Robert Savage

Well, I have started my first open source project. It is called “maven-external-dependency-plugin“ and is hosted over on the Google Code site. I started using Maven about a year ago in a large project at work and have really gown to love all that it offers and its immense extensibility. We use Maven for Java and Adobe Flex based projects and it works very well for us. However, one of the really frustrating things for me is to come across dependencies that are not hosted in a public Maven repository. On the Java side, this is a bit of a more rare occurrence, but with Flex, a large portion of that community is not Maven-minded. This means that I have to mange those dependencies by adding them to my local M2 repository and then manually deploy them to a group repository so that all team members can access these artifacts. Keeping them up to date becomes a pain mainly because of the manual effort involved and because it is not part of the standard workflow. I have been using batch files for managing these one-offs but that leaved me as the sole person responsible for maintaining these dependencies.

So … there has to be a better way … Right?

Well, I have thought for a long time … wouldn’t it be helpful to have a Maven plugin that could automatically download a file from a URL and install it to my local repository and them maybe also deploy it to my group’s Maven repository?    I has looked around at several Maven plugins out there trying to piece together a solution to perform this task.  But I did not find an out of the box solution that could be easily implemented and be robust and straight-forward.   So why not created my own mojo and contribute to the community?   How difficult could it be?

My first experience with Maven plugin development was working on a custom modified version of the Israfil Flex plugin to compile our Flex-based projects about a year ago.  Out of the box it got me to 90% of what I needed to accomplish, but there were something it could not do when compiling Flex modules, I don’t remember the specifics now but I think it had something to do with compiling multiple Flex modules and generating multiple module artifacts in a single project.  I abandoned this effort long ago in favor of the much more capable and powerful  “flex-mojos“.  So I jumped into the Java code for this plugin and made the necessary tweaks to meet my needs.

I remembered how simple it was to extend and how easy it was to create a Maven plugin so this weekend I created the “maven-external-dependency-plugin“.  This Maven (mojo) plugin is used to aid in managing external Maven artifacts that are not published public Maven repositories.

The goal of this project is to allow you to define a configuration for external (not hosted in M2 repo) artifacts that will automatically download the artifact, install to you local M2 repository and optionally deploy to your team/company M2 repository.

Granted there is still a bit of manual effort involved for updating the POM configuration information for these external dependencies when new versions are available, but this should eliminate the manual effort of having to install and deploy these types of files by hand.

Here is an example of an artifact configured to download from an external URL and install to the local Maven repository

   <!-- THIS JAR IS HOSTED ON GOOGLE CODE,
        BUT IS NOT AVAILABLE IN A MAVEN REPO -->
   <artifactItem>
       <groupId>com.google.code</groupId>
       <artifactId>google-api-translate-java</artifactId>
       <version>0.92</version>
       <packaging>jar</packaging>
       <downloadUrl>
          http://google-api-translate-java.googlecode.com/files/google-api-translate-java-{version}.jar
       </downloadUrl>
       <install>true</install>
       <force>false</force>
   </artifactItem>

Please visit this link for a complete example of a POM file configured to this this plugin: http://code.google.com/p/maven-external-dependency-plugin/source/browse/trunk/maven-external-dependency-plugin-test/pom.xml

Please visit the “maven-external-dependency-plugin” project site on Google Code for more information.