Question

I’m trying to set up a multi-module Maven project, and the inter-module dependencies are apparently not being set up correctly.

I have:

<modules>
  <module>commons</module>
  <module>storage</module>
</modules>

in the parent POM (which has a packaging-type pom)
and then subdirectories commons/ and storage/ which define JAR poms with the same name.

Storage depends on Commons.

In the main (master) directory, I run mvn dependency:tree and see:

[INFO] Building system
[INFO]    task-segment: [dependency:tree]
[INFO] ------------------------------------------------------------------------
[INFO] [dependency:tree {execution: default-cli}]
[INFO] domain:system:pom:1.0-SNAPSHOT
[INFO] \- junit:junit:jar:3.8.1:test
[INFO] ------------------------------------------------------------------------
[INFO] Building commons
[INFO]    task-segment: [dependency:tree]
[INFO] ------------------------------------------------------------------------
[INFO] [dependency:tree {execution: default-cli}]
...correct tree...
[INFO] ------------------------------------------------------------------------
[INFO] Building storage
[INFO]    task-segment: [dependency:tree]
[INFO] ------------------------------------------------------------------------
Downloading: http://my.repo/artifactory/repo/domain/commons/1.0-SNAPSHOT/commons-1.0-SNAPSHOT.jar
[INFO] Unable to find resource 'domain:commons:jar:1.0-SNAPSHOT' in repository my.repo (http://my.repo/artifactory/repo)
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Failed to resolve artifact.

Missing:
----------
1) domain:commons:jar:1.0-SNAPSHOT

Why does the dependency on “commons” fail, even though the reactor has obviously seen it because it successfully processes its dependency tree? It should definitely not be going to the ‘net to find it as it’s right there…

The pom for storage:

<?xml version="1.0" encoding="UTF-8"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <modelVersion>4.0.0</modelVersion>
  <packaging>jar</packaging>
  <parent>
    <artifactId>system</artifactId>
    <groupId>domain</groupId>
    <version>1.0-SNAPSHOT</version>
  </parent>
  <groupId>domain</groupId>
  <artifactId>storage</artifactId>
  <name>storage</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <!-- module dependencies -->
    <dependency>
      <groupId>domain</groupId>
      <artifactId>commons</artifactId>
      <version>1.0-SNAPSHOT</version>
    </dependency>

    <!-- other dependencies -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

Thanks for any suggestions!

(Edit)

To clarify, what I am looking for here is this: I don’t want to have to install module X to build module Y which depends on X, given that both are modules referenced from the same parent POM. This makes intuitive sense to me that if I have two things in the same source tree, I shouldn’t have to install intermediate products to continue the build. Hopefully my thinking makes some sense here…

Answer 1

I think the problem is that when you specify a dependency Maven expects to have it as jar (or whatever) packaged and available from at least a local repo. I’m sure that if you run mvn install on your commons project first everything will work.