Maven Repository Layout

The layout is responsible for translating the artifact coordinates into generic paths, that is later used to construct some URI (file path, URL, it depends on context). Obviously, since Maven inception in 2002 the layout evolved as well. For simplicity, we will cover current layout (aka “maven2” or “default”), as since Maven 3.x release, the deprecated “Maven1 layout” (aka “legacy”) is not supported anymore.

This above implies following: if the repository contains a file that is “not on layout” (does not obey layout transformation rules discussed below), that file is “not addressable” by Maven coordinates, you cannot address that file in Maven nor make it to download it using GAV coordinates!

The original premise of layout was simplicity: from historical perspective, a remote repository was expected to be run by some computer with file storage (where artifacts were laid down) and served by a HTTP server, essentially publishing the files on file paths for consumption (mainly for HTTP GET requests).

The transformation rule is quite simple for that matter: consider artifact properties below:

And using these properties transformed as above, we can construct following path (if classifier not present):

${groupId as directory}/${artifactId}/${baseVersion}/${artifactId}-${version}.${extension}

or if classifier present:

${groupId as directory}/${artifactId}/${baseVersion}/${artifactId}-${version}-${classifier}.${extension}

So the example artifact above noted as GAV:

org.apache.maven:apache-maven:3.8.4:bin:tar.gz

is translated to path as:

org/apache/maven/apache-maven/3.8.4/apache-maven-3.8.4-bin.tar.gz

And that is it! By applying this “algorithm” above to ANY Artifact we can build up the path segment that artifact is expected to be.

Important note: in case of locally installed artifacts (those you built locally and invoked mvn install) will use Artifact baseVersion property instead of version. The full-blown “timestamped” versions are used only in remote repositories, when the artifact is deployed.