Presents your 
JAVA E-NEWSLETTER for June 2, 2003

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MAKE RUNNING APPS EASIER WITH FOREHEAD

Writing a complex application in Java is easy compared to deploying and
running it. However, you can make running your application much easier,
regardless of the complexity of your classpath, by using the open source
tool called forehead. Beyond simple application execution, forehead
provides sophisticated control of Java ClassLoaders.

To use forehead, you create a script or batch file that starts forehead,
which, in turn, starts your application. Here is the batch file used to
start forehead:

java -Dapp.home=. -Dforehead.conf.file=forehead.conf -cp forehead-1.0-b4.jar
com.werken.forehead.Forehead %1 %2 %3 %4 %5

The heart of the forehead system is the forehead configuration file. In
the configuration file, you can import system properties, define class
loaders, and specify an application starting point.

Forehead loads classes using the ClassLoaders you define, in the order
you define them. This gives you total control over how your applications'
classes are loaded. This can be particularly helpful when you have
libraries that contain duplicate files (though this scenario isn't 
preferable, it's sometimes a reality).

Not only can you define ClassLoaders, but you can also define
hierarchies of ClassLoaders, where one ClassLoader depends on one or 
more parent.

The following is a simple forehead configuration file:

+app.home

[root]
    ${app.home}/
    ${app.home}/lib/activation.jar
    ${app.home}/lib/commons-collections.jar
    ${app.home}/lib/commons-lang-1.0-b1.1.jar
    ${app.home}/lib/GenJavaCore.jar
    ${app.home}/lib/j2ee.jar
    ${app.home}/lib/log4j-1.2.6.jar
    ${app.home}/lib/mail.jar
    ${app.home}/lib/simple-jndi-0.4.jar
    ${app.home}/lib/flashchecker.jar

=[root]com.genscape.flashchecker.Client

If your applications and their classpaths are nontrivial, then take a
look at forehead. Even if your classpaths aren't complex, forehead can make
executing your applications more manageable.
http://forehead.werken.com/

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