diff --git a/src/etc/testcases/taskdefs/dynamictask.xml b/src/etc/testcases/taskdefs/dynamictask.xml
new file mode 100644
index 000000000..63ee19ad5
--- /dev/null
+++ b/src/etc/testcases/taskdefs/dynamictask.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0"?>
+
+<project name="dynamic-test" default="simple">
+
+  <path id="testclasses">
+    <pathelement location="../../../../build/testcases" />
+    <pathelement path="${java.class.path}" />
+  </path>
+
+  <target name="simple">
+    <taskdef name="dyna"
+             classname="org.apache.tools.ant.taskdefs.DynamicTask">
+      <classpath refid="testclasses" />
+    </taskdef>
+    <dyna prop1="1" prop2="2">
+      <sub prop3="3"/>
+      <anything prop4="4"/>
+    </dyna>
+  </target>
+
+</project>
diff --git a/src/main/org/apache/tools/ant/DynamicConfigurator.java b/src/main/org/apache/tools/ant/DynamicConfigurator.java
new file mode 100644
index 000000000..763b7bdcf
--- /dev/null
+++ b/src/main/org/apache/tools/ant/DynamicConfigurator.java
@@ -0,0 +1,67 @@
+/*
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2002 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution, if
+ *    any, must include the following acknowlegement:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowlegement may appear in the software itself,
+ *    if and wherever such third-party acknowlegements normally appear.
+ *
+ * 4. The names "The Jakarta Project", "Ant", and "Apache Software
+ *    Foundation" must not be used to endorse or promote products derived
+ *    from this software without prior written permission. For written
+ *    permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache"
+ *    nor may "Apache" appear in their names without prior written
+ *    permission of the Apache Group.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+
+package org.apache.tools.ant;
+
+/**
+ * Enables a task to control unknown attributes and elements.
+ *
+ * @author Erik Hatcher
+ * @since Ant 1.5
+ */
+public interface DynamicConfigurator {
+    public void setDynamicAttribute(String name, String value);
+
+    public Object createDynamicElement(String name);
+}
diff --git a/src/main/org/apache/tools/ant/IntrospectionHelper.java b/src/main/org/apache/tools/ant/IntrospectionHelper.java
index 971ff79cb..e288d678c 100644
--- a/src/main/org/apache/tools/ant/IntrospectionHelper.java
+++ b/src/main/org/apache/tools/ant/IntrospectionHelper.java
@@ -54,6 +54,7 @@
 
 package org.apache.tools.ant;
 
+import org.apache.tools.ant.DynamicConfigurator;
 import org.apache.tools.ant.types.Path;
 import org.apache.tools.ant.types.EnumeratedAttribute;
 
@@ -405,15 +406,19 @@ public class IntrospectionHelper implements BuildListener {
      *                           method fails.
      */
     public void setAttribute(Project p, Object element, String attributeName,
-                             String value)
-        throws BuildException {
-        AttributeSetter as 
-            = (AttributeSetter) attributeSetters.get(attributeName);
+                             String value) throws BuildException {
+        AttributeSetter as = (AttributeSetter) attributeSetters.get(attributeName);
         if (as == null) {
-            String msg = p.getElementName(element) +
-            //String msg = "Class " + element.getClass().getName() +
-                " doesn't support the \"" + attributeName + "\" attribute.";
-            throw new BuildException(msg);
+            if (element instanceof DynamicConfigurator) {
+                DynamicConfigurator dc = (DynamicConfigurator) element;
+                dc.setDynamicAttribute(attributeName, value);
+                return;
+            }
+            else {
+                String msg = getElementName(p, element) +
+                    " doesn't support the \"" + attributeName + "\" attribute.";
+                throw new BuildException(msg);
+            }
         }
         try {
             as.set(p, element, value);
@@ -498,6 +503,16 @@ public class IntrospectionHelper implements BuildListener {
     public Object createElement(Project project, Object parent, 
         String elementName) throws BuildException {
         NestedCreator nc = (NestedCreator) nestedCreators.get(elementName);
+        if (nc == null && parent instanceof DynamicConfigurator) {
+            DynamicConfigurator dc = (DynamicConfigurator) parent;
+            Object nestedElement = dc.createDynamicElement(elementName);
+            if (nestedElement != null) {
+                if (nestedElement instanceof ProjectComponent) {
+                    ((ProjectComponent) nestedElement).setProject(project);
+                }
+                return nestedElement;
+            }
+        }
         if (nc == null) {
             String msg = project.getElementName(parent) +
                 " doesn't support the nested \"" + elementName + "\" element.";
diff --git a/src/testcases/org/apache/tools/ant/taskdefs/DynamicTask.java b/src/testcases/org/apache/tools/ant/taskdefs/DynamicTask.java
new file mode 100644
index 000000000..2623addc5
--- /dev/null
+++ b/src/testcases/org/apache/tools/ant/taskdefs/DynamicTask.java
@@ -0,0 +1,82 @@
+/*
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2002 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution, if
+ *    any, must include the following acknowlegement:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowlegement may appear in the software itself,
+ *    if and wherever such third-party acknowlegements normally appear.
+ *
+ * 4. The names "The Jakarta Project", "Ant", and "Apache Software
+ *    Foundation" must not be used to endorse or promote products derived
+ *    from this software without prior written permission. For written
+ *    permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache"
+ *    nor may "Apache" appear in their names without prior written
+ *    permission of the Apache Group.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+
+package org.apache.tools.ant.taskdefs;
+
+import org.apache.tools.ant.DynamicConfigurator;
+import org.apache.tools.ant.Task;
+
+public class DynamicTask extends Task implements DynamicConfigurator {
+
+    public void execute() {
+    }
+
+    public void setDynamicAttribute(String name, String value) {
+        project.setNewProperty(name, value);
+    }
+
+    public Object createDynamicElement(String name) {
+        return new Sub();
+    }
+
+    public class Sub implements DynamicConfigurator {
+        public void setDynamicAttribute(String name, String value) {
+            project.setNewProperty(name, value);
+        }
+
+        public Object createDynamicElement(String name) {
+            return null;
+        }
+    }
+}
diff --git a/src/testcases/org/apache/tools/ant/taskdefs/DynamicTest.java b/src/testcases/org/apache/tools/ant/taskdefs/DynamicTest.java
new file mode 100644
index 000000000..86b548f67
--- /dev/null
+++ b/src/testcases/org/apache/tools/ant/taskdefs/DynamicTest.java
@@ -0,0 +1,76 @@
+/*
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2002 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution, if
+ *    any, must include the following acknowlegement:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowlegement may appear in the software itself,
+ *    if and wherever such third-party acknowlegements normally appear.
+ *
+ * 4. The names "The Jakarta Project", "Ant", and "Apache Software
+ *    Foundation" must not be used to endorse or promote products derived
+ *    from this software without prior written permission. For written
+ *    permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache"
+ *    nor may "Apache" appear in their names without prior written
+ *    permission of the Apache Group.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+
+package org.apache.tools.ant.taskdefs;
+
+import org.apache.tools.ant.BuildFileTest;
+
+public class DynamicTest extends BuildFileTest { 
+    
+    public DynamicTest(String name) { 
+        super(name);
+    }
+    
+    public void setUp() { 
+        configureProject("src/etc/testcases/taskdefs/dynamictask.xml");
+    }
+
+    public void testSimple() {
+        executeTarget("simple");
+        assertEquals("1", project.getProperty("prop1"));
+        assertEquals("2", project.getProperty("prop2"));
+        assertEquals("3", project.getProperty("prop3"));
+        assertEquals("4", project.getProperty("prop4"));
+    }
+}