diff --git a/proposal/mutant/src/java/antcore/org/apache/ant/antcore/execution/CoreExecService.java b/proposal/mutant/src/java/antcore/org/apache/ant/antcore/execution/CoreExecService.java
index 9d0c206de..a94f957b8 100644
--- a/proposal/mutant/src/java/antcore/org/apache/ant/antcore/execution/CoreExecService.java
+++ b/proposal/mutant/src/java/antcore/org/apache/ant/antcore/execution/CoreExecService.java
@@ -1,59 +1,60 @@
 /*
- * The Apache Software License, Version 1.1
+ *  The Apache Software License, Version 1.1
  *
- * Copyright (c) 2002 The Apache Software Foundation.  All rights
- * reserved.
+ *  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:
+ *  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.
+ *  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.
+ *  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.
+ *  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.
+ *  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.
+ *  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 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/>.
+ *  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.ant.antcore.execution;
 import java.io.File;
 import java.net.MalformedURLException;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import org.apache.ant.antcore.modelparser.XMLProjectParser;
@@ -73,8 +74,13 @@ import org.apache.ant.init.LoaderUtils;
  * @created 8 February 2002
  */
 public class CoreExecService implements ExecService {
+
     /** The Frame this service instance is working for */
     private Frame frame;
+    
+    /** A map of subbuild keys to the frame of the subbuild. */
+    private Map subBuilds = new HashMap();
+
 
     /**
      * Constructor
@@ -85,82 +91,38 @@ public class CoreExecService implements ExecService {
         this.frame = frame;
     }
 
-    /**
-     * Run a sub-build.
-     *
-     * @param antFile the file containing the XML description of the model
-     * @param targets A list of targets to be run
-     * @param properties the initiali properties to be used in the build
-     * @exception ExecutionException if the subbuild cannot be run
-     */
-    public void runBuild(File antFile, Map properties, List targets)
-         throws ExecutionException {
-        try {
-            // Parse the build file into a project
-            XMLProjectParser parser = new XMLProjectParser();
-            Project project
-                 = parser.parseBuildFile(InitUtils.getFileURL(antFile));
-            runBuild(project, properties, targets);
-        } catch (MalformedURLException e) {
-            throw new ExecutionException(e);
-        } catch (XMLParseException e) {
-            throw new ExecutionException(e);
-        }
-    }
-
-    /**
-     * Run a sub-build.
-     *
-     * @param model the project model to be used for the build
-     * @param targets A list of targets to be run
-     * @param properties the initiali properties to be used in the build
-     * @exception ExecutionException if the subbuild cannot be run
-     */
-    public void runBuild(Project model, Map properties, List targets)
-         throws ExecutionException {
-        Frame newFrame = frame.createFrame(model);
-        newFrame.setInitialProperties(properties);
-        newFrame.runBuild(targets);
-    }
-
-    /**
-     * Run a sub-build using the current frame's project model
-     *
-     * @param targets A list of targets to be run
-     * @param properties the initiali properties to be used in the build
-     * @exception ExecutionException if the subbuild cannot be run
-     */
-    public void callTarget(Map properties, List targets)
-         throws ExecutionException {
-        runBuild(frame.getProject(), properties, targets);
-    }
 
     /**
-     * Execute a task. The task should have already been initialised by
-     * the core. This is checked
+     * Execute a task. The task should have already been initialised by the
+     * core. This is checked
      *
      * @param task the task to be executed
      * @exception ExecutionException if there is an execution problem
      */
     public void executeTask(Task task) throws ExecutionException {
         AntContext context = task.getAntContext();
+
         if (!(context instanceof ExecutionContext)) {
             throw new ExecutionException("The Task was not configured with an"
                  + " appropriate context");
         }
         ExecutionContext execContext = (ExecutionContext) context;
-        
+
         frame.getEventSupport().fireTaskStarted(task);
+
         Throwable failureCause = null;
+
         try {
-            ClassLoader currentLoader 
-                = LoaderUtils.setContextLoader(execContext.getClassLoader());
+            ClassLoader currentLoader
+                 = LoaderUtils.setContextLoader(execContext.getClassLoader());
+
             task.execute();
             LoaderUtils.setContextLoader(currentLoader);
         } catch (Throwable e) {
             ExecutionException ee =
                 new ExecutionException(e.getClass().getName() + ": "
                  + e.getMessage(), e);
+
             failureCause = ee;
             throw ee;
         } finally {
@@ -168,6 +130,17 @@ public class CoreExecService implements ExecService {
         }
     }
 
+
+    /**
+     * Get the base directory for this execution of this frame
+     *
+     * @return the base directory
+     */
+    public File getBaseDir() {
+        return frame.getBaseDir();
+    }
+
+
     /**
      * get the name of the project associated with this execution.
      *
@@ -177,13 +150,99 @@ public class CoreExecService implements ExecService {
         return frame.getProjectName();
     }
 
+
     /**
-     * Get the base directory for this execution of this frame
+     * Handle subbuild output.
      *
-     * @return the base directory
+     * @param subbuildKey the core's key for managing the subbuild.
+     * @param line the content produce by the current thread.
+     * @param isErr true if this content is from the thread's error stream.
      */
-    public File getBaseDir() {
-        return frame.getBaseDir();
+    public void handleBuildOutput(Object subbuildKey, String line,
+                                  boolean isErr) throws ExecutionException {
+        getSubbuildFrame(subbuildKey).threadOutput(line, isErr);                                      
+    }
+
+
+    private Frame getSubbuildFrame(Object key) throws ExecutionException {
+        Frame subFrame = (Frame) subBuilds.get(key);
+
+        if (subFrame == null) {
+            throw new ExecutionException("Could not find execution frame "
+                 + "for subbuild");
+        }
+        return subFrame;
+    }
+    
+    /**
+     * Run a build which have been previously setup
+     *
+     * @param targets A list of targets to be run
+     * @param key Description of the Parameter
+     * @exception ExecutionException if the build cannot be run
+     */
+    public void runBuild(Object key, List targets) throws ExecutionException {
+        getSubbuildFrame(key).runBuild(targets);
+        subBuilds.remove(key);
+    }
+
+
+    /**
+     * Setup a sub-build.
+     *
+     * @param antFile the file containing the XML description of the model
+     * @param properties the initiali properties to be used in the build
+     * @return Description of the Return Value
+     * @exception ExecutionException if the subbuild cannot be run
+     */
+    public Object setupBuild(File antFile, Map properties)
+         throws ExecutionException {
+        try {
+            // Parse the build file into a project
+            XMLProjectParser parser = new XMLProjectParser();
+            Project project
+                 = parser.parseBuildFile(InitUtils.getFileURL(antFile));
+
+            return setupBuild(project, properties);
+        } catch (MalformedURLException e) {
+            throw new ExecutionException(e);
+        } catch (XMLParseException e) {
+            throw new ExecutionException(e);
+        }
+    }
+
+
+    /**
+     * Setup a sub-build.
+     *
+     * @param model the project model to be used for the build
+     * @param properties the initiali properties to be used in the build
+     * @return Description of the Return Value
+     * @exception ExecutionException if the subbuild cannot be run
+     */
+    public Object setupBuild(Project model, Map properties)
+         throws ExecutionException {
+        Frame newFrame = frame.createFrame(model);
+
+        newFrame.setInitialProperties(properties);
+
+        Object key = new Object();
+
+        subBuilds.put(key, newFrame);
+        return key;
+    }
+
+
+    /**
+     * Setup a sub-build using the current frame's project model
+     *
+     * @param properties the initiali properties to be used in the build
+     * @return Description of the Return Value
+     * @exception ExecutionException if the subbuild cannot be run
+     */
+    public Object setupBuild(Map properties)
+         throws ExecutionException {
+        return setupBuild(frame.getProject(), properties);
     }
 }
 
diff --git a/proposal/mutant/src/java/antcore/org/apache/ant/antcore/execution/Frame.java b/proposal/mutant/src/java/antcore/org/apache/ant/antcore/execution/Frame.java
index 51f11dc1f..1bbf53a09 100644
--- a/proposal/mutant/src/java/antcore/org/apache/ant/antcore/execution/Frame.java
+++ b/proposal/mutant/src/java/antcore/org/apache/ant/antcore/execution/Frame.java
@@ -84,8 +84,8 @@ import org.apache.ant.init.InitConfig;
  * contains the data values set by Ant tasks as they are executed, including
  * task definitions, property values, etc.
  *
- * @author    Conor MacNeill
- * @created   14 January 2002
+ * @author Conor MacNeill
+ * @created 14 January 2002
  */
 public class Frame implements DemuxOutputReceiver {
     /** the base dir of the project */
@@ -151,12 +151,11 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Create an Execution Frame for the given project
      *
-     * @param standardLibs            The libraries of tasks and types
-     *      available to this frame
-     * @param config                  the user config to use for this
-     *      execution of Ant
-     * @param initConfig              Ant's initialisation config
-     * @exception ExecutionException  if a component of the library cannot be
+     * @param standardLibs The libraries of tasks and types available to this
+     *      frame
+     * @param config the user config to use for this execution of Ant
+     * @param initConfig Ant's initialisation config
+     * @exception ExecutionException if a component of the library cannot be
      *      imported
      */
     protected Frame(Map standardLibs, InitConfig initConfig,
@@ -171,11 +170,9 @@ public class Frame implements DemuxOutputReceiver {
      * Replace ${} style constructions in the given value with the string
      * value of the corresponding data values in the frame
      *
-     * @param value                   the string to be scanned for property
-     *      references.
-     * @return                        the string with all property references
-     *      replaced
-     * @exception ExecutionException  if any of the properties do not exist
+     * @param value the string to be scanned for property references.
+     * @return the string with all property references replaced
+     * @exception ExecutionException if any of the properties do not exist
      */
     public String replacePropertyRefs(String value) throws ExecutionException {
         return dataService.replacePropertyRefs(value);
@@ -185,15 +182,15 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Sets the Project of the Frame
      *
-     * @param project                 The new Project value
-     * @exception ExecutionException  if any required sub-frames cannot be
+     * @param project The new Project value
+     * @exception ExecutionException if any required sub-frames cannot be
      *      created and configured
      */
     protected void setProject(Project project) throws ExecutionException {
         this.project = project;
         referencedFrames = new HashMap();
 
-        for (Iterator i = project.getReferencedProjectNames(); i.hasNext();) {
+        for (Iterator i = project.getReferencedProjectNames(); i.hasNext(); ) {
             String referenceName = (String) i.next();
             Project referencedProject
                  = project.getReferencedProject(referenceName);
@@ -211,7 +208,7 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * get the name of the project associated with this frame.
      *
-     * @return   the project's name
+     * @return the project's name
      */
     public String getProjectName() {
         if (project != null) {
@@ -224,10 +221,10 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Set a value in this frame or any of its imported frames.
      *
-     * @param name                    the name of the value
-     * @param value                   the actual value
-     * @param mutable                 if true, existing values can be changed
-     * @exception ExecutionException  if the value name is invalid
+     * @param name the name of the value
+     * @param value the actual value
+     * @param mutable if true, existing values can be changed
+     * @exception ExecutionException if the value name is invalid
      */
     protected void setDataValue(String name, Object value, boolean mutable)
          throws ExecutionException {
@@ -253,9 +250,9 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Set the initial properties to be used when the frame starts execution
      *
-     * @param properties              a Map of named properties which may in
-     *      fact be any object
-     * @exception ExecutionException  if the properties cannot be set
+     * @param properties a Map of named properties which may in fact be any
+     *      object
+     * @exception ExecutionException if the properties cannot be set
      */
     protected void setInitialProperties(Map properties)
          throws ExecutionException {
@@ -271,7 +268,7 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Set the values of various magic properties
      *
-     * @exception ExecutionException  if the properties cannot be set
+     * @exception ExecutionException if the properties cannot be set
      */
     protected void setMagicProperties() throws ExecutionException {
         URL antHomeURL = initConfig.getAntHome();
@@ -291,11 +288,10 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Get a definition from a referenced frame
      *
-     * @param definitionName          the name of the definition relative to
-     *      this frame
-     * @return                        the appropriate import info object from
-     *      the referenced frame's imports
-     * @exception ExecutionException  if the referenced definition cannot be
+     * @param definitionName the name of the definition relative to this frame
+     * @return the appropriate import info object from the referenced frame's
+     *      imports
+     * @exception ExecutionException if the referenced definition cannot be
      *      found
      */
     protected ImportInfo getReferencedDefinition(String definitionName)
@@ -318,7 +314,7 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Gets the project model this frame is working with
      *
-     * @return   the project model
+     * @return the project model
      */
     protected Project getProject() {
         return project;
@@ -330,7 +326,7 @@ public class Frame implements DemuxOutputReceiver {
      * is an expensive operation since it must clone all of the property
      * stores in all frames
      *
-     * @return   a Map containing the frames properties indexed by their full
+     * @return a Map containing the frames properties indexed by their full
      *      name.
      */
     protected Map getAllProperties() {
@@ -359,7 +355,7 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Get the Ant initialization configuration for this frame.
      *
-     * @return   Ant's initialization configuration
+     * @return Ant's initialization configuration
      */
     protected InitConfig getInitConfig() {
         return initConfig;
@@ -369,7 +365,7 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Get the config instance being used by this frame.
      *
-     * @return   the config associated with this frame.
+     * @return the config associated with this frame.
      */
     protected AntConfig getConfig() {
         return config;
@@ -379,11 +375,10 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Get the core's implementation of the given service interface.
      *
-     * @param serviceInterfaceClass   the service interface for which an
+     * @param serviceInterfaceClass the service interface for which an
      *      implementation is require
-     * @return                        the core's implementation of the service
-     *      interface
-     * @exception ExecutionException  if the core does not provide an
+     * @return the core's implementation of the service interface
+     * @exception ExecutionException if the core does not provide an
      *      implementatin of the requested interface
      */
     protected Object getCoreService(Class serviceInterfaceClass)
@@ -402,7 +397,7 @@ public class Frame implements DemuxOutputReceiver {
      * Get the EventSupport instance for this frame. This tracks the build
      * listeners on this frame
      *
-     * @return   the EventSupport instance
+     * @return the EventSupport instance
      */
     protected BuildEventSupport getEventSupport() {
         return eventSupport;
@@ -412,7 +407,7 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Gets the baseDir of the Frame
      *
-     * @return   the baseDir value
+     * @return the baseDir value
      */
     protected File getBaseDir() {
         return baseDir;
@@ -422,9 +417,9 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Get a referenced frame by its reference name
      *
-     * @param referenceName  the name under which the frame was imported.
-     * @return               the Frame asscociated with the given reference
-     *      name or null if there is no such project.
+     * @param referenceName the name under which the frame was imported.
+     * @return the Frame asscociated with the given reference name or null if
+     *      there is no such project.
      */
     protected Frame getReferencedFrame(String referenceName) {
         return (Frame) referencedFrames.get(referenceName);
@@ -434,7 +429,7 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Get the frames representing referenced projects.
      *
-     * @return   an iterator which returns the referenced ExeuctionFrames..
+     * @return an iterator which returns the referenced ExeuctionFrames..
      */
     protected Iterator getReferencedFrames() {
         return referencedFrames.values().iterator();
@@ -444,8 +439,8 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Get the name of an object in its frame
      *
-     * @param fullname  The name of the object
-     * @return          the name of the object within its containing frame
+     * @param fullname The name of the object
+     * @return the name of the object within its containing frame
      */
     protected String getNameInFrame(String fullname) {
         int index = fullname.lastIndexOf(Project.REF_DELIMITER);
@@ -460,11 +455,10 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Get a value from this frame or any imported frame
      *
-     * @param name                    the name of the data value - may contain
-     *      reference delimiters
-     * @return                        the data value fetched from the
-     *      appropriate frame
-     * @exception ExecutionException  if the value is not defined
+     * @param name the name of the data value - may contain reference
+     *      delimiters
+     * @return the data value fetched from the appropriate frame
+     * @exception ExecutionException if the value is not defined
      */
     protected Object getDataValue(String name) throws ExecutionException {
         Frame frame = getContainingFrame(name);
@@ -484,10 +478,10 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Indicate if a data value has been set
      *
-     * @param name                    the name of the data value - may contain
-     *      reference delimiters
-     * @return                        true if the value exists
-     * @exception ExecutionException  if the containing frame for the value
+     * @param name the name of the data value - may contain reference
+     *      delimiters
+     * @return true if the value exists
+     * @exception ExecutionException if the containing frame for the value
      *      does not exist
      */
     protected boolean isDataValueSet(String name) throws ExecutionException {
@@ -509,9 +503,9 @@ public class Frame implements DemuxOutputReceiver {
      * Get the execution frame which contains, directly, the named element
      * where the name is relative to this frame
      *
-     * @param elementName  The name of the element
-     * @return             the execution frame for the project that contains
-     *      the given target
+     * @param elementName The name of the element
+     * @return the execution frame for the project that contains the given
+     *      target
      */
     protected Frame getContainingFrame(String elementName) {
         int index = elementName.lastIndexOf(Project.REF_DELIMITER);
@@ -541,12 +535,12 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Add a collection of properties to this frame
      *
-     * @param properties              the collection of property values,
-     *      indexed by their names
-     * @exception ExecutionException  if the frame cannot be created.
+     * @param properties the collection of property values, indexed by their
+     *      names
+     * @exception ExecutionException if the frame cannot be created.
      */
     protected void addProperties(Map properties) throws ExecutionException {
-        for (Iterator i = properties.keySet().iterator(); i.hasNext();) {
+        for (Iterator i = properties.keySet().iterator(); i.hasNext(); ) {
             String name = (String) i.next();
             Object value = properties.get(name);
 
@@ -558,10 +552,9 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Create a new frame for a given project
      *
-     * @param project                 the project model the frame will deal
-     *      with
-     * @return                        an Frame ready to build the project
-     * @exception ExecutionException  if the frame cannot be created.
+     * @param project the project model the frame will deal with
+     * @return an Frame ready to build the project
+     * @exception ExecutionException if the frame cannot be created.
      */
     protected Frame createFrame(Project project)
          throws ExecutionException {
@@ -569,7 +562,7 @@ public class Frame implements DemuxOutputReceiver {
              = new Frame(standardLibs, initConfig, config);
 
         newFrame.setProject(project);
-        for (Iterator j = eventSupport.getListeners(); j.hasNext();) {
+        for (Iterator j = eventSupport.getListeners(); j.hasNext(); ) {
             BuildListener listener = (BuildListener) j.next();
 
             newFrame.addBuildListener(listener);
@@ -581,8 +574,8 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Log a message as a build event
      *
-     * @param message  the message to be logged
-     * @param level    the priority level of the message
+     * @param message the message to be logged
+     * @param level the priority level of the message
      */
     protected void log(String message, int level) {
         eventSupport.fireMessageLogged(project, message, level);
@@ -592,10 +585,10 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Add a build listener to this execution frame
      *
-     * @param listener  the listener to be added to the frame
+     * @param listener the listener to be added to the frame
      */
     protected void addBuildListener(BuildListener listener) {
-        for (Iterator i = getReferencedFrames(); i.hasNext();) {
+        for (Iterator i = getReferencedFrames(); i.hasNext(); ) {
             Frame referencedFrame = (Frame) i.next();
 
             referencedFrame.addBuildListener(listener);
@@ -607,10 +600,10 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Remove a build listener from the execution
      *
-     * @param listener  the listener to be removed
+     * @param listener the listener to be removed
      */
     protected void removeBuildListener(BuildListener listener) {
-        for (Iterator i = getReferencedFrames(); i.hasNext();) {
+        for (Iterator i = getReferencedFrames(); i.hasNext(); ) {
             Frame subFrame = (Frame) i.next();
 
             subFrame.removeBuildListener(listener);
@@ -622,9 +615,8 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Run the given list of targets
      *
-     * @param targets                 a list of target names which are to be
-     *      evaluated
-     * @exception ExecutionException  if there is a problem in the build
+     * @param targets a list of target names which are to be evaluated
+     * @exception ExecutionException if there is a problem in the build
      */
     protected void runBuild(List targets) throws ExecutionException {
         determineBaseDirs();
@@ -640,7 +632,7 @@ public class Frame implements DemuxOutputReceiver {
                 executeTarget(defaultTarget);
             }
         } else {
-            for (Iterator i = targets.iterator(); i.hasNext();) {
+            for (Iterator i = targets.iterator(); i.hasNext(); ) {
                 String targetName = (String) i.next();
 
                 log("Executing target: " + targetName, MessageLevel.MSG_DEBUG);
@@ -653,10 +645,9 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Execute the tasks of a target in this frame with the given name
      *
-     * @param targetName              the name of the target whose tasks will
-     *      be evaluated
-     * @exception ExecutionException  if there is a problem executing the
-     *      tasks of the target
+     * @param targetName the name of the target whose tasks will be evaluated
+     * @exception ExecutionException if there is a problem executing the tasks
+     *      of the target
      */
     protected void executeTarget(String targetName) throws ExecutionException {
         // to execute a target we must determine its dependencies and
@@ -666,7 +657,7 @@ public class Frame implements DemuxOutputReceiver {
             // firstly build a list of fully qualified target names to execute.
             List dependencyOrder = project.getTargetDependencies(targetName);
 
-            for (Iterator i = dependencyOrder.iterator(); i.hasNext();) {
+            for (Iterator i = dependencyOrder.iterator(); i.hasNext(); ) {
                 String fullTargetName = (String) i.next();
                 Frame frame = getContainingFrame(fullTargetName);
                 String localTargetName = getNameInFrame(fullTargetName);
@@ -682,8 +673,8 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Run the tasks returned by the given iterator
      *
-     * @param taskIterator            the iterator giving the tasks to execute
-     * @exception ExecutionException  if there is execution problem while
+     * @param taskIterator the iterator giving the tasks to execute
+     * @exception ExecutionException if there is execution problem while
      *      executing tasks
      */
     protected void executeTasks(Iterator taskIterator)
@@ -727,9 +718,9 @@ public class Frame implements DemuxOutputReceiver {
      * Execute the given target's tasks. The target must be local to this
      * frame's project
      *
-     * @param targetName              the name of the target within this frame
-     *      that is to be executed.
-     * @exception ExecutionException  if there is a problem executing tasks
+     * @param targetName the name of the target within this frame that is to
+     *      be executed.
+     * @exception ExecutionException if there is a problem executing tasks
      */
     protected void executeTargetTasks(String targetName)
          throws ExecutionException {
@@ -778,11 +769,11 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Initialize the frame by executing the project level tasks if any
      *
-     * @exception ExecutionException  if the top level tasks of the frame
+     * @exception ExecutionException if the top level tasks of the frame
      *      failed
      */
     protected void initialize() throws ExecutionException {
-        for (Iterator i = getReferencedFrames(); i.hasNext();) {
+        for (Iterator i = getReferencedFrames(); i.hasNext(); ) {
             Frame referencedFrame = (Frame) i.next();
 
             referencedFrame.initialize();
@@ -797,7 +788,7 @@ public class Frame implements DemuxOutputReceiver {
     /**
      * Determine the base directory for each frame in the frame hierarchy
      *
-     * @exception ExecutionException  if the base directories cannot be
+     * @exception ExecutionException if the base directories cannot be
      *      determined
      */
     private void determineBaseDirs() throws ExecutionException {
@@ -825,7 +816,7 @@ public class Frame implements DemuxOutputReceiver {
         }
         setDataValue(MagicProperties.BASEDIR, baseDir.getAbsolutePath(), true);
 
-        for (Iterator i = getReferencedFrames(); i.hasNext();) {
+        for (Iterator i = getReferencedFrames(); i.hasNext(); ) {
             Frame refFrame = (Frame) i.next();
 
             refFrame.determineBaseDirs();
@@ -859,8 +850,8 @@ public class Frame implements DemuxOutputReceiver {
      * the thread producing the content. The content is broken up into
      * separate lines
      *
-     * @param line   the content produce by the current thread.
-     * @param isErr  true if this content is from the thread's error stream.
+     * @param line the content produce by the current thread.
+     * @param isErr true if this content is from the thread's error stream.
      */
     public void threadOutput(String line, boolean isErr) {
         eventSupport.threadOutput(line, isErr);
diff --git a/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/Ant.java b/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/Ant.java
index 6d42294fe..64d5b63c5 100644
--- a/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/Ant.java
+++ b/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/Ant.java
@@ -105,11 +105,8 @@ public class Ant extends AntBase {
      * @exception ExecutionException if the build can't be run
      */
     public void execute() throws ExecutionException {
-        System.out.println("Starting Ant Task");
         if (baseDir == null) {
-            ExecService execService
-                = (ExecService) getCoreService(ExecService.class);
-            baseDir = execService.getBaseDir();
+            baseDir = getExecService().getBaseDir();
         }
         
         File antFile = null;
@@ -125,11 +122,9 @@ public class Ant extends AntBase {
         
         setProperty(MagicProperties.BASEDIR, baseDir.getAbsolutePath());
         
-        ExecService execService
-             = (ExecService) getCoreService(ExecService.class);
-
-        execService.runBuild(antFile, getProperties(), getTargets());
-        System.out.println("Ending Ant Task");
+        Object key = getExecService().setupBuild(antFile, getProperties());
+        setSubBuildKey(key);
+        getExecService().runBuild(key, getTargets());
     }
 }
 
diff --git a/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/AntBase.java b/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/AntBase.java
index 8731f2f42..7860df2ba 100644
--- a/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/AntBase.java
+++ b/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/AntBase.java
@@ -1,55 +1,55 @@
 /*
- * The Apache Software License, Version 1.1
+ *  The Apache Software License, Version 1.1
  *
- * Copyright (c) 2002 The Apache Software Foundation.  All rights
- * reserved.
+ *  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:
+ *  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.
+ *  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.
+ *  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.
+ *  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.
+ *  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.
+ *  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 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/>.
+ *  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.ant.antlib.system;
 import java.util.ArrayList;
@@ -60,6 +60,7 @@ import org.apache.ant.common.antlib.AbstractComponent;
 import org.apache.ant.common.antlib.AbstractTask;
 import org.apache.ant.common.antlib.AntContext;
 import org.apache.ant.common.service.DataService;
+import org.apache.ant.common.service.ExecService;
 import org.apache.ant.common.util.ExecutionException;
 
 /**
@@ -85,46 +86,49 @@ public abstract class AntBase extends AbstractTask {
 
 
         /**
-         * Sets the name of the Property
+         * Gets the name of the Property
          *
-         * @param name the new name value
+         * @return the name value
          */
-        public void setName(String name) {
-            this.name = name;
+        public String getName() {
+            return name;
         }
 
+
         /**
-         * Sets the value of the Property
+         * Gets the value of the Property
          *
-         * @param value the new value value
+         * @return the value value
          */
-        public void setValue(String value) {
-            this.value = value;
+        public String getValue() {
+            return value;
         }
 
+
         /**
-         * Gets the name of the Property
+         * Sets the name of the Property
          *
-         * @return the name value
+         * @param name the new name value
          */
-        public String getName() {
-            return name;
+        public void setName(String name) {
+            this.name = name;
         }
 
+
         /**
-         * Gets the value of the Property
+         * Sets the value of the Property
          *
-         * @return the value value
+         * @param value the new value value
          */
-        public String getValue() {
-            return value;
+        public void setValue(String value) {
+            this.value = value;
         }
 
+
         /**
          * Validate this data type instance
          *
-         * @exception ExecutionException if either attribute has not been
-         *      set
+         * @exception ExecutionException if either attribute has not been set
          */
         public void validateComponent() throws ExecutionException {
             if (name == null) {
@@ -138,6 +142,7 @@ public abstract class AntBase extends AbstractTask {
         }
     }
 
+
     /**
      * A simple class to store information about references being passed
      *
@@ -150,42 +155,47 @@ public abstract class AntBase extends AbstractTask {
         /** The id to be used in the sub-build for this reference */
         private String toId;
 
+
         /**
-         * Sets the refId of the Reference
+         * Gets the refId of the Reference
          *
-         * @param refId the new refId value
+         * @return the refId value
          */
-        public void setRefId(String refId) {
-            this.refId = refId;
+        public String getRefId() {
+            return refId;
         }
 
+
         /**
-         * Sets the toId of the Reference
+         * Gets the toId of the Reference
          *
-         * @param toId the new toId value
+         * @return the toId value
          */
-        public void setToId(String toId) {
-            this.toId = toId;
+        public String getToId() {
+            return toId;
         }
 
+
         /**
-         * Gets the refId of the Reference
+         * Sets the refId of the Reference
          *
-         * @return the refId value
+         * @param refId the new refId value
          */
-        public String getRefId() {
-            return refId;
+        public void setRefId(String refId) {
+            this.refId = refId;
         }
 
+
         /**
-         * Gets the toId of the Reference
+         * Sets the toId of the Reference
          *
-         * @return the toId value
+         * @param toId the new toId value
          */
-        public String getToId() {
-            return toId;
+        public void setToId(String toId) {
+            this.toId = toId;
         }
 
+
         /**
          * Validate this data type instance
          *
@@ -200,68 +210,36 @@ public abstract class AntBase extends AbstractTask {
         }
     }
 
-    /** The name of the target to be evaluated in the sub-build */
-    private String targetName;
 
+    /** The core's data service for manipulating the properties */
+    private DataService dataService;
+
+    /** The core's ExecutionService for running builds and external programs */
+    private ExecService execService;
+    
     /**
-     * flag which indicates if all current properties should be passed to
-     * the subbuild
+     * flag which indicates if all current properties should be passed to the
+     * subbuild
      */
     private boolean inheritAll = true;
 
     /**
-     * flag which indicates if all current references should be passed to
-     * the subbuild
+     * flag which indicates if all current references should be passed to the
+     * subbuild
      */
     private boolean inheritRefs = false;
 
     /** The properties which will be passed to the sub-build */
     private Map properties = new HashMap();
 
-    /** The core's data service for manipulating the properties */
-    private DataService dataService;
-
     /**
-     * Sets the target to be executed in the subbuild
-     *
-     * @param targetName the name of the target to build
+     * The key to the subbuild with which the Ant task can manage the subbuild
      */
-    public void setTarget(String targetName) {
-        this.targetName = targetName;
-    }
-
-    /**
-     * Indicate if all properties should be passed
-     *
-     * @param inheritAll true if all properties should be passed
-     */
-    public void setInheritAll(boolean inheritAll) {
-        this.inheritAll = inheritAll;
-    }
+    private Object subbuildKey;
 
-    /**
-     * Indicate if all references are to be passed to the subbuild
-     *
-     * @param inheritRefs true if the sub-build should be given all the
-     *      current references
-     */
-    public void setInheritRefs(boolean inheritRefs) {
-        this.inheritRefs = inheritRefs;
-    }
+    /** The name of the target to be evaluated in the sub-build */
+    private String targetName;
 
-    /**
-     * Initialise this task
-     *
-     * @param context core's context
-     * @param componentType the component type of this component (i.e its
-     *      defined name in the build file)
-     * @exception ExecutionException if we can't access the data service
-     */
-    public void init(AntContext context, String componentType)
-         throws ExecutionException {
-        super.init(context, componentType);
-        dataService = (DataService) getCoreService(DataService.class);
-    }
 
     /**
      * Add a property to be passed to the subbuild
@@ -272,6 +250,7 @@ public abstract class AntBase extends AbstractTask {
         properties.put(property.getName(), property.getValue());
     }
 
+
     /**
      * Add a reference to be passed
      *
@@ -281,11 +260,13 @@ public abstract class AntBase extends AbstractTask {
      */
     public void addReference(Reference reference) throws ExecutionException {
         String refId = reference.getRefId();
+
         if (!dataService.isDataValueSet(refId)) {
             throw new ExecutionException("RefId \"" + refId + "\" is not set");
         }
         Object value = dataService.getDataValue(refId);
         String toId = reference.getToId();
+
         if (toId == null) {
             toId = refId;
         }
@@ -293,16 +274,35 @@ public abstract class AntBase extends AbstractTask {
         properties.put(toId, value);
     }
 
+
     /**
-     * Set a property for the subbuild
+     * Get the core's execution service
      *
-     * @param propertyName the property name
-     * @param propertyValue the value of the property
+     * @return the core's execution service.
      */
-    protected void setProperty(String propertyName, Object propertyValue) {
-        properties.put(propertyName, propertyValue);
+    protected ExecService getExecService() {
+        return execService;
+    }
+
+
+    /**
+     * Get the properties to be used with the sub-build
+     *
+     * @return the properties the sub-build will start with
+     */
+    protected Map getProperties() {
+        if (!inheritAll) {
+            return properties;
+        }
+
+        // need to combine existing properties with new ones
+        Map subBuildProperties = dataService.getAllProperties();
+
+        subBuildProperties.putAll(properties);
+        return subBuildProperties;
     }
 
+
     /**
      * Get the list of targets to be executed
      *
@@ -310,27 +310,112 @@ public abstract class AntBase extends AbstractTask {
      */
     protected List getTargets() {
         List targets = new ArrayList();
+
         if (targetName != null) {
             targets.add(targetName);
         }
         return targets;
     }
 
+
     /**
-     * Get the properties to be used with the sub-build
+     * Handle error information produced by the task. When a task prints to
+     * System.err the container may catch this and redirect the content back
+     * to the task by invoking this method. This method must NOT call
+     * System.err, directly or indirectly.
      *
-     * @return the properties the sub-build will start with
+     * @param line The line of error info produce by the task
      */
-    protected Map getProperties() {
-        if (!inheritAll) {
-            return properties;
+    public void handleSystemErr(String line) {
+        if (subbuildKey == null) {
+            super.handleSystemErr(line);
+        } else {
         }
+    }
 
-        // need to combine existing properties with new ones
-        Map subBuildProperties = dataService.getAllProperties();
-        subBuildProperties.putAll(properties);
-        return subBuildProperties;
+
+    /**
+     * Handle Output produced by the task. When a task prints to System.out
+     * the container may catch this and redirect the content back to the task
+     * by invoking this method. This method must NOT call System.out, directly
+     * or indirectly.
+     *
+     * @param line The line of content produce by the task
+     */
+    public void handleSystemOut(String line) {
+        if (subbuildKey == null) {
+            super.handleSystemOut(line);
+        } else {
+        }
     }
 
+
+    /**
+     * Initialise this task
+     *
+     * @param context core's context
+     * @param componentType the component type of this component (i.e its
+     *      defined name in the build file)
+     * @exception ExecutionException if we can't access the data service
+     */
+    public void init(AntContext context, String componentType)
+         throws ExecutionException {
+        super.init(context, componentType);
+        dataService = (DataService) getCoreService(DataService.class);
+        execService = (ExecService) getCoreService(ExecService.class);
+
+    }
+
+
+    /**
+     * Indicate if all properties should be passed
+     *
+     * @param inheritAll true if all properties should be passed
+     */
+    public void setInheritAll(boolean inheritAll) {
+        this.inheritAll = inheritAll;
+    }
+
+
+    /**
+     * Indicate if all references are to be passed to the subbuild
+     *
+     * @param inheritRefs true if the sub-build should be given all the
+     *      current references
+     */
+    public void setInheritRefs(boolean inheritRefs) {
+        this.inheritRefs = inheritRefs;
+    }
+
+
+    /**
+     * Set a property for the subbuild
+     *
+     * @param propertyName the property name
+     * @param propertyValue the value of the property
+     */
+    protected void setProperty(String propertyName, Object propertyValue) {
+        properties.put(propertyName, propertyValue);
+    }
+
+
+    /**
+     * Set the key of the subbuild
+     *
+     * @param key the key returned by the Ant core for managing the subbuild
+     */
+    protected void setSubBuildKey(Object key) {
+        this.subbuildKey = key;
+    }
+
+
+    /**
+     * Sets the target to be executed in the subbuild
+     *
+     * @param targetName the name of the target to build
+     */
+    public void setTarget(String targetName) {
+        this.targetName = targetName;
+    }
 }
 
diff --git a/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/AntCall.java b/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/AntCall.java
index f74fb6d03..b118cfdf3 100644
--- a/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/AntCall.java
+++ b/proposal/mutant/src/java/antlibs/system/org/apache/ant/antlib/system/AntCall.java
@@ -69,12 +69,12 @@ public class AntCall extends AntBase {
      * @exception ExecutionException if the build fails
      */
     public void execute() throws ExecutionException {
-        ExecService execService
-             = (ExecService) getCoreService(ExecService.class);
         setProperty(MagicProperties.BASEDIR, 
-            execService.getBaseDir().getAbsolutePath());
+            getExecService().getBaseDir().getAbsolutePath());
 
-        execService.callTarget(getProperties(), getTargets());
+        Object key = getExecService().setupBuild(getProperties());
+        setSubBuildKey(key);
+        getExecService().runBuild(key, getTargets());
     }
 
     /**
diff --git a/proposal/mutant/src/java/common/org/apache/ant/common/event/BuildListenerAdapter.java b/proposal/mutant/src/java/common/org/apache/ant/common/event/BuildListenerAdapter.java
new file mode 100644
index 000000000..9702d98ff
--- /dev/null
+++ b/proposal/mutant/src/java/common/org/apache/ant/common/event/BuildListenerAdapter.java
@@ -0,0 +1,135 @@
+/*
+ *  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.ant.common.event;
+
+/**
+ * Abstract adapter for build listeners which don't want to implement all of
+ * the BuildListener methods
+ *
+ * @author    Conor MacNeill
+ * @created   9 April 2002
+ */
+public abstract class BuildListenerAdapter implements BuildListener {
+    /**
+     * Fired before any targets are started.
+     *
+     * @param event  the build event for this notification
+     */
+    public void buildStarted(BuildEvent event) {
+    }
+
+
+    /**
+     * Fired after the last target has finished. This event will still be
+     * thrown if an error occured during the build.
+     *
+     * @param event  the build event for this notification
+     */
+    public void buildFinished(BuildEvent event) {
+    }
+
+
+
+    /**
+     * Fired when a target is started.
+     *
+     * @param event  the build event for this notification
+     */
+    public void targetStarted(BuildEvent event) {
+    }
+
+
+
+    /**
+     * Fired when a target has finished. This event will still be thrown if an
+     * error occured during the build.
+     *
+     * @param event  the build event for this notification
+     */
+    public void targetFinished(BuildEvent event) {
+    }
+
+
+
+    /**
+     * Fired when a task is started.
+     *
+     * @param event  the build event for this notification
+     */
+    public void taskStarted(BuildEvent event) {
+    }
+
+
+
+    /**
+     * Fired when a task has finished. This event will still be throw if an
+     * error occured during the build.
+     *
+     * @param event  the build event for this notification
+     */
+    public void taskFinished(BuildEvent event) {
+    }
+
+
+
+    /**
+     * Fired whenever a message is logged.
+     *
+     * @param event  the build event for this notification
+     */
+    public void messageLogged(BuildEvent event) {
+    }
+
+}
+
diff --git a/proposal/mutant/src/java/common/org/apache/ant/common/service/ExecService.java b/proposal/mutant/src/java/common/org/apache/ant/common/service/ExecService.java
index 376eaff62..a00b96cd9 100644
--- a/proposal/mutant/src/java/common/org/apache/ant/common/service/ExecService.java
+++ b/proposal/mutant/src/java/common/org/apache/ant/common/service/ExecService.java
@@ -67,37 +67,46 @@ import org.apache.ant.common.util.ExecutionException;
  */
 public interface ExecService {
     /**
-     * Run a sub-build.
+     * Setup a sub-build.
      *
      * @param antFile the file containing the XML description of the model
-     * @param targets A list of targets to be run
      * @param properties the initiali properties to be used in the build
-     * @exception ExecutionException if the subbuild cannot be run
+     * @exception ExecutionException if the subbuild cannot be setup
+     * @return a key to the build allowing it to be executed and managed
      */
-    void runBuild(File antFile, Map properties, List targets)
+    Object setupBuild(File antFile, Map properties)
          throws ExecutionException;
 
     /**
-     * Run a sub-build.
+     * Setup a sub-build.
      *
      * @param model the project model to be used for the build
-     * @param targets A list of targets to be run
      * @param properties the initiali properties to be used in the build
-     * @exception ExecutionException if the subbuild cannot be run
+     * @exception ExecutionException if the subbuild cannot be setup
+     * @return a key to the build allowing it to be executed and managed
      */
-    void runBuild(Project model, Map properties, List targets)
+    Object setupBuild(Project model, Map properties)
          throws ExecutionException;
 
     /**
-     * Run a sub-build using the current frame's project model
+     * Setup a sub-build using the current frame's project model
      *
-     * @param targets A list of targets to be run
      * @param properties the initiali properties to be used in the build
-     * @exception ExecutionException if the subbuild cannot be run
+     * @exception ExecutionException if the subbuild cannot be setup
      */
-    void callTarget(Map properties, List targets)
+    Object setupBuild(Map properties)
          throws ExecutionException;
 
+    /**
+     * Run a build which have been previously setup
+     *
+     * @param buildKey the buildKey returned previously when the build was
+     *        setup
+     * @param targets A list of targets to be run
+     * @exception ExecutionException if the build cannot be run
+     */
+   void runBuild(Object buildKey, List targets) throws ExecutionException;
+         
     /**
      * execute a task. The task should have already been initialised by
      * the core
@@ -120,5 +129,15 @@ public interface ExecService {
      * @return the base directory for this execution of Ant
      */
     File getBaseDir();
+    
+    /**
+     * Handle subbuild output.
+     *
+     * @param subbuildKey the core's key for managing the subbuild.
+     * @param line the content produce by the current thread.
+     * @param isErr true if this content is from the thread's error stream.
+     */
+    void handleBuildOutput(Object subbuildKey, String line, boolean isErr) 
+        throws ExecutionException;
 }