jetty startup errors with signer information errors

Question

Since I've set some maven dependencies to "provided" instead of "compile" scope I got this error when starting up jetty:

• JEE5 application
• should run on WebSphere 7 and Jetty 7
• Spring 3

The error:

java.lang.SecurityException: class "javax.servlet.ServletRequestListener"'s signer information does not match signer information of other classes in the same package
    at java.lang.ClassLoader.checkCerts(ClassLoader.java:806)
    at java.lang.ClassLoader.preDefineClass(ClassLoader.java:487)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:625)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClassFromSelf(ClassRealm.java:386)
    at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:42)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:244)
    at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:230)
    at org.eclipse.jetty.server.handler.ContextHandler.setEventListeners(ContextHandler.java:554)
    at org.eclipse.jetty.webapp.WebAppContext.setEventListeners(WebAppContext.java:946)
    at org.eclipse.jetty.webapp.WebAppContext.addEventListener(WebAppContext.java:972)
    at org.eclipse.jetty.webapp.TagLibConfiguration.preConfigure(TagLibConfiguration.java:492)
    at org.eclipse.jetty.webapp.WebAppContext.preConfigure(WebAppContext.java:418)
    at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:454)
    at org.mortbay.jetty.plugin.JettyWebAppContext.doStart(JettyWebAppContext.java:256)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.server.handler.HandlerCollection.doStart(HandlerCollection.java:224)
    at org.eclipse.jetty.server.handler.ContextHandlerCollection.doStart(ContextHandlerCollection.java:167)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.server.handler.HandlerCollection.doStart(HandlerCollection.java:224)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:90)
    at org.eclipse.jetty.server.Server.doStart(Server.java:260)
    at org.mortbay.jetty.plugin.JettyServer.doStart(JettyServer.java:65)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.mortbay.jetty.plugin.AbstractJettyMojo.startJetty(AbstractJettyMojo.java:511)
    at org.mortbay.jetty.plugin.AbstractJettyMojo.execute(AbstractJettyMojo.java:364)
    at org.mortbay.jetty.plugin.JettyRunMojo.execute(JettyRunMojo.java:516)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:319)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)

The maven section is:

<?xml version="1.0" encoding="UTF-8"?>
<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>

    <packaging>war</packaging>
    <artifactId>myApp.war</artifactId>
    <!--name??-->

    <parent>
        <groupId>com.example</groupId>
        <artifactId>myApp</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <properties>
        <java-version>1.5</java-version>
        <org.springframework-version>3.0.5.RELEASE</org.springframework-version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <org.aspectj-version>1.6.9</org.aspectj-version>
        <org.slf4j-version>1.6.1</org.slf4j-version>
        <cxf.version>2.5.2</cxf.version>
        <jetty.version>7.6.3.v20120416</jetty.version>
        <skipTests>true</skipTests>
        <log4j.version>1.2.15</log4j.version>
    </properties>

    <!-- … -->
             <plugin>
                 <groupId>org.mortbay.jetty</groupId>
                 <artifactId>jetty-maven-plugin</artifactId>
                 <version>${jetty.version}</version>

                 <dependencies>
                     <dependency>
                         <groupId>commons-dbcp</groupId>
                         <artifactId>commons-dbcp</artifactId>
                         <version>1.4</version>
                     </dependency>
                     <dependency>
                         <groupId>commons-logging</groupId>
                         <artifactId>commons-logging</artifactId>
                         <version>1.1</version>
                         <type>jar</type>
                     </dependency>
                 </dependencies>

                 <configuration>
                     <scanIntervalSeconds>5</scanIntervalSeconds>
                     <webAppConfig>
                         <contextPath>/</contextPath>
                     </webAppConfig>
                     <connectors>
                         <connector implementation="org.eclipse.jetty.server.bio.SocketConnector">
                             <port>8080</port>
                             <!-- this connector defaults to 1300 for some reason -->
                         </connector>
                     </connectors>
                     <!--
                     <useProvided>true</useProvided>
                     -->
                 </configuration>
             </plugin>

Can't get the cause. Any hints welcome ;)

Answer 1

It looks as though you are including the servlet API as a provided dependency, and adding this to Jetty's classpath. This is colliding with Jetty's own bundled servlet API classes and causing the exception.

It is absolutely correct to include the servlet API as a provided dependency- the problem is in the <useProvided> parameter in the plugin configuration, which is adding the servlet API to the classpath. It would be better to exclude this, and, if you have any other dependencies with provided scope that aren't already in Jetty, then add them to the plugin dependencies, as you have done with commons-dbcp.

See also the comments in http://jira.codehaus.org/browse/JETTY-429, which discuss similar potential confusions.