Maven doesn't see dependency

Question

I'm trying to add dependency to one module. here is the code:

<dependency>
    <groupId>com.messagedna.dlp</groupId>
       <artifactId>producer</artifactId>
       <version>1.0</version>
    </dependency>

Here is the part of the pom file of the module producer :

<parent>
      <artifactId>DLP</artifactId>
      <groupId>com.messagedna.dlp</groupId>
      <version>1.0</version>
  </parent>
  <groupId>com.messagedna.dlp</groupId>
  <artifactId>producer</artifactId>
  <version>1.0</version>
  <packaging>jar</packaging>

  <name>producer</name>

but when I'm trying to compile the first module I get the following:

Downloading: http://repo1.maven.org/maven2/com/messagedna/dlp/producer/1.0/producer-1.0.pom
[INFO] Unable to find resource 'com.messagedna.dlp:producer:pom:1.0' in repository central (http://repo1.maven.org/maven2)
Downloading: http://repo1.maven.org/maven2/com/messagedna/dlp/producer/1.0/producer-1.0.jar
[INFO] Unable to find resource 'com.messagedna.dlp:producer:jar:1.0' in repository central (http://repo1.maven.org/maven2)
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Failed to resolve artifact.

Missing:
----------
1) com.messagedna.dlp:producer:jar:1.0

  Try downloading the file manually from the project website.

  Then, install it using the command: 
      mvn install:install-file -DgroupId=com.messagedna.dlp -DartifactId=producer -Dversion=1.0 -Dpackaging=jar -Dfile=/path/to/file

  Alternatively, if you host your own repository you can deploy the file there: 
      mvn deploy:deploy-file -DgroupId=com.messagedna.dlp -DartifactId=producer -Dversion=1.0 -Dpackaging=jar -Dfile=/path/to/file -Durl=[url] -DrepositoryId=[id]

  Path to dependency: 
    1) com.messagedna.dlp:DLPServer:war:1.0-SNAPSHOT
    2) com.messagedna.dlp:producer:jar:1.0

----------
1 required artifact is missing.

for artifact: 
  com.messagedna.dlp:DLPServer:war:1.0-SNAPSHOT

from the specified remote repositories:
  central (http://repo1.maven.org/maven2)

how to make it build?

Answer 1

It looks like you haven't set up a proper parent-child relationship between the producer project and the one that depends on it. Until you set that up, you'll need to manually run mvn install on the producer project before trying to build any of the projects that depend on it.

Answer 2

To use a library in maven it must be

• in maven central
• in another repository you have access to.
• install locally.

If it is none of these, you need to follow the instructions maven gives you.