------
 Introduction
 ------
 Dan Fabulich
 ------
 2013-07-22
 ------

~~ Licensed to the Apache Software Foundation (ASF) under one
~~ or more contributor license agreements.  See the NOTICE file
~~ distributed with this work for additional information
~~ regarding copyright ownership.  The ASF licenses this file
~~ to you under the Apache License, Version 2.0 (the
~~ "License"); you may not use this file except in compliance
~~ with the License.  You may obtain a copy of the License at
~~
~~   http://www.apache.org/licenses/LICENSE-2.0
~~
~~ Unless required by applicable law or agreed to in writing,
~~ software distributed under the License is distributed on an
~~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
~~ KIND, either express or implied.  See the License for the
~~ specific language governing permissions and limitations
~~ under the License.

${project.name}

+----

THIS PLUGIN IS RETIRED. IT IS NO LONGER MAINTAINED.
THIS PLUGIN IS RETIRED. IT IS NO LONGER MAINTAINED.
THIS PLUGIN IS RETIRED. IT IS NO LONGER MAINTAINED.
THIS PLUGIN IS RETIRED. IT IS NO LONGER MAINTAINED.

+----

 This plugin can build a subset of interdependent projects in a
 reactor.  It should be useful in large reactor builds that include
 irrelevant stuff you're not working on.

* Goals Overview

  The Reactor plugin has several goals:

  * {{{./resume-mojo.html}reactor:resume}} resumes a reactor at a certain point (e.g. when it fails
    in the middle)

    Example: <<<mvn reactor:resume -Dfrom=bar>>>

  * {{{./make-mojo.html}reactor:make}} builds a project X and all of the reactor projects on which X depends

    Example: <<<mvn reactor:make -Dmake.folders=foo,bar>>>

  * {{{./make-dependents-mojo.html}reactor:make-dependents}}  builds a project X and all of the reactor projects that depend on X (the reverse of reactor:make)

    Example: <<<mvn reactor:make-dependents -Dmake.folders=foo,bar>>>

  * {{{./make-scm-changes-mojo.html}reactor:make-scm-changes}}  build all reactor projects that you personally
     have changed (according to SCM) and all reactor projects that depend
     on your changes

     Example: <<<mvn reactor:make-scm-changes>>>

* make vs. make-dependents

  The goals <<<reactor:make>>> and <<<reactor:make-dependents>>> are very similar.  They differ in the <direction> of dependency analysis.

  For example, suppose project "fooUI" depends on project "barBusinessLogic", which depends on project "bazDataAccess".

+---+
fooUI --> barBusinessLogic --> bazDataAccess
+---+

  Ordinarily, when building, you'll first build bazDataAccess, then barBusinessLogic, then fooUI.

  * <<make>>: In order to "make" barBusinessLogic, you first have to build bazDataAccess.  So if you run reactor:make on barBusinessLogic, it will build bazDataAccess, and then build barBusinessLogic; it won't build fooUI.  (This should remind you of the traditional "make" tool.)

+---+
barBusinessLogic --> bazDataAccess
+---+

  * <<make-dependents>>: Because fooUI depends on barBusinessLogic, fooUI is a "dependent" project of barBusinessLogic.  Anything that depends on barBusinessLogic is one of barBusinessLogic's "dependents."  Hence, reactor:make-dependents will build barBusinessLogic, and then build fooUI.

+---+
fooUI --> barBusinessLogic
+---+

  []

  <<In other words, reactor:make walks *down* the dependency tree, whereas reactor:make-dependents walks *up* the dependency tree.>>

* Examples

  To provide you with better understanding on some usages of the Reactor
  Plugin, you can take a look at the {{{./examples.html}examples}} page.