Web Development

6.1 Running a Web Application in a Servlet Container

6.1.1. Task

You need to run a web application in a servlet container.

6.1.2. Action

Configure your web application's Maven project to inlcude the Maven Jetty plugin as shown in the following POM:

To start the web application in Jetty, run the run goal from the Maven Jetty plugin by running mvn jetty:run.

At this point, you can use a web browser to navigate to http://localhost:8080/sample-web/ to interact with the web application.

6.1.3. Detail

Consider a simple web application with a single index.jsp page that contains a form, and a single Servlet that calculates a number from the Fibonacci sequence.

Example 6.1. Simple Form Accepting an Index to Pass to the Fibonacci Servlet

The following class is the Servlet which calculates the Fibonacci sequence. It takes a single parameter index and simply prints of the number at the specified position of the Fibonacci sequence.

Example 6.2. Fibonacci Servlet which Calculates a Number from the Fibonacci Sequence

The following web.xml configures the FibonacciServlet to respond to the request path <context>/fib.

Example 6.3. Web Application Descriptor for sample-web

After running mvn:jetty, you can load the initial form by going to http://localhost:8080/sample-web/index.jsp. Populating the form with an index and pressing calculate will load the Fibonacci servlet and print out the number at that position of the sequence.

6.2. Starting a WAR Dependency in a Servlet Container

6.2.1. Task

You need to configure Maven to download and start a web application from a repository manager.

6.2.2. Action

Use the Maven Dependency plugin to copy the web application's WAR artifact to your project. Then configure the Maven Jetty plugin to execute the web application using the plugin's dependencies element to configure the classpath for Jetty.

<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.sonatype.mcookbook</groupId>
<artifactId>start-jackrabbit</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>start-jackrabbit</name>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>default-cli</id>
<configuration>
<artifactItems>
<artifactItem>
<groupId>org.apache.jackrabbit</groupId>
<artifactId>jackrabbit-webapp</artifactId>
<version>1.6.0</version>
<type>war</type>
<overWrite>true</overWrite>
<destFileName>jackrabbit-webapp.war</destFileName>
</artifactItem>
</artifactItems>
<outputDirectory>
${project.build.directory}/war
</outputDirectory>
<overWriteReleases>true</overWriteReleases>
<overWriteSnapshots>true</overWriteSnapshots>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.mortbay.jetty</groupId>
<artifactId>maven-jetty-plugin</artifactId>
<version>6.1.22</version>
<executions>
<execution>
<id>default-cli</id>
<configuration>
<contextPath>jackrabbit</contextPath>
<daemon>false</daemon>
<webApp
${project.build.directory}/war/jackrabbit-webapp.war
</webApp>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.apache.jackrabbit</groupId>
<artifactId>jackrabbit-webapp</artifactId>
<version>1.6.0</version>
<type>war</type>
</dependency>
<dependency>
<groupId>javax.jcr</groupId>
<artifactId>jcr</artifactId>
<version>2.0</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.apache.jackrabbit</groupId>
<artifactId>jackrabbit-webapp</artifactId>
<version>1.6.0</version>
<type>war</type>
</dependency>
</dependencies>
</project>

This POM uses some advanced concepts to configure the default command-line options for both the Maven Dependency plugin and the Maven Jetty plugin. It also downloads and executes the jackrabbit-webapp.war artifact from the Central Maven repository.

To download the Jackrabbit web application and execute it in Jetty, copy the POM to an empty directory and run mvn clean dependency:copy jetty:run-war. Because you've configured the default command-line options in the POM, you should Maven downloading Jackrabbit, all of its dependencies, and starting the application in Jetty on port 8080.

Once Maven has started Jetty with the jackrabbit-webapp.war JAR, go to a web browser and open http://localhost:8080/jackrabbit. You should see the Apache Jackrabbit administrative web interface.

While this isn't the most straightforward use of a Maven POM, it does demonstrate the power of using Maven's dependency management and plugin configuration to distribute the settings necessary to execute a web application. If you used such a mechanism to distribute your own web applications, you could configure a web application and all of the information required to download your web application, it's dependencies, the servlet container, and any configuration needed to run your application.