ANT

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ANT Another Neat Tool

• Representation and Management of Data on the
  Internet

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What is ANT?

• A cross-platform build tool (like make)
• A scripting framework
• Based on industry standards (Java and XML)
• Open Source (development coordinated by the
  Apache Jakarta project)

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What can we do with ANT?

• Can be used to
• compile java programs
• create javadoc documentation
• create jar, zip, tar, war files
• delete and copy files
• validate XML files
• etc. (send mail, anything you want)

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ANT Buildfiles

• An ANT buildfile is a file that contains the
  instructions for ANTs tasks
• A buildfile is written in XML
• A buildfile has the following elements
• Project - a top level collection of targets
• Property - an ANT variable
• Target - a collection of tasks
• Task - a unit of ANT execution (a step)

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ANT Buildfiles
project
. . .
. . .
property
property
Target
Target
. . .
Task
Task
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Buildfile Example
ltproject name"MyProject" default"dist"
basedir"."gt ltproperty name"src" value."/gt
ltproperty name"build" location"build"/gt
lttarget name"compile description"compile the
source"gt lt!-- Compile the java code from
src into build --gt ltjavac
srcdir"src" destdir"build"/gt lt/targetgt
lttarget namejar" descriptionbuild the JAR
file"gt ltjar destfile"dist/lib/app.jar"base
dir"build/classes"/gt lt/targetgt lttarget
name"clean" description"clean up"gt lt!--
Delete the build and dist directory trees
--gt ltdelete dir"build"/gtltdelete
dir"dist"/gt lt/targetgt lt/projectgt
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Projects

• The project is the root element of the buildfile
• One project per buildfile
• Projects can have 3 attributes
• name name of project (optional)
• default default target to use (required)
• basedir base directory for paths (optional)

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Properties

• Properties (global values) are typically defined
  as follows
• ltproperty namepropName valuepropVal/gt
• Note Properties are XML elements without
  contents, therefore we use /gt
• A property named propName can be referred to
  later using the syntax propName
• You can define any properties you want
• Properties are not variable the first value they
  are given remains for the whole build!

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Special Property Definitions

• ltproperty name"src" location"srcFile"/gt
• sets src to the absolute file name of srcFile,
  taken to be relative to the project's basedir
• ltproperty file"pFile"/gt
• reads a set of properties from a file called
  pFile
• ltproperty environment"env"/gt
• Later, you may use env.VAR_NAME to get the
  systems environment variable called VAR_NAME
• Built-in Properties (predefined)
• ant.file, ant.java.version, os.name, user.name,
  user.home, etc

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Tasks

• A task is a piece of code to be executed
• The general form of a task element is
• lttaskname param1"value1" param2"value2"... /gt
• ANT comes with some built-in tasks, which cover
  most of the basic needs for development of
  applications
• One can also define new tasks (not covered here)

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Some Built-In Tasks Examples

• Directory tasks
• ltmkdir dir"workDir"/gt, ltdelete
  dir"workDir"/gt
• Archive tasks
• ltjar jarfile"archive.jar" basedir"build.classe
  s"/gt
• lttar tarfile"archive.tar" basedir"src"/gt
• ltgzip zipfile"archive.tar.gz" src"archive.tar"/gt
  
• Output tasks
• ltecho message"Hello, user.name"/gt

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More Built-In Tasks Examples

• Java tasks
• ltjava classname"Ex4Main"/gt
• ltjava classname"Main"gtltarg value"-h"/gt lt/javagt
• ltjavac srcdir"src" destdir"build"/gt
• compiles only files that need to be compiled
  (time based)
• Invoking external programs
• ltexec executable"emacs"gt
• ltarg value"readme.txt"/gt
• lt/execgt

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Targets

• A target is a collection of tasks to be performed
  when the target is executed
• Targets have the attributes
• name name of the target (required)
• depends comma separated list of targets on which
  the target depends (optional)
• if, unless, description details omitted (read
  about it in the ANT documentation)

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A BuildFile Adding a Target

• ltproject nameMyProject defaultcompilegt
• ltproperty name"buildDir" value"build"/gt
• ltproperty namesrcDir" value."/gt
• lttarget name"compile"gt
• ltjavac srcdir"srcDir" destdir"buildDir"/
  gt lt/targetgt
• lt/projectgt

A Task
We could also have written ltjavac srcdir.
destdirbuild"/gt
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• ltproject name"MyProject" default"dist"
  basedir"."gt
• lt!-- set global properties for this build --gt
• ltproperty name"src" value"."/gt
• ltproperty name"build" value"build"/gt
• ltproperty name"dist" value"dist"/gt
• lttarget name"compile"gt
• lt!-- Compile java code from src into
  build --gt
• ltjavac srcdir"src" destdir"build"/gt
• lt/targetgt

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• lttarget name"dist" depends"compile"gt
• lt!-- Create the distribution directory --gt
• ltmkdir dir"dist/lib"/gt
• lt!-- Put everything in build into the jar
  file
• MyProject.jar file --gt
• ltjar jarfile"dist/lib/MyProject.jar"
  basedir"build"/gt
• lt/targetgt
• lttarget name"clean"gt
• lt!-- Delete the build and dist directory
  trees --gt
• ltdelete dir"build"/gt
• ltdelete dir"dist"/gt
• lt/targetgt
• lt/projectgt

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More about Depends

• ANT tries to execute the targets in depends
  from left to right
• However, a target may be executed earlier when
  another one depends on it

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Example 1
lttarget name"A"/gt lttarget name"B"
depends"A"/gt lttarget name"C" depends"B"/gt
lttarget name"D" depends"C,B,A"/gt

• Execute ant D
• In what order will the tasks be performed?

Try D
Try C
Try B
Try A

• Note B is executed before C!
• Note B is executed once!

Do D
Do C
Do B
Do A
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Example 2
lttarget name"A dependsB/gt lttarget name"B"
depends"A"/gt

• Execute ant A
• In what order will the tasks be performed?
• The build fails, ant reacts with
• Circular dependency A lt- B lt- A

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Running ANT

• Type ant
• ANT looks for the file build.xml, and performs
  the default task specified there
• Use the buildfile option to specify a different
  buildfile
• You can specify a different target to be
  performed
• You can define parameters using the D option

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Examples

• Run ANT using build.xml on the default target
• ant
• Run ANT using the test.xml file on the default
  target
• ant -buildfile test.xml
• Run ANT using the test.xml file on a target
  called dist
• ant -buildfile test.xml dist
• Run ANT using the test.xml file on a target
  called dist, setting the build property to the
  value build/classes
  
• ant -buildfile test.xml -Dbuildbuild/classes
  dist

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Make versus ANT

• Make OS dependent -tasks are shell commands
• Runs fast for small tasks
• ANT OS independent -tasks implemented as Java
  classes
• requires Java ( JDK 1.2)
• Slow for small tasks requires JVM
• Make Non-standard syntax (infamous tabbing
  problem)
• ANT XML based syntax
• Make state dependencies between program files
• ANT state dependencies between tasks (not
  between program files)

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References

• To learn more about ANT
• Look at the documentation on the web (reference
  from the table of lecture schedule)
• Pay attention to the section Built-in Tasks
  there are many tasks and task parameters you
  might find useful