Introduction

Maven, a Yiddish word meaning accumulator of knowledge, began as an attempt to simplify the build processes in the Jakarta Turbine project. There were several projects, each with their own Ant build files, that were all slightly different. JARs were checked into CVS. We wanted a standard way to build the projects, a clear definition of what the project consisted of, an easy way to publish project information, and a way to share JARs across several projects.

The result is a tool that can now be used for building and managing any Java-based project. We hope that we have created something that will make the day-to-day work of Java developers easier and generally help with the comprehension of any Java-based project.

Maven’s Objectives

Maven’s primary goal is to allow a developer to comprehend the complete state of a development effort in the shortest period of time. In order to attain this goal, Maven deals with several areas of concern:

   Making the build process easy

   Providing a uniform build system

   Providing quality project information

   Encouraging better development practices

Making the build process easy

While using Maven doesn’t eliminate the need to know about the underlying mechanisms, Maven does shield developers from many details.

Providing a uniform build system

Maven builds a project using its project object model (POM) and a set of plugins. Once you familiarize yourself with one Maven project, you know how all Maven projects build. This saves time when navigating many projects.

Providing quality project information

Maven provides useful project information that is in part taken from your POM and in part generated from your project’s sources. For example, Maven can provide:

   Change log created directly from source control

   Cross referenced sources

   Mailing lists managed by the project

   Dependencies used by the project

   Unit test reports including coverage

Third party code analysis products also provide Maven plugins that add their reports to the standard information given by Maven.

Providing guidelines for best practices development

Maven aims to gather current principles for best practices development and make it easy to guide a project in that direction.

For example, specification, execution, and reporting of unit tests are part of the normal build cycle using Maven. Current unit testing best practices were used as guidelines:

 Keeping test source code in a separate, but parallel source tree

 Using test case naming conventions to locate and execute tests

 Having test cases setup their environment instead of customizing the build for test preparation

Maven also assists in project workflow such as release and issue management.

Maven also suggests some guidelines on how to layout your project’s directory structure. Once you learn the layout, you can easily navigate other projects that use Maven.

While takes an opinionated approach to project layout, some projects may not fit with this structure for historical reasons. While Maven is designed to be flexible to the needs of different projects, it cannot cater to every situation without compromising its objectives.

If your project has an unusual build structure that cannot be reorganized, you may have to forgo some features or the use of Maven altogether.

Feature Summary

The following are the key features of Maven in a nutshell:

Simple project setup that follows best practices - get a new project or module started in seconds

Consistent usage across all projects - means no ramp up time for new developers coming onto a project

Superior dependency management including automatic updating, dependency closures (also known as transitive dependencies)

Able to easily work with multiple projects at the same time

A large and growing repository of libraries and metadata to use out of the box, and arrangements in place with the largest Open Source projects for real-time availability of their latest releases

Extensible, with the ability to easily write plugins in Java or scripting languages

Instant access to new features with little or no extra configuration

Ant tasks for dependency management and deployment outside of Maven

Model based builds: Maven is able to build any number of projects into predefined output types such as a JAR, WAR, or distribution based on metadata about the project, without the need to do any scripting in most cases.

Coherent site of project information: Using the same metadata as for the build process, Maven is able to generate a web site or PDF including any documentation you care to add, and adds to that standard reports about the state of development of the project. Examples of this information can be seen at the bottom of the left-hand navigation of this site under the "Project Information" and "Project Reports" submenus.

Release management and distribution publication: Without much additional configuration, Maven will integrate with your source control system (such as Subversion or Git) and manage the release of a project based on a certain tag. It can also publish this to a distribution location for use by other projects. Maven is able to publish individual outputs such as a JAR, an archive including other dependencies and documentation, or as a source distribution.

Dependency management: Maven encourages the use of a central repository of JARs and other dependencies. Maven comes with a mechanism that your project's clients can use to download any JARs required for building your project from a central JAR repository much like Perl's CPAN. This allows users of Maven to reuse JARs across projects and encourages communication between projects to ensure that backward compatibility issues are dealt with.

Source : https://maven.apache.org