Question

I hope I’m explaining this as accurately as possible, and I want to know if I set up the maven dependencies correctly, or if there’s a better way to do it.

Most of my development team’s projects rely on a home-grown jar that is deployed at server class loader. The reason for this jar to reside at this level is to the ease of updating the jar at one place without repackaging each project that’s using it, assuming changes made to it are backward-compatible.

I develop my web apps against Jetty in my local development. So, in order for the web apps to work locally, I set up the dependencies this way:-

<dependencies>
    <!-- Configuring external jar dependency -->
    <dependency>
        <groupId>com.test.app</groupId>
        <artifactId>app-jar</artifactId>
        <version>1.0</version>
        <scope>system</scope>
        <systemPath>${env.EXTERNAL_JAR}</systemPath>
    </dependency>

    ...
</dependencies>

<build>
    <plugins>
        <!-- Configuring Jetty -->
        <plugin>
            <groupId>org.mortbay.jetty</groupId>
            <artifactId>maven-jetty-plugin</artifactId>
            <version>6.1.26</version>
            <configuration>
                <contextPath>/${project.parent.artifactId}</contextPath>
                <jettyEnvXml>${env.JETTY_ENV_XML}</jettyEnvXml>
                <scanIntervalSeconds>1</scanIntervalSeconds>
                <connectors>
                    <connector implementation="org.mortbay.jetty.nio.SelectChannelConnector">
                        <port>7777</port>
                    </connector>
                </connectors>
                <webAppConfig>
                    <extraClasspath>${env.EXTERNAL_JAR}</extraClasspath>
                </webAppConfig>
            </configuration>
        </plugin>

        ...
    </plugins>
</build>

In this approach, I set up an environment variable that points to the external jar path, and reference it in my pom.xml as ${env.EXTERNAL_JAR}.

After doing some reading, it seems like using “system” scope is considered a bad practice. So, I installed this external jar in Nexus and change the scope to “provided”:-

<dependency>
    <groupId>com.test.app</groupId>
    <artifactId>app-jar</artifactId>
    <version>1.0</version>
    <scope>provided</scope>
</dependency>

This allows me to compile my project properly, but I’m not sure if it is even possible for me to get rid of the “EXTERNAL_JAR” environment variable completely because it’s still needed by Jetty for the runtime to work properly. My take is using “provided” scope is a little tedious and more work, because I now need to remember to update the jar in Nexus when it is modified AND I still need to update the jar located at the path pointed by the environment variable.

Is there a way for me to expose the external jar to Jetty through maven dependencies, yet not being packaged into the project when the war file is built?

What are you advice on this? Should I just stick with “system” scope so that I just need to update the jar at one place, or should I use “provided” scope? Or if there’s even a better way to do this?

Thanks much.

Answer 1

You should be able to add dependencies to the jetty plugin. And then I have the provided scope for the project itself.

http://docs.codehaus.org/display/JETTY/Maven+Jetty+Plugin

as in

<project>
... 
      <plugin> 
        <groupId>org.mortbay.jetty</groupId> 
        <artifactId>maven-jetty-plugin</artifactId> 
        <configuration> 
          <systemProperties> 
            <systemProperty> 
              <name>logback.configurationFile</name> 
              <value>./src/etc/logback.xml</value> 
            </systemProperty> 
          </systemProperties> 
        </configuration> 
        <dependencies>
          <dependency> 
            <groupId>ch.qos.logback</groupId> 
            <artifactId>logback-classic</artifactId> 
            <version>0.9.15</version> 
          </dependency> 
        </dependencies> 
      </plugin>
...
<project>