Guide to using Modello
Modello is a tool for generating resources from a simple model. From a simple model you can generate things like:
- Java sources
- XML serialization code for the model
- XML deserialization code for model
- Model documentation
- XSD
A typical modello model looks like the following:
<model xmlns="http://codehaus-plexus.github.io/MODELLO/2.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://codehaus-plexus.github.io/MODELLO/2.0.0 https://codehaus-plexus.github.io/modello/xsd/modello-2.0.0.xsd"
xml.namespace="https://maven.apache.org/plugins/maven-archetype-plugin/archetype-descriptor/${version}"
xml.schemaLocation="https://maven.apache.org/xsd/archetype-descriptor-${version}.xsd">
<id>archetype-descriptor</id>
<name>ArchetypeDescriptor</name>
<description>
<![CDATA[
<p>This is a reference for the Archetype descriptor used to describe archetypes's metadata.</p>
<p>The metadata about an archetype is stored in the <code>archetype-metadata.xml</code> file located
in the <code>META-INF/maven</code> directory of its jar file.</p>]]>
</description>
<defaults>
<default>
<key>package</key>
<value>org.apache.maven.archetype.metadata</value>
</default>
</defaults>
<classes>
<class rootElement="true" xml.tagName="archetype-descriptor">
<name>ArchetypeDescriptor</name>
<version>1.0.0+</version>
<superClass>AbstractArchetypeDescriptor</superClass>
<fields>
<field xml.attribute="true">
<name>name</name>
<version>1.0.0+</version>
<type>String</type>
<required>true</required>
<description>Name of the Archetype, that will be displayed to the user when choosing an archetype.</description>
</field>
<field xml.attribute="true">
<name>partial</name>
<version>1.0.0+</version>
<type>boolean</type>
<required>false</required>
<description>Is this archetype representing a full Maven project or only parts?</description>
</field>
<field>
<name>requiredProperties</name>
<version>1.0.0+</version>
<description>List of required properties to generate a project from this archetype.</description>
<association>
<type>RequiredProperty</type>
<multiplicity>*</multiplicity>
</association>
</field>
</fields>
</class>
<class>
<name>ModuleDescriptor</name>
<version>1.0.0+</version>
<superClass>AbstractArchetypeDescriptor</superClass>
<fields>
<field xml.attribute="true">
<name>id</name>
<version>1.0.0+</version>
<type>String</type>
<required>true</required>
<description>The module's artifactId.</description>
</field>
<field xml.attribute="true">
<name>dir</name>
<version>1.0.0+</version>
<type>String</type>
<required>true</required>
<description>The module's directory.</description>
</field>
<field xml.attribute="true">
<name>name</name>
<version>1.0.0+</version>
<type>String</type>
<required>true</required>
<description>The module's name.</description>
</field>
</fields>
</class>
<class>
<name>AbstractArchetypeDescriptor</name>
<version>1.0.0+</version>
<fields>
<field xdoc.separator="blank">
<name>fileSets</name>
<version>1.0.0+</version>
<association>
<type>FileSet</type>
<multiplicity>*</multiplicity>
</association>
<required>true</required>
<description>File sets definition.</description>
</field>
<field xdoc.separator="blank">
<name>modules</name>
<version>1.0.0+</version>
<association>
<type>ModuleDescriptor</type>
<multiplicity>*</multiplicity>
</association>
<required>false</required>
<description>Modules definition.</description>
</field>
</fields>
</class>
<class>
<name>FileSet</name>
<version>1.0.0+</version>
<description><![CDATA[
A fileset defines the way the project's files located in the jar file are used by the Archetype Plugin to generate a project.
If file or directory name contains <code>__<i>property</i>__</code> pattern, it is replaced with corresponding property value.
]]></description>
<fields>
<field xml.attribute="true">
<name>filtered</name>
<version>1.0.0+</version>
<type>boolean</type>
<required>false</required>
<description><![CDATA[
Filesets can be filtered, which means the selected files will be used as
<a href="https://velocity.apache.org/engine/1.5/user-guide.html">Velocity templates</a>.
They can be non-filtered, which means the selected files will be copied without modification.
]]></description>
</field>
<field xml.attribute="true">
<name>packaged</name>
<version>1.0.0+</version>
<type>boolean</type>
<required>false</required>
<description>Filesets can be packaged, which means the selected files will be generated/copied in a directory
structure that is prepended by the package property. They can be non-packaged, which means that the selected
files will be generated/copied without that prepend.</description>
</field>
<field xml.attribute="true">
<name>encoding</name>
<version>1.0.0+</version>
<type>String</type>
<required>false</required>
<description>Encoding to use when filtering content.</description>
</field>
<field>
<name>directory</name>
<version>1.0.0+</version>
<type>String</type>
<required>false</required>
<defaultValue/>
<description>The directory where the files will be searched for, which is also the directory where the
project's files will be generated.</description>
</field>
<field>
<name>includes</name>
<version>1.0.0+</version>
<association>
<type>String</type>
<multiplicity>*</multiplicity>
</association>
<required>false</required>
<description>Inclusion definition "à la" Ant.</description>
</field>
<field>
<name>excludes</name>
<version>1.0.0+</version>
<association>
<type>String</type>
<multiplicity>*</multiplicity>
</association>
<required>false</required>
<description>Exclusion definition "à la" Ant.</description>
</field>
</fields>
<codeSegments>
<codeSegment>
<code><![CDATA[
public String toString()
{
return
getDirectory() + " ("
+ ( isFiltered() ? "Filtered" : "Copied" )
+ "-"
+ ( isPackaged() ? "Packaged" : "Flat" )
+ ") ["
+ org.codehaus.plexus.util.StringUtils.join( getIncludes().iterator(), ", " )
+ " -- "
+ org.codehaus.plexus.util.StringUtils.join( getExcludes().iterator(), ", " )
+ "]";
}
]]></code>
</codeSegment>
</codeSegments>
</class>
<class>
<name>RequiredProperty</name>
<version>1.0.0+</version>
<description>Definition of a property required when generating a project from this archetype.</description>
<fields>
<field xml.attribute="true">
<name>key</name>
<version>1.0.0+</version>
<type>String</type>
<required>true</required>
<description>Key value of the property.</description>
</field>
<field>
<name>defaultValue</name>
<type>String</type>
<required>false</required>
<description>Default value of the property.</description>
</field>
<field>
<name>validationRegex</name>
<version>1.1.0+</version>
<type>String</type>
<required>false</required>
<description>A regular expression used to validate the property.</description>
</field>
</fields>
</class>
</classes>
</model>
To utilize Modello, you would configure the modello-maven-plugin something like the following where you want to generate the Java sources for the model, the xpp3 serialization code and the xpp3 deserialization code (see modello-plugin-xpp3 for more details):
<project>
...
<build>
<plugins>
<plugin>
<groupId>org.codehaus.modello</groupId>
<artifactId>modello-maven-plugin</artifactId>
<version>1.8.3</version>
<executions>
<execution>
<goals>
<!-- Generate the xpp3 reader code -->
<goal>xpp3-reader</goal>
<!-- Generate the xpp3 writer code -->
<goal>xpp3-writer</goal>
<!-- Generate the Java sources for the model itself -->
<goal>java</goal>
</goals>
</execution>
</executions>
<configuration>
<models>
<model>src/main/mdo/archetype-descriptor.mdo</model>
</models>
<version>1.0.0</version>
<useJava5>true</useJava5>
</configuration>
</plugin>
</plugins>
</build>
...
</project>