Help me understand making maven project w/ non-maven jar dependencies usable by others

Question

Hi, I'm in the process of learning maven (and java packaging & distribution) with a new oss project I'm making as practice. Here's my situation, all java of course:

My main project is ProjectA, maven-based in a github repository. I have also created one utility project, maven-based, in github: ProjectB. ProjectA depends on a project I have heavily modified that originally was from a google-code ant-based repository, ProjectC.

So, how do I set up the build for ProjectA such that someone can download ProjectA.jar and use it without needing to install jars for ProjectB and ProjectC, and also how do I set up the build such that someone could check out ProjectA and run only 'mvn package' for a full compile?

(Additionally, what should I do with my modified version of ProjectC? include the class files directly into ProjectA, or fork the project into something that could then be used by as a maven dependency?)

I've been reading around, links such as this SO question and this SO question, but I'm unclear how those relate to my particular circumstance. So, any help would be appreciated. Thanks!

Answer 1

You have to publish the code from the additional dependencies. Two options:

1. Use the maven-shade-plugin to create a maven artifact containing all the content of the B and C jars, and publish that under your own G/A/V coordinates.
2. Publish copies of B and C under your own G/A/V coordinates using the maven-deploy-plugin to your forge just as you will publish your own code. Different forges have different policies; but if you abide by the licenses of B and C you should be OK.

Answer 2

So, how do I set up the build for ProjectA such that someone can download ProjectA.jar and use it without needing to install jars for ProjectB and ProjectC

Assuming ProjectA is a JAR, you can create an executable JAR that bundles the dependencies with the Maven Assembly Plugin (and the predefined jar-with-dependencies descriptor) or with the Maven Shade Plugin.

how do I set up the build such that someone could check out ProjectA and run only 'mvn package' for a full compile?

You have to deploy the dependencies to a repository that can be read over HTTP and to declare this repository in your pom.xml. AFAIK, git-hub doesn't offer any facility for that. But any web hosting service with FTP access (or better, scp) should do the trick. If your project is open source, another option would be to use Sonatype's OSS Repository Hosting service.

Just in case, you might want to read this blog post but you won't learn much more things.

The easiest would still be to organize the 3 projects as a multi-modules maven project and to build all modules.

Additionally, what should I do with my modified version of ProjectC?

From a modularization point of view (assuming you found a solution for the above part about repository), it would certainly make sense to have it as a separate module, especially if there is an opportunity someone can use ProjectC outside your project.