Developing Build Scripts

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Developing Build Scripts

• Using the Ant Build Tool
• July 28, 2003

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What is a build script?

• A special script designed to compile source code
  into a format that can be executed.

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Why are build scripts needed?

• Build process is complex
• Manage complexity
• Provide consistent and repeatable results
• Prevent modules from be inadvertently forgotten
  in the deployment process

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How are build scripts created?

• The same way homes are built with tools.
• A common tool used to create software builds is
  the Ant tool.

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About Ant

• Stands for Another Neat Tool
• Thoroughly tested and well understood in the Java
  community primarily for executing build
  deployment scripts.
• May also be used for other batch process needs
• Based on cross platform technologies (e.g. Java
  and XML).
• Executes quickly and has proven to be effective
  in large scale enterprise deployments.
• Received Java Pro 2003 Readers' Choice Award for
  Most Valuable Java Deployment Technology

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Ant Concepts

• Build script file
• Script file execution
• Next steps

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Build Script File

• Building blocks of the Ant script
• Project
• Targets
• Tasks

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Project Tag

• No buildfile can be without one, nor can it have
  more than one.
• The ltprojectgt tag has three attributes name,
  default, and basedir.
• name gives the project a name
• default refers to the automatic target in which
  execute
• basedir defines the root directory of a project
• The ltprojectgt tag is not connected in any way
  with any project name outside of Ant.

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Project Example

• Create a project titled MyProject.
• ltproject name"MyProject" default"all"
  basedir"."gt
• ...
• lt/projectgt

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Target Tag

• Typically consist of coarse-grained operations
• Consist of tasks that do the actual work of
  accomplishing the target goal

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Target Example

• The purpose of this target is to compile source
  code and create a Java ARchive (JAR) from the
  compiled classes.
• lttarget name"build-lib"gt
• ltjavac srcdirsrc.java.dir"
• destdir"build.dir"
• debug"on"
• deprecation"on"
• includes"/.java"gt
• ltclasspathgt
• ltpathelement location"."/gt
• ltpathelement location"lib.dir/somelib
  .jar"/gt
• lt/classpathgt
• lt/javacgt
• ltjar jarfile"dist/lib/finallib.jar"
  basedir"build.dir"/gt
• lt/targetgt

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Task Tag

• Solve the more granular goals of a build
• perform the actual work
• compiling source code
• packaging classes
• copying files and/or directories

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Task Example

• This task in particular copies a set of files
  from one directory to another.
• ltcopy todir"weblogic.dir/server.home/public
  _html/jsp"gt ltfileset dir"src.www.dir/jsp"/gt
• lt/copygt

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Build Script Execution

• Once the build script is created, execute the
  ant.bat file from the prompt
• Ant searches first to the default build.xml file
• Can specify another build script file as an
  argument from the prompt
• The compilation is performed by the Java
  Development Kit found in the system path

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Items to Consider

• Limitations in deployment
• Eclipse does provide extensions for Ant

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Summary

• Purpose of deployment scripts
• Ant build deployment tool concepts
• Ant build script examples
• Extensions to the Ant tool

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Next Steps

• Ant Website http//ant.apache.org/
• OReilly Book Ant the Definitive Guide

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