QPID-4189: Add unit tests for ConfiguredObjectToMapConverter

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1369015 13f79535-47bb-0310-9956-ffa450edef68

5 files changed, 350 insertions, 130 deletions

diff --git a/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/ConfiguredObjectToMapConverter.java b/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/ConfiguredObjectToMapConverter.java
new file mode 100644
index 0000000000..03dd7c66a8
--- /dev/null
+++ b/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/ConfiguredObjectToMapConverter.java
@@ -0,0 +1,132 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+package org.apache.qpid.server.management.plugin.servlet.rest;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.qpid.server.model.ConfiguredObject;
+import org.apache.qpid.server.model.Model;
+import org.apache.qpid.server.model.Statistics;
+
+public class ConfiguredObjectToMapConverter
+{
+    /** Name of the key used for the statistics map */
+    public static final String STATISTICS_MAP_KEY = "statistics";
+
+    private Model _model = Model.getInstance();
+
+    public Map<String, Object> convertObjectToMap(final ConfiguredObject confObject,
+                                                  Class<? extends  ConfiguredObject> clazz,
+                                                  int depth)
+    {
+        Map<String, Object> object = new LinkedHashMap<String, Object>();
+
+        incorporateAttributesIntoMap(confObject, object);
+        incorporateStatisticsIntoMap(confObject, object);
+
+        if(depth > 0)
+        {
+            incorporateChildrenIntoMap(confObject, clazz, depth, object);
+        }
+        return object;
+    }
+
+    /**
+     * Used for unit test only.
+     */
+    void setModel(Model model)
+    {
+        _model = model;
+    }
+
+    private void incorporateAttributesIntoMap(
+            final ConfiguredObject confObject, Map<String, Object> object)
+    {
+        for(String name : confObject.getAttributeNames())
+        {
+            Object value = confObject.getAttribute(name);
+            if(value instanceof ConfiguredObject)
+            {
+                object.put(name, ((ConfiguredObject) value).getName());
+            }
+            else if(value != null)
+            {
+                object.put(name, value);
+            }
+        }
+    }
+
+    private void incorporateStatisticsIntoMap(
+            final ConfiguredObject confObject, Map<String, Object> object)
+    {
+        Statistics statistics = confObject.getStatistics();
+        Map<String, Object> statMap = new HashMap<String, Object>();
+
+        if (statistics != null)
+        {
+            for(String name : statistics.getStatisticNames())
+            {
+                Object value = statistics.getStatistic(name);
+                if(value != null)
+                {
+                    statMap.put(name, value);
+                }
+            }
+
+            if(!statMap.isEmpty())
+            {
+                object.put(STATISTICS_MAP_KEY, statMap);
+            }
+        }
+    }
+
+    private void incorporateChildrenIntoMap(
+            final ConfiguredObject confObject,
+            Class<? extends ConfiguredObject> clazz, int depth,
+            Map<String, Object> object)
+    {
+        for(Class<? extends ConfiguredObject> childClass : _model.getChildTypes(clazz))
+        {
+            Collection<? extends ConfiguredObject> children = confObject.getChildren(childClass);
+            if(children != null)
+            {
+                List<Map<String, Object>> childObjects = new ArrayList<Map<String, Object>>();
+
+                for(ConfiguredObject child : children)
+                {
+                    childObjects.add(convertObjectToMap(child, childClass, depth-1));
+                }
+
+                if(!childObjects.isEmpty())
+                {
+                    object.put(childClass.getSimpleName().toLowerCase()+"s",childObjects);
+                }
+            }
+        }
+    }
+
+
+
+}
diff --git a/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/RestServlet.java b/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/RestServlet.java
index 593377beed..6a79916d07 100644
--- a/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/RestServlet.java
+++ b/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/RestServlet.java
@@ -16,9 +16,9 @@
  */
 package org.apache.qpid.server.management.plugin.servlet.rest;
 
+import java.io.BufferedWriter;
 import java.io.IOException;
-import java.io.PrintWriter;
-import java.net.SocketAddress;
+import java.io.Writer;
 import java.util.*;
 import javax.servlet.ServletConfig;
 import javax.servlet.ServletException;
@@ -49,6 +49,8 @@ public class RestServlet extends AbstractServlet
 
     private volatile boolean initializationRequired = false;
 
+    private final ConfiguredObjectToMapConverter _objectConverter = new ConfiguredObjectToMapConverter();
+
     public RestServlet()
     {
         super();
@@ -133,7 +135,7 @@ public class RestServlet extends AbstractServlet
 
         for(int i = 0; i < _hierarchy.length; i++)
         {
-            if(i == 0 || Model.getChildTypes(_hierarchy[i - 1]).contains(_hierarchy[i]))
+            if(i == 0 || Model.getInstance().getChildTypes(_hierarchy[i - 1]).contains(_hierarchy[i]))
             {
 
                 for(ConfiguredObject parent : parents)
@@ -257,7 +259,7 @@ public class RestServlet extends AbstractServlet
                                                                 ConfiguredObject child)
     {
         Collection<ConfiguredObject> ancestors = new HashSet<ConfiguredObject>();
-        Collection<Class<? extends ConfiguredObject>> parentTypes = Model.getParentTypes(childType);
+        Collection<Class<? extends ConfiguredObject>> parentTypes = Model.getInstance().getParentTypes(childType);
 
         for(Class<? extends ConfiguredObject> parentClazz : parentTypes)
         {
@@ -282,119 +284,33 @@ public class RestServlet extends AbstractServlet
         return ancestors;
     }
 
-
-    protected Map<String, Object> convertObjectToMap(final ConfiguredObject confObject,
-                                                     Class<? extends  ConfiguredObject> clazz,
-                                                     int depth)
-    {
-        Map<String, Object> object = new LinkedHashMap<String, Object>();
-
-        for(String name : confObject.getAttributeNames())
-        {
-            Object value = confObject.getAttribute(name);
-            if(value instanceof ConfiguredObject)
-            {
-                object.put(name, ((ConfiguredObject) value).getName());
-            }
-            else if(value != null)
-            {
-                object.put(name, value);
-            }
-        }
-
-        Statistics statistics = confObject.getStatistics();
-        Map<String, Object> statMap = new HashMap<String, Object>();
-        for(String name : statistics.getStatisticNames())
-        {
-            Object value = statistics.getStatistic(name);
-            if(value != null)
-            {
-                statMap.put(name, value);
-            }
-        }
-
-        if(!statMap.isEmpty())
-        {
-            object.put("statistics", statMap);
-        }
-
-        if(depth > 0)
-        {
-            for(Class<? extends ConfiguredObject> childClass : Model.getChildTypes(clazz))
-            {
-                Collection<? extends ConfiguredObject> children = confObject.getChildren(childClass);
-                if(children != null)
-                {
-                    List<Map<String, Object>> childObjects = new ArrayList<Map<String, Object>>();
-
-                    for(ConfiguredObject child : children)
-                    {
-                        childObjects.add(convertObjectToMap(child, childClass, depth-1));
-                    }
-
-                    if(!childObjects.isEmpty())
-                    {
-                        object.put(childClass.getSimpleName().toLowerCase()+"s",childObjects);
-                    }
-                }
-            }
-        }
-        return object;
-    }
-
     @Override
     protected void onGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
     {
         response.setContentType("application/json");
         response.setStatus(HttpServletResponse.SC_OK);
 
-        response.setHeader("Cache-Control","no-cache");
-        response.setHeader("Pragma","no-cache");
-        response.setDateHeader ("Expires", 0);
+        setCachingHeadersOnResponse(response);
 
         Collection<ConfiguredObject> allObjects = getObjects(request);
 
-        @SuppressWarnings("unchecked")
-        Map params = new HashMap(request.getParameterMap());
-
-        int depth = 1;
-        try
-        {
-            depth = Integer.parseInt(String.valueOf(params.remove("depth")));
-        }
-        catch (NumberFormatException e)
-        {
-            // Ignore
-        }
+        // TODO - sort special params, everything else should act as a filter
+        int depth = getDepthParameterFromRequest(request);
 
         List<Map<String, Object>> output = new ArrayList<Map<String, Object>>();
-
-        // TODO - depth and sort special params, everything else should act as a filter
-        if(request.getParameter(DEPTH_PARAM)!=null)
-        {
-            try
-            {
-                depth = Integer.parseInt(request.getParameter(DEPTH_PARAM));
-            }
-            catch (NumberFormatException e)
-            {
-
-            }
-        }
-
         for(ConfiguredObject configuredObject : allObjects)
         {
-            output.add(convertObjectToMap(configuredObject, getConfiguredClass(),depth));
+            output.add(_objectConverter.convertObjectToMap(configuredObject, getConfiguredClass(),
+                    depth));
         }
 
-        final PrintWriter writer = response.getWriter();
+        final Writer writer = new BufferedWriter(response.getWriter());
         ObjectMapper mapper = new ObjectMapper();
         mapper.configure(SerializationConfig.Feature.INDENT_OUTPUT, true);
         mapper.writeValue(writer, output);
 
         response.setContentType("application/json");
         response.setStatus(HttpServletResponse.SC_OK);
-
     }
 
     private Class<? extends ConfiguredObject> getConfiguredClass()
@@ -462,7 +378,7 @@ public class RestServlet extends AbstractServlet
                 {
                     for(int j = i-1; j >=0; j--)
                     {
-                        if(Model.getChildTypes(_hierarchy[j]).contains(_hierarchy[i]))
+                        if(Model.getInstance().getChildTypes(_hierarchy[j]).contains(_hierarchy[i]))
                         {
                             for(ConfiguredObject parent : objects[j])
                             {
@@ -482,7 +398,7 @@ public class RestServlet extends AbstractServlet
             }
             List<ConfiguredObject> parents = new ArrayList<ConfiguredObject>();
             Class<? extends ConfiguredObject> objClass = getConfiguredClass();
-            Collection<Class<? extends ConfiguredObject>> parentClasses = Model.getParentTypes(objClass);
+            Collection<Class<? extends ConfiguredObject>> parentClasses = Model.getInstance().getParentTypes(objClass);
             for(int i = _hierarchy.length-2; i >=0 ; i--)
             {
                 if(parentClasses.contains(_hierarchy[i]))
@@ -565,9 +481,7 @@ public class RestServlet extends AbstractServlet
         response.setContentType("application/json");
         response.setStatus(HttpServletResponse.SC_OK);
 
-        response.setHeader("Cache-Control","no-cache");
-        response.setHeader("Pragma","no-cache");
-        response.setDateHeader ("Expires", 0);
+        setCachingHeadersOnResponse(response);
         try
         {
             Collection<ConfiguredObject> allObjects = getObjects(request);
@@ -583,4 +497,31 @@ public class RestServlet extends AbstractServlet
             setResponseStatus(response, e);
         }
     }
+
+    private void setCachingHeadersOnResponse(HttpServletResponse response)
+    {
+        response.setHeader("Cache-Control","no-cache");
+        response.setHeader("Pragma","no-cache");
+        response.setDateHeader ("Expires", 0);
+    }
+
+    private int getDepthParameterFromRequest(HttpServletRequest request)
+    {
+        int depth = 1;
+        final String depthString = request.getParameter(DEPTH_PARAM);
+        if(depthString!=null)
+        {
+            try
+            {
+                depth = Integer.parseInt(depthString);
+            }
+            catch (NumberFormatException e)
+            {
+                LOGGER.warn("Could not parse " + depthString + " as integer");
+            }
+        }
+        return depth;
+    }
+
+
 }
diff --git a/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/StructureServlet.java b/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/StructureServlet.java
index e4ba374f89..60f977ca66 100644
--- a/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/StructureServlet.java
+++ b/qpid/java/broker-plugins/management-http/src/main/java/org/apache/qpid/server/management/plugin/servlet/rest/StructureServlet.java
@@ -73,7 +73,7 @@ public class StructureServlet extends AbstractServlet
         structure.put("id", object.getId());
         structure.put("name", object.getName());
 
-        for(Class<? extends ConfiguredObject> childClass : Model.getChildTypes(clazz))
+        for(Class<? extends ConfiguredObject> childClass : Model.getInstance().getChildTypes(clazz))
         {
             Collection<? extends ConfiguredObject> children = object.getChildren(childClass);
             if(children != null)
diff --git a/qpid/java/broker-plugins/management-http/src/test/java/org/apache/qpid/server/management/plugin/servlet/rest/ConfiguredObjectToMapConverterTest.java b/qpid/java/broker-plugins/management-http/src/test/java/org/apache/qpid/server/management/plugin/servlet/rest/ConfiguredObjectToMapConverterTest.java
new file mode 100644
index 0000000000..8e5c5e1c10
--- /dev/null
+++ b/qpid/java/broker-plugins/management-http/src/test/java/org/apache/qpid/server/management/plugin/servlet/rest/ConfiguredObjectToMapConverterTest.java
@@ -0,0 +1,141 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+package org.apache.qpid.server.management.plugin.servlet.rest;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import static org.apache.qpid.server.management.plugin.servlet.rest.ConfiguredObjectToMapConverter.STATISTICS_MAP_KEY;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+
+import junit.framework.TestCase;
+
+import org.apache.qpid.server.model.ConfiguredObject;
+import org.apache.qpid.server.model.Model;
+import org.apache.qpid.server.model.Statistics;
+
+public class ConfiguredObjectToMapConverterTest extends TestCase
+{
+    private ConfiguredObjectToMapConverter _converter = new ConfiguredObjectToMapConverter();
+    private ConfiguredObject _configuredObject = mock(ConfiguredObject.class);
+
+    @Override
+    protected void setUp() throws Exception
+    {
+        super.setUp();
+    }
+
+    public void testConfiguredObjectWithSingleStatistics() throws Exception
+    {
+        final String statisticName = "statisticName";
+        final int statisticValue = 10;
+
+        Statistics mockStatistics = createMockStatistics(statisticName, statisticValue);
+        when(_configuredObject.getStatistics()).thenReturn(mockStatistics);
+
+        Map<String, Object> resultMap = _converter.convertObjectToMap(_configuredObject, ConfiguredObject.class, 0);
+        Map<String, Object> statsAsMap = (Map<String, Object>) resultMap.get(STATISTICS_MAP_KEY);
+        assertNotNull("Statistics should be part of map", statsAsMap);
+        assertEquals("Unexpected number of statistics", 1, statsAsMap.size());
+        assertEquals("Unexpected statistic value", statisticValue, statsAsMap.get(statisticName));
+    }
+
+    public void testConfiguredObjectWithSingleNonConfiguredObjectAttribute() throws Exception
+    {
+        final String attributeName = "attribute";
+        final String attributeValue = "value";
+        configureMockToReturnOneAttribute(_configuredObject, attributeName, attributeValue);
+
+        Map<String, Object> resultMap = _converter.convertObjectToMap(_configuredObject, ConfiguredObject.class, 0);
+        assertEquals("Unexpected number of attributes", 1, resultMap.size());
+        assertEquals("Unexpected attribute value", attributeValue, resultMap.get(attributeName));
+    }
+
+    /*
+     * For now, it is the name of the configured object is returned as the attribute value, rather than the
+     * configured object itself
+     */
+    public void testConfiguredObjectWithSingleConfiguredObjectAttribute() throws Exception
+    {
+        final String attributeName = "attribute";
+        final ConfiguredObject attributeValue = mock(ConfiguredObject.class);
+        when(attributeValue.getName()).thenReturn("attributeConfiguredObjectName");
+
+        configureMockToReturnOneAttribute(_configuredObject, attributeName, attributeValue);
+
+        Map<String, Object> resultMap = _converter.convertObjectToMap(_configuredObject, ConfiguredObject.class, 0);
+        assertEquals("Unexpected number of attributes", 1, resultMap.size());
+        assertEquals("Unexpected attribute value", "attributeConfiguredObjectName", resultMap.get(attributeName));
+    }
+
+    public void testConfiguredObjectWithChildAndDepth1()
+    {
+        final String childAttributeName = "childattribute";
+        final String childAttributeValue = "childvalue";
+
+        Model model = createTestModel();
+        _converter.setModel(model);
+
+        TestChild mockChild = mock(TestChild.class);
+        configureMockToReturnOneAttribute(mockChild, childAttributeName, childAttributeValue);
+        when(_configuredObject.getChildren(TestChild.class)).thenReturn(Arrays.asList(mockChild));
+
+        Map<String, Object> resultMap = _converter.convertObjectToMap(_configuredObject, ConfiguredObject.class, 1);
+        assertEquals("Unexpected parent map size", 1, resultMap.size());
+
+        final List<Map<String, Object>> childList = (List<Map<String, Object>>) resultMap.get("testchilds");
+        assertEquals("Unexpected number of children", 1, childList.size());
+        final Map<String, Object> childMap = childList.get(0);
+        assertEquals("Unexpected child map size", 1, childMap.size());
+        assertNotNull(childMap);
+
+        assertEquals("Unexpected child attribute value", childAttributeValue, childMap.get(childAttributeName));
+    }
+
+    private Model createTestModel()
+    {
+        Model model = mock(Model.class);
+        final List<Class<? extends ConfiguredObject>> list = new ArrayList<Class<? extends ConfiguredObject>>();
+        list.add(TestChild.class);
+        when(model.getChildTypes(ConfiguredObject.class)).thenReturn(list);
+        return model;
+    }
+
+    private void configureMockToReturnOneAttribute(ConfiguredObject mockConfiguredObject, String attributeName, Object attributeValue)
+    {
+        when(mockConfiguredObject.getAttributeNames()).thenReturn(Arrays.asList(attributeName));
+        when(mockConfiguredObject.getAttribute(attributeName)).thenReturn(attributeValue);
+    }
+
+    private Statistics createMockStatistics(String statName, int statValue)
+    {
+        Statistics mockStatistics = mock(Statistics.class);
+        when(mockStatistics.getStatisticNames()).thenReturn(Arrays.asList(statName));
+        when(mockStatistics.getStatistic(statName)).thenReturn(statValue);
+        return mockStatistics;
+    }
+
+    private static interface TestChild extends ConfiguredObject
+    {
+    }
+}
diff --git a/qpid/java/broker/src/main/java/org/apache/qpid/server/model/Model.java b/qpid/java/broker/src/main/java/org/apache/qpid/server/model/Model.java
index fd429321c8..36179fc105 100644
--- a/qpid/java/broker/src/main/java/org/apache/qpid/server/model/Model.java
+++ b/qpid/java/broker/src/main/java/org/apache/qpid/server/model/Model.java
@@ -29,33 +29,20 @@ import java.util.Map;
 
 public class Model
 {
-    private static final Map<Class<? extends ConfiguredObject>, Collection<Class<? extends ConfiguredObject>>>
-            PARENTS = new HashMap<Class<? extends ConfiguredObject>, Collection<Class<? extends ConfiguredObject>>>();
+    private static final Model MODEL_INSTANCE = new Model();
 
+    private final Map<Class<? extends ConfiguredObject>, Collection<Class<? extends ConfiguredObject>>>
+            _parents = new HashMap<Class<? extends ConfiguredObject>, Collection<Class<? extends ConfiguredObject>>>();
 
-    private static final Map<Class<? extends ConfiguredObject>, Collection<Class<? extends ConfiguredObject>>>
-            CHILDREN = new HashMap<Class<? extends ConfiguredObject>, Collection<Class<? extends ConfiguredObject>>>();
+    private final Map<Class<? extends ConfiguredObject>, Collection<Class<? extends ConfiguredObject>>>
+            _children = new HashMap<Class<? extends ConfiguredObject>, Collection<Class<? extends ConfiguredObject>>>();
 
-    static void addRelationship(Class<? extends ConfiguredObject> parent, Class<? extends ConfiguredObject> child)
+    public static Model getInstance()
     {
-        Collection<Class<? extends ConfiguredObject>> parents = PARENTS.get(child);
-        if(parents == null)
-        {
-            parents = new ArrayList<Class<? extends ConfiguredObject>>();
-            PARENTS.put(child, parents);
-        }
-        parents.add(parent);
-
-        Collection<Class<? extends ConfiguredObject>> children = CHILDREN.get(parent);
-        if(children == null)
-        {
-            children = new ArrayList<Class<? extends ConfiguredObject>>();
-            CHILDREN.put(parent, children);
-        }
-        children.add(child);
+        return MODEL_INSTANCE;
     }
 
-    static
+    private Model()
     {
         addRelationship(Broker.class, VirtualHost.class);
         addRelationship(Broker.class, Port.class);
@@ -78,20 +65,39 @@ public class Model
 
         addRelationship(Session.class, Consumer.class);
         addRelationship(Session.class, Publisher.class);
-
     }
 
-    public static Collection<Class<? extends ConfiguredObject>> getParentTypes(Class<? extends ConfiguredObject> child)
+    public Collection<Class<? extends ConfiguredObject>> getParentTypes(Class<? extends ConfiguredObject> child)
     {
-        Collection<Class<? extends ConfiguredObject>> parentTypes = PARENTS.get(child);
-        return parentTypes == null ? Collections.EMPTY_LIST
+        Collection<Class<? extends ConfiguredObject>> parentTypes = _parents.get(child);
+        return parentTypes == null ? Collections.<Class<? extends ConfiguredObject>>emptyList()
                                    : Collections.unmodifiableCollection(parentTypes);
     }
 
-    public static Collection<Class<? extends ConfiguredObject>> getChildTypes(Class<? extends ConfiguredObject> parent)
+    public Collection<Class<? extends ConfiguredObject>> getChildTypes(Class<? extends ConfiguredObject> parent)
     {
-        Collection<Class<? extends ConfiguredObject>> childTypes = CHILDREN.get(parent);
-        return childTypes == null ? Collections.EMPTY_LIST
+        Collection<Class<? extends ConfiguredObject>> childTypes = _children.get(parent);
+        return childTypes == null ? Collections.<Class<? extends ConfiguredObject>>emptyList()
                                   : Collections.unmodifiableCollection(childTypes);
     }
+
+    private void addRelationship(Class<? extends ConfiguredObject> parent, Class<? extends ConfiguredObject> child)
+    {
+        Collection<Class<? extends ConfiguredObject>> parents = _parents.get(child);
+        if(parents == null)
+        {
+            parents = new ArrayList<Class<? extends ConfiguredObject>>();
+            _parents.put(child, parents);
+        }
+        parents.add(parent);
+
+        Collection<Class<? extends ConfiguredObject>> children = _children.get(parent);
+        if(children == null)
+        {
+            children = new ArrayList<Class<? extends ConfiguredObject>>();
+            _children.put(parent, children);
+        }
+        children.add(child);
+    }
+
 }