Maven is a project management and comprehension tool that handles builds, reporting, and handling of dependencies. It uses a Project Object Model (POM) file to manage projects. The POM file contains metadata like dependencies, plugins, and configurations. Maven standardizes builds through lifecycles and phases. It manages dependencies through a repository of artifacts. Liferay has integrated Maven support to allow plugin development with Maven through plugins, archetypes, and prebuilt EE artifacts.

1. Liferay Maven SDK
Mika Koivisto
Senior Software Engineer

2. What is Maven?
Project management tool
Build, test, report, assemble, release
Small core expandable with plugins
Project Object Model (POM)
Convention over configuration
Dependency management
Common lifecycle

3. Typical Ant build.xml
<project name="my-project" default="dist" basedir=".">
<property name="src" location="src/main/java"/>
<property name="build" location="target/classes"/>
<property name="dist" location="target"/>
<target name="init">
<tstamp/>
<mkdir dir="${build}"/>
</target>
<target name="compile" depends="init" description="compile the source " >
<javac srcdir="${src}" destdir="${build}"/>
</target>
<target name="dist" depends="compile">
<mkdir dir="${dist}/lib"/>
<jar jarfile="${dist}/lib/MyProject-${DSTAMP}.jar" basedir="${build}"/>
</target>
<target name="clean">
<delete dir="${build}"/>
<delete dir="${dist}"/>
</target>
</project>

4. Same in Maven pom.xml
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>com.liferay.sample</groupId>
<artifactId>my-project</artifactId>
<version>1.0-SNAPSHOT</version>
</project>

5. The Project Object Model
Analogous to Makefile or build.xml
Versioned <major>.<minor>.<incremental>-<qualifier>
Packaging (pom, jar, war, ejb, ear, etc.)
Inheritance
Multi-module
Dependencies
Profiles
Properties

6. Dependency Management
Declarative
Transitive
Identified by: groupId, artifactId, version and type
combination
Scoped: compile, provided, runtime, test or system
Coping with 3rd party dependencies

7. Dependency Management

8. Build Lifecycle
Three standard lifecycles: clean, default and site
Lifecycles have phases
Goals are attached to phases
Lifecycle phases differs based on package type
Common goals:
process-resources, compile
process-test-resources, test-compile, test
install, deploy

9. Repositories
Place where all artifacts are stored
Local
Locate in USER_HOME/.m2/repository
Cached copy of remote downloads
May contain project locally built artifacts
Remote
Central (repo1.maven.org), internal or external
Proxy or Cache

10. Archetype
Project template
Available for various project types
Run mvn archetype:generate to create interactively or
specify with parameters
$ mvn archetype:generate
-DarchetypeArtifactId=liferay-portlet-archetype
-DarchetypeGroupId=com.liferay.maven.archetypes
-DarchetypeVersion=6.1.0-SNAPSHOT
-DgroupId=com.liferay.sample
-DartifactId=sample-portlet
-Dversion=1.0-SNAPSHOT
-DinteractiveMode=false

11. Liferay and Maven
Goal is to make maven a first class citizen in Liferay
plugin development (alternative to ant based sdk)
No Liferay core will not be built with maven, for now :-)
Inspired by a community members effort in 5.2.3 (Milen
Dyankov)
Mostly developed by Me and Thiago Moreira with
community feedback and patches

12. Current state
CE artifacts published to Central through Sonatypes
repository
Artifacts: portal-client, portal-impl, portal-service, portal-
web, tunnel-web, util-bridges, util-java and util-taglib
Artifacts include javadoc and source archives
Archetypes for hook, ext, layouttpl, portlet,
servicebuilder, theme and web

13. Current state
Plugins: ExtBuilder, LangBuilder, PluginDeployer,
PluginDirectDeployer, ServiceBuilder, ThemeMerger,
ThumbnailBuilder and WSDDBuilder
All plugins package in one maven plugin package
liferay-maven-plugin
Maven 2.2.x compatible
Some issues with Maven 3.0.x

14. Liferay EE and Maven
Problematic because EE artifacts are not published to
public repositories
Building EE artifacts from source also not possible
because EE source does not have build scripts
Solution: Provide prebuilt package with install script to
install them in either local repository or internal remote
repository like Sonatype Nexus

15. Installing artifacts locally
In Liferay portal source (not needed once released)
ant -f build-maven.xml zip-maven
Unzip liferay-portal-maven-<version>.zip
Install artifacts by running
ant install
Deploy to repository (optional)
Edit lp.maven.repository.url in build.properties
Run ant deploy

16. Creating a portlet
mvn archetype:generate
-DarchetypeArtifactId=liferay-portlet-archetype
-DarchetypeGroupId=com.liferay.maven.archetypes
-DarchetypeVersion=6.1.0-SNAPSHOT
-DarchetypeCatalog=local,remote
-DartifactId=sample-portlet
-DgroupId=com.liferay.sample
-Dversion=1.0-SNAPSHOT

17. Maven Best Practices
Setup internal repository and maven proxy
Reduces build time by caching dependencies
Increases build stability and repeatability
Allows enforcing rules regarding allowed libraries
Never use 3rd party SNAPHOT dependencies
Declare your dependencies and don’t rely on transitive
dependencies for libraries that you need

18. Resources
Maven: The Complete Reference
http://www.sonatype.com/books/mvnref-book/reference/
Maven by Example
http://www.sonatype.com/books/mvnex-book/reference/
Maven homepage
http://maven.apache.org
My maven incubator - bleeding edge and some extras
https://github.com/mikakoivisto/liferay-maven-incubation

19. Credits
Figures from Maven: The Complete Reference by
Sonatype, Inc.
http://www.sonatype.com/books/mvnref-book/reference/

20. Thank You!