Maven

Maven is a build automation widely used tool primarily for Java projects.

Maven is built using a plugin-based architecture that allows it to make use of any application controllable through standard input. Theoretically, this would allow anyone to write plugins to interface with build tools (compilers, unit test tools, etc.) for any other language.

Maven uses an XML file to describe the software project being built, its dependencies on other external modules and components, the build order, directories, and required plug-ins. It comes with pre-defined targets for performing certain well-defined tasks such as compilation of code and its packaging. The Major advantage of Maven is it dynamically downloads the libraries and plug-ins. The public repositories and local repositories can be configured in settings.xml.

A Project Object Model (POM) provides all the configuration for a single project. General configuration covers the project's name, its owner and its dependencies on other projects. One can also configure individual phases of the build process, which are implemented as plugins. For example, one can configure the compiler-plugin to use Java version 1.5 for compilation, or specify packaging the project even if some unit test fails.

Larger projects should be divided into several modules, or sub-projects, each with its own POM. One can then write a root POM through which one can compile all the modules with a single command. POMs can also inherit configuration from other POMs. All POMs inherit from the Super POM by default configured as parent. The Super POM provides default configuration, such as default source directories, default plugins, and so on.

Maven follows a pre defined phases in its lifecycle starting from downloading the dependencies, compiling, testing, packaging to installing in repositories and deploying. Following is the maven build lifecycle

Even though a build phase is responsible for a specific step in the build lifecycle, the manner in which it carries out those responsibilities may vary. And this is done by declaring the plugin goals bound to those build phases. A plugin goal represents a specific task (finer than a build phase) which contributes to the building and managing of a project. It may be bound to zero or more build phases. A goal not bound to any build phase could be executed outside of the build lifecycle by direct invocation. The order of execution depends on the order in which the goal(s) and the build phase(s) are invoked. For example, The clean and package arguments are build phases, while the dependency : copy-dependencies is a goal (of a plugin). Furthermore, a build phase can also have zero or more goals bound to it. If a build phase has no goals bound to it, that build phase will not execute. But if it has one or more goals bound to it, it will execute all the goals.