Maven Concepts: Difference between revisions
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It is specified as [[Maven_pom.xml#. | It is specified as [[Maven_pom.xml#.3Cname.3E|<name>]] at the top of the POM file. | ||
=Lifecycle= | =Lifecycle= | ||
Revision as of 05:58, 2 January 2017
Internal
Maven Coordinates
groupId:artifactId:version is the minimum amount of information to fully and unequivocally identify an artifact, and constitute an address and a timestamp. This information is referred to as maven coordinates. More details about each component below.
Group ID
The group ID is an unique identifier (ideally, globally) for a project. It is specified as <groupId> at the top of the POM file.
Conventionally uses a dot notation, but it does not have to. When it does use the dot notation, the groupId does NOT have to correspond to the package structure of the project it designates; it is, though, a good practice to follow. When stored within a repository, the dots are replaced by OS specific directory separators, which becomes a relative directory structure from the base repository.
Artifact ID
The artifact ID is generally the name that the project is known by. It is specified as <artifactId> at the top of the POM file. The artifact ID, along with the group ID, create a key that ideally separates this project from every other project in the world.
Under particular circumstances, the artifact ID may contain version information. For example, if the project is an extension for JBoss DataGrid 7 (and only works with JBoss DataGrid version 7), it is fine to use the following artifact ID: "jboss-datgrid-7.0". The project will have its own versioning scheme, independent of "7.0", and a project artifact will be named similarly to "jboss-datagrid-7.0-1.0.0-SNAPSHOT-1.jar"
Artifact Name
The artifactId is used to generate the project's artifact name, according to the pattern artifactId-version.packaging.
The name of the artifact file generated in the target directory of the project can be overridden using the finalName element. However, the name of the artifact published to repository ignores finalName.
Version
The version represents a timestamp for a specific incarnation of the project's artifact, in the history of the project. The information is used within an artifact's repository to separate versions from each other. It is specified as <version> at the top of the POM file.
For more details on a project's module version management, see "Modules and Versions" section.
Packaging
The packaging represents the project's artifact type. It is specified as <packaging> at the top of the POM file.
When no packaging is declared, Maven assumes the artifact is, by default, a "jar". The valid types are Plexus role-hints of the component role org.apache.maven.lifecycle.mapping.LifecycleMapping. The current core packaging values are: "pom" (for an example see multi-module projects), "jar", "maven-plugin", "ejb", "war", "ear", "rar" and "par". The packaging value defines the default list of goals to be bound to phases associated with that particular package structure.
Some packaging types are available only if a particular plugin was declared in <build> and the <extensions> was turned on to true for that plugin.
If you need to specify packaging in the Maven coordinates of a project, it is specified after artifact ID: groupId:artifactId:packaging:version.
Classifier
The classifier allows to distinguish artifacts that were built from the same POM but differ in their content. It is some optional and arbitrary string that - if present - is appended to the artifact name just after the version number.
A common use case for classifiers is the need to attach secondary artifacts to the project's main artifact (for example, javadocs or sources).
It is specified as <classifier> at the top of the POM file. If you need to specify the classifier in the Maven coordinates of a project, it is specified after packaging: groupId:artifactId:packaging:classifier:version.
Classifiers are also used by the assembly plugin.
Name
It is specified as <name> at the top of the POM file.
Lifecycle
For details on the Maven lifecycles and phases, see:
Type
POM
Profile
Plugin
A Maven plugin are pieces of functionality that provide goals. A plugin has one or more goals, and each goal represents a capability of that plugin. Available Plugins:
System Properties
System properties can be declared and exposed to the build in the <properties> section of pom.xml. See:
Dependencies
Repositories
Multi-Module Maven Projects
Fileset
System Properties
Resources
The concept of "resource" is used by the "resources" plugin. See Maven Resources Plugin - The "Resources" section.