Samstag, Juli 15, 2006

Checkout Maven

I worked for a company where they used Maven as a standard build tool. They used maven1, but I had some spare time the last couple of weeks, so I used it to play with maven2. I read the book Maven from the Developers Notebook series and Better Build with Maven.

First of all, why use Maven instead of Ant, which are most familiar with?

1) Its a collection of best practices of build & configuration managment: Where do I put my configuration files, how do I integrate common tools like xdoclet, clover or checkstyle, make project reports, where do I put my external jars, how to announce a new version, do the deployment and so on. When I checkout old projects of mine, which are based on Ant, I always have to look in the build.xml how and where files are copied and so on. With maven thats not the case, because everything is just at the right place. And because with Ant there is no standard build structure, every project is different.

2) Reuse: Maven has a plugin concept. Every task is a plugin which gets loaded when you use it the first time, or gets updated if there is a new version. Even common tasks like clean are plugins. So you dont need to write scripts, you just call mvn clean without having any definition of clean in your project file.

3) Productivity: you start creating a new project with mvn archetype:create -DgroupId=your.main.package -DartifactId=projectname and you get a basic project structure. You define your final archive like jar, war or ear, add your external jar dependencies to pom.xml, call mvn eclipse:eclipse or mvn idea:idea, you get your project files for your IDE and can start working within seconds. And finally mvn install compiles your code, runs your unit tests and packages your archive. All that is done without the need to write any build code. Last but not least maven2 is faster than Ant.

There is much more you get with maven for free, like cruisecontrol integration, repository integration plus reports and stats, you can run your httpunit or cactus tests out-of-the-box.

The dependency managment is great: Maven supports transitive dependencies, so if you use Struts you just add Struts to your dependencies and get all jars needed by Struts. Maven provides automatic conflict managment. And every dependency has a scope, some jars are just needed at compile time, for tests and so on. All that is nothing you have to worry about, you just add the scope tag to your dependency.

So I really believe every java developer should consider using Maven, at least give it a try and play around with it a little bit.