Guidelines for Multi-moduled Maven Project []

Moved to the page http://3rdstage.wikia.com/wiki/Tips_on_Maven in my wiki as of 23th Jul. 2012.

Guidelines for Multi-moduled Maven Project

Separate parent project from container project.

Define properties in the parent POM file as possible.

Define the following properties explicitly for clearness and control.

• Encoding related properties whose default value are dependent on platform.
• project.build.sourceEncoding
• project.reporting.outputEncoding
• Properties to skip situationally unnecessary long running goals.
• skipTests
• maven.javadoc.skip
• maven.deploy.skip
• checkstyle.skip
• Properties to run maven more stable way.
• dependency.locations.enabled : refer If your maven site build is too slow
• Paths for executable programs external to Maven
• graphviz.home

Define all plugins in the <pluginManagement> element of parent POM file.

• Don't specify version to plugin definitions in child POM files.

Define repositories in the parent POM file as possible.

Define plugins to analyze or diagnose the sources or resources of the project as a reporting plugin as possible.

Start values for path with ${project.basedir}, ${project.build.directory}, ${project.build.outputDirectory} or so on

• When just specifying relative path such as 'target/classes', the result directory could be different if you build the project from the enclosing project in multi-module case.
• If you specify the path with leading ${project.build.directory}, the resulting directory always would be one that is calculated with the current POM's project.

Use resources in target/classes not in src/main/resources, considering resource filtering.

Sample of Parent POM

This is the real sample of parent POM I am using.

Tips on Maven []

Moved to the pages http://3rdstage.wikia.com/wiki/Readings_on_Maven and http://3rdstage.wikia.com/wiki/Tips_on_Maven in my wiki as of 23th Jul. 2012.

Overview

• Maven Getting Started Guide : http://maven.apache.org/guides/getting-started/index.html
• POM Reference : http://maven.apache.org/pom.html

• Maven Build Lifecycle : http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html
• Maven Plugin List : http://maven.apache.org/plugins/
• Maven Shared Components : http://maven.apache.org/shared/
• mvn Command Line Options : http://www.sonatype.com/books/mvnref-book/reference/running.html#running-sect-help-option

Readings : references, tutorials and articles

• XML Schema and description for Maven POM file(maven-4.0.0.xsd).
• Maven Model 3.0 API
• Maven Core 3.0 API
• API of MavenProject class
• The mvn Command

Sonatype books

• Maven the Complete Reference
• Developing with Eclipse and Maven
• Maven by Example
• Maven Cookbook
• Repository Management with Nexus

Maven assemblies

• Guide to creating assemblies
• Maven Assembly Descriptor Reference
• Maven the Complete Reference/Maven Assemblies

Maven snapshot repositories

• Repository - SNAPSHOT Handling
• Maven Concepts Repositories
• Guide to deploying 3rd party JARs to remote repository
• Setting Up a Maven Repository

Deployment process and security

• <servers> element in settings.xml
• Password encryption
• Maven Wagon
• Uploading a directory using sftp with Maven

Site process

• Creating a site
• XML Schema Reference for the site descriptor
• Configuring the site descriptor
• Maven Project Info Reports Plugin
• Customizing Site Appearance
• Doxia Modules Guide
• doxia-module-markdown
• How to use confluence format? (in Maven site generation)

Release process

• Using the Maven Release plugin: Things to know
• Archiva Release Process (Real-world sample of Maven release plugin)

Property and Interpolation

• POM Expression evaluation

misc

• Multiple Module Projects with Eclipse
• Attach Library Sources and Javadocs
  Guides to download sources and javadocs of artifacts
• Running Maven Checkstyle plugin safely with multi module project.
  Using just propertyExpansion much simpler than http://maven.apache.org/plugins/maven-checkstyle-plugin/examples/multi-module-config.html
• Defining custom Maven build command for any project.
  Specify ${project_loc} at 'Base directory' field and select 'Run' item at 'Display in favorites menu' field in 'Common' tab.
• reportPlugins doesn't inherit more information from pluginManagement.
• Naked Objects' Sister Projects 1.0: Developers Guide
• How do I get m2eclipse to recognize $M2_OPTS?

Referencing Maven project properties of List type

//@todo

This syntax works within pom.xml and Ant build files using Maven Ant plugin. But this doesn't working with resource filtering of Maven. I can't find any explain or reason for this. Is it a bug?

   ...
   <artifact:pom id="this-pom" file="${basedir}/pom.xml"/>
   <xsddoc out="${this-pom.reporting.outputDirectory}/xsddocs"
      verbose="true">
      <fileset dir="${this-pom.build.resources[0].directory}" 
         includes="**/*.xsd"/>
   </xsddoc>
   ...

Build Lifecycle, Build Phase, Plugin and Goal

• Plugin Prefix Resolution

Simple tips and troubleshooting

• The value of Maven property "project.build.directory" in normal case is ${basedir}/target. You can confirm this using the following command line : "mvn help:evaluate -Dexpression=project.build.directory".

• Solving "org.apache.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 60" exception when running site:site goal
  Simply add a dependency on a newer version(eg. 3.8) of icu4j
• Solving "[ERROR] Unable to determine if resource ... exists in .." error.
  Or just add <dependency.locations.enabled>false</dependency.locations.enabled> into the <properties> element of POM file.
• Using <addClasspath> when you have no dependencies fails with FileNotFoundException
  Configuring to add classpath to MANIFEST file can cause unreasonable exception when running maven-jar-plugin without compile or run-time scope dependency. If you run package with -X option, you can identify exception whose stack goes like this.

Dependency on local library not in Maven repository and with no POM file

Sometimes your project may have dependency on a JAR file that is not registered to any of Maven repositories and so have no it's own POM file. In this case, you can use <systemPath> element to specify your module's dependency on it.

Note that systemPath could be specified only with system scope. You should specify groupId, artifactId, and version 'cause they are mandatory but you can specify any value and don't need pom file.

Escaping expression interpolation

It may necessary not to interpolate Maven expression in resources. In other words, you just want to leave ${some-property} as it is. For this, you can specify the escape string with escapeString parameter of maven-resource-plugin. You can also define maven.resources.escapeString property in your POM file.

For more refer this page : http://maven.apache.org/plugins/maven-resources-plugin/resources-mojo.html#escapeString

Client configuration

The location of client configuration files for subversion is dependent on operating system.

• Windows : %USERPROFILE%\Application Data\Subversion\config
• Linux : ~/.subversion/config

Configurable options are described here : http://svnbook.red-bean.com/en/1.5/svn.advanced.confarea.html#svn.advanced.confarea.opts.config

Working with Subversion working copy in format of ver. 1.7

The default configuration of Maven release plugin(maven-release-plugin) up to ver. 2.2.2 or Maven scm plugin(maven-scm-plugin) up to ver. 1.6 can't work correctly with Subversion working copy in format of ver. 1.7.
To solve this problem, you should override the configuration of release plugin or scm plugin to use maven-scm-provider-svnjava and svnkit 1.7.

For now, svnkit 1.7 has no release and is in snapshot version.

If you let the plugins use svnkit 1.3.x which is default setting as of now, you would meet the exceptions like the following.

For more, refer the followings,

• Maven SCM Subversion Provider - Java Impl.
• svnkit download

Notable Maven Repositories, Plug-ins and Skins []

Moved to the page http://3rdstage.wikia.com/wiki/Notable_Maven_Repositories,_Plug-ins_and_Skins in my wiki as of 23th Jul. 2012.

Maven Repositories

• Sonatype Nexus Open Source Version
  http://repo.expertvill.net/
• Main Repositories
  http://mvnrepository.com/
• JBoss Maven Repository
  1. JBoss Maven Snapshot Repositories
  2. JBoss Maven Release Repositories
  JBoss Maven repsoitories include hibernate releases and snapshots.
• SUN Jars Repository
  http://maven.apache.org/guides/mini/guide-coping-with-sun-jars.html
• DocBook Repository
  http://docbook.sourceforge.net/maven/repository/
  About configuring pom.xml, refer http://wiki.docbook.org/topic/Maven.

Maven Plug-ins

• Resource Plugin : http://maven.apache.org/plugins/maven-resources-plugin/
• Eclipse Plugin : http://maven.apache.org/plugins/maven-eclipse-plugin/
• Doxia Plugin : http://maven.apache.org/doxia/doxia/doxia-maven-plugin/
• JBoss Plugin : http://mojo.codehaus.org/jboss-maven-plugin/
• Jetty Plugin : http://docs.codehaus.org/display/JETTY/Maven+Jetty+Plugin
• IzPack Plugin : http://izpack.codehaus.org/izpack-maven-plugin/
• Properties Plugin : http://mojo.codehaus.org/properties-maven-plugin/
  Provides goals to read and write properties from and to files.
• Build Number Plugin : http://mojo.codehaus.org/buildnumber-maven-plugin/
  Designed to get a unique build number for each time you build your project.
• Versions Plugin : http://mojo.codehaus.org/versions-maven-plugin/
  Manages the versions of artifacts in a project's POM.
• Timestamp Plugin : http://code.google.com/p/maven-timestamp-plugin/
  Provides formatted timestamps for maven builds.
• Spring BeanDoc Plugin : http://mojo.codehaus.org/maven-springbeandoc-plugin/
  Generates pretty reports for Spring configuration files.
• Graphviz Plugin : http://graphviz-maven-plugin.bryon.us/
  Uses the Graphviz library to render .dot files into images.
• Replacer Plugin : http://code.google.com/p/maven-replacer-plugin/
  Replace tokens within a file with a given value and fully supports regular expressions.
• FreeMarker Pre Processor(FMPP) Plugin : http://code.google.com/p/freemarkerpp-maven-plugin/
  Allows to process FreeMarker templates, inject data into those templates in order to produce code, artifacts, reports or anything desired.
• Expression Plugin : https://github.com/jdcasey/expression-maven-plugin
  Allow users to resolve expressions interactively.

Code analysis tools plug-in

• FindBugs Plugin : http://mojo.codehaus.org/findbugs-maven-plugin/
• Checkstyle Plugin : http://maven.apache.org/plugins/maven-checkstyle-plugin/
  Generates a report regarding the code style used by the developers.
• Dependency Graph Plugin : http://el4j.sourceforge.net/plugins/maven-depgraph-plugin/
  Draws a dependency graph of the project the mojo is executed in.
• Sonar Plugin : http://mojo.codehaus.org/sonar-maven-plugin/
  Enables to analyze and report metrics on source code.

Collaboration tools plug-in

• Confluence Plugin : http://code.google.com/p/maven-confluence-plugin/
  Documents a project (using maven site style) and send result to a live confluence site.
• Redmine Plugin : http://www.nuiton.org/embedded/jredmine/maven-jredmine-plugin/

Source configuration management tools plug-in

• SVN Revision Number Plugin : http://code.google.com/p/maven-svn-revision-number-plugin/
  Retrieves the revision number and the status of the Subversion working copy directory and sets project properties that can be used later in the build process.
  • To work with working copy of SVN 1.7 or higher, you should setup dependencies for this plugin to use svnkit 1.7.0-SNAPSHOT. For this refer : http://code.google.com/p/maven-svn-revision-number-plugin/issues/detail?id=10

Non-java build plug-in

• Native Maven Plugin : http://mojo.codehaus.org/maven-native/native-maven-plugin/index.html
  Use this plugin to compile c and c++ source under Maven 2 with compilers such as gcc, msvc, gcj etc ...
• Maven NAR Plugin : http://duns.github.com/maven-nar-plugin/
  allows you to compile native code (c++, c and fortran) on a number of different architectures (Linux, Windows, MacOSX, Solaris, ...) and with a number of different compilers/linkers (g++, Microsoft Visual C++, CC, ...).

Maven Skins

• Fluido skin : http://code.google.com/p/fluido-skin/
  rounded corners and code syntax highlight