Week 10: build automation

Large software projects can require a very complex process to compile the code and package the resulting executable to be distributed. This process can involve many steps, such as testing and packaging resources and configuration files. For this reason, it's useful to automate as much of the process as possible, even for small projects.

You might have been using an IDE like NetBeans or Eclipse to provide some of this functionality: those IDEs will automatically compile your project, and possible perform other tasks such as testing or generating documentation. We're going to use Apache Ant to illustrate how to generalize this process.

XML

Ant uses XML format for its configuration file. XML is a markup language that can be used to model hierarchical data. There are tons of tools available for parsing, transforming, and displaying data described using XML.

Ant

To install (on Windows; other operating systems are easier), download Ant unzip it to any desired location, and set the following environment variables:

• ANT_HOME should be set to the full path of the directory you just unzipped, for example something like C:\Users\jlepak\programs\apache-ant-1.9.0
• Update PATH to contain the bin folder where ant.bat is saved. More information on setting PATH.
• If you get an error about JAVA_HOME being incorrect, you'll need to define a JAVA_HOME environment variable that points to the location of your JDK. This is usually something like C:\Program Files\Java\jdk1.7.0.

The course materials contain a very simple example in examples/ant-example/ that we'll build on in class (see the examples/ant-example directory). Here's the Ant setup file, that we'll improve and add to:

<project>
  <property name="build.dir" location="build" />
  <property name="src.dir" location="src" />

  <target name="hello">
    <echo message="Hello!!!" />
  </target>
  
  <target name="init" description="Initialize build">
    <mkdir dir="${build.dir}" />
  </target>
  
  <target name="compile" depends="init" description="Compile all source files">
    <javac srcdir="${src.dir}" destdir="${build.dir}" />
  </target>

  <target name="dist" depends="compile" description="Build jar file">
    <jar destfile="Hello.jar" basedir="${build.dir}">
	  <manifest>
		<!-- This is XML comment syntax -->
		<!-- This attribute defines which class runs when running the jar 
			 (or with the way Java is commonly set up in Windows, when the 
			 jar is double-clicked). -->
	    <attribute name="Main-Class" value="HelloGUI" />
	  </manifest>
	</jar>
  </target>
</project>

The dist target will package the program and allow it to run like a normal executable (on Windows at least - you can see the setup by typing ftype jarfile).

Readings

For XML information, check out this XML tutorial. For tons more detail, check out the introductory chapters of Beginning XML.

For Ant, start with this Ant tutorial, which is part of the extensive Ant manual. See the intro chapters in Ant in Action for lots more information.