Ant

- take control of compilation, packaging, testing, and deployment stages of the build process in a way that is portable, scalable, and often reusable.

- three levels: project (each build file), target (dependencies), task (extensible, e.g, javac, mkdir)

 <-- target is to resolve dependencies, conditionally execution. e.g., -->
 <target name="m.clean">
  ....
  <property name="cleaned" value="true"/>
 </target>
<target name="m.compile">
  <javac destdir="..." ></javac>
  <antcall target="m.binding" />
</target>

<target name="m.binding" if="cleaned">
    <bind load="true"> ...</bind>
</target>

- DataTypes: Path, Fileset, Patternset, Filterset, ZipFilest, etc.

- Ant properties ${property.name}
i. built in properties such as ant.file (the absolute path of the build file, can use ant.file.fgl-common-build where fgl-common-build is the project name of the build file which is included in the main build file)

ii. JVM system properties, e.g., user.name, java.home

iii. Set with 'property' task

      <property name="build.debug" value="on"/>  -- name/value pair
      <property file="build.properties" /> -- load from properties file
      <property name="src.dir" location="somedir" /> - refer to relative path

iv. load environment varialbe

      <property environment="env" /> 

v. set property conditionally

<!-- if debug, set debugLevel to all; else lines only -->
<condition property="debugLevel" value="lines,vars,source"     else="lines,source">
  <istrue value="${debug}"/>
</condition>

all env vairables are loaded with prefix env such as env.CATALINA_HOME
Properties are immutable. A property define in build file doesn't override the one from property file. However, there are ways to break the immutability of property using <ant/>, <antcall>, <available> and -D command line operation. Among them, -D has the highest priority.