1.23.2007

Groovy Ant Builder

The other day, I was tasked to modify a Java web application. However, after checking out the source code from CVS, I found no build script. It looks like I'm expected to use WSAD to compile and package the application. This is a direct hit in my one of my software development principle: Never rely on an IDE to build an application. Anybody should be able to check out the code and build it with some non-GUI build tool.

The client already use Maven for other projects. However, the application I needed to modify did not have the Maven standard directory layout. The CVS repository also contains the library this application depends on. Because of firewall restrictions, it is not easy to use Maven dependency management (jar download are not permitted by the proxy). They run their own Maven repository but adding stuff in it is no easy task.

The easiest solution to quickly get the job done, would have to create an Ant build script. However, I did not have Ant installed and the proxy would not allow me to download it.

I did have Groovy installed on my portable hard-drive. Since Groovy comes bundled with Ant jars and the Groovy Ant Builder, this was now the fastest path to creating my build script.

And it fact, it was quite easy to get the job done. Task are easily defined and the builder syntax remove all the pain of XML build script. Here is an example of my compile task :
void compile() {
ant.mkdir(dir: "${classes_dir}")
ant.javac(destdir: "${classes_dir}",
srcdir: "${src_dir}",
classpath: "${compile_classpath}",
target: "1.4",
source: "1.4"
)
ant.copy(todir: "${classes_dir}") {
fileset(dir: "${src_dir}") {
exclude(name: "**/*.java")
}
}
}

The thing that seams to be missing is the proper declaration of task dependencies. It seems that the only way to do dependencies is to call another task from a task :
void war() {
compile()
ant.mkdir(dir: "${dist_dir}")
...
}
This seems a bit backward. And I don't know if dependencies will be called many time if they are referenced my many tasks (I will have to test it).

I did consider using Raven, but right now, it lack customization when you want to exclude stuff from the build or if you do not want to use dependencies (but prefer to specify your own compilation classpath).

I also looked at Gant but did not use it for two reason. First, I was not able to download it (proxy restriction) and second, for some reason, when I look at their example, I find them a bit ugly and it seems that you have two ways of doing stuff.

For my particular problem, Groovy Ant Builder allowed me to get the job done quickly and easily. It reminded of things I dislike about Groovy syntax like have to use def to define variable (but not to define methods) and having to specify void as a return type when my methods does not return anything. I much prefer Ruby syntax.

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