Speakers: Chandra Gunter and Rodrigo Graciano

@CGuntur and @rodrigograciano

For more, see the 2024 DevNexus Blog Table of Contents

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General

• Apache Maven 4 is still in alpha
• Avoid profiles where can
• Shoutout for mvn verify (vs maven install)
• Sample code: https://github.com/c-guntur/maven4

Pain Points in Maven 3

• Painful to maintain versions in multi module projects – flatten-maven-plugin helps with child versions but has hissues with profile interpolation. ci-friendly-flatten-maven-plugin solves profile interpolation problem but requires including third party plugin
• No implicit way to separate build info from consumer info. Why do consumers need SCM location and Jira link – flatten-maven-plugin and c-friendly-flatten-maven-plugin help
• Handling versions of sibling modules is a chore
• We use default versions for plugins. Ex: compiler version has default so not everyone specifies.
  Creating BOM (Bill of Materials) not easy. No way to identify that default version is in use

Maven 4

• Requires Java 17+ to run Maven and Java 17 to compile (but can use Java 17 to compile earlier version)
• New schema version in <project> xmlns
• <moduleVersion> is now 4.1.0
• Can use <version>${revision}</version> without plugin – can pass from root pom or command line
• Get warning in build log if use the default version number of any plugins
• Two poms in .m2 for artifact. artifact-version-build.pom is what is used to build and artifact-version.pom is the consumer pom that goes to the repo when deploy
• No need to specify version number of parent in multi module project. Figures out automatically. Version is still allowed. It is an optional field so can specify older version at will.
  • Build caching is improved so faster performance. ex: less re-compiling

My take

I didn’t take notes on Maven itself only the differences between Maven 3 and 4. I know it was necessary to get everyone on the same page. Given everyone raised their hand on using Maven, I wonder if could have been briefer. (Got to limitations of Maven 3 at 20 minute mark) I liked the interaction between the presenters to make it a conversation. The list of Maven 3 problems was great. And the demo of how Maven 4 fixes was good.