1. Using Maven2

2. Free Maven Books Better Builds with Maven
Maven: The Definitive Guide (alpha)‏

3. The Maven Site

4. What is Maven? Build lifecycle Dependency management tool
Artifact repository
Collection of plugins
Project reporting tool
Set of conventions
Distilled experience

5. What Else is Maven? Succinct command line tool
Designed for Java/Java EE/other
Holder/publisher of project documentation
Generator of project metrics
Customisable: environment, lifecycle, etc
Inheritable
Declarative
Encourager of modularity and reuse
Integrated with SCM tools
Integrated with IDEs
Integrated with Ant
System of repositories
Project kick starter
Release manager
Deployer
Enabler of portable build knowledge
Encourager of best practice
Community
Not perfect

6. Quick Start Download Maven2, unzip, add bin directory to $PATH
Configure proxy in ~/.m2/settings.xml if required
$ mvn archetype:create \ -DgroupId=com.example \ -DartifactId=my-app

7. Directory Structure Convention
Java sources: src/main/java
Unit tests: src/test/java
pom.xml

8. pom.xml – The Project Object Model
<project xmlns="
xmlns:xsi="
xsi:schemaLocation="
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>my-app</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>my-app</name>
<url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>

9. Directory Structure Convention
Added:
My app sources
Properties file: src/main/resources/ messages.poperties
My unit test

10. Killer App package com.example; public class MessagePrinter {
public void printMessage(String message, OutputStream os){
PrintWriter pw = new PrintWriter(os);
pw.print(message);
pw.flush(); }
public class Hello {
public static void main(String[] args){
ResourceBundle messages = ResourceBundle.getBundle("messages");
MessagePrinter mp = new MessagePrinter();
mp.printMessage(messages.getString("message1"), System.out);
mp.printMessage("\n", System.out); }

11. My Application POM <project ...> ...
<name>My Application</name>
<url>
<build>
<plugins>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>com.example.Hello</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>
</build>
</project>

12. Eclipse Integration
Maven2 plugin for Eclipse; either from project root execute: $ mvn eclipse:eclipse and import with Eclipse, or create the project in Eclipse and add the Maven2 project nature

13. Eclipse Integration

14. Ready for Take Off
$ mvn package

15. stdout [INFO] Scanning for projects...
[INFO] Building My Application
[INFO] task-segment: [package]
[INFO] [resources:resources]
[INFO] Using default encoding to copy filtered resources.
[INFO] [compiler:compile]
[INFO] Compiling 1 source file to /home/russell/Desktop/maven-presentation/example/my-app/target/classes
[INFO] [resources:testResources]
[INFO] [compiler:testCompile]
[INFO] Compiling 1 source file to /home/russell/Desktop/maven-presentation/example/my-app/target/test-classes
[INFO] [surefire:test]
[INFO] Surefire report directory: /home/russell/Desktop/maven-presentation/example/my-app/target/surefire-reports
T E S T S
Running com.example.AppTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: sec
Results :
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] [jar:jar]
[INFO] Building jar: /home/russell/Desktop/maven-presentation/example/my-app/target/my-app-1.0-SNAPSHOT.jar
[INFO]
[INFO] BUILD SUCCESSFUL
[INFO] Total time: 3 seconds
[INFO] Finished at: Wed Jul 04 11:11:55 NZST 2007
[INFO] Final Memory: 4M/11M

16. The (Almost) Finished Product
Classes and test classes compiled
Resources copied to classes directory
Test reports created
Jar file created
$ java -jar my-app-1.0-SNAPSHOT.jar
Hello World!

17. Plugins & Goals
A plugin contains one or more goals (Goal a.k.a. Mojo; Maven + Pojo = Mojo
A plugin is a Maven artifact
A goal is uniquely referenced/invoked by: groupId:artifactId:version:goal e.g: org.apache.maven.plugins:maven-eclipse-plugin:eclipse defaults shorten this to: eclipse:eclipse

18. Anatomy of a Maven Command
1. Invoke a specific goal:
$ mvn [options] plugin:goal [parameter]...
e.g:
$ mvn -e eclipse:eclipse
-> Generate Eclipse configuration, print verbose error messages
2. Invoke goals bound to the lifecycle(s) up to and including a phase:
$ mvn [options] phase... [parameter]...
e.g:
$ mvn clean package -Dmaven.test.skip=true
-> Clean target, build package, skip tests

19. Maven Lifecycles Three built-in lifecycles:
default
clean
site
You can create your own lifecycle, but only if you have really weird build requirements!

20. The Default Build Lifecycle

21. Project Packaging <project ...>
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>my-app</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
...
</project>

22. Lifecycle Bindings

23. Build Lifecycle
$ mvn package

24. stdout [INFO] Scanning for projects...
[INFO] Building My Application
[INFO] task-segment: [package]
[INFO] [resources:resources]
[INFO] Using default encoding to copy filtered resources.
[INFO] [compiler:compile]
[INFO] Compiling 1 source file to /home/russell/Desktop/maven-presentation/example/my-app/target/classes
[INFO] [resources:testResources]
[INFO] [compiler:testCompile]
[INFO] Compiling 1 source file to /home/russell/Desktop/maven-presentation/example/my-app/target/test-classes
[INFO] [surefire:test]
[INFO] Surefire report directory: /home/russell/Desktop/maven-presentation/example/my-app/target/surefire-reports
T E S T S
Running com.example.AppTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: sec
Results :
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] [jar:jar]
[INFO] Building jar: /home/russell/Desktop/maven-presentation/example/my-app/target/my-app-1.0-SNAPSHOT.jar
[INFO]
[INFO] BUILD SUCCESSFUL
[INFO] Total time: 3 seconds
[INFO] Finished at: Wed Jul 04 11:11:55 NZST 2007
[INFO] Final Memory: 4M/11M

25. Dependencies <project ...> ... <dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
Explicitly declared, including version
Resolved by Maven, not required in project directory / source control repository
Scoped: compile, provided, runtime, test
SNAPSHOT dependencies updated
Transitive
Strictly acyclic (a DAG not a tree)‏

26. Killer App Reloaded public class Hello {
public static void main(String[] args) {
ReloadableResourceBundleMessageSource messages
= new ReloadableResourceBundleMessageSource();
messages.setCacheSeconds(1);
messages.setBasename("messages");
MessagePrinter mp = new MessagePrinter();
Scanner scanner = new Scanner(System.in);
do {
String message = messages.getMessage("message1", null,
Locale.getDefault());
mp.printMessage(message, System.out);
mp.printMessage("\n", System.out);
mp.printMessage("Keep playing? [Y/n]\n", System.out);
} while (!"n".equals(scanner.nextLine())); }

27. Dependencies Version ranges
<project ...>
...
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>[2.0,)</version>
<exclusions>
<exclusion>
<artifactId>spring-aop</artifactId>
</exclusion>
</project>
Version ranges
Use exclusions to trim unwanted dependencies

28. Transitive Dependencies

29. Reloadable Message Source
Hello World!
Keep playing? [Y/n] y
Hello Again World! n
Note for anyone trying this at home: there's a bit of classpath config required to get this working nicely. It's easiest to run it on the Eclipse console, and modify the target messages.properties

30. Configuring Plugins e.g. Ant
<project...>
...
<build>
<plugins>
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<phase>generate-sources</phase>
<configuration>
<tasks>
<!--
Place any ant task here. You can add anything you can add
between <target> and </target> in a build.xml.
-->
</tasks>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

31. Standard Maven Plugins
Listed at:
clean
compiler
deploy
install
resources
site
surefire
verifier
ear
ejb
jar
rar
war
changelog
changes
checkstyle
clover
doap
docck
javadoc
jxr
pmd
project-info-reports
surefire-report
ant
antlr
antrun
archetype
assembly
dependency
enforcer
gpg
help
invoker
one
plugin
release
remote-resources
repository
scm
source
eclipse
idea
Codehaus:
build-helper
castor
javacc
jdepend
native
sql
taglist
Other:
cargo
jaxme
jetty
jalopy

32. POM Inheritance No source or target defined in POM, yet this works:
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>my-app</artifactId>
<version>1.0-SNAPSHOT</version>
</project>
No source or target defined in POM, yet this works:
$ mvn compile

33. Super POM To fully resolve the POM: $ mvn help:effective-pom | less
<project>
<build>
...
<outputDirectory>target/classes</outputDirectory>
<sourceDirectory>src/main/java</sourceDirectory>
<resources>
<resource>
<directory>src/main/resources</directory>
</resource>
</resources>
</build>
</project>
To fully resolve the POM:
$ mvn help:effective-pom | less

34. POM Inheritance <project>
<groupId>com.example</groupId>
<artifactId>org-pom</artifactId>
<version>1</version>
<!-- configure
JDK version, e.g: 1.5
standard reports, etc. -->
</project>
<project>
<parent>
<groupId>com.example</groupId>
<artifactId>org-pom</artifactId>
<version>1</version>
</parent>
<artifactId>my-app</artifactId>
...
</project>

35. Maven Repositories Repositories store artifacts: plugins
project dependencies
Central: (or mirror)‏
Local: ~/.m2/repository
The first execution of a plugin, or requirement for a dependency pulls the artifact from central and caches it locally

36. Maven Repositories Problems:
Reliant on network and external repository for dependencies and plugins
Can't deploy to Central Maven repository for reuse as dependencies of other projects (though usually wouldn't want to)‏

37. Organisation Repository
No longer reliant on network or external repository for dependencies and plugins
Can deploy to organisation repository in order to share artifacts
Multiple repository configurations possible
Multiple repository tools available: Archiva, Proximity, Artifactory

38. Archiva

39. Install and Deploy
$ mvn deploy

40. Install and Deploy
$ mvn deploy

41. SCM Integration Fully implemented: Bazaar CVS Mercurial Perforce
StarTeam
Subversion
CM Synergy
Partially implemented:
ClearCase
File system
Visual Source Safe

42. Configuring SCM </project> <project>
<groupId>com.example</groupId>
<artifactId>my-app</artifactId>
...
<scm>
<connection>
scm:svn:
</connection>
<developerConnection>
scm:svn:
</developerConnection>
<url>
</url>
</scm>
</project>

43. SCM Integration, What For?
Use SCM agnostic commands: $ mvn scm:checkin -Dmessage="to the cause" $ mvn scm:update
Project bootstrapping: $ mvn scm:bootstrap
Available for use by Maven tools, e.g: documented and linked in project website, published in Archiva summary
Continuous Integration, SCM details located in project rather than CI tool
Release management

44. Cutting a Release $ mvn release:prepare [-DdryRun=true]
Checks SCM for modifications
Checks for use of SNAPSHOT dependencies or plugins
Runs $ mvn clean integration-test
Requests release info:
version numbers
Creates new POMs:
pom.xml for tag
pom.xml for next version
release-pom.xml
Creates tag in SCM
$ mvn release:perform
Uses release-pom.xml, deploys project, generates site, etc.

45. Website / Reports (1)‏ Project website:
Conventions for structuring documentation, supporting various formats: DocBook simple, FML, XDOC, APT, Twiki
Directory structure conventions, supporting multiple types of documentation, e.g: public, user, developer, etc.
Configurable, skinnable site
Project info from POM: contact details: organisation, developers; SCM details, etc.

46. Website / Reports (2)‏
Metrics, checks, and project reports (on website):
Javadoc
Test results
Code coverage (Cobertura)‏
Checkstyle, PMD, JDepend, Clirr
Database documentation (Hibernate)‏
Dependency report
TODO report (//TODO, FIXME, configurable)‏
Linked and line-numbered HTML sources
Release notes and roadmap from issue tracker

47. Quick Tour

48. In Brief (1)‏ Java EE support: WAR, EAR packaging
Rapid web app development
Integration (in container) testing
Deployment to environments
Multi-module projects
Enable / encourage reuse between projects
Maven inter-module dependency eliminates cycles between modules
Nicely supported in NetBeans
Not nicely supported in Eclipse – nested projects

49. In Brief (2)‏ Continuous Integration: CruiseControl Continuum
Reuses project information as defined in POM
Profiles
Build activity carried out under different conditions, e.g: personal requirements, dev / test / release, continuous integration
Maven settings
Help

50. Problems History: Maven 1, might have left a bad taste
Steep learning curve
Once you've got it, the knowledge is portable to other projects built with Maven
Complex needs require complex configuration
Alan Kay: Simple things should be simple. Complex things should be possible
Verbose XML config
Docs aren't great, but getting better
Error messages often do not provide much (or any) detail (e.g. archetype problem)‏
Ensuring the project is buildable and testable in the IDE as well as with Maven can be complex
Multi-module projects not supported by Eclipse (but they are in Netbeans)‏

51. Stuff to Look at
Buildr – a build system configured in Ruby that reuses parts of Maven:
repositories;
directory structure conventions;
Rake – a Ruby build tool

52. Get reading and enjoy the ride
Still Interested?
Get reading and enjoy the ride

53. Questions?