Maven: The Definitive Guide

Simple Project Object Model

When Maven executes, it looks to the Project Object Model for information about the project. The POM answers such questions as: What type of project is this? What is the project’s name? Are there any build customizations for this project? Example 3-1 shows the default pom.xml file created by the Maven Archetype plugin’s create goal.

Example 3-1. Simple project’s pom.xml file

<project xmlns="http://maven.apache.org/POM/4.0.0" 
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
         http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.sonatype.mavenbook.ch03</groupId>
  <artifactId>simple</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>simple</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

This pom.xml file is the most basic POM you will ever deal with for a Maven project. Usually a POM file is considerably more complex, defining multiple dependencies and customizing plugin behavior. The first few elements—groupId, artifactId, packaging, version—are known as the Maven coordinates, which uniquely identify a project. name and url are descriptive elements of the POM, providing a human-readable name and associating the project with a project web site. Lastly, the dependencies ...