Maven is a build tool and project management tool that uses a POM (Project Object Model) file to manage projects. The POM file contains project attributes like groupId, artifactId, version and dependencies. Maven uses standard conventions for project directory structure and a lifecycle of phases like compile, test, package to build projects. It also supports inheritance, plugins and dependency management to build projects in a consistent, automated way.

1. Project management and Comprehension tool

2. Maven... What is it?
Dependency Management
Plugin-ins
POM
Lifecycles
Inheritance

3. Maven... What is it?
"build tool"
• Generates deployable artifacts from the source code.
• Preprocessing, compilation, packaging, testing and
distribution.
"project management tool"
• GeneratesWeb Site (Project Documentation)
• Run Reports

4. Convention over Configuration
Systems should "just work“.
o Pre-defined directory structures
• Source
•Tests
• Documentation
o Based on goals
• compile, test, package, install, deploy, site…
o Just learn the conventions!
o Archetype plugin for easy project creation
• mvn archetype:generate

5. Standard Directory Layout

6. POM (Project Object Model)
o Fundamental unit of work in Maven
o Maven projects, dependencies, builds, artifacts: all of these are objects to be modeled
and described.These objects are described by an XML file called a Project Object Model
(POM).
Reference: pom.xml

7. POM – Important Attributes
project It is the root element of pom.xml file.
modelVersion It is the sub element of project. It specifies the modelVersion. It
should be set to 4.0.0.
groupId * It is the sub element of project. It specifies the id for the project
group.
artifactId * It is the sub element of project. It specifies the id for the artifact
(project). An artifact is something that is either produced or used
by a project. Examples of artifacts produced by Maven for a
project include: JARs, source and binary distributions, and WARs.
Version * It is the sub element of project. It specifies the version of the
artifact under given group.
* MavenCoordinates

8. Dependency Management
 Mechanism for centralizing dependency information.
 Managing dependencies become difficult task once we've to deal with multi-
module projects (consists of hundreds of modules/sub-projects). Maven provides
a high degree of control to manage such scenarios.

9. Dependency Management(Contd.)
o MavenCo-Ordinates – groupid, artifactid, version.
o type – packaging type.
• jar
• pom
• test-jar
• ejb-client etc.
o scope - compile (default), provided, runtime, test, system
o systemPath - use only if the dependency scope is “system”.
o optional - Marks optional a dependency when this project itself is a dependency.

10. Dependency Management(Contd.)

11. Maven - Plug-ins
Maven is actually a plugin execution framework where every task is actually done by plugins.
Types:
 Build Plugin -They execute during the build and should be configured in the <build/> element of
pom.xml.
Ex: maven-dependency-plugin
 Reporting Plugin -They execute during the site generation and they should be configured in the
<reporting/> element of the pom.xml
Ex: maven-site-plugin

12. Maven - Plug-ins(Contd.)

13. Maven - Plug-ins(Contd.)
Beyond the standard coordinate of groupId:artifactId:version, there are elements which configure the
plugin or this builds interaction with it.
inherited - true or false, whether or not this plugin configuration should apply to POMs which inherit from
this one. Default value is true.
configuration - package specific configuration
executions - configure the execution of a plugin's goals.

14. Lifecycles
Lifecycle is an organized sequence of phases that exist to give order to a set of
goals.
1) Clean
1) pre-clean
2) clean
3) post-clean
2) Default (sometimes called build)
1) validate
2) compile
3) test
4) package
5) verify
6) install
7) deploy
3) Site
1) pre-site
2) site
3) post-site
4) site-deploy

15. Inheritance
o Provides inheritance via the parent element.
o All Maven POMs inherit values from a parent POM. If a POM does not specify a direct
parent using the <parent> element, that POM will inherit values from the Super POM.
o The packaging type required to be pom for parent and aggregation (multi-module)
projects.

16. Inheritance (Contd.)
The elements in the parent POM that are inherited by its children are:
 dependencies
 developers and contributors
 plugin lists
 reports lists
 plugin executions with matching ids
 plugin configuration

17. Super POM
o All Maven project POMs extend the Super POM, which defines a set of defaults shared
by all projects.This Super POM is a part of the Maven installation.
o An analogy to how the Super POM is the parent for all Maven POM files, would be how
java.lang.Object is the top of the class hierarchy for all Java classes.

19.  https://maven.apache.org/pom.html#What_is_the_POM
 https://maven.apache.org/guides/mini/guide-configuring-plugins.html
 https://www.tutorialspoint.com//maven/index.htm
 https://dzone.com/articles/5-maven-tips
 https://maven.apache.org/settings.html