Editing Apache Maven (section)

=== Dependencies ===
A central feature in Maven is [[Dependency (project management)|dependency management]]. Maven's dependency-handling mechanism is organized around a coordinate system identifying individual artifacts such as software libraries or modules. The POM example above references the JUnit coordinates as a direct dependency of the project. A project that needs, say, the [[Hibernate (Java)|Hibernate]] library simply has to declare Hibernate's project coordinates in its POM. Maven will automatically download the dependency and the dependencies that Hibernate itself needs (called [[Transitive dependency|transitive dependencies]]) and store them in the user's local repository. Maven 2 [https://search.maven.org/ Central Repository]<ref name="maven2repo"/> is used by default to search for libraries, but one can configure the repositories to be used (e.g., company-private repositories) within the POM.

The fundamental difference between Maven and Ant is that Maven's design regards all projects as having a certain structure and a set of supported task work-flows (e.g., getting resources from source control, compiling the project, unit testing, etc.). While most software projects in effect support these operations and actually do have a well-defined structure, Maven requires that this structure and the operation implementation details be defined in the POM file. Thus, Maven [[Convention over configuration|relies on a convention]] on how to define projects and on the list of work-flows that are generally supported in all projects.<ref>{{cite web|title=Maven: The Complete Reference |url=http://www.sonatype.com/books/mvnref-book/reference/installation-sect-compare-ant-maven.html |publisher=Sonatype |access-date=11 April 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130421060027/http://www.sonatype.com/books/mvnref-book/reference/installation-sect-compare-ant-maven.html |archive-date=21 April 2013 }}</ref>

There are search engines such as The Central Repository Search Engine,<ref>[https://search.maven.org/ The Central Repository Search Engine]</ref> which can be used to find out coordinates for different open-source libraries and frameworks.

Projects developed on a single machine can depend on each other through the local repository. The local repository is a simple folder structure that acts both as a cache for downloaded dependencies and as a centralized storage place for locally built artifacts. The Maven command <code>mvn install</code> builds a project and places its binaries in the local repository. Then, other projects can utilize this project by specifying its coordinates in their POMs.