Self ordering WebApp Configurations

apache-jstl/src/test/java/org/eclipse/jetty/jstl/JstlTest.java

@@ -27,6 +27,7 @@ import java.net.URI;
 
 import javax.servlet.jsp.JspException;
 
+import org.eclipse.jetty.annotations.AnnotationConfiguration;
 import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.server.ServerConnector;
 import org.eclipse.jetty.toolchain.test.FS;
@@ -63,15 +64,7 @@ public class JstlTest
         File testTagLibDir = MavenTestingUtils.getProjectDir("src/test/taglibjar");
         JAR.create(testTagLibDir,new File(libDir, "testtaglib.jar"));
         
-        // Configure WebAppContext
+        // Configure WebAppCont
- 
-        Configuration.ClassList classlist = Configuration.ClassList
-                .setServerDefault(server);
-
-        classlist.addBefore(
-                "org.eclipse.jetty.webapp.JettyWebXmlConfiguration",
-                "org.eclipse.jetty.annotations.AnnotationConfiguration");
-        
         WebAppContext context = new WebAppContext();
         context.setContextPath("/");
         
@@ -79,6 +72,9 @@ public class JstlTest
         FS.ensureEmpty(scratchDir);
         JspConfig.init(context,testWebAppDir.toURI(),scratchDir);
         
+        context.addConfiguration(new AnnotationConfiguration());
+        
+        
         server.setHandler(context);
         
         // Start Server

examples/embedded/src/main/java/org/eclipse/jetty/embedded/LikeJettyXml.java

@@ -176,10 +176,7 @@ public class LikeJettyXml
         server.addBean(deployer);
         
         // === setup jetty plus ==
-        Configuration.ClassList.setServerDefault(server).addAfter(
+        Configuration.ClassList.setServerDefault(server).addIfAbsent("org.eclipse.jetty.plus.webapp.EnvConfiguration","org.eclipse.jetty.plus.webapp.PlusConfiguration");
-                "org.eclipse.jetty.webapp.FragmentConfiguration",
-                "org.eclipse.jetty.plus.webapp.EnvConfiguration",
-                "org.eclipse.jetty.plus.webapp.PlusConfiguration");
 
         // === jetty-stats.xml ===
         StatisticsHandler stats = new StatisticsHandler();

examples/embedded/src/main/java/org/eclipse/jetty/embedded/OneWebAppWithJsp.java

@@ -21,10 +21,10 @@ package org.eclipse.jetty.embedded;
 import java.io.File;
 import java.lang.management.ManagementFactory;
 
+import org.eclipse.jetty.annotations.AnnotationConfiguration;
 import org.eclipse.jetty.jmx.MBeanContainer;
 import org.eclipse.jetty.security.HashLoginService;
 import org.eclipse.jetty.server.Server;
-import org.eclipse.jetty.webapp.Configuration;
 import org.eclipse.jetty.webapp.WebAppContext;
 
 public class OneWebAppWithJsp
@@ -64,14 +64,11 @@ public class OneWebAppWithJsp
         webapp.setWar( warFile.getAbsolutePath() );
         webapp.setExtractWAR(true);
 
+        
         // This webapp will use jsps and jstl. We need to enable the
         // AnnotationConfiguration in order to correctly
         // set up the jsp container
-        Configuration.ClassList classlist = Configuration.ClassList
+        webapp.addConfiguration(new AnnotationConfiguration());
-                .setServerDefault( server );
-        classlist.addBefore(
-                "org.eclipse.jetty.webapp.JettyWebXmlConfiguration",
-                "org.eclipse.jetty.annotations.AnnotationConfiguration" );
 
         // Set the ContainerIncludeJarPattern so that jetty examines these
         // container-path jars for tlds, web-fragments etc.

examples/embedded/src/main/java/org/eclipse/jetty/embedded/ServerWithAnnotations.java

@@ -20,12 +20,14 @@ package org.eclipse.jetty.embedded;
 
 import java.io.File;
 
+import org.eclipse.jetty.annotations.AnnotationConfiguration;
 import org.eclipse.jetty.plus.jndi.EnvEntry;
 import org.eclipse.jetty.plus.jndi.Resource;
 import org.eclipse.jetty.plus.jndi.Transaction;
+import org.eclipse.jetty.plus.webapp.EnvConfiguration;
+import org.eclipse.jetty.plus.webapp.PlusConfiguration;
 import org.eclipse.jetty.security.HashLoginService;
 import org.eclipse.jetty.server.Server;
-import org.eclipse.jetty.webapp.Configuration;
 import org.eclipse.jetty.webapp.WebAppContext;
 
 /**
@@ -38,18 +40,13 @@ public class ServerWithAnnotations
         // Create the server
         Server server = new Server(8080);
 
-        // Enable parsing of jndi-related parts of web.xml and jetty-env.xml
-        Configuration.ClassList classlist = Configuration.ClassList
-                .setServerDefault(server);
-        classlist.addAfter("org.eclipse.jetty.webapp.FragmentConfiguration",
-                "org.eclipse.jetty.plus.webapp.EnvConfiguration",
-                "org.eclipse.jetty.plus.webapp.PlusConfiguration");
-        classlist.addBefore(
-                "org.eclipse.jetty.webapp.JettyWebXmlConfiguration",
-                "org.eclipse.jetty.annotations.AnnotationConfiguration");
 
         // Create a WebApp
         WebAppContext webapp = new WebAppContext();
+        
+        // Enable parsing of jndi-related parts of web.xml and jetty-env.xml
+        webapp.addConfiguration(new EnvConfiguration(),new PlusConfiguration(),new AnnotationConfiguration());
+        
         webapp.setContextPath("/");
         File warFile = new File(
                 "../../jetty-distribution/target/distribution/demo-base/webapps/test.war");

examples/embedded/src/main/java/org/eclipse/jetty/embedded/ServerWithJNDI.java

@@ -21,8 +21,9 @@ package org.eclipse.jetty.embedded;
 import java.io.File;
 import java.util.Properties;
 
+import org.eclipse.jetty.plus.webapp.EnvConfiguration;
+import org.eclipse.jetty.plus.webapp.PlusConfiguration;
 import org.eclipse.jetty.server.Server;
-import org.eclipse.jetty.webapp.Configuration;
 import org.eclipse.jetty.webapp.WebAppContext;
 
 /**
@@ -36,20 +37,16 @@ public class ServerWithJNDI
         // Create the server
         Server server = new Server(8080);
 
-        // Enable parsing of jndi-related parts of web.xml and jetty-env.xml
-        Configuration.ClassList classlist = Configuration.ClassList
-                .setServerDefault(server);
-        classlist.addAfter("org.eclipse.jetty.webapp.FragmentConfiguration",
-                "org.eclipse.jetty.plus.webapp.EnvConfiguration",
-                "org.eclipse.jetty.plus.webapp.PlusConfiguration");
-
         // Create a WebApp
         WebAppContext webapp = new WebAppContext();
         webapp.setContextPath("/");
         File warFile = new File(
                 "../../jetty-distribution/target/distribution/demo-base/webapps/test.war");
         webapp.setWar(warFile.getAbsolutePath());
-        server.setHandler(webapp);
+        server.setHandler(webapp);        
+
+        // Enable parsing of jndi-related parts of web.xml and jetty-env.xml
+        webapp.addConfiguration(new EnvConfiguration(),new PlusConfiguration());
 
         // Register new transaction manager in JNDI
         // At runtime, the webapp accesses this as java:comp/UserTransaction

jetty-annotations/src/main/config/etc/jetty-annotations.xml

@@ -7,8 +7,7 @@
   <!-- =========================================================== -->
   <Call class="org.eclipse.jetty.webapp.Configuration$ClassList" name="setServerDefault">
     <Arg><Ref refid="Server" /></Arg>
-    <Call name="addBefore">
+    <Call name="addIfAbsent">
-      <Arg name="beforeClass">org.eclipse.jetty.webapp.JettyWebXmlConfiguration</Arg>
       <Arg>
         <Array type="String">
           <Item>org.eclipse.jetty.annotations.AnnotationConfiguration</Item>

jetty-annotations/src/main/java/org/eclipse/jetty/annotations/AnnotationConfiguration.java

@@ -45,6 +45,7 @@ import javax.servlet.annotation.HandlesTypes;
 
 import org.eclipse.jetty.annotations.AnnotationParser.Handler;
 import org.eclipse.jetty.plus.annotation.ContainerInitializer;
+import org.eclipse.jetty.plus.webapp.PlusConfiguration;
 import org.eclipse.jetty.util.ConcurrentHashSet;
 import org.eclipse.jetty.util.MultiException;
 import org.eclipse.jetty.util.StringUtil;
@@ -53,10 +54,14 @@ import org.eclipse.jetty.util.log.Logger;
 import org.eclipse.jetty.util.resource.Resource;
 import org.eclipse.jetty.util.statistic.CounterStatistic;
 import org.eclipse.jetty.webapp.AbstractConfiguration;
+import org.eclipse.jetty.webapp.FragmentConfiguration;
 import org.eclipse.jetty.webapp.FragmentDescriptor;
+import org.eclipse.jetty.webapp.JettyWebXmlConfiguration;
 import org.eclipse.jetty.webapp.MetaDataComplete;
+import org.eclipse.jetty.webapp.MetaInfConfiguration;
 import org.eclipse.jetty.webapp.WebAppContext;
 import org.eclipse.jetty.webapp.WebDescriptor;
+import org.eclipse.jetty.webapp.WebXmlConfiguration;
 
 /**
  * Configuration for Annotations
@@ -89,6 +94,14 @@ public class AnnotationConfiguration extends AbstractConfiguration
     protected CounterStatistic _webInfClassesStats;
     protected Pattern _sciExcludePattern;
     protected ServiceLoader<ServletContainerInitializer> _loadedInitializers = null;
+    
+
+    public AnnotationConfiguration()
+    {
+        super(new String[]{WebXmlConfiguration.class.getName(),MetaInfConfiguration.class.getName(),FragmentConfiguration.class.getName(),PlusConfiguration.class.getName()},
+              new String[]{JettyWebXmlConfiguration.class.getName()});
+    }
+    
     /**
      * TimeStatistic
      *

jetty-ant/src/main/java/org/eclipse/jetty/ant/AntWebInfConfiguration.java

@@ -37,6 +37,12 @@ import org.eclipse.jetty.webapp.WebXmlConfiguration;
 public class AntWebInfConfiguration extends WebInfConfiguration
 {
 
+    @Override
+    public String getName()
+    {
+        return WebInfConfiguration.class.getName();
+    }
+    
     
     @Override
     public void preConfigure(final WebAppContext context) throws Exception

jetty-ant/src/main/java/org/eclipse/jetty/ant/AntWebXmlConfiguration.java

@@ -23,6 +23,7 @@ import java.util.List;
 
 import org.eclipse.jetty.util.log.Log;
 import org.eclipse.jetty.util.log.Logger;
+import org.eclipse.jetty.webapp.WebInfConfiguration;
 import org.eclipse.jetty.webapp.WebXmlConfiguration;
 
 
@@ -36,8 +37,6 @@ public class AntWebXmlConfiguration extends WebXmlConfiguration
 {
     private static final Logger LOG = Log.getLogger(WebXmlConfiguration.class);
 
-
-
     /** List of classpath files. */
     private List classPathFiles;
 
@@ -50,6 +49,12 @@ public class AntWebXmlConfiguration extends WebXmlConfiguration
         super();
     }
 
+    @Override
+    public String getName()
+    {
+        return WebXmlConfiguration.class.getName();
+    }
+    
     public void setClassPathFiles(List classPathFiles)
     {
         this.classPathFiles = classPathFiles;

jetty-maven-plugin/src/main/java/org/eclipse/jetty/maven/plugin/JettyWebAppContext.java

@@ -400,17 +400,24 @@ public class JettyWebAppContext extends WebAppContext
     
     
     @Override
-    protected void loadConfigurations() throws Exception
+    protected void loadConfigurations()
     {
         super.loadConfigurations();
         
-        //inject configurations with config from maven plugin    
+        try
-        for (Configuration c:getConfigurations())
         {
-            if (c instanceof EnvConfiguration && getJettyEnvXml() != null)
+            //inject configurations with config from maven plugin    
-                ((EnvConfiguration)c).setJettyEnvXml(Resource.toURL(new File(getJettyEnvXml())));
+            for (Configuration c:getConfigurations())
-            else if (c instanceof MavenQuickStartConfiguration && getQuickStartWebDescriptor() != null)
+            {
-                ((MavenQuickStartConfiguration)c).setQuickStartWebXml(getQuickStartWebDescriptor());         
+                if (c instanceof EnvConfiguration && getJettyEnvXml() != null)
+                    ((EnvConfiguration)c).setJettyEnvXml(Resource.toURL(new File(getJettyEnvXml())));
+                else if (c instanceof MavenQuickStartConfiguration && getQuickStartWebDescriptor() != null)
+                    ((MavenQuickStartConfiguration)c).setQuickStartWebXml(getQuickStartWebDescriptor());         
+            }
+        }
+        catch(Exception e)
+        {
+            throw new RuntimeException(e);
         }
     }
 

jetty-maven-plugin/src/main/java/org/eclipse/jetty/maven/plugin/MavenQuickStartConfiguration.java

@@ -42,7 +42,7 @@ public class MavenQuickStartConfiguration extends QuickStartConfiguration
     
     private Resource _quickStartWebXml;
 
-
+    
     public void setQuickStartWebXml (Resource r)
     {
         _quickStartWebXml = r;

jetty-maven-plugin/src/main/java/org/eclipse/jetty/maven/plugin/MavenWebInfConfiguration.java

@@ -50,6 +50,12 @@ public class MavenWebInfConfiguration extends WebInfConfiguration
     protected static int COUNTER = 0; 
     protected Resource _originalResourceBase;
     protected List<Resource>  _unpackedOverlayResources;
+
+    @Override
+    public String getName()
+    {
+        return WebInfConfiguration.class.getName();
+    }
     
     /** 
      * @see org.eclipse.jetty.webapp.WebInfConfiguration#configure(org.eclipse.jetty.webapp.WebAppContext)

jetty-osgi/jetty-osgi-boot/src/main/java/org/eclipse/jetty/osgi/boot/AbstractWebAppProvider.java

@@ -24,12 +24,15 @@ import java.util.Dictionary;
 import java.util.Enumeration;
 import java.util.HashMap;
 
+import org.eclipse.jetty.annotations.AnnotationConfiguration;
 import org.eclipse.jetty.deploy.App;
 import org.eclipse.jetty.deploy.AppProvider;
 import org.eclipse.jetty.deploy.DeploymentManager;
 import org.eclipse.jetty.osgi.boot.internal.serverfactory.ServerInstanceWrapper;
 import org.eclipse.jetty.osgi.boot.internal.webapp.OSGiWebappClassLoader;
 import org.eclipse.jetty.osgi.boot.utils.BundleFileLocatorHelperFactory;
+import org.eclipse.jetty.plus.webapp.EnvConfiguration;
+import org.eclipse.jetty.plus.webapp.PlusConfiguration;
 import org.eclipse.jetty.server.handler.ContextHandler;
 import org.eclipse.jetty.util.Loader;
 import org.eclipse.jetty.util.component.AbstractLifeCycle;
@@ -584,14 +587,13 @@ public abstract class AbstractWebAppProvider extends AbstractLifeCycle implement
 
         //add before JettyWebXmlConfiguration
         if (annotationsAvailable())
-            defaults.addBefore("org.eclipse.jetty.webapp.JettyWebXmlConfiguration", 
+            defaults.addIfAbsent(AnnotationConfiguration.class.getName());
-                               "org.eclipse.jetty.osgi.annotations.AnnotationConfiguration");
 
         //add in EnvConfiguration and PlusConfiguration just after FragmentConfiguration
         if (jndiAvailable())
-            defaults.addAfter("org.eclipse.jetty.webapp.FragmentConfiguration",
+            defaults.addIfAbsent(
-                              "org.eclipse.jetty.plus.webapp.EnvConfiguration",
+                    EnvConfiguration.class.getName(),
-                              "org.eclipse.jetty.plus.webapp.PlusConfiguration");
+                    PlusConfiguration.class.getName());
        String[] asArray = new String[defaults.size()];
        return defaults.toArray(asArray);
     }

jetty-osgi/jetty-osgi-boot/src/main/java/org/eclipse/jetty/osgi/boot/OSGiWebInfConfiguration.java

@@ -65,6 +65,11 @@ public class OSGiWebInfConfiguration extends WebInfConfiguration
     public static final String FRAGMENT_AND_REQUIRED_BUNDLES = "org.eclipse.jetty.osgi.fragmentAndRequiredBundles";
     public static final String FRAGMENT_AND_REQUIRED_RESOURCES = "org.eclipse.jetty.osgi.fragmentAndRequiredResources";
     
+    @Override
+    public String getName()
+    {
+        return WebInfConfiguration.class.getName();
+    }
     
     /* ------------------------------------------------------------ */
     /** 

jetty-plus/src/main/config/etc/jetty-plus.xml

@@ -11,8 +11,7 @@
   <!-- =========================================================== -->
   <Call class="org.eclipse.jetty.webapp.Configuration$ClassList" name="setServerDefault">
     <Arg><Ref refid="Server" /></Arg>
-    <Call name="addAfter">
+    <Call name="addIfAbsent">
-      <Arg name="afterClass">org.eclipse.jetty.webapp.FragmentConfiguration</Arg>
       <Arg>
         <Array type="String">
           <Item>org.eclipse.jetty.plus.webapp.EnvConfiguration</Item>

jetty-plus/src/main/java/org/eclipse/jetty/plus/webapp/EnvConfiguration.java

@@ -41,8 +41,12 @@ import org.eclipse.jetty.util.log.Log;
 import org.eclipse.jetty.util.log.Logger;
 import org.eclipse.jetty.webapp.AbstractConfiguration;
 import org.eclipse.jetty.webapp.Configuration;
+import org.eclipse.jetty.webapp.FragmentConfiguration;
+import org.eclipse.jetty.webapp.JettyWebXmlConfiguration;
+import org.eclipse.jetty.webapp.MetaInfConfiguration;
 import org.eclipse.jetty.webapp.WebAppClassLoader;
 import org.eclipse.jetty.webapp.WebAppContext;
+import org.eclipse.jetty.webapp.WebXmlConfiguration;
 import org.eclipse.jetty.xml.XmlConfiguration;
 
 
@@ -56,6 +60,12 @@ public class EnvConfiguration extends AbstractConfiguration
     private static final String JETTY_ENV_BINDINGS = "org.eclipse.jetty.jndi.EnvConfiguration";
     private URL jettyEnvXmlUrl;
 
+    public EnvConfiguration()
+    {
+        super(new String[]{WebXmlConfiguration.class.getName(),MetaInfConfiguration.class.getName(),FragmentConfiguration.class.getName()},
+              new String[]{PlusConfiguration.class.getName(),JettyWebXmlConfiguration.class.getName()});
+    }    
+    
     public void setJettyEnvXml (URL url)
     {
         this.jettyEnvXmlUrl = url;

jetty-plus/src/main/java/org/eclipse/jetty/plus/webapp/PlusConfiguration.java

@@ -30,7 +30,11 @@ import org.eclipse.jetty.plus.jndi.Transaction;
 import org.eclipse.jetty.util.log.Log;
 import org.eclipse.jetty.util.log.Logger;
 import org.eclipse.jetty.webapp.AbstractConfiguration;
+import org.eclipse.jetty.webapp.FragmentConfiguration;
+import org.eclipse.jetty.webapp.JettyWebXmlConfiguration;
+import org.eclipse.jetty.webapp.MetaInfConfiguration;
 import org.eclipse.jetty.webapp.WebAppContext;
+import org.eclipse.jetty.webapp.WebXmlConfiguration;
 
 
 /**
@@ -44,6 +48,12 @@ public class PlusConfiguration extends AbstractConfiguration
 
     private Integer _key;
 
+    public PlusConfiguration()
+    {
+        super(new String[]{EnvConfiguration.class.getName(),WebXmlConfiguration.class.getName(),MetaInfConfiguration.class.getName(),FragmentConfiguration.class.getName()},
+              new String[]{JettyWebXmlConfiguration.class.getName()});
+    }    
+    
     @Override
     public void preConfigure (WebAppContext context)
     throws Exception

jetty-quickstart/src/main/java/org/eclipse/jetty/quickstart/QuickStartConfiguration.java

@@ -39,6 +39,12 @@ public class QuickStartConfiguration extends WebInfConfiguration
 {
     private static final Logger LOG = Log.getLogger(QuickStartConfiguration.class);
 
+    @Override
+    public String getName()
+    {
+        return WebInfConfiguration.class.getName();
+    }
+    
     /**
      * @see org.eclipse.jetty.webapp.AbstractConfiguration#preConfigure(org.eclipse.jetty.webapp.WebAppContext)
      */

jetty-util/src/main/java/org/eclipse/jetty/util/TopologicalSort.java

@@ -49,12 +49,13 @@ public class TopologicalSort<T>
 {
     private final Map<T,Set<T>> _dependencies = new HashMap<>();
 
+    
     /**
      * Add a dependency to be considered in the sort.
      * @param dependent The dependent item will be sorted after all its dependencies
      * @param dependency The dependency item, will be sorted before its dependent item
      */
-    public void addDependency(T dependent, T dependency)
+    public void addDependency(T dependent, T... dependency)
     {
         Set<T> set = _dependencies.get(dependent);
         if (set==null)
@@ -62,7 +63,20 @@ public class TopologicalSort<T>
             set=new HashSet<>();
             _dependencies.put(dependent,set);
         }
-        set.add(dependency);
+        for (T d:dependency)
+            set.add(d);
+    }
+    
+    /** 
+     * An alternative to {@link #addDependency(Object, Object)}, which is
+     * equivalent to addDependency(after,before) as the after item is dependent
+     * of the before item.
+     * @param before The item will be sorted before the after
+     * @param after The item will be sorted after the before
+     */
+    public void addBeforeAfter(T before, T after)
+    {
+        addDependency(after,before);
     }
     
     /** Sort the passed array according to dependencies previously set with

jetty-webapp/src/main/java/org/eclipse/jetty/webapp/AbstractConfiguration.java

@@ -18,8 +18,52 @@
 
 package org.eclipse.jetty.webapp;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
 public class AbstractConfiguration implements Configuration
 {
+    private final List<String> _after;
+    private final List<String> _before;
+    
+    protected AbstractConfiguration()
+    {
+        _after=Collections.emptyList();
+        _before=Collections.emptyList();
+    }
+
+    protected AbstractConfiguration(String[] before,String[] after)
+    {
+        _after=Collections.unmodifiableList(after==null?Collections.emptyList():Arrays.asList(after));
+        _before=Collections.unmodifiableList(before==null?Collections.emptyList():Arrays.asList(before));
+    }
+    
+    protected AbstractConfiguration(List<String> after,List<String> before)
+    {
+        _after=Collections.unmodifiableList(after==null?Collections.emptyList():new ArrayList<>(after));
+        _before=Collections.unmodifiableList(before==null?Collections.emptyList():new ArrayList<>(before));
+    }
+    
+    @Override
+    public String getName()
+    {
+        return this.getClass().getName();
+    }
+
+    @Override
+    public List<String> getAfterThis()
+    {
+        return _after;
+    }
+
+    @Override
+    public List<String> getBeforeThis()
+    {
+        return _before;
+    }
+
     public void preConfigure(WebAppContext context) throws Exception
     {
     }

jetty-webapp/src/main/java/org/eclipse/jetty/webapp/Configuration.java

@@ -20,13 +20,18 @@ package org.eclipse.jetty.webapp;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.ListIterator;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
 
 import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.util.Loader;
+import org.eclipse.jetty.util.TopologicalSort;
 import org.eclipse.jetty.util.annotation.Name;
 
-
 /* ------------------------------------------------------------------------------- */
 /** Base Class for WebApplicationContext Configuration.
  * This class can be extended to customize or extend the configuration
@@ -35,6 +40,26 @@ import org.eclipse.jetty.util.annotation.Name;
 public interface Configuration 
 {
     public final static String ATTR="org.eclipse.jetty.webapp.configuration";
+
+    /* ------------------------------------------------------------------------------- */
+    /** Get the name of the configuration used for a {@link TopologicalSort}
+     * @return The name of the Configuration (defaults to classname)
+     */
+    public default String getName() { return this.getClass().getName(); } 
+
+    /* ------------------------------------------------------------------------------- */
+    /** Get known Configuration Dependencies.
+     * @return The names of Configurations that {@link TopologicalSort} must order 
+     * before this configuration.
+     */
+    public default List<String> getBeforeThis() { return Collections.emptyList(); }
+
+    /* ------------------------------------------------------------------------------- */
+    /** Get known Configuration Dependents.
+     * @return The names of Configurations that {@link TopologicalSort} must order 
+     * after this configuration.
+     */
+    public default List<String> getAfterThis(){ return Collections.emptyList(); }
     
     /* ------------------------------------------------------------------------------- */
     /** Set up for configuration.
@@ -94,9 +119,10 @@ public interface Configuration
      */
     public void cloneConfigure (WebAppContext template, WebAppContext context) throws Exception;
     
-    
+    public class ClassList 
-    public class ClassList extends ArrayList<String>
     {        
+        List<Configuration> _instances = new ArrayList<>();
+        
         /* ------------------------------------------------------------ */
         /** Get/Set/Create the server default Configuration ClassList.
          * <p>Get the class list from: a Server bean; or the attribute (which can
@@ -107,14 +133,14 @@ public interface Configuration
          * @param server The server the default is for
          * @return the server default ClassList instance of the configuration classes for this server. Changes to this list will change the server default instance.
          */
-        public static ClassList setServerDefault(Server server)
+        public static ClassList setServerDefault(Server server) throws ClassNotFoundException, InstantiationException, IllegalAccessException
         {
             ClassList cl=server.getBean(ClassList.class);
             if (cl!=null)
                 return cl;
             cl=serverDefault(server);
             server.addBean(cl);
-            server.setAttribute(ATTR,null);
+            server.setAttribute(Configuration.ATTR,null);
             return cl;
         }
 
@@ -134,7 +160,7 @@ public interface Configuration
                 cl= server.getBean(ClassList.class);
                 if (cl!=null)
                     return new ClassList(cl);
-                Object attr = server.getAttribute(ATTR);
+                Object attr = server.getAttribute(Configuration.ATTR);
                 if (attr instanceof ClassList)
                     return new ClassList((ClassList)attr);
                 if (attr instanceof String[])
@@ -148,28 +174,78 @@ public interface Configuration
             this(WebAppContext.DEFAULT_CONFIGURATION_CLASSES);
         }
         
+        private Configuration newConfiguration(String classname)
+        {
+            try
+            {
+                Class<Configuration> clazz = Loader.loadClass(classname);
+                return clazz.newInstance();
+            }
+            catch (ClassNotFoundException | InstantiationException | IllegalAccessException e)
+            {
+                throw new RuntimeException(e);
+            }
+        }
+        
         public ClassList(String[] classes)
         {
-            addAll(Arrays.asList(classes));
+            for (String c:classes)
+                _instances.add(newConfiguration(c));
         }
 
         public ClassList(List<String> classes)
         {
-            addAll(classes);
+            for (String c:classes)
+                _instances.add(newConfiguration(c));
+        }
+
+        public ClassList(Configuration.ClassList classlist)
+        {
+            _instances.addAll(classlist._instances);
+        }
+
+        public void add(@Name("configClass")String... configClass)
+        {
+            loop: for (String c : configClass)
+            {
+                Configuration configuration = newConfiguration(c);
+                ListIterator<Configuration> i = _instances.listIterator();
+                while(i.hasNext())
+                {
+                    Configuration next = i.next();
+                    if (next.getName().equals(configuration.getName()))
+                    {
+                        i.set(configuration);
+                        continue loop;
+                    }
+                }
+                _instances.add(configuration);
+            }
+        }
+        
+        public void addIfAbsent(@Name("configClass")String... configClass)
+        {
+            for (String c : configClass)
+            {
+                Configuration configuration = newConfiguration(c);
+                
+                if (!_instances.stream().map(i->{return i.getName();}).anyMatch(n->{return configuration.getName().equals(n);}))
+                    _instances.add(configuration);
+            }
         }
         
         public void addAfter(@Name("afterClass") String afterClass,@Name("configClass")String... configClass)
         {
             if (configClass!=null && afterClass!=null)
             {
-                ListIterator<String> iter = listIterator();
+                ListIterator<Configuration> iter = _instances.listIterator();
                 while (iter.hasNext())
                 {
-                    String cc=iter.next();
+                    Configuration c=iter.next();
-                    if (afterClass.equals(cc))
+                    if (afterClass.equals(c.getClass().getName()) || afterClass.equals(c.getName()))
                     {
-                        for (int i=0;i<configClass.length;i++)
+                        for (String cc: configClass)
-                            iter.add(configClass[i]);
+                            iter.add(newConfiguration(cc));
                         return;
                     }
                 }
@@ -181,21 +257,42 @@ public interface Configuration
         {
             if (configClass!=null && beforeClass!=null)
             {
-                ListIterator<String> iter = listIterator();
+                ListIterator<Configuration> iter = _instances.listIterator();
                 while (iter.hasNext())
                 {
-                    String cc=iter.next();
+                    Configuration c=iter.next();
-                    if (beforeClass.equals(cc))
+                    if (beforeClass.equals(c.getClass().getName()) || beforeClass.equals(c.getName()))
                     {
                         iter.previous();
-                        for (int i=0;i<configClass.length;i++)
+                        for (String cc: configClass)
-                            iter.add(configClass[i]);
+                            iter.add(newConfiguration(cc));
                         return;
                     }
                 }
             }
+            
             throw new IllegalArgumentException("beforeClass '"+beforeClass+"' not found in "+this);
         }
-        
+
+        public int size()
+        {
+            return _instances.size();
+        }
+
+        public String[] toArray(String[] asArray)
+        {
+            return _instances.stream().map(i->{return i.getClass().getName();}).toArray(n->{return new String[n];});
+        }
+
+        public List<Configuration> getConfigurations()
+        {
+            return _instances.stream().map(i->{return newConfiguration(i.getClass().getName());}).collect(Collectors.toList());
+        }
+     
+        @Override
+        public String toString()
+        {
+            return getConfigurations().toString();
+        }
     }
 }

jetty-webapp/src/main/java/org/eclipse/jetty/webapp/FragmentConfiguration.java

@@ -31,6 +31,11 @@ import org.eclipse.jetty.util.resource.Resource;
 public class FragmentConfiguration extends AbstractConfiguration
 {
     public final static String FRAGMENT_RESOURCES="org.eclipse.jetty.webFragments";
+
+    public FragmentConfiguration()
+    {
+        super(new String[]{MetaInfConfiguration.class.getName()},null);
+    }
     
     @Override
     public void preConfigure(WebAppContext context) throws Exception
@@ -40,7 +45,6 @@ public class FragmentConfiguration extends AbstractConfiguration
 
         //find all web-fragment.xmls
         findWebFragments(context, context.getMetaData());
-        
     }
 
 

jetty-webapp/src/main/java/org/eclipse/jetty/webapp/JettyWebXmlConfiguration.java

@@ -48,6 +48,13 @@ public class JettyWebXmlConfiguration extends AbstractConfiguration
     public static final String XML_CONFIGURATION = "org.eclipse.jetty.webapp.JettyWebXmlConfiguration";
     public static final String JETTY_WEB_XML = "jetty-web.xml";
 
+
+    public JettyWebXmlConfiguration()
+    {
+        super(new String[]{WebXmlConfiguration.class.getName(),FragmentConfiguration.class.getName(),MetaInfConfiguration.class.getName()},null);
+    }
+    
+    
     /**
      * Configure
      * Apply web-jetty.xml configuration

jetty-webapp/src/main/java/org/eclipse/jetty/webapp/MetaInfConfiguration.java

@@ -70,6 +70,12 @@ public class MetaInfConfiguration extends AbstractConfiguration
     public static final String METAINF_FRAGMENTS = FragmentConfiguration.FRAGMENT_RESOURCES;
     public static final String METAINF_RESOURCES = WebInfConfiguration.RESOURCE_DIRS;
 
+    /* ------------------------------------------------------------------------------- */
+    public MetaInfConfiguration()
+    {
+        super(new String[]{WebXmlConfiguration.class.getName()},null);
+    }
+
     @Override
     public void preConfigure(final WebAppContext context) throws Exception
     {        

jetty-webapp/src/main/java/org/eclipse/jetty/webapp/WebAppContext.java

@@ -35,6 +35,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import javax.management.RuntimeErrorException;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletRegistration.Dynamic;
 import javax.servlet.ServletSecurityElement;
@@ -61,6 +62,7 @@ import org.eclipse.jetty.servlet.ServletHandler;
 import org.eclipse.jetty.util.AttributesMap;
 import org.eclipse.jetty.util.Loader;
 import org.eclipse.jetty.util.MultiException;
+import org.eclipse.jetty.util.TopologicalSort;
 import org.eclipse.jetty.util.URIUtil;
 import org.eclipse.jetty.util.annotation.ManagedAttribute;
 import org.eclipse.jetty.util.annotation.ManagedObject;
@@ -96,13 +98,16 @@ public class WebAppContext extends ServletContextHandler implements WebAppClassL
 
     private String[] __dftProtectedTargets = {"/web-inf", "/meta-inf"};
 
+    /* default configurations.
+     * Order is determined by Topological sort in preconfigure
+     */
     public static final String[] DEFAULT_CONFIGURATION_CLASSES =
     {
         "org.eclipse.jetty.webapp.WebInfConfiguration",
         "org.eclipse.jetty.webapp.WebXmlConfiguration",
         "org.eclipse.jetty.webapp.MetaInfConfiguration",
         "org.eclipse.jetty.webapp.FragmentConfiguration",
-        "org.eclipse.jetty.webapp.JettyWebXmlConfiguration"
+        "org.eclipse.jetty.webapp.JettyWebXmlConfiguration",
     } ;
 
     // System classes are classes that cannot be replaced by
@@ -289,7 +294,6 @@ public class WebAppContext extends ServletContextHandler implements WebAppClassL
         return _unavailableException;
     }
 
-
     /* ------------------------------------------------------------ */
     /** 
      * Set Resource Alias.
@@ -447,6 +451,30 @@ public class WebAppContext extends ServletContextHandler implements WebAppClassL
         // Setup configurations
         loadConfigurations();
 
+        // Sort the configurations
+        Map<String,Configuration> map = new HashMap<>();
+        TopologicalSort<Configuration> sort = new TopologicalSort<>();
+        for (Configuration c:_configurations)
+            map.put(c.getName(),c);
+        for (Configuration c:_configurations)
+        {
+            for (String b:c.getBeforeThis())
+            {
+                Configuration before=map.get(b);
+                if (before!=null)
+                    sort.addBeforeAfter(before,c);
+            }
+            for (String a:c.getAfterThis())
+            {
+                Configuration after=map.get(a);
+                if (after!=null)
+                    sort.addBeforeAfter(c,after);
+            }
+        }
+        sort.sort(_configurations);
+        if (LOG.isDebugEnabled())
+            LOG.debug("sorted {}",_configurations);
+        
         // Setup system classes
         loadSystemClasses();
 
@@ -790,7 +818,7 @@ public class WebAppContext extends ServletContextHandler implements WebAppClassL
     }
 
     /* ------------------------------------------------------------ */
-    private void loadServerClasses()
+    protected void loadServerClasses()
     {
         if (_serverClasses != null)
         {
@@ -916,16 +944,27 @@ public class WebAppContext extends ServletContextHandler implements WebAppClassL
 
     /* ------------------------------------------------------------ */
     protected void loadConfigurations()
-        throws Exception
     {
         //if the configuration instances have been set explicitly, use them
         if (_configurations.size()>0)
             return;
         
         if (_configurationClasses.size()==0)
-            _configurationClasses.addAll(Configuration.ClassList.serverDefault(getServer()));
+        {
-        for (String configClass : _configurationClasses)
+            _configurations.addAll(Configuration.ClassList.serverDefault(getServer()).getConfigurations());
-            _configurations.add((Configuration)Loader.loadClass(configClass).newInstance());
+        }
+        else
+        {
+            try
+            {
+                for (String configClass : _configurationClasses)
+                    _configurations.add((Configuration)Loader.loadClass(configClass).newInstance());
+            }
+            catch (InstantiationException | IllegalAccessException | ClassNotFoundException e)
+            {
+                throw new RuntimeException(e);
+            }
+        }
     }
 
     /* ------------------------------------------------------------ */
@@ -990,6 +1029,18 @@ public class WebAppContext extends ServletContextHandler implements WebAppClassL
             _configurations.addAll(Arrays.asList(configurations));
     }
 
+
+    /* ------------------------------------------------------------ */
+    public void addConfiguration(Configuration... configuration)
+    {
+        if (isStarted())
+            throw new IllegalStateException();
+        loadConfigurations();
+        for (Configuration c:configuration)
+            _configurations.add(c);
+    }
+
+    
     /* ------------------------------------------------------------ */
     /**
      * The default descriptor is a web.xml format file that is applied to the context before the standard WEB-INF/web.xml
@@ -1541,4 +1592,5 @@ public class WebAppContext extends ServletContextHandler implements WebAppClassL
     {
         return _metadata;
     }
+
 }

jetty-webapp/src/main/java/org/eclipse/jetty/webapp/WebInfConfiguration.java

@@ -60,6 +60,16 @@ public class WebInfConfiguration extends AbstractConfiguration
 
     protected Resource _preUnpackBaseResource;
     
+    public WebInfConfiguration()
+    {
+        super();
+    }
+
+    public WebInfConfiguration(List<String> after, List<String> before)
+    {
+        super(after,before);
+        // TODO Auto-generated constructor stub
+    }
 
 
     @Override

jetty-webapp/src/main/java/org/eclipse/jetty/webapp/WebXmlConfiguration.java

@@ -35,7 +35,13 @@ public class WebXmlConfiguration extends AbstractConfiguration
 {
     private static final Logger LOG = Log.getLogger(WebXmlConfiguration.class);
 
-    
+
+    /* ------------------------------------------------------------------------------- */
+    public WebXmlConfiguration()
+    {
+        super(new String[]{WebInfConfiguration.class.getName()},null);
+    }
+
     /* ------------------------------------------------------------------------------- */
     /**
      * 

jetty-webapp/src/test/java/org/eclipse/jetty/webapp/WebAppContextTest.java

@@ -60,36 +60,6 @@ public class WebAppContextTest
         assertTrue(Arrays.equals(classNames, wac.getConfigurationClasses()));
     }
 
-    @Test
-    public void testConfigurationClassesExplicit ()
-    {
-        String[] classNames = {"x.y.z"};
-
-        Server server = new Server();
-        server.setAttribute(Configuration.ATTR, classNames);
-
-        //test an explicitly set classnames list overrides that from the server
-        WebAppContext wac = new WebAppContext();
-        String[] myClassNames = {"a.b.c", "d.e.f"};
-        wac.setConfigurationClasses(myClassNames);
-        wac.setServer(server);
-        String[] names = wac.getConfigurationClasses();
-        assertTrue(Arrays.equals(myClassNames, names));
-
-
-        //test if no explicit classnames, they come from the server
-        WebAppContext wac2 = new WebAppContext();
-        wac2.setServer(server);
-        try
-        {
-            wac2.loadConfigurations();
-        }
-        catch(Exception e)
-        {
-            Log.getRootLogger().ignore(e);
-        }
-        assertTrue(Arrays.equals(classNames, wac2.getConfigurationClasses()));
-    }
 
     @Test
     public void testConfigurationInstances ()

tests/test-webapps/test-jndi-webapp/src/main/templates/jetty-test-jndi-header.xml

@@ -12,28 +12,6 @@
     </Arg>
   </New>
 
-  <!-- =============================================================== -->
-  <!-- Configure the webapp                                            -->
-  <!-- =============================================================== -->
- <!-- Only uncomment if you are not using etc/jetty-plus.xml from start.ini
-
-  <Set name="configurationClasses">
-    <Call class="org.eclipse.jetty.webapp.Configuration$ClassList" name="serverDefault">
-      <Arg><Ref refid="Server" /></Arg>
-      <Call name="addAfter">
-        <Arg name="afterClass">org.eclipse.jetty.webapp.FragmentConfiguration</Arg>
-        <Arg>
-          <Array type="String">
-            <Item>org.eclipse.jetty.plus.webapp.EnvConfiguration</Item>
-            <Item>org.eclipse.jetty.plus.webapp.PlusConfiguration</Item>
-            <Item>org.eclipse.jetty.annotations.AnnotationConfiguration</Item>
-          </Array>
-        </Arg>
-      </Call>
-    </Call>
-  </Set>
- -->
-
   <Set name="contextPath">/test-jndi</Set>
   <Set name="war"><Property name="jetty.webapps" default="."/>/test-jndi.war</Set>
   <Set name="extractWAR">true</Set>

tests/test-webapps/test-servlet-spec/test-spec-webapp/src/main/templates/annotations-context-header.xml

@@ -14,30 +14,6 @@
     </Arg>
   </New>
 
-
-  <!-- =============================================================== -->
-  <!-- Configure the webapp                                            -->
-  <!-- =============================================================== -->
-  <!-- Only uncomment this if you are not using the plus and 
-       annotations sections of start.ini
-
-  <Set name="configurationClasses">
-    <Call class="org.eclipse.jetty.webapp.Configuration$ClassList" name="serverDefault">
-      <Arg><Ref refid="Server" /></Arg>
-      <Call name="addAfter">
-        <Arg name="afterClass">org.eclipse.jetty.webapp.FragmentConfiguration</Arg>
-        <Arg>
-          <Array type="String">
-            <Item>org.eclipse.jetty.plus.webapp.EnvConfiguration</Item>
-            <Item>org.eclipse.jetty.plus.webapp.PlusConfiguration</Item>
-            <Item>org.eclipse.jetty.annotations.AnnotationConfiguration</Item>
-          </Array>
-        </Arg>
-      </Call>
-    </Call>
-  </Set>
-  -->
-
   <Set name="contextPath">/test-spec</Set>
   <Set name="war"><Property name="jetty.webapps"/>/test-spec.war</Set>
   <Set name="configurationDiscovered">true</Set>