Maven: The Definitive Guide

Controlling the Contents of an Assembly

In theory, id and format are the only absolute requirements for a valid assembly descriptor; however, many assembly archivers will fail if they do not have at least one file to include in the output archive. The task of defining the files to be included in the assembly is handled by the five main sections of the assembly descriptor: files, fileSets, dependencySets, repositories, and moduleSets. To explore these sections most effectively, we’ll start by discussing the most elemental section: files. Then, we’ll move onto the two most commonly used sections, fileSets and dependencySets. Once you understand the workings of fileSets and dependencySets, it’s easier to understand repositories and moduleSets.

Files Section

The files section is the simplest part of the assembly descriptor. It is designed for files that have a definite location relative to your project’s directory. Using this section, you have absolute control over the exact set of files that are included in your assembly, exactly what they are named, and where they will reside in the archive. See Example 12-6.

Example 12-6. Including a JAR file in an assembly using files

<assembly>
  ...
  <files>
    <file>
      <source>target/my-app-1.0.jar</source>
      <outputDirectory>lib</outputDirectory>
      <destName>my-app.jar</destName>
      <fileMode>0644</fileMode>
    </file>
  </files>
  ...
</assembly>

Assuming you were building a project called my-app with a version of 1.0, Example 12-6 would include your project’s ...