EAR Enterprise Application

In addition to having a master buildfile called main (we discussed the master buildfile in Chapter 4), we want to deploy all our applications into an application server that can accept them. The main buildfile serves two purposes:

It ensures that all the subprojects are created in the correct order.
It builds an enterprise archive (EAR) file so that the EJBs and Web applications can be easily deployed to a single application server.

The HelloWorld Main Project Buildfile

The main project's buildfile is structured (not surprisingly, we hope) very much like the other buildfiles . There are setProps, init, prepare, clean, build, and package targets. One of the key differences is that the main buildfile delegates the clean and build targets to the subproject while ensuring that they execute in the correct order. Also, the package section creates an EAR file. Refer to the following listing to see the final main buildfile.

 <project name="main" default="package" >          <target name="setProps" unless="setProps"                            description="setup the properites.">         <property name="outdir" value="/tmp/app" />          <property name="setProps" value="true" />     </target>          <target name="init" depends="setProps"                             description="initialize the properties.">          <tstamp/>          <property name="dist" value="${outdir}/dist" />          <property name="deploy" value="${outdir}/deploy" />          <property name="build" value="${outdir}/classes" />          <property name="lib" value="${outdir}/lib" />     </target>     <target name="clean" depends="init"                            description="clean up the output directories.">            <ant dir="./Model" target="clean">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />            </ant>            <ant dir="./EJBeans" target="clean">                <property name="outdir" value="${outdir}" />                  <property name="setProps" value="true" />                <property name="jboss" value="/tools/jboss/jboss/deploy" />            </ant>            <ant dir="./WebApplication" target="clean">                <property name="outdir" value="${outdir}" />                  <property name="setProps" value="true" />                <property name="ejb" value="true" />            </ant>            <ant dir="./Application" target="clean">                <property name="outdir" value="${outdir}" />                  <property name="setProps" value="true" />            </ant>            <delete dir="${outdir}" />     </target>          <target name="prepare" depends="init"                            description="prepare the output directory.">           <mkdir dir="${build}" />           <mkdir dir="${lib}" />           <mkdir dir="${dist}" />           <mkdir dir="${deploy}" />           <mkdir dir="${dist}/META-INF" />     </target>     <target name="build" depends="prepare"              description="build the model and application modules.">                    <ant dir="./Model" target="package">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />           </ant>           <ant dir="./EJBeans" target="deploy">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />                <property name="jboss" value="/tools/jboss/jboss/deploy" />           </ant>           <ant dir="./Applet" target="package">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />           </ant>           <ant dir="./WebApplication" target="deploy">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />                <property name="ejb" value="true" />           </ant>           <ant dir="./Application" target="package">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />           </ant>     </target>     <target name="package" depends="build">           <copy file="./META-INF/application.xml"                                      todir="${dist}/META-INF" />           <jar jarfile="${deploy}/hello.ear"                                       basedir="${dist}" />     </target> </project>

Analyzing the Buildfile for the Enterprise Application

The build target uses the ant task (<ant>) to call the other Ant buildfiles. The build target is as follows :

 <target name="build" depends="prepare"              description="build the model and application modules.">                    <ant dir="./Model" target="package">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />           </ant>           <ant dir="./EJBeans" target="deploy">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />                <property name="jboss" value="/tools/jboss/jboss/deploy" />           </ant>           <ant dir="./Applet" target="package">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />           </ant>           <ant dir="./WebApplication" target="deploy">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />                <property name="ejb" value="true" />           </ant>           <ant dir="./Application" target="package">                <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />           </ant>     </target>

Notice that each call to invoke another buildfile sets the relative directory of the subproject's buildfile (<ant dir="./Model" target="package">) and the target of the buildfile. Because we named each buildfile of each subproject build.xml, we only need to specify the directory. In addition to specifying the target that we want to execute, the ant task passes two properties to each subproject, as follows:

 <property name="outdir" value="${outdir}" />                <property name="setProps" value="true" />

The second property ensures that the subproject's setProps target is not executed, by setting the property "setProps". Remember, the "setProps" property for each project is not executed if the setProps property is set (<target name="setProps" unless="setProps">). The first property ensures that the value of the outdir of the main project is passed to the subproject. When we combine these two properties, it's easy to set a new directory for all the output of the main project and all its subprojects at the command line, demonstrated (using bash) as follows:

 rick@CANIS_MAJOR /usr/rick/cvs/XPToolKit/examples/chap5/MVCHelloWorld $ ant -DsetProps=no -Doutdir=/usr/rick/output

These lines could be used to redirect the output to a directory to which you have access, if you are developing on a Unix box.

The clean target follows many of the same concepts as the build target, so we will not discuss it in detail. The next major piece of the main project is the package target, as follows:

 <target name="package" depends="build">           <copy file="./META-INF/application.xml"                                      todir="${dist}/META-INF" />           <jar jarfile="${deploy}/hello.ear"                                       basedir="${dist}" />     </target>

This code copies the application.xml metadata from the ./META-INF directory to the distribution directory. The distribution directory is also where the webapplication project buildfile's package target and the enterprise beans project buildfile's package target put their WAR and EJB JAR file, respectively.

The next task is for the main's package target to jar the WAR, EJ JAR, and application.xml files into a JAR file format. It does this with the jar task, as follows:

 <jar jarfile="${deploy}/hello.ear"                               basedir="${dist}" />

The output of the file is hello.ear, which is put into the deployment directory. The deployment directory is defined in the init target (for example, /tmp/deploy). The application.xml file is the deployment descriptor for the EAR file.

Enterprise Application Deployment Descriptor

If our intention is to deploy the Web application and the enterprise beans as a single logical unit, it may be useful to create an EAR file as we did. In order for the J2EE container to understand what we are deploying, we have to tell it with the deployment descriptor in the following listing.

 <application>   <display-name>Hello World Application</display-name>   <description>Hello World Application.</description>   <module>     <web>       <web-uri>hello.war</web-uri>       <context-root>helloworld</context-root>     </web>   </module>   <module>     <ejb>greet-ejbs.jar</ejb>   </module> </application>

Looking at this code, you may wonder why we don't list the model library, the applet JAR, the enterprise bean client JAR, and so on. Remember, they were included with the WAR file. Instead, the deployment descriptor describes two modules: our Hello World Web application and our Hello World enterprise beans. First the Web application:

 <module>     <web>       <web-uri>hello.war</web-uri>       <context-root>helloworld</context-root>     </web>   </module>

Notice that the URI for the Web application is set to helloworld; thus, when we deploy it, it runs under the helloworld directory ( http://localhost/helloworld) . Next, we defined the Enterprise JavaBean module as follows:

 <web>       <web-uri>hello.war</web-uri>       <context-root>helloworld</context-root>     </web>

We can use it to deploy in one simple step to any J2EE container that supports both Web applications and enterprise beans.