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Using maven and embedded jetty: ClassCastException

Answer 1

+1 A:

You may be dealing with "classloader hell" in JETTY, where it uses a parent classloader for the JETTY instance which is separate from the one used for your webapplication and so even though they should be identical classes they aren't.

There are some options in the JETTY configuration to force use of the same classloader, that may help in your integration tests.

Classloading - JETTY

Jetty provides configuration options to control all three of these options. The method org.mortbay.jetty.webapp.WebAppContext.setParentLoaderPriority(boolean) allows the normal java 2 behaviour to be used and all classes will be loaded from the system classpath if possible. This is very useful if the libraries that a web application uses are having problems loading classes that are both in a web application and on the system classpath.

I'm not sure how you access JETTY configuration in Cargo, but in the normal JETTY maven plugin you would do something like:

<plugin>
    <groupId>org.mortbay.jetty</groupId>
    <artifactId>jetty-maven-plugin</artifactId>
    <version>7.0.0.pre5</version>
    <configuration>
        <jettyConfig>${jetty.configs}</jettyConfig>
        <reload>manual</reload>
        <contextPath>/</contextPath>
        <webAppConfig>
            <parentLoaderPriority>true</parentLoaderPriority>

        </webAppConfig>
    </configuration>
</plugin>

Dougnukem 2010-03-29 22:32:44

Answer 2

+2 A:

Specifying the version of the embedded Jetty used by Cargo is not supported (there is an old open issue about that, see CARGO-571). And indeed, if we look at the log, we see that it uses jetty-6.1.1rc1:

2010-03-29 16:20:46.715::INFO:  jetty-6.1.1rc1

So, first, remove the jetty dependency inside the plugin configuration which is actually the cause of the ClassCastException.

But once the dependency removed, I faced another obscure commons-logging issue:

Caused by: org.apache.commons.logging.LogConfigurationException: Invalid class loader hierarchy.  You have more than one version of 'org.apache.commons.logging.Log' visible, which is not allowed.

And the cause seems to be this part:

            <execution>
                <id>start-container</id>
                <phase>pre-integration-test</phase>
                <goals>
                    <goal>start</goal>
                    <goal>deployer-deploy</goal>
                </goals>
            </execution>

To be honest, I don't know why you call the deploy-deploy goal here. Without it, Cargo does deploy the declared deployable. So there is IMO no need to specify this goal. And if you remove it, there is no exception (and that the second "fix").

To summarize, the following configuration works:

<profile>
  <id>container-cargo-jetty</id>
  <properties>
    <skip.test.phase>true</skip.test.phase>
  </properties>
  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.cargo</groupId>
        <artifactId>cargo-maven2-plugin</artifactId>
        <version>1.0</version>
        <configuration>
          <wait>false</wait>
          <container>
            <containerId>jetty6x</containerId>
            <type>embedded</type>
          </container>
          <configuration>
           <properties>
             <cargo.servlet.port>8080</cargo.servlet.port>
             <cargo.logging>medium</cargo.logging>
            </properties>
          </configuration>
          <deployer>
            <deployables>
              <deployable>
                <groupId>myapp</groupId>
                <artifactId>myapp</artifactId>
                <type>war</type>
                <properties>
                  <context>/myapp</context>
                </properties>
              </deployable>
            </deployables>
          </deployer>
        </configuration>
        <executions>
          <execution>
            <id>start-container</id>
            <phase>pre-integration-test</phase>
            <goals>
              <goal>start</goal>
            </goals>
          </execution>
          <execution>
            <id>stop-container</id>
            <phase>post-integration-test</phase>
            <goals>
              <goal>stop</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

Pascal Thivent 2010-03-29 22:34:52

Without goal 'deploy-deploy' the application will be NOT deployed. I had class loader problems with Apache commons logging. Finally I switched to jetty-maven-plugin.

amra 2010-04-02 16:41:06

@amra Weird, it DOES work for me without `deploy-deploy` (I tested this before posting).

Pascal Thivent 2010-04-02 16:55:32

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Using maven and embedded jetty: ClassCastException

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