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We started with the idea to add some of our project dependencies as modules with the JBoss AS 7. Soon we found out that we also wanted to provide an extension to the JBoss server. But the method of creating the directory of modules proofs to be quite cumbersome – especially if your libraries have a larger number of direct and transitive dependencies.

Then we were looking for a tool to generate the modules directory for us. We found some Ant scripts provided by JBoss, but these where not overwhelmingly documented – and Ant build scripts was not what we were looking for.

We are using Maven and it seem that some of the module information is already available from the project object model (POM). So we began to create our own tool – a pluging for Maven: smartics-jboss-modules-maven-plugin.

The Idea

What is the basic idea? The Maven plugin is usually applied to a BOM or a JBoss extension POM. It traverses the dependency tree and generated a module for each dependency. Since you do not want every dependency as a module, usually because a version of the module is already provided in a slot within the JBoss server or several artifacts should be placed in one module, you may add rules on which modules to skip, how to name modules, how to apply additional information – all dependent on the name of the Maven dependency.

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Example with smartics-exceptions

Here is an example: smartics - exceptions is a library for Java that helps to implement exceptions with unique identifiers, error codes, message text construction (I18N), exceptions metadata and reporting. This was our first candidate we want to provide as a module.

So here is the essential part of the smartics - exceptions BOM:

 <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>de.smartics.exceptions</groupId>
        <artifactId>smart-exceptions-core</artifactId>
        <version>${project.version}</version>
      </dependency>
      <dependency>
        <groupId>de.smartics.exceptions</groupId>
        <artifactId>smart-exceptions-i18n</artifactId>
        <version>${project.version}</version>
      </dependency>
      <dependency>
        <groupId>de.smartics.exceptions</groupId>
        <artifactId>smart-exceptions-report</artifactId>
        <version>${project.version}</version>
      </dependency>
    </dependencies>
  </dependencyManagement>

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It just states that every dependency matching the given groupId should be added to the module named de.smartics.exceptions (the text inside the groupId is a regular expression with a group – therefore the brackets – and the ${g1} signals that the matched group identifier is also the name of the module). One the plugin’s website you’ll find the XSD for the modules descriptor.

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