repository</goal>
            </goals>
        </execution>
    </executions>
</plugin>

If you look at the code carefully, you’ll find “app-env” as a parameter to “environmentSetupFileName” tag. It is quite useful in passing environment variables to the resultant script. Using app-env (for UNIX) and app-env.bat (for Windows) environment setup files, I could pass a modified $REPO environment variable so that the copied repository containing dependencies is shared between booter-unix and booter-windows folders as follows:

|-- booter-unix

|   |-- bin

|   |   |-- applicationName
|   |   `-- app-env

|   `-- etc

|       `-- applicationName.xml

|-- booter-windows

|   |-- bin

|   |   |-- app-env.bat

|   |   `-- applicationName.bat

|   `-- etc

|       `-- applicationName.xml

|-- etc

|   |-- config.properties

|   `-- log4j.properties

`-- repo

    |-- <dependency1>.jar

    |-- <dependency2>.jar

    |-- ...

To copy the environment files and result of appassembler:generate-daemons maven goal to the appropriate locations we can use “maven-assembly-plugin” as follows:

<plugin>
    <artifactId>maven-assembly-plugin</artifactId>
    <configuration>
        <descriptor>src/main/conf/descriptor.xml</descriptor>
    </configuration>
    <executions>
       <execution>
          <goals>
              <goal>single</goal>
          </goals>
          <phase>package</phase>
       </execution>
    </executions>
</plugin>

Here’s what src/main/conf/assembly.xml looks like:

<assembly>
    <id>bin</id>
    <formats>
        <format>tar.gz</format>
        <format>zip</format>
        <format>dir</format>
    </formats>
    <fileSets>
        <fileSet>
            <directory>target/appassembler/booter-unix</directory>
            <outputDirectory>/booter-unix</outputDirectory>
            <excludes>
                <exclude>*.bat</exclude>
                <exclude>*.cmd</exclude>
            </excludes>
            <lineEnding>unix</lineEnding>
            <fileMode>0744</fileMode>
        </fileSet>
        <fileSet>
            <directory>target/appassembler/booter-windows</directory>
            <outputDirectory>/booter-windows</outputDirectory>
        </fileSet>
        <fileSet>
            <directory>target/appassembler/repo</directory>
            <outputDirectory>/repo</outputDirectory>
        </fileSet>
        <fileSet>
            <directory>src/main/conf</directory>
            <includes>
                <include>app-env.bat</include>
            </includes>
            <outputDirectory>/booter-windows/bin</outputDirectory>
        </fileSet>
        <fileSet>
            <directory>src/main/conf</directory>
            <includes>
                <include>app-env</include>
            </includes>
            <outputDirectory>/booter-unix/bin</outputDirectory>
            <lineEnding>unix</lineEnding>
        </fileSet>
    </fileSets>
</assembly>

Now, if you run “mvn clean package”, it provides you the structure as mentioned in listing 2. You can execute the script from booter-windows/bin/applicationName.bat on Windows without worrying about long classpaths now.