12.4. Coordinates

Let us now backtrack and try to make sense of what we did so far.

Maven coordinates

Maven coordinates are used to identify artifacts in a repository.

• groupId:
  • A descriptor of the organization that created the artifact,
  • which is usually the organization's reverse domain.
• artifactId:
  • A descriptor of the artifact,
  • which is usually the project's name.
• version:
  • The version of the artifact.

Here are some examples.

<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>5.6.0</version>

<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.13.1</version>

Maven versions

Example: 3.2.1-98234-beta

• Major version: 3
• Minor version: 2
• Incremental version (patch): 1
• Build number: 98234
• Qualifier: beta

Most often you will see either:

• MajorVersion.MinorVersion.IncrementalVersion; or
• MajorVersion.MinorVersion

Snapshot versions

Example: 3.2.1-SNAPSHOT

The SNAPSHOT qualifier says that this is a development version that is likely to change.

By default, Maven will check remote repositories once per day, which is configurable.

If a dependency does not have the SNAPSHOT qualifier, it will remain as it is unless we change it.

Semantic Versioning

Maven does not define when to update the major, minor, or incremental versions.

A guideline that we can follow is the Semantic Versioning specification, which reads as follows.

Given a version number MAJOR.MINOR.PATCH, increment the:

1. MAJOR version when you make incompatible API changes,
2. MINOR version when you add functionality in a backwards compatible manner, and
3. PATCH version when you make backwards compatible bug fixes.

Additional labels for pre-release and build metadata are available as extensions to the MAJOR.MINOR.PATCH format.