This is a talk I gave recently to the department of Computer Science at University of Illinois at Chicago on Apache Maven. Hope it's useful. http://www.cs.uic.edu/Main/NewsItem?audience=public&ind=498

1. Apache Maven :
A maven in build automation
Venkat Raghavan G
M.S - Computer Science
ADVIS Laboratory.
Department of Computer Science University of Illinois at Chicago.

2. Motivation..
• Large number of modules with proper description/status.
•
• Rectify implementation issues – Eg: Integrate with a build server or use JARs with
other projects.
• How about decreasing training time for developers?
• Spend more time on programming than organizing it.
• What about Ant, buildr… Gradle*?
• The goal is to simplify tests, build, integrations and reporting.
University of Illinois at Chicago. Venkat Raghavan G

3. Maven - Introduction
• Officially described as “Software project management & comprehension” tool.
•
• Widely recognized as a build automation tool, typically for Java projects.
• Based on Project-Object-Model (POM)
• It has a plugin execution framework .
• Maintains a model of a project :
• Dependency management
• Remote repositories
• Reuse of build logic
• Tool portability
University of Illinois at Chicago. Venkat Raghavan G

4. Today’s talk..
• Maven Introduction
•
• POM
• Plugin execution framework
• Build Lifecycle
• Creating a maven project
• Advanced Topics*
University of Illinois at Chicago. Venkat Raghavan G

5. Maven - History
• Initiated in 2001 as an Apache Jakarta project.
•
• Moved to Turbine after that.
• Active development by 2003
• Maven 2.0 in 2005 (POM)
• Maven 3.0 in 2010
• Maven 3.0.4 in Jan 2012
University of Illinois at Chicago. Venkat Raghavan G

6. Installation
• Download tar.gz and extract to ~/
•
• Set ‘M2_HOME’ environment variable to ~/<maven>
• Set ‘M2_HOME/bin’ to PATH : use bashrc or make a symbolic link in /usr/bin
• Type ‘mvn’ to see the options.
University of Illinois at Chicago. Venkat Raghavan G

7. Project Object Model (POM)
• Heart of Maven 2
•
• XML – Containing Project info and configuration details
• build path, dependencies, testing resources, team members, structure etc.
• Super POM – Default POM. All POMs extend Super POM.
<project>
<modelVersion>3.0.0</modelVersion>
<name>Maven Project</name>
<repositories>
<repository>
<id>central</id>
<name>In-house Repository </name>
<layout>default</layout>
<url>http://repos.uic.edu/maven2</url> <snapshots>
</repository> </repositories> …..
University of Illinois at Chicago. Venkat Raghavan G

8. Ant “build.xml”
<project name=“sample" default="dist" basedir=".">
<description>
•
Compare Ant & POM
</description>
<property name="src" location="src/main/java"/>
<property name="build" location="target/classes"/>
<property name="dist" location="target"/>
Maven “POM.xml”
<target name="init"> <project>
<mkdir dir="${build}"/> <modelVersion>1.0.0</modelVersion>
</target>
<groupId>edu.uic.lab1</groupId>
<target name="compile" depends="init“ description="compile the source " > <artifactId>Project1</artifactId>
<javac srcdir="${src}" destdir="${build}"/> <version>1.0</version>
</target> </project>
<target name="dist" depends="compile“ description="generate the distribution"
>
<mkdir dir="${dist}/lib"/>
<jar jarfile="${dist}/build/sample.jar" basedir="${build}"/>
</target>
…
…….
University of Illinois at Chicago. Venkat Raghavan G

9. Convention over configuration..
src/main/java Application/Library sources
•
src/main/resources Application/Library resources • Standardized structure
src/main/filters Resource filter files • Can be overridden but
src/main/assembly Assembly descriptors not recommended
src/main/config Configuration files
src/main/scripts Application/Library scripts
src/main/webapp Web application sources
src/test/java Test sources
src/test/resources Test resources
src/test/filters Test resource filter files
src/site Site
LICENSE.txt Project's license
Notices and attributions required by libraries
NOTICE.txt
that the project depends on
README.txt Project's readme
University of Illinois at Chicago. Venkat Raghavan G

10. More on POM..
<project>
<modelVersion>1.0.0</modelVersion>
<groupId>edu.uic.lab1</groupId> Default POM
<artifactId>Project1</artifactId>
<version>1.0</version>
<properties>
<project.build.sourceEncoding>UTF-8 Properties – encoding, Java
</project.build.sourceEncoding> system, user-defined, etc.
</properties>
<repositories>
<repository>
<id>repo1</id> Location for maven to lookup
<url>http://project1.uic.edu/maven2</url> when materializing the project.
</repository>
</repositories> ..
University of Illinois at Chicago. Venkat Raghavan G

11. More on POM..
<dependencies>
<dependency>
<groupId>log4j</groupId> Defining dependencies
<artifactId>log4j</artifactId>
<version>1.2.12</version>
</dependency>
</dependencies>
<build>
<sourceDirectory>src</sourceDirectory>
<testSourceDirectory>test</testSourceDirectory>
<resources>
<resource>
SuperPOM - Overriding
<directory>resources</directory>
</resource>
</resources>
</build>
University of Illinois at Chicago. Venkat Raghavan G

12. Dependency configuration
• Artifact is identified by coordinates
•
<dependencies>
<dependency>
• groupid, artifactid, version <groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.12</version>
• No more version conflicts or binary data in VCS. <scope> test</scope>
• Quick checkout, reuse artifacts </dependency>
</dependencies>
• Version : <major>.<minor>.<revision>
• Dependency scopes:
1. compile – packaged into the build file => JAR, WAR
2. provided – not packaged but used for compile => Servlet
3. runtime – not for compile but for tests => taglibs
4. test – used only for test => JUnit
5. system – similar to ‘provided’ => 3rd party softwares
University of Illinois at Chicago. Venkat Raghavan G

13. Plugin execution framework
<build>
••Maven, by itself, is a dummy XML framework <plugins>
<plugin>
• Plugins turn them into a giant tool. <artifactId>maven-enforcer-plugin
</artifactId>
• Collection of one or more ‘goals’ <version>1.1.1</version>
<executions>
• Does ‘executions’. <execution>
<id>enforce-java</id>
<goals>
• Custom plugin can be written. <goal>enforce</goal>
</goals>
• Java, Groovy, Ruby etc.
<configuration>
<rules>
<requireJavaVersion>
<version>[1.6.0-0,1.6.0-32]</version>
</requireJavaVersion>
</rules>
</configuration>…..
University of Illinois at Chicago. Venkat Raghavan G

14. Repository configuration
••Central repository : <repositories>
<repository>
• http://repo1.maven.org/maven2 <id>central</id>
• Huge set of libraries are available <url>http://repo1.maven.org/maven2
</url>
</repository>
• Local repository : </repositories>
• ~/${maven-folder}/repository
• Contains artifacts
• used by maven
• used by projects
• created by projects
University of Illinois at Chicago. Venkat Raghavan G

15. Creating a new repository
••Get a web space.
• Create a new maven project.
• Add ‘extension’ for a protocol in POM: Eg: – wagon-ftp
• Add ‘distributionManagement’ repository – the new FTP address
• To keep it secure, add credentials to ~/.m2/settings.xml
• mvn deploy
• Share your repository link to the world!
University of Illinois at Chicago. Venkat Raghavan G

16. Default life-cycle..
Plugins
generate-sources archetype
compile
compiler
test-compile
test
POM surefire
package
integration-test jar
install
deploy install
University of Illinois at Chicago. Venkat Raghavan G

17. Few maven commands..
••mvn dependency:analyze  Cleans up the dependencies again
• mvn dependency:tree (or) mvn dependency:list  To learn about dependencies.
• mvn install  Install the o/p to the repository
• mvn clean  Cleans the target directory
• mvn package  Creates war/jar
• mvn compile  Compiles the project
• mvn test  Tests as defined in POM
University of Illinois at Chicago. Venkat Raghavan G

18. Creating a maven project..
• Understand “archetype”
• mvn archetype:generate -DgroupId=edu.uic –DartifactId=project1 –
DarchetypeGroupId=maven-archetype-quickstart
• Creates maven project with default POM
• Creates src/main/java and src/test/java folders
University of Illinois at Chicago. Venkat Raghavan G

19. Extra POM elements..
• <developers> <developer>….
• <contributors><contributor>…
• <organization>
• <licenses><license>…
• <reporting>
And so on…
University of Illinois at Chicago. Venkat Raghavan G

20. Some useful links..
••POM Reference -- http://maven.apache.org/pom.html
• Repository using FTP -- http://stuartsierra.com/2009/09/08/run-your-own-maven-
repository
• Advanced reading -- http://shop.oreilly.com/product/9780596517335.do
University of Illinois at Chicago. Venkat Raghavan G

21. Advanced topics..
•
Inheritance
• “Management” prefix keyword.
• ‘pluginManagement’ and ‘dependencyManagement’
• Does inheritance
• Used in more complex projects
• Be careful! Not to be confused with ‘plugins’/’dependencies’
University of Illinois at Chicago. Venkat Raghavan G

22. Advanced topics..
•
Profiles
• Customize build based on environments.
• Eg: production, development
• Allows build portability
<profiles>
<profile>
<id>production</id>
<build> …. </build>
</profile>
</profiles>
University of Illinois at Chicago. Venkat Raghavan G

23. Advanced topics..
•
Creating website
• Create a maven project
• Add jetty plugin and run “mvn jetty:run”
• Add site-descriptors to pom.xml
• Document using APT, Xdoc or FML (Maven uses Doxia)
• Deploy
University of Illinois at Chicago. Venkat Raghavan G

24. Advanced topics..
•
Add security
• Restrict users for deployment, build, distribution etc.
• Create a private key : mvn –ecrypt-master-password myPassword
• Add <settingssecurity> to ~/{maven2}/settings-security.xml
• You can register in the server through “settings.xml”.
University of Illinois at Chicago. Venkat Raghavan G

25. Summary
• Maven – more than a build automation tool
• Convention over configuration
• Central repository and dependency management
• Execution of life-cycle phases through plugin
• Software project management services viz. websites, reporting etc.
• Integration with eclipse IDE through m2e plugin
University of Illinois at Chicago. Venkat Raghavan G

26. •
Thank You!!
University of Illinois at Chicago. Venkat Raghavan G