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 -----
 Introduction
 -----
 Hervé Boutemy
 -----
 2013-03-19
 -----

Maven Model Builder

 The effective model builder, with profile activation, inheritance, interpolation, ...

 The main component is <<<ModelBuilder>>>
 ({{{./apidocs/org/apache/maven/model/building/ModelBuilder.html}javadoc}},
 {{{./xref/org/apache/maven/model/building/ModelBuilder.html}source}}),
 with its <<<DefaultModelBuilder>>> implementation
 ({{{./apidocs/org/apache/maven/model/building/DefaultModelBuilder.html}javadoc}},
 {{{./xref/org/apache/maven/model/building/DefaultModelBuilder.html}source}})
 that manages the steps sequence.

 The sequence is divided into 2 phases:

 * phase 1

   ** profile activation: see {{{./apidocs/org/apache/maven/model/profile/activation/package-summary.html}available activators}}.
   Notice that model interpolation hasn't happened yet, then interpolation for file-based activation is limited to
   <<<$\{basedir}>>> (since Maven 3), System properties and request properties

   ** raw model validation: <<<ModelValidator>>> ({{{./apidocs/org/apache/maven/model/validation/ModelValidator.html}javadoc}}),
   with its <<<DefaultModelValidator>>> implementation
   ({{{./xref/org/apache/maven/model/validation/DefaultModelValidator.html}source}})

   ** model normalization - merge duplicates: <<<ModelNormalizer>>> ({{{./apidocs/org/apache/maven/model/normalization/ModelNormalizer.html}javadoc}}),
   with its <<<DefaultModelNormalizer>>> implementation
   ({{{./xref/org/apache/maven/model/normalization/DefaultModelNormalizer.html}source}})

   ** profile injection: <<<ProfileInjector>>> ({{{./apidocs/org/apache/maven/model/profile/ProfileInjector.html}javadoc}}),
   with its <<<DefaultProfileInjector>>> implementation
   ({{{./xref/org/apache/maven/model/profile/DefaultProfileInjector.html}source}})

   ** parent resolution until {{{./super-pom.html}super-pom}}

   ** inheritance assembly (see {{{./index.html#Inheritance_Assembly}below}})

   ** model interpolation (see {{{./index.html#Model_Interpolation}below}})

   ** url normalization: <<<UrlNormalizer>>> ({{{./apidocs/org/apache/maven/model/path/UrlNormalizer.html}javadoc}}),
   with its <<<DefaultUrlNormalizer>>> implementation
   ({{{./xref/org/apache/maven/model/path/DefaultUrlNormalizer.html}source}})

   []

 * phase 2, with optional plugin processing

   ** model path translation: <<<ModelPathTranslator>>> ({{{./apidocs/org/apache/maven/model/path/ModelPathTranslator.html}javadoc}}),
   with its <<<DefaultModelPathTranslator>>> implementation
   ({{{./xref/org/apache/maven/model/path/DefaultModelPathTranslator.html}source}})

   ** plugin management injection: <<<PluginManagementInjector>>> ({{{./apidocs/org/apache/maven/model/management/PluginManagementInjector.html}javadoc}}),
   with its <<<DefaultPluginManagementInjector>>> implementation
   ({{{./xref/org/apache/maven/model/management/DefaultPluginManagementInjector.html}source}})

   ** <(optional)> lifecycle bindings injection: <<<LifecycleBindingsInjector>>> ({{{./apidocs/org/apache/maven/model/plugin/LifecycleBindingsInjector.html}javadoc}}),
   with its <<<DefaultLifecycleBindingsInjector>>> implementation
   ({{{./xref/org/apache/maven/model/plugin/DefaultLifecycleBindingsInjector.html}source}})

   ** dependency management import (for dependencies of type <<<pom>>> in the <<<\<dependencyManagement\>>>> section)

   ** dependency management injection: <<<DependencyManagementInjector>>> ({{{./apidocs/org/apache/maven/model/management/DependencyManagementInjector.html}javadoc}}),
   with its <<<DefaultDependencyManagementInjector>>> implementation
   ({{{./xref/org/apache/maven/model/management/DefaultDependencyManagementInjector.html}source}})

   ** model normalization - inject default values: <<<ModelNormalizer>>> ({{{./apidocs/org/apache/maven/model/normalization/ModelNormalizer.html}javadoc}}),
   with its <<<DefaultModelNormalizer>>> implementation
   ({{{./xref/org/apache/maven/model/normalization/DefaultModelNormalizer.html}source}})

   ** <(optional)> reports configuration: <<<ReportConfigurationExpander>>> ({{{./apidocs/org/apache/maven/model/plugin/ReportConfigurationExpander.html}javadoc}}),
   with its <<<DefaultReportConfigurationExpander>>> implementation
   ({{{./xref/org/apache/maven/model/plugin/DefaultReportConfigurationExpander.html}source}})

   ** <(optional)> reports conversion to decoupled site plugin: <<<ReportingConverter>>> ({{{./apidocs/org/apache/maven/model/plugin/ReportingConverter.html}javadoc}}),
   with its <<<DefaultReportingConverter>>> implementation
   ({{{./xref/org/apache/maven/model/plugin/DefaultReportingConverter.html}source}})

   ** <(optional)> plugins configuration: <<<PluginConfigurationExpander>>> ({{{./apidocs/org/apache/maven/model/plugin/PluginConfigurationExpander.html}javadoc}}),
   with its <<<DefaultPluginConfigurationExpander>>> implementation
   ({{{./xref/org/apache/maven/model/plugin/DefaultPluginConfigurationExpander.html}source}})

   ** effective model validation: <<<ModelValidator>>> ({{{./apidocs/org/apache/maven/model/validation/ModelValidator.html}javadoc}}),
   with its <<<DefaultModelValidator>>> implementation
   ({{{./xref/org/apache/maven/model/validation/DefaultModelValidator.html}source}})

   []

 []


* Inheritance Assembly

  Inheritance Assembly consists in filling current model empty fields with values taken from parent model.
  It is done in <<<InheritanceAssembler>>> ({{{./apidocs/org/apache/maven/model/inheritance/InheritanceAssembler.html}javadoc}}),
  with its <<<DefaultInheritanceAssembler>>> implementation
  ({{{./xref/org/apache/maven/model/inheritance/DefaultInheritanceAssembler.html}source}}).

  By default, every model field is inherited as-is from parent, with a few exceptions that are intentionally not inherited:
  <<<modelVersion>>>, <<<artifactId>>>, <<<profiles>>> (injected in phase 1) and <<<prerequisites>>>.

  Notice that the 5 URLs from the model (<<<project.url>>>, <<<project.scm.connection>>>, <<<project.scm.developerConnection>>>,
  <<<project.scm.url>>> and <<<project.distributionManagement.site.url>>>) have a special inheritance handling:
  
  ** if not configured in current model, the inherited value is the parent's one with current artifact id appended,

  ** since Maven 3.5.0, if <<<project.directory>>> POM property value is defined, it is used instead of artifact id:
  this permits default inheritance calculations when module directory name is not equal to artifact id. Notice that this
  property is not inherited from a POM to its child: childs POM will use child artifact id if property is not
  set.

  []

* Model Interpolation

  Model Interpolation consists in replacing <<<$\{...\}>>> with calculated value. It is done in <<<StringSearchModelInterpolator>>>
  ({{{./apidocs/org/apache/maven/model/interpolation/StringSearchModelInterpolator.html}javadoc}},
  {{{./xref/org/apache/maven/model/interpolation/StringSearchModelInterpolator.html}source}}).

  Notice that model interpolation happens <after> profile activation, then profile activation doesn't benefit from every values:
  interpolation for file-based activation is limited to <<<$\{basedir}>>> (which was introduced in Maven 3 and is not deprecated
  in this context), System properties and request properties.

  Values are evaluated in sequence from different syntaxes:

*----+------+------+
|| value || evaluation result || common examples ||
*----+------+------+
| <<<project.*>>>\
<<<pom.*>>> (<deprecated>)\
<<<*>>> (<deprecated>) | POM content (see {{{../maven-model/maven.html}POM reference}}) | <<<$\{project.version\}>>>\
 | | <<<$\{project.build.finalName\}>>>\
 | | <<<$\{project.artifactId\}>>>\
 | | <<<$\{project.build.directory\}>>> |
*----+------+------+
| <<<project.basedir>>>\
<<<pom.basedir>>> (<deprecated>)\
<<<basedir>>> (<deprecated>) | the directory containing the <<<pom.xml>>> file | <<<$\{project.basedir\}>>> |
*----+------+------+
| <<<project.baseUri>>>\
<<<pom.baseUri>>> (<deprecated>) | the directory containing the <<<pom.xml>>> file as URI | <<<$\{project.baseUri\}>>> |
*----+------+------+
| <<<build.timestamp>>>\
<<<maven.build.timestamp>>> | the UTC timestamp of build start, in <<<yyyy-MM-dd'T'HH:mm:ss'Z'>>> default format, which can be overridden with <<<maven.build.timestamp.format>>> POM property | <<<$\{maven.build.timestamp\}>>> |
*----+------+------+
| <<<*>>> | user properties, set from CLI with <<<-Dproperty=value>>> | <<<$\{skipTests\}>>> |
*----+------+------+
| <<<*>>> | model properties, such as project properties set in the pom | <<<$\{any.key\}>>> |
*----+------+------+
| <<<maven.home>>> | The path to the current Maven home. | <<<$\{maven.home\}>>> |
*----+------+------+
| <<<maven.version>>> | The version number of the current Maven execution <(since 3.0.4)>. For example, "<<<3.0.5>>>". | <<<$\{maven.version\}>>> |
*----+------+------+
| <<<maven.build.version>>> | The full build version of the current Maven execution <(since 3.0.4)>. For example, "<<<Apache Maven 3.2.2 (r01de14724cdef164cd33c7c8c2fe155faf9602da; 2013-02-19T14:51:28+01:00)>>>". | <<<$\{maven.build.version\}>>> |
*----+------+------+
| <<<*>>> | Java system properties (see {{{http://download.oracle.com/javase/6/docs/api/java/lang/System.html#getProperties()}JDK reference}}) | <<<$\{user.home\}>>>\
 | | <<<$\{java.home\}>>> |
*----+------+------+
| <<<env.*>>>\
<<<*>>> | environment variables | <<<$\{env.PATH\}>>> |
*----+------+------+
| <<<settings.*>>> | Local user settings (see {{{../maven-settings/settings.html}settings reference}}) | <<<$\{settings.localRepository\}>>> |
*----+------+------+

**  Notice

  * after model interpolation, <<<$\{...\}>>> content can remain in the model that will be evaluated later
  when setting plugin parameters. This happens in particular with <<<settings.*>>> values for
  {{{../maven-settings/settings.html}Settings Model}},

  * encoding configuration have been defined as POM properties looking like POM content but not added to POM model to maintain
  compatibility with previous Maven versions:

    * <<<$\{project.build.sourceEncoding\}>>> for
    {{{https://cwiki.apache.org/confluence/display/MAVEN/POM+Element+for+Source+File+Encoding}source files encoding}}
    (defaults to platform encoding)

    * <<<$\{project.reporting.outputEncoding\}>>> for
    {{{https://cwiki.apache.org/confluence/display/MAVENOLD/Reporting+Encoding+Configuration}reporting output files encoding}}
    (defaults to <<<UTF-8>>>)

    []

  []
