HONEYCOMB-122 Update reader registry to share similar APIs as writer

+ Extract common registry builder base code
(Reader registry is not flat, so there is not full control over ordering as with writers
but it is sufficient)
+ Split CompositeReader into CompositeReader, SubtreeReader and GenericReader
+ No need to build composite structure in ReaderFactories (registry does that internally)
+ Keep only ReaderCustomizer + ListReaderCustomizer, no root reader (same for writers)

Change-Id: Ic4e5bc96ad47a6cbcada4efcc2209db5c16d2a6c
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>

30 files changed, 1457 insertions, 718 deletions

diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/AbstractSubtreeManagerRegistryBuilderBuilder.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/AbstractSubtreeManagerRegistryBuilderBuilder.java
new file mode 100644
index 000000000..23a66337f
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/AbstractSubtreeManagerRegistryBuilderBuilder.java
@@ -0,0 +1,213 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Sets;
+import io.fd.honeycomb.v3po.translate.ModifiableSubtreeManagerRegistryBuilder;
+import io.fd.honeycomb.v3po.translate.SubtreeManager;
+import io.fd.honeycomb.v3po.translate.SubtreeManagerRegistryBuilder;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+import javax.annotation.Nonnull;
+import org.jgrapht.experimental.dag.DirectedAcyclicGraph;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public abstract class AbstractSubtreeManagerRegistryBuilderBuilder<S extends SubtreeManager<? extends DataObject>, R>
+        implements ModifiableSubtreeManagerRegistryBuilder<S>, SubtreeManagerRegistryBuilder<R>, AutoCloseable {
+
+    // Using directed acyclic graph to represent the ordering relationships between writers
+    private final DirectedAcyclicGraph<InstanceIdentifier<?>, Order>
+            handlersRelations = new DirectedAcyclicGraph<>((sourceVertex, targetVertex) -> new Order());
+    private final Map<InstanceIdentifier<?>, S> handlersMap = new HashMap<>();
+
+    /**
+     * Add handler without any special relationship to any other type.
+     */
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> add(@Nonnull final S handler) {
+        // Make IID wildcarded just in case
+        // + the way InstanceIdentifier.create + equals work for Identifiable items is unexpected, meaning updates would
+        // not be matched to writers in registry
+        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(handler.getManagedDataObjectType());
+        checkWriterNotPresentYet(targetType);
+        handlersRelations.addVertex(targetType);
+        handlersMap.put(targetType, handler);
+        return this;
+    }
+
+    /**
+     * Add handler without any special relationship to any other type.
+     */
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> subtreeAdd(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
+                                                                         @Nonnull final S handler) {
+        add(getSubtreeHandler(handledChildren, handler));
+        return this;
+    }
+
+    private void checkWriterNotPresentYet(final InstanceIdentifier<?> targetType) {
+        Preconditions.checkArgument(!handlersMap.containsKey(targetType),
+                "Writer for type: %s already present: %s", targetType, handlersMap.get(targetType));
+    }
+
+    /**
+     * Add handler with relationship: to be executed before handler handling relatedType.
+     */
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> addBefore(@Nonnull final S handler,
+                                                                        @Nonnull final InstanceIdentifier<?> relatedType) {
+        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(handler.getManagedDataObjectType());
+        final InstanceIdentifier<?> wildcardedRelatedType = RWUtils.makeIidWildcarded(relatedType);
+        checkWriterNotPresentYet(targetType);
+        handlersRelations.addVertex(targetType);
+        handlersRelations.addVertex(wildcardedRelatedType);
+        addEdge(targetType, wildcardedRelatedType);
+        handlersMap.put(targetType, handler);
+        return this;
+    }
+
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> addBefore(@Nonnull final S handler,
+                                                                        @Nonnull final Collection<InstanceIdentifier<?>> relatedTypes) {
+        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(handler.getManagedDataObjectType());
+        checkWriterNotPresentYet(targetType);
+        handlersRelations.addVertex(targetType);
+        relatedTypes.stream()
+                .map(RWUtils::makeIidWildcarded)
+                .forEach(handlersRelations::addVertex);
+        relatedTypes.stream()
+                .map(RWUtils::makeIidWildcarded)
+                .forEach(type -> addEdge(targetType, type));
+        handlersMap.put(targetType, handler);
+        return this;
+    }
+
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> subtreeAddBefore(
+            @Nonnull final Set<InstanceIdentifier<?>> handledChildren,
+            @Nonnull final S handler,
+            @Nonnull final InstanceIdentifier<?> relatedType) {
+        return addBefore(getSubtreeHandler(handledChildren, handler), relatedType);
+    }
+
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> subtreeAddBefore(
+            @Nonnull final Set<InstanceIdentifier<?>> handledChildren,
+            @Nonnull final S handler,
+            @Nonnull final Collection<InstanceIdentifier<?>> relatedTypes) {
+        return addBefore(getSubtreeHandler(handledChildren, handler), relatedTypes);
+    }
+
+    protected abstract S getSubtreeHandler(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
+                                           @Nonnull final S handler);
+
+    /**
+     * Add handler with relationship: to be executed after handler handling relatedType.
+     */
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> addAfter(@Nonnull final S handler,
+                                                                       @Nonnull final InstanceIdentifier<?> relatedType) {
+        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(handler.getManagedDataObjectType());
+        final InstanceIdentifier<?> wildcardedRelatedType = RWUtils.makeIidWildcarded(relatedType);
+        checkWriterNotPresentYet(targetType);
+        handlersRelations.addVertex(targetType);
+        handlersRelations.addVertex(wildcardedRelatedType);
+        // set edge to indicate before relationship, just reversed
+        addEdge(wildcardedRelatedType, targetType);
+        handlersMap.put(targetType, handler);
+        return this;
+    }
+
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> addAfter(@Nonnull final S handler,
+                                                                       @Nonnull final Collection<InstanceIdentifier<?>> relatedTypes) {
+        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(handler.getManagedDataObjectType());
+        checkWriterNotPresentYet(targetType);
+        handlersRelations.addVertex(targetType);
+        relatedTypes.stream()
+                .map(RWUtils::makeIidWildcarded)
+                .forEach(handlersRelations::addVertex);
+        // set edge to indicate before relationship, just reversed
+        relatedTypes.stream()
+                .map(RWUtils::makeIidWildcarded)
+                .forEach(type -> addEdge(type, targetType));
+        handlersMap.put(targetType, handler);
+        return this;
+    }
+
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> subtreeAddAfter(
+            @Nonnull final Set<InstanceIdentifier<?>> handledChildren,
+            @Nonnull final S handler,
+            @Nonnull final InstanceIdentifier<?> relatedType) {
+        return addAfter(getSubtreeHandler(handledChildren, handler), relatedType);
+    }
+
+    @Override
+    public AbstractSubtreeManagerRegistryBuilderBuilder<S, R> subtreeAddAfter(
+            @Nonnull final Set<InstanceIdentifier<?>> handledChildren,
+            @Nonnull final S handler,
+            @Nonnull final Collection<InstanceIdentifier<?>> relatedTypes) {
+        return addAfter(getSubtreeHandler(handledChildren, handler), relatedTypes);
+    }
+
+
+    private void addEdge(final InstanceIdentifier<?> targetType,
+                         final InstanceIdentifier<?> relatedType) {
+        try {
+            handlersRelations.addDagEdge(targetType, relatedType);
+        } catch (DirectedAcyclicGraph.CycleFoundException e) {
+            throw new IllegalArgumentException(String.format(
+                    "Unable to add writer with relation: %s -> %s. Loop detected", targetType, relatedType), e);
+        }
+    }
+
+    protected ImmutableMap<InstanceIdentifier<?>, S> getMappedHandlers() {
+        final ImmutableMap.Builder<InstanceIdentifier<?>, S> builder = ImmutableMap.builder();
+        // Iterate writer types according to their relationships from graph
+        handlersRelations.iterator()
+                .forEachRemaining(writerType -> {
+                    // There might be types stored just for relationship sake, no real writer, ignoring those
+                    if (handlersMap.containsKey(writerType)) {
+                        builder.put(writerType, handlersMap.get(writerType));
+                    }
+                });
+
+        // TODO we could optimize subtree handlers, if there is a dedicated handler for a node managed by a subtree
+        // handler, recreate the subtree handler with a subset of handled child nodes
+        // This way it is not necessary to change the configuration of subtree writer, just to add a dedicated child
+        // writer. This will be needed if we ever switch to annotations for reader/writer hierarchy initialization
+
+        return builder.build();
+    }
+
+    @Override
+    public void close() throws Exception {
+        handlersMap.clear();
+        // Wrap sets into another set to avoid concurrent modification ex in graph
+        handlersRelations.removeAllEdges(Sets.newHashSet(handlersRelations.edgeSet()));
+        handlersRelations.removeAllVertices(Sets.newHashSet(handlersRelations.vertexSet()));
+    }
+
+    // Represents edges in graph
+    private class Order {}
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/RWUtils.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/RWUtils.java
index 55ae9ecf0..ba9d8e16f 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/RWUtils.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/RWUtils.java
@@ -22,7 +22,6 @@ import com.google.common.base.Predicate;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Maps;
 import io.fd.honeycomb.v3po.translate.SubtreeManager;
-import io.fd.honeycomb.v3po.translate.read.ChildReader;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -32,7 +31,6 @@ import java.util.stream.Collectors;
 import java.util.stream.StreamSupport;
 import javax.annotation.Nonnull;
 import org.opendaylight.yangtools.yang.binding.Augmentation;
-import org.opendaylight.yangtools.yang.binding.ChildOf;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.Identifiable;
 import org.opendaylight.yangtools.yang.binding.Identifier;
@@ -75,24 +73,6 @@ public final class RWUtils {
         return Iterables.get(pathArguments, i + 1);
     }
 
-    public static <T> List<ChildReader<? extends ChildOf<T>>> emptyChildReaderList() {
-        return Collections.emptyList();
-    }
-
-    public static <T> List<ChildReader<? extends Augmentation<T>>> emptyAugReaderList() {
-        return Collections.emptyList();
-    }
-
-    public static <T> List<ChildReader<? extends Augmentation<T>>> singletonAugReaderList(
-        ChildReader<? extends Augmentation<T>> item) {
-        return Collections.<ChildReader<? extends Augmentation<T>>>singletonList(item);
-    }
-
-    public static <T> List<ChildReader<? extends ChildOf<T>>> singletonChildReaderList(
-        ChildReader<? extends ChildOf<T>> item) {
-        return Collections.<ChildReader<? extends ChildOf<T>>>singletonList(item);
-    }
-
     /**
      * Replace last item in ID with a provided IdentifiableItem of the same type
      */
@@ -170,25 +150,16 @@ public final class RWUtils {
         }
     };
 
-    @SuppressWarnings("unchecked")
-    public static <D extends DataObject> InstanceIdentifier<D> appendTypeToId(
-        final InstanceIdentifier<? extends DataObject> parentId, final InstanceIdentifier<D> type) {
-        Preconditions.checkArgument(!parentId.contains(type),
-            "Unexpected InstanceIdentifier %s, already contains %s", parentId, type);
-        final InstanceIdentifier.PathArgument t = Iterables.getOnlyElement(type.getPathArguments());
-        return (InstanceIdentifier<D>) InstanceIdentifier.create(Iterables.concat(
-            parentId.getPathArguments(), Collections.singleton(t)));
-    }
-
     /**
      * Transform a keyed instance identifier into a wildcarded one.
      */
-    public static InstanceIdentifier<?> makeIidWildcarded(final InstanceIdentifier<?> id) {
+    @SuppressWarnings("unchecked")
+    public static <D extends DataObject> InstanceIdentifier<D> makeIidWildcarded(final InstanceIdentifier<D> id) {
         final List<InstanceIdentifier.PathArgument> transformedPathArguments =
                 StreamSupport.stream(id.getPathArguments().spliterator(), false)
                         .map(RWUtils::cleanPathArgumentFromKeys)
                         .collect(Collectors.toList());
-        return InstanceIdentifier.create(transformedPathArguments);
+        return (InstanceIdentifier<D>) InstanceIdentifier.create(transformedPathArguments);
     }
 
     private static InstanceIdentifier.PathArgument cleanPathArgumentFromKeys(final InstanceIdentifier.PathArgument pathArgument) {
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/TransactionMappingContext.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/TransactionMappingContext.java
index 60f4282f5..6abc3b1eb 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/TransactionMappingContext.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/TransactionMappingContext.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.fd.honeycomb.v3po.translate.util.write;
+package io.fd.honeycomb.v3po.translate.util;
 
 import com.google.common.base.Optional;
 import com.google.common.util.concurrent.CheckedFuture;
@@ -28,7 +28,7 @@ import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 
 /**
- * Binding Transaction backed mapping context
+ * Binding Transaction backed mapping context.
  */
 public class TransactionMappingContext implements MappingContext {
 
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/AbstractGenericReader.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/AbstractGenericReader.java
new file mode 100644
index 000000000..9bfbc2450
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/AbstractGenericReader.java
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util.read;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.annotations.Beta;
+import com.google.common.base.Optional;
+import io.fd.honeycomb.v3po.translate.read.ReadContext;
+import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
+import io.fd.honeycomb.v3po.translate.read.Reader;
+import io.fd.honeycomb.v3po.translate.util.RWUtils;
+import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+@Beta
+public abstract class AbstractGenericReader<D extends DataObject, B extends Builder<D>> implements Reader<D, B> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(AbstractGenericReader.class);
+
+    private final InstanceIdentifier<D> instanceIdentifier;
+
+    protected AbstractGenericReader(final InstanceIdentifier<D> managedDataObjectType) {
+        this.instanceIdentifier = RWUtils.makeIidWildcarded(managedDataObjectType);
+    }
+
+    @Nonnull
+    @Override
+    public final InstanceIdentifier<D> getManagedDataObjectType() {
+        return instanceIdentifier;
+    }
+
+    /**
+     * @param id {@link InstanceIdentifier} pointing to current node. In case of keyed list, key must be present.
+     *
+     */
+    protected Optional<D> readCurrent(@Nonnull final InstanceIdentifier<D> id,
+                                      @Nonnull final ReadContext ctx) throws ReadFailedException {
+        LOG.debug("{}: Reading current: {}", this, id);
+        final B builder = getBuilder(id);
+        // Cache empty value to determine if anything has changed later TODO cache in a field
+        final D emptyValue = builder.build();
+
+        LOG.trace("{}: Reading current attributes", this);
+        readCurrentAttributes(id, builder, ctx);
+
+        // Need to check whether anything was filled in to determine if data is present or not.
+        final D built = builder.build();
+        final Optional<D> read = built.equals(emptyValue)
+            ? Optional.absent()
+            : Optional.of(built);
+
+        LOG.debug("{}: Current node read successfully. Result: {}", this, read);
+        return read;
+    }
+
+    @Nonnull
+    @Override
+    @SuppressWarnings("unchecked")
+    public Optional<? extends DataObject> read(@Nonnull final InstanceIdentifier<? extends DataObject> id,
+                                               @Nonnull final ReadContext ctx)
+            throws ReadFailedException {
+        LOG.trace("{}: Reading : {}", this, id);
+        checkArgument(id.getTargetType().equals(getManagedDataObjectType().getTargetType()));
+        return readCurrent((InstanceIdentifier<D>) id, ctx);
+    }
+
+    @Override
+    public String toString() {
+        return String.format("Reader[%s]", getManagedDataObjectType().getTargetType().getSimpleName());
+    }
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/BindingBrokerReader.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/BindingBrokerReader.java
index 58695cf8b..68aa3956e 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/BindingBrokerReader.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/BindingBrokerReader.java
@@ -25,23 +25,29 @@ import javax.annotation.Nonnull;
 import org.opendaylight.controller.md.sal.binding.api.DataBroker;
 import org.opendaylight.controller.md.sal.binding.api.ReadOnlyTransaction;
 import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
+import org.opendaylight.yangtools.concepts.Builder;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 
 /**
- * Simple DataBroker backed reader allowing to delegate reads to different brokers
+ * Simple DataBroker backed reader allowing to delegate reads to different brokers.
  */
-public final class BindingBrokerReader<D extends DataObject> implements Reader<D> {
+public final class BindingBrokerReader<D extends DataObject, B extends Builder<D>>
+        implements Reader<D, B>, AutoCloseable {
 
     private final InstanceIdentifier<D> instanceIdentifier;
     private final DataBroker dataBroker;
     private final LogicalDatastoreType datastoreType;
+    private final ReflexiveReaderCustomizer<D, B> reflexiveReaderCustomizer;
 
-    public BindingBrokerReader(final Class<D> managedDataObjectType, final DataBroker dataBroker,
-                               final LogicalDatastoreType datastoreType) {
+    public BindingBrokerReader(final InstanceIdentifier<D> instanceIdentifier,
+                               final DataBroker dataBroker,
+                               final LogicalDatastoreType datastoreType,
+                               final Class<B> builderClass) {
+        this.reflexiveReaderCustomizer = new ReflexiveReaderCustomizer<>(instanceIdentifier.getTargetType(), builderClass);
+        this.instanceIdentifier = instanceIdentifier;
         this.dataBroker = dataBroker;
         this.datastoreType = datastoreType;
-        this.instanceIdentifier = InstanceIdentifier.create(managedDataObjectType);
     }
 
     @Nonnull
@@ -59,9 +65,32 @@ public final class BindingBrokerReader<D extends DataObject> implements Reader<D
         }
     }
 
+    @Override
+    public void merge(@Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final D readValue) {
+        reflexiveReaderCustomizer.merge(parentBuilder, readValue);
+    }
+
+    @Nonnull
+    @Override
+    public B getBuilder(final InstanceIdentifier<D> id) {
+        return reflexiveReaderCustomizer.getBuilder(id);
+    }
+
+    @Override
+    public void readCurrentAttributes(@Nonnull final InstanceIdentifier<D> id,
+                                      @Nonnull final B builder,
+                                      @Nonnull final ReadContext ctx) throws ReadFailedException {
+        throw new UnsupportedOperationException("Not supported");
+    }
+
     @Nonnull
     @Override
     public InstanceIdentifier<D> getManagedDataObjectType() {
         return instanceIdentifier;
     }
+
+    @Override
+    public void close() throws Exception {
+        // Noop
+    }
 }
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/CloseableReader.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/CloseableReader.java
deleted file mode 100644
index 5492062e3..000000000
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/CloseableReader.java
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- * Copyright (c) 2016 Cisco and/or its affiliates.
- *
- * Licensed 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 io.fd.honeycomb.v3po.translate.util.read;
-
-import com.google.common.base.Optional;
-import io.fd.honeycomb.v3po.translate.read.ReadContext;
-import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
-import io.fd.honeycomb.v3po.translate.read.Reader;
-import javax.annotation.Nonnull;
-import org.opendaylight.yangtools.yang.binding.DataObject;
-import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
-
-/**
- * Closeable wrapper for a reader
- */
-public final class CloseableReader<D extends DataObject> implements Reader<D>, AutoCloseable {
-
-    private Reader<D> compositeRootReader;
-
-    public CloseableReader(@Nonnull final Reader<D> compositeRootReader) {
-        this.compositeRootReader = compositeRootReader;
-    }
-
-    @Nonnull
-    @Override
-    public Optional<? extends DataObject> read(@Nonnull InstanceIdentifier<? extends DataObject> id,
-                                               @Nonnull ReadContext ctx) throws ReadFailedException {
-        return compositeRootReader.read(id, ctx);
-    }
-
-    @Nonnull
-    @Override
-    public InstanceIdentifier<D> getManagedDataObjectType() {
-        return compositeRootReader.getManagedDataObjectType();
-    }
-
-    @Override
-    public String toString() {
-        return compositeRootReader.toString();
-    }
-
-    @Override
-    public void close() throws Exception {
-        //NOOP
-    }
-}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/KeepaliveReaderWrapper.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/KeepaliveReaderWrapper.java
index d59111faa..d782bcc7f 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/KeepaliveReaderWrapper.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/KeepaliveReaderWrapper.java
@@ -14,15 +14,15 @@
  * limitations under the License.
  */
 
-package io.fd.honeycomb.v3po.translate.util;
+package io.fd.honeycomb.v3po.translate.util.read;
 
 import com.google.common.base.Optional;
 import com.google.common.base.Preconditions;
 import io.fd.honeycomb.v3po.translate.MappingContext;
 import io.fd.honeycomb.v3po.translate.ModificationCache;
-import io.fd.honeycomb.v3po.translate.read.ChildReader;
 import io.fd.honeycomb.v3po.translate.read.ReadContext;
 import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
+import io.fd.honeycomb.v3po.translate.read.Reader;
 import java.io.Closeable;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
@@ -39,13 +39,13 @@ import org.slf4j.LoggerFactory;
  * Reader wrapper that periodically invokes a read to determine whether reads are still fully functional.
  * In case a specific error occurs, Keep-alive failure listener gets notified.
  */
-public final class KeepaliveReaderWrapper<D extends DataObject> implements ChildReader<D>, Runnable, Closeable {
+public final class KeepaliveReaderWrapper<D extends DataObject, B extends Builder<D>> implements Reader<D, B>, Runnable, Closeable {
 
     private static final Logger LOG = LoggerFactory.getLogger(KeepaliveReaderWrapper.class);
 
     private static final NoopReadContext CTX = new NoopReadContext();
 
-    private final ChildReader<D> delegate;
+    private final Reader<D, B> delegate;
     private final Class<? extends Exception> exceptionType;
     private final KeepaliveFailureListener failureListener;
     private final ScheduledFuture<?> scheduledFuture;
@@ -59,7 +59,7 @@ public final class KeepaliveReaderWrapper<D extends DataObject> implements Child
      * @param delayInSeconds number of seconds to wait between keepalive calls
      * @param failureListener listener to be called whenever a keepalive failure is detected
      */
-    public KeepaliveReaderWrapper(@Nonnull final ChildReader<D> delegate,
+    public KeepaliveReaderWrapper(@Nonnull final Reader<D, B> delegate,
                                   @Nonnull final ScheduledExecutorService executor,
                                   @Nonnull final Class<? extends Exception> exception,
                                   @Nonnegative final int delayInSeconds,
@@ -73,17 +73,25 @@ public final class KeepaliveReaderWrapper<D extends DataObject> implements Child
     }
 
     @Nonnull
-    @Override
-    public Optional<? extends DataObject> read(@Nonnull final InstanceIdentifier<? extends DataObject> id,
+    public Optional<? extends DataObject> read(@Nonnull final InstanceIdentifier id,
                                                @Nonnull final ReadContext ctx) throws ReadFailedException {
         return delegate.read(id, ctx);
     }
 
-    @Override
-    public void read(@Nonnull final InstanceIdentifier<? extends DataObject> id,
-                     @Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final ReadContext ctx)
-        throws ReadFailedException {
-        delegate.read(id, parentBuilder, ctx);
+    public void readCurrentAttributes(@Nonnull final InstanceIdentifier<D> id,
+                                      @Nonnull final B builder,
+                                      @Nonnull final ReadContext ctx) throws ReadFailedException {
+        delegate.readCurrentAttributes(id, builder, ctx);
+    }
+
+    @Nonnull
+    public B getBuilder(final InstanceIdentifier<D> id) {
+        return delegate.getBuilder(id);
+    }
+
+    public void merge(@Nonnull final Builder<? extends DataObject> parentBuilder,
+                      @Nonnull final D readValue) {
+        delegate.merge(parentBuilder, readValue);
     }
 
     @Nonnull
@@ -99,7 +107,7 @@ public final class KeepaliveReaderWrapper<D extends DataObject> implements Child
             final Optional<? extends DataObject> read = read(delegate.getManagedDataObjectType(), CTX);
             LOG.debug("Keepalive executed successfully with data: {}", read);
         } catch (Exception e) {
-            if(exceptionType.isAssignableFrom(e.getClass())) {
+            if (exceptionType.isAssignableFrom(e.getClass())) {
                 LOG.warn("Keepalive failed. Notifying listener", e);
                 failureListener.onKeepaliveFailure();
             }
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/NoopReaderCustomizer.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/NoopReaderCustomizer.java
index cf494efbe..a4de9febb 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/NoopReaderCustomizer.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/NoopReaderCustomizer.java
@@ -18,13 +18,13 @@ package io.fd.honeycomb.v3po.translate.util.read;
 
 import io.fd.honeycomb.v3po.translate.read.ReadContext;
 import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
-import io.fd.honeycomb.v3po.translate.spi.read.RootReaderCustomizer;
+import io.fd.honeycomb.v3po.translate.spi.read.ReaderCustomizer;
 import org.opendaylight.yangtools.concepts.Builder;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 
 public abstract class NoopReaderCustomizer<C extends DataObject, B extends Builder<C>> implements
-    RootReaderCustomizer<C, B> {
+        ReaderCustomizer<C, B> {
 
     @Override
     public void readCurrentAttributes(InstanceIdentifier<C> id, final B builder, final ReadContext context) throws
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveAugmentReaderCustomizer.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveAugmentReaderCustomizer.java
deleted file mode 100644
index 38107edff..000000000
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveAugmentReaderCustomizer.java
+++ /dev/null
@@ -1,59 +0,0 @@
-/*
- * Copyright (c) 2016 Cisco and/or its affiliates.
- *
- * Licensed 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 io.fd.honeycomb.v3po.translate.util.read;
-
-import static com.google.common.base.Preconditions.checkArgument;
-
-import com.google.common.base.Optional;
-import com.google.common.collect.Lists;
-import io.fd.honeycomb.v3po.translate.spi.read.ChildReaderCustomizer;
-import io.fd.honeycomb.v3po.translate.util.ReflectionUtils;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
-import org.opendaylight.yangtools.concepts.Builder;
-import org.opendaylight.yangtools.yang.binding.Augmentation;
-import org.opendaylight.yangtools.yang.binding.DataObject;
-
-/**
- * Might be slow !
- */
-public class ReflexiveAugmentReaderCustomizer<C extends DataObject, B extends Builder<C>>
-    extends ReflexiveRootReaderCustomizer<C, B>
-    implements ChildReaderCustomizer<C,B> {
-
-    private final Class<C> augType;
-
-    public ReflexiveAugmentReaderCustomizer(final Class<B> builderClass, final Class<C> augType) {
-        super(builderClass);
-        this.augType = augType;
-    }
-
-    @Override
-    public void merge(final Builder<? extends DataObject> parentBuilder, final C readValue) {
-        final Optional<Method> method =
-            ReflectionUtils.findMethodReflex(parentBuilder.getClass(), "addAugmentation",
-                Lists.newArrayList(Class.class, Augmentation.class), parentBuilder.getClass());
-
-        checkArgument(method.isPresent(), "Not possible to add augmentations to builder: %s", parentBuilder);
-        try {
-            method.get().invoke(parentBuilder, augType, readValue);
-        } catch (IllegalAccessException | InvocationTargetException e) {
-            throw new IllegalArgumentException("Unable to set " + readValue + " to " + parentBuilder, e);
-        }
-    }
-
-}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveChildReaderCustomizer.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveChildReaderCustomizer.java
deleted file mode 100644
index 3d5f9f4e8..000000000
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveChildReaderCustomizer.java
+++ /dev/null
@@ -1,57 +0,0 @@
-/*
- * Copyright (c) 2016 Cisco and/or its affiliates.
- *
- * Licensed 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 io.fd.honeycomb.v3po.translate.util.read;
-
-import com.google.common.base.Optional;
-import com.google.common.base.Preconditions;
-import io.fd.honeycomb.v3po.translate.util.ReflectionUtils;
-import io.fd.honeycomb.v3po.translate.spi.read.ChildReaderCustomizer;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
-import java.util.Collections;
-import org.opendaylight.yangtools.concepts.Builder;
-import org.opendaylight.yangtools.yang.binding.DataObject;
-
-/**
- * Might be slow !
- */
-public class ReflexiveChildReaderCustomizer<C extends DataObject, B extends Builder<C>>
-    extends ReflexiveRootReaderCustomizer<C, B>
-    implements ChildReaderCustomizer<C,B> {
-
-    public ReflexiveChildReaderCustomizer(final Class<B> builderClass) {
-        super(builderClass);
-    }
-
-    // TODO Could be just a default implementation in interface (making this a mixin)
-
-    @Override
-    public void merge(final Builder<? extends DataObject> parentBuilder, final C readValue) {
-        final Optional<Method> method =
-            ReflectionUtils.findMethodReflex(parentBuilder.getClass(), "set",
-                Collections.<Class<?>>singletonList(readValue.getClass()), parentBuilder.getClass());
-
-        Preconditions.checkArgument(method.isPresent(), "Unable to set %s to %s", readValue, parentBuilder);
-
-        try {
-            method.get().invoke(parentBuilder, readValue);
-        } catch (IllegalAccessException | InvocationTargetException e) {
-            throw new IllegalArgumentException("Unable to set " + readValue + " to " + parentBuilder, e);
-        }
-    }
-
-}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveReader.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveReader.java
new file mode 100644
index 000000000..51725e728
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveReader.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util.read;
+
+import io.fd.honeycomb.v3po.translate.read.ReadContext;
+import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
+import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+/**
+ * Reader that performs no read operation on its own, just fills in the hierarchy.
+ * <p/>
+ * Might be slow due to reflection !
+ */
+public final class ReflexiveReader<C extends DataObject, B extends Builder<C>> extends AbstractGenericReader<C, B> {
+
+    private final ReflexiveReaderCustomizer<C, B> customizer;
+
+    public ReflexiveReader(final InstanceIdentifier<C> identifier, final Class<B> builderClass) {
+        super(identifier);
+        this.customizer = new ReflexiveReaderCustomizer<>(identifier.getTargetType(), builderClass);
+    }
+
+    @Override
+    public void readCurrentAttributes(@Nonnull final InstanceIdentifier<C> id, @Nonnull final B builder,
+                                      @Nonnull final ReadContext ctx)
+            throws ReadFailedException {
+        customizer.readCurrentAttributes(id, builder, ctx);
+    }
+
+    @Nonnull
+    @Override
+    public B getBuilder(final InstanceIdentifier<C> id) {
+        return customizer.getBuilder(id);
+    }
+
+    @Override
+    public void merge(@Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final C readValue) {
+        customizer.merge(parentBuilder, readValue);
+    }
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveReaderCustomizer.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveReaderCustomizer.java
new file mode 100644
index 000000000..f9efca3dc
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveReaderCustomizer.java
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util.read;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.Lists;
+import io.fd.honeycomb.v3po.translate.util.ReflectionUtils;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Collections;
+import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.Augmentation;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+/**
+ * Might be slow !
+ */
+final class ReflexiveReaderCustomizer<C extends DataObject, B extends Builder<C>> extends NoopReaderCustomizer<C, B> {
+
+    private final Class<C> typeClass;
+    private final Class<B> builderClass;
+
+    public ReflexiveReaderCustomizer(final Class<C> typeClass, final Class<B> builderClass) {
+        this.typeClass = typeClass;
+        this.builderClass = builderClass;
+    }
+
+    protected Class<C> getTypeClass() {
+        return typeClass;
+    }
+
+    protected Class<B> getBuilderClass() {
+        return builderClass;
+    }
+
+    @Nonnull
+    @Override
+    public B getBuilder(@Nonnull InstanceIdentifier<C> id) {
+        try {
+            return builderClass.newInstance();
+        } catch (InstantiationException | IllegalAccessException e) {
+            throw new IllegalStateException("Unable to instantiate " + builderClass, e);
+        }
+    }
+
+    @Override
+    public void merge(@Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final C readValue) {
+        if (Augmentation.class.isAssignableFrom(typeClass)) {
+            mergeAugmentation(parentBuilder, (Class<? extends Augmentation<?>>) typeClass, readValue);
+        } else {
+            mergeRegular(parentBuilder, readValue);
+        }
+    }
+
+    private static void mergeRegular(@Nonnull final Builder<? extends DataObject> parentBuilder,
+                                     @Nonnull final DataObject readValue) {
+        final Optional<Method> method =
+                ReflectionUtils.findMethodReflex(parentBuilder.getClass(), "set",
+                        Collections.singletonList(readValue.getClass()), parentBuilder.getClass());
+
+        checkArgument(method.isPresent(), "Unable to set %s to %s", readValue, parentBuilder);
+
+        try {
+            method.get().invoke(parentBuilder, readValue);
+        } catch (IllegalAccessException | InvocationTargetException e) {
+            throw new IllegalArgumentException("Unable to set " + readValue + " to " + parentBuilder, e);
+        }
+    }
+
+    private static void mergeAugmentation(@Nonnull final Builder<? extends DataObject> parentBuilder,
+                                          @Nonnull final Class<? extends Augmentation<?>> typeClass,
+                                          @Nonnull final DataObject readValue) {
+        final Optional<Method> method =
+                ReflectionUtils.findMethodReflex(parentBuilder.getClass(), "addAugmentation",
+                        Lists.newArrayList(Class.class, Augmentation.class), parentBuilder.getClass());
+
+        checkArgument(method.isPresent(), "Not possible to add augmentations to builder: %s", parentBuilder);
+        try {
+            method.get().invoke(parentBuilder, typeClass, readValue);
+        } catch (IllegalAccessException | InvocationTargetException e) {
+            throw new IllegalArgumentException("Unable to set " + readValue + " to " + parentBuilder, e);
+        }
+    }
+
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveRootReaderCustomizer.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveRootReaderCustomizer.java
deleted file mode 100644
index 029f359bb..000000000
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveRootReaderCustomizer.java
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- * Copyright (c) 2016 Cisco and/or its affiliates.
- *
- * Licensed 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 io.fd.honeycomb.v3po.translate.util.read;
-
-import org.opendaylight.yangtools.concepts.Builder;
-import org.opendaylight.yangtools.yang.binding.DataObject;
-import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
-
-/**
- * Might be slow !
- */
-public class ReflexiveRootReaderCustomizer<C extends DataObject, B extends Builder<C>>  extends NoopReaderCustomizer<C, B> {
-
-    private final Class<B> builderClass;
-
-    public ReflexiveRootReaderCustomizer(final Class<B> builderClass) {
-        this.builderClass = builderClass;
-    }
-
-    @Override
-    public B getBuilder(InstanceIdentifier<C> id) {
-        try {
-            return builderClass.newInstance();
-        } catch (InstantiationException | IllegalAccessException e) {
-            throw new IllegalStateException("Unable to instantiate " + builderClass, e);
-        }
-    }
-}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/CompositeReader.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/CompositeReader.java
new file mode 100644
index 000000000..64ecaf095
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/CompositeReader.java
@@ -0,0 +1,192 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util.read.registry;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.base.Optional;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Iterables;
+import io.fd.honeycomb.v3po.translate.read.ListReader;
+import io.fd.honeycomb.v3po.translate.read.ReadContext;
+import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
+import io.fd.honeycomb.v3po.translate.read.Reader;
+import io.fd.honeycomb.v3po.translate.util.RWUtils;
+import io.fd.honeycomb.v3po.translate.util.read.AbstractGenericReader;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.Identifiable;
+import org.opendaylight.yangtools.yang.binding.Identifier;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+class CompositeReader<D extends DataObject, B extends Builder<D>> extends AbstractGenericReader<D, B> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(CompositeReader.class);
+
+    private final Reader<D, B> delegate;
+    private final ImmutableMap<Class<?>, Reader<? extends DataObject, ? extends Builder<?>>> childReaders;
+
+    private CompositeReader(final Reader<D, B> reader,
+                            final ImmutableMap<Class<?>, Reader<? extends DataObject, ? extends Builder<?>>> childReaders) {
+        super(reader.getManagedDataObjectType());
+        this.delegate = reader;
+        this.childReaders = childReaders;
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <D extends DataObject> InstanceIdentifier<D> appendTypeToId(
+        final InstanceIdentifier<? extends DataObject> parentId, final InstanceIdentifier<D> type) {
+        final InstanceIdentifier.PathArgument t = new InstanceIdentifier.Item<>(type.getTargetType());
+        return (InstanceIdentifier<D>) InstanceIdentifier.create(Iterables.concat(
+            parentId.getPathArguments(), Collections.singleton(t)));
+    }
+
+    @Nonnull
+    @Override
+    public Optional<? extends DataObject> read(@Nonnull final InstanceIdentifier<? extends DataObject> id,
+                                               @Nonnull final ReadContext ctx) throws ReadFailedException {
+        if (shouldReadCurrent(id)) {
+            return readCurrent((InstanceIdentifier<D>) id, ctx);
+        } else if (shouldDelegateToChild(id)) {
+            return readSubtree(id, ctx);
+        } else {
+            // Fallback
+            return delegate.read(id, ctx);
+        }
+    }
+
+    private boolean shouldReadCurrent(@Nonnull final InstanceIdentifier<? extends DataObject> id) {
+        return id.getTargetType().equals(getManagedDataObjectType().getTargetType());
+    }
+
+    private boolean shouldDelegateToChild(@Nonnull final InstanceIdentifier<? extends DataObject> id) {
+        return childReaders.containsKey(RWUtils.getNextId(id, getManagedDataObjectType()).getType());
+    }
+
+    private Optional<? extends DataObject> readSubtree(final InstanceIdentifier<? extends DataObject> id,
+                                                       final ReadContext ctx) throws ReadFailedException {
+        final InstanceIdentifier.PathArgument nextId = RWUtils.getNextId(id, getManagedDataObjectType());
+        final Reader<?, ? extends Builder<?>> nextReader = childReaders.get(nextId.getType());
+        checkArgument(nextReader != null, "Unable to read: %s. No delegate present, available readers at next level: %s",
+                id, childReaders.keySet());
+        return nextReader.read(id, ctx);
+    }
+
+    @SuppressWarnings("unchecked")
+    private void readChildren(final InstanceIdentifier<D> id, @Nonnull final ReadContext ctx, final B builder)
+            throws ReadFailedException {
+        for (Reader child : childReaders.values()) {
+            LOG.debug("{}: Reading child node from: {}", this, child);
+            final InstanceIdentifier childId = appendTypeToId(id, child.getManagedDataObjectType());
+
+            if (child instanceof ListReader) {
+                final List<? extends DataObject> list = ((ListReader) child).readList(childId, ctx);
+                ((ListReader) child).merge(builder, list);
+            } else {
+                final Optional<? extends DataObject> read = child.read(childId, ctx);
+                if (read.isPresent()) {
+                    child.merge(builder, read.get());
+                }
+            }
+        }
+    }
+
+    @Override
+    public void readCurrentAttributes(@Nonnull final InstanceIdentifier<D> id, @Nonnull final B builder,
+                                      @Nonnull final ReadContext ctx)
+            throws ReadFailedException {
+        delegate.readCurrentAttributes(id, builder, ctx);
+        readChildren(id, ctx, builder);
+    }
+
+    @Nonnull
+    @Override
+    public B getBuilder(final InstanceIdentifier<D> id) {
+        return delegate.getBuilder(id);
+    }
+
+    @Override
+    public void merge(@Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final D readValue) {
+        delegate.merge(parentBuilder, readValue);
+    }
+
+    /**
+     * Wrap a Reader as a Composite Reader.
+     */
+    static <D extends DataObject, B extends Builder<D>> Reader<D, B> createForReader(
+            @Nonnull final Reader<D, B> reader,
+            @Nonnull final ImmutableMap<Class<?>, Reader<?, ? extends Builder<?>>> childReaders) {
+
+        return (reader instanceof ListReader)
+                ? new CompositeListReader<>((ListReader) reader, childReaders)
+                : new CompositeReader<>(reader, childReaders);
+    }
+
+    private static class CompositeListReader<D extends DataObject & Identifiable<K>, B extends Builder<D>, K extends Identifier<D>>
+            extends CompositeReader<D, B>
+            implements ListReader<D, K, B> {
+
+        private final ListReader<D, K, B> delegate;
+
+        private CompositeListReader(final ListReader<D, K, B> reader,
+                                    final ImmutableMap<Class<?>, Reader<? extends DataObject, ? extends Builder<?>>> childReaders) {
+            super(reader, childReaders);
+            this.delegate = reader;
+        }
+
+        @Nonnull
+        @Override
+        public List<D> readList(@Nonnull final InstanceIdentifier<D> id, @Nonnull final ReadContext ctx)
+                throws ReadFailedException {
+            LOG.trace("{}: Reading all list entries", this);
+            final List<K> allIds = delegate.getAllIds(id, ctx);
+            LOG.debug("{}: Reading list entries for: {}", this, allIds);
+
+            // Override read list in order to perform readCurrent + readChildren here
+            final ArrayList<D> allEntries = new ArrayList<>(allIds.size());
+            for (K key : allIds) {
+                final InstanceIdentifier.IdentifiableItem<D, K> currentBdItem = RWUtils.getCurrentIdItem(id, key);
+                final InstanceIdentifier<D> keyedId = RWUtils.replaceLastInId(id, currentBdItem);
+                final Optional<D> read = readCurrent(keyedId, ctx);
+                if (read.isPresent()) {
+                    final DataObject singleItem = read.get();
+                    checkArgument(getManagedDataObjectType().getTargetType().isAssignableFrom(singleItem.getClass()));
+                    allEntries.add(getManagedDataObjectType().getTargetType().cast(singleItem));
+                }
+            }
+            return allEntries;
+        }
+
+        @Override
+        public void merge(@Nonnull final Builder<? extends DataObject> builder, @Nonnull final List<D> readData) {
+            delegate.merge(builder, readData);
+        }
+
+        @Override
+        public List<K> getAllIds(@Nonnull final InstanceIdentifier<D> id,
+                                 @Nonnull final ReadContext ctx) throws ReadFailedException {
+            return delegate.getAllIds(id, ctx);
+        }
+    }
+
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/DelegatingReaderRegistry.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/CompositeReaderRegistry.java
index 387f3cc7c..0a948c7a8 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/DelegatingReaderRegistry.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/CompositeReaderRegistry.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.fd.honeycomb.v3po.translate.util.read;
+package io.fd.honeycomb.v3po.translate.util.read.registry;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
@@ -25,13 +25,14 @@ import com.google.common.collect.Multimap;
 import io.fd.honeycomb.v3po.translate.read.ListReader;
 import io.fd.honeycomb.v3po.translate.read.ReadContext;
 import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
-import io.fd.honeycomb.v3po.translate.read.ReaderRegistry;
-import io.fd.honeycomb.v3po.translate.util.RWUtils;
 import io.fd.honeycomb.v3po.translate.read.Reader;
+import io.fd.honeycomb.v3po.translate.read.registry.ReaderRegistry;
+import io.fd.honeycomb.v3po.translate.util.RWUtils;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.concepts.Builder;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 import org.slf4j.Logger;
@@ -40,21 +41,21 @@ import org.slf4j.LoggerFactory;
 /**
  * Simple reader registry able to perform and aggregated read (ROOT read) on top of all provided readers. Also able to
  * delegate a specific read to one of the delegate readers.
- *
+ * <p/>
  * This could serve as a utility to hold & hide all available readers in upper layers.
  */
-public final class DelegatingReaderRegistry implements ReaderRegistry {
+public final class CompositeReaderRegistry implements ReaderRegistry {
 
-    private static final Logger LOG = LoggerFactory.getLogger(DelegatingReaderRegistry.class);
+    private static final Logger LOG = LoggerFactory.getLogger(CompositeReaderRegistry.class);
 
-    private final Map<Class<? extends DataObject>, Reader<? extends DataObject>> rootReaders;
+    private final Map<Class<? extends DataObject>, Reader<? extends DataObject, ? extends Builder<?>>> rootReaders;
 
     /**
-     * Create new {@link DelegatingReaderRegistry}
+     * Create new {@link CompositeReaderRegistry}.
      *
      * @param rootReaders List of delegate readers
      */
-    public DelegatingReaderRegistry(@Nonnull final List<Reader<? extends DataObject>> rootReaders) {
+    public CompositeReaderRegistry(@Nonnull final List<Reader<? extends DataObject, ? extends Builder<?>>> rootReaders) {
         this.rootReaders = RWUtils.uniqueLinkedIndex(checkNotNull(rootReaders), RWUtils.MANAGER_CLASS_FUNCTION);
     }
 
@@ -67,7 +68,7 @@ public final class DelegatingReaderRegistry implements ReaderRegistry {
         LOG.trace("Reading from all delegates: {}", rootReaders.values());
 
         final Multimap<InstanceIdentifier<? extends DataObject>, DataObject> objects = LinkedListMultimap.create();
-        for (Reader<? extends DataObject> rootReader : rootReaders.values()) {
+        for (Reader<? extends DataObject, ? extends Builder<?>> rootReader : rootReaders.values()) {
             LOG.debug("Reading from delegate: {}", rootReader);
 
             if (rootReader instanceof ListReader) {
@@ -94,20 +95,10 @@ public final class DelegatingReaderRegistry implements ReaderRegistry {
             throws ReadFailedException {
         final InstanceIdentifier.PathArgument first = checkNotNull(
                 Iterables.getFirst(id.getPathArguments(), null), "Empty id");
-        final Reader<? extends DataObject> reader = rootReaders.get(first.getType());
+        final Reader<? extends DataObject, ? extends Builder<?>> reader = rootReaders.get(first.getType());
         checkNotNull(reader,
                 "Unable to read %s. Missing reader. Current readers for: %s", id, rootReaders.keySet());
         LOG.debug("Reading from delegate: {}", reader);
         return reader.read(id, ctx);
     }
-
-    /**
-     * @throws UnsupportedOperationException This getter is not supported for reader registry since it does not manage a
-     *                                       specific node type
-     */
-    @Nonnull
-    @Override
-    public InstanceIdentifier<DataObject> getManagedDataObjectType() {
-        throw new UnsupportedOperationException("Root registry has no type");
-    }
 }
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/CompositeReaderRegistryBuilder.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/CompositeReaderRegistryBuilder.java
new file mode 100644
index 000000000..3adda713d
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/CompositeReaderRegistryBuilder.java
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util.read.registry;
+
+import com.google.common.collect.ImmutableMap;
+import io.fd.honeycomb.v3po.translate.read.Reader;
+import io.fd.honeycomb.v3po.translate.read.registry.ModifiableReaderRegistryBuilder;
+import io.fd.honeycomb.v3po.translate.read.registry.ReaderRegistry;
+import io.fd.honeycomb.v3po.translate.read.registry.ReaderRegistryBuilder;
+import io.fd.honeycomb.v3po.translate.util.AbstractSubtreeManagerRegistryBuilderBuilder;
+import io.fd.honeycomb.v3po.translate.util.read.ReflexiveReader;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import javax.annotation.Nonnull;
+import javax.annotation.concurrent.NotThreadSafe;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+@NotThreadSafe
+public final class CompositeReaderRegistryBuilder
+        extends AbstractSubtreeManagerRegistryBuilderBuilder<Reader<? extends DataObject, ? extends Builder<?>>, ReaderRegistry>
+        implements ModifiableReaderRegistryBuilder, ReaderRegistryBuilder {
+
+    private static final Logger LOG = LoggerFactory.getLogger(CompositeReaderRegistryBuilder.class);
+
+    @Override
+    protected Reader<? extends DataObject, ? extends Builder<?>> getSubtreeHandler(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
+                                                                                   @Nonnull final Reader<? extends DataObject, ? extends Builder<?>> reader) {
+        return SubtreeReader.createForReader(handledChildren, reader);
+    }
+
+    @Override
+    public <D extends DataObject> void addStructuralReader(@Nonnull InstanceIdentifier<D> id,
+                                                           @Nonnull Class<? extends Builder<D>> builderType) {
+        add(new ReflexiveReader<>(id, builderType));
+    }
+
+    /**
+     * Create {@link CompositeReaderRegistry} with Readers ordered according to submitted relationships.
+     * <p/>
+     * Note: The ordering only applies between nodes on the same level, inter-level and inter-subtree relationships are
+     * ignored.
+     */
+    @Override
+    public ReaderRegistry build() {
+        ImmutableMap<InstanceIdentifier<?>, Reader<? extends DataObject, ? extends Builder<?>>> mappedReaders =
+                getMappedHandlers();
+        LOG.debug("Building Reader registry with Readers: {}",
+                mappedReaders.keySet().stream()
+                        .map(InstanceIdentifier::getTargetType)
+                        .map(Class::getSimpleName)
+                        .collect(Collectors.joining(", ")));
+
+        LOG.trace("Building Reader registry with Readers: {}", mappedReaders);
+        final List<InstanceIdentifier<?>> readerOrder = new ArrayList<>(mappedReaders.keySet());
+
+        // Wrap readers into composite readers recursively, collect roots and create registry
+        final TypeHierarchy typeHierarchy = TypeHierarchy.create(mappedReaders.keySet());
+        final List<Reader<? extends DataObject, ? extends Builder<?>>> orderedRootReaders =
+                typeHierarchy.getRoots().stream()
+                        .map(rootId -> toCompositeReader(rootId, mappedReaders, typeHierarchy))
+                        .collect(Collectors.toList());
+
+        // We are violating the ordering from mappedReaders, since we are forming a composite structure
+        // but at least order root writers
+        orderedRootReaders.sort((reader1, reader2) -> readerOrder.indexOf(reader1.getManagedDataObjectType())
+                - readerOrder.indexOf(reader2.getManagedDataObjectType()));
+
+        return new CompositeReaderRegistry(orderedRootReaders);
+    }
+
+    private Reader<? extends DataObject, ? extends Builder<?>> toCompositeReader(
+            final InstanceIdentifier<?> instanceIdentifier,
+            final ImmutableMap<InstanceIdentifier<?>, Reader<? extends DataObject, ? extends Builder<?>>> mappedReaders,
+            final TypeHierarchy typeHierarchy) {
+
+        // Order child readers according to the mappedReadersCollection
+        final ImmutableMap.Builder<Class<?>, Reader<?, ? extends Builder<?>>> childReadersMapB = ImmutableMap.builder();
+        for (InstanceIdentifier<?> childId : mappedReaders.keySet()) {
+            if (typeHierarchy.getDirectChildren(instanceIdentifier).contains(childId)) {
+                childReadersMapB.put(childId.getTargetType(), toCompositeReader(childId, mappedReaders, typeHierarchy));
+            }
+        }
+
+        final ImmutableMap<Class<?>, Reader<?, ? extends Builder<?>>> childReadersMap = childReadersMapB.build();
+        return childReadersMap.isEmpty()
+                ? mappedReaders.get(instanceIdentifier)
+                : CompositeReader.createForReader(mappedReaders.get(instanceIdentifier), childReadersMap);
+    }
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/SubtreeReader.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/SubtreeReader.java
new file mode 100644
index 000000000..98fcac673
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/SubtreeReader.java
@@ -0,0 +1,250 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util.read.registry;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.base.Optional;
+import com.google.common.base.Predicate;
+import com.google.common.collect.Iterables;
+import io.fd.honeycomb.v3po.translate.read.ListReader;
+import io.fd.honeycomb.v3po.translate.read.ReadContext;
+import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
+import io.fd.honeycomb.v3po.translate.read.Reader;
+import io.fd.honeycomb.v3po.translate.util.RWUtils;
+import io.fd.honeycomb.v3po.translate.util.ReflectionUtils;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.Identifiable;
+import org.opendaylight.yangtools.yang.binding.Identifier;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Simple Reader delegate for subtree Readers (Readers handling also children nodes) providing a list of all the
+ * children nodes being handled.
+ */
+class SubtreeReader<D extends DataObject, B extends Builder<D>> implements Reader<D, B> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(SubtreeReader.class);
+
+    private final Reader<D, B> delegate;
+    private final Set<InstanceIdentifier<?>> handledChildTypes = new HashSet<>();
+
+    private SubtreeReader(final Reader<D, B> delegate, Set<InstanceIdentifier<?>> handledTypes) {
+        this.delegate = delegate;
+        for (InstanceIdentifier<?> handledType : handledTypes) {
+            // Iid has to start with Reader's handled root type
+            checkArgument(delegate.getManagedDataObjectType().getTargetType().equals(
+                    handledType.getPathArguments().iterator().next().getType()),
+                    "Handled node from subtree has to be identified by an instance identifier starting from: %s."
+                            + "Instance identifier was: %s", getManagedDataObjectType().getTargetType(), handledType);
+            checkArgument(Iterables.size(handledType.getPathArguments()) > 1,
+                    "Handled node from subtree identifier too short: %s", handledType);
+            handledChildTypes.add(InstanceIdentifier.create(Iterables.concat(
+                    getManagedDataObjectType().getPathArguments(), Iterables.skip(handledType.getPathArguments(), 1))));
+        }
+    }
+
+    /**
+     * Return set of types also handled by this Reader. All of the types are children of the type managed by this Reader
+     * excluding the type of this Reader.
+     */
+    Set<InstanceIdentifier<?>> getHandledChildTypes() {
+        return handledChildTypes;
+    }
+
+    @Override
+    @Nonnull
+    public Optional<? extends DataObject> read(
+            @Nonnull final InstanceIdentifier<? extends DataObject> id,
+            @Nonnull final ReadContext ctx) throws ReadFailedException {
+        final InstanceIdentifier<?> wildcarded = RWUtils.makeIidWildcarded(id);
+
+        // Reading entire subtree and filtering if is current reader responsible
+        if (getHandledChildTypes().contains(wildcarded)) {
+            LOG.debug("{}: Subtree node managed by this writer requested: {}. Reading current and filtering", this, id);
+            // If there's no dedicated reader, use read current
+            final InstanceIdentifier<D> currentId = RWUtils.cutId(id, getManagedDataObjectType());
+            final Optional<? extends DataObject> current = read(currentId, ctx);
+            // then perform post-reading filtering (return only requested sub-node)
+            final Optional<? extends DataObject> readSubtree = current.isPresent()
+                ? filterSubtree(current.get(), id, getManagedDataObjectType().getTargetType())
+                : current;
+
+            LOG.debug("{}: Subtree: {} read successfully. Result: {}", this, id, readSubtree);
+            return readSubtree;
+
+        // Fallback solution, try delegate, maybe it can read the ID
+        } else {
+            return delegate.read(id, ctx);
+        }
+    }
+
+    @Override
+    public void readCurrentAttributes(@Nonnull final InstanceIdentifier<D> id, @Nonnull final B builder,
+                                      @Nonnull final ReadContext ctx)
+            throws ReadFailedException {
+        delegate.readCurrentAttributes(id, builder, ctx);
+    }
+
+    @Nonnull
+    @Override
+    public B getBuilder(final InstanceIdentifier<D> id) {
+        return delegate.getBuilder(id);
+    }
+
+    @Override
+    public void merge(@Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final D readValue) {
+        delegate.merge(parentBuilder, readValue);
+    }
+
+    @Nonnull
+    private static Optional<? extends DataObject> filterSubtree(@Nonnull final DataObject parent,
+                                                                @Nonnull final InstanceIdentifier<? extends DataObject> absolutPath,
+                                                                @Nonnull final Class<?> managedType) {
+        final InstanceIdentifier.PathArgument nextId =
+                RWUtils.getNextId(absolutPath, InstanceIdentifier.create(parent.getClass()));
+
+        final Optional<? extends DataObject> nextParent = findNextParent(parent, nextId, managedType);
+
+        if (Iterables.getLast(absolutPath.getPathArguments()).equals(nextId)) {
+            return nextParent; // we found the dataObject identified by absolutePath
+        } else if (nextParent.isPresent()) {
+            return filterSubtree(nextParent.get(), absolutPath, nextId.getType());
+        } else {
+            return nextParent; // we can't go further, return Optional.absent()
+        }
+    }
+
+    private static Optional<? extends DataObject> findNextParent(@Nonnull final DataObject parent,
+                                                                 @Nonnull final InstanceIdentifier.PathArgument nextId,
+                                                                 @Nonnull final Class<?> managedType) {
+        // TODO is there a better way than reflection ? e.g. convert into NN and filter out with a utility
+        Optional<Method> method = ReflectionUtils.findMethodReflex(managedType, "get",
+                Collections.emptyList(), nextId.getType());
+
+        if (method.isPresent()) {
+            return Optional.fromNullable(filterSingle(parent, nextId, method.get()));
+        } else {
+            // List child nodes
+            method = ReflectionUtils.findMethodReflex(managedType,
+                    "get" + nextId.getType().getSimpleName(), Collections.emptyList(), List.class);
+
+            if (method.isPresent()) {
+                return filterList(parent, nextId, method.get());
+            } else {
+                throw new IllegalStateException(
+                        "Unable to filter " + nextId + " from " + parent + " getters not found using reflexion");
+            }
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    private static Optional<? extends DataObject> filterList(final DataObject parent,
+                                                             final InstanceIdentifier.PathArgument nextId,
+                                                             final Method method) {
+        final List<? extends DataObject> invoke = (List<? extends DataObject>) invoke(method, nextId, parent);
+
+        checkArgument(nextId instanceof InstanceIdentifier.IdentifiableItem<?, ?>,
+                "Unable to perform wildcarded read for %s", nextId);
+        final Identifier key = ((InstanceIdentifier.IdentifiableItem) nextId).getKey();
+        // TODO replace with stream().filter().findFirst() when we switch to using java's Optional instead of Guava's
+        // because now we would have to do awkward Optional transformation since findFirstReturns guava's optional
+        return Iterables.tryFind(invoke, new Predicate<DataObject>() {
+
+            @Override
+            public boolean apply(@Nullable final DataObject input) {
+                final Optional<Method> keyGetter = ReflectionUtils.findMethodReflex(nextId.getType(), "get",
+                                Collections.emptyList(), key.getClass());
+                final Object actualKey;
+                actualKey = invoke(keyGetter.get(), nextId, input);
+                return key.equals(actualKey);
+            }
+        });
+    }
+
+    private static DataObject filterSingle(final DataObject parent,
+                                           final InstanceIdentifier.PathArgument nextId, final Method method) {
+        return nextId.getType().cast(invoke(method, nextId, parent));
+    }
+
+    private static Object invoke(final Method method,
+                                 final InstanceIdentifier.PathArgument nextId, final DataObject parent) {
+        try {
+            return method.invoke(parent);
+        } catch (IllegalAccessException | InvocationTargetException e) {
+            throw new IllegalArgumentException("Unable to get " + nextId + " from " + parent, e);
+        }
+    }
+
+    @Override
+    @Nonnull
+    public InstanceIdentifier<D> getManagedDataObjectType() {
+        return delegate.getManagedDataObjectType();
+    }
+
+    /**
+     * Wrap a Reader as a subtree Reader.
+     */
+    static <D extends DataObject, B extends Builder<D>> Reader<D, B> createForReader(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
+                                                                                     @Nonnull final Reader<D, B> reader) {
+        return (reader instanceof ListReader)
+                ? new SubtreeListReader<>((ListReader) reader, handledChildren)
+                : new SubtreeReader<>(reader, handledChildren);
+    }
+
+    private static final class SubtreeListReader<D extends DataObject & Identifiable<K>, B extends Builder<D>, K extends Identifier<D>>
+            extends SubtreeReader<D, B> implements ListReader<D, K, B> {
+
+        private final ListReader<D, K, B> delegate;
+
+        private SubtreeListReader(final ListReader<D, K, B> delegate,
+                                  final Set<InstanceIdentifier<?>> handledTypes) {
+            super(delegate, handledTypes);
+            this.delegate = delegate;
+        }
+
+        @Nonnull
+        @Override
+        public List<D> readList(@Nonnull final InstanceIdentifier<D> id, @Nonnull final ReadContext ctx)
+                throws ReadFailedException {
+            return delegate.readList(id, ctx);
+        }
+
+        @Override
+        public void merge(@Nonnull final Builder<? extends DataObject> builder, @Nonnull final List<D> readData) {
+            delegate.merge(builder, readData);
+        }
+
+        @Override
+        public List<K> getAllIds(@Nonnull final InstanceIdentifier<D> id,
+                                 @Nonnull final ReadContext ctx) throws ReadFailedException {
+            return delegate.getAllIds(id, ctx);
+        }
+    }
+
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/TypeHierarchy.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/TypeHierarchy.java
new file mode 100644
index 000000000..005e3bc8d
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/read/registry/TypeHierarchy.java
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util.read.registry;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.collect.Iterables;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import javax.annotation.Nonnull;
+import org.jgrapht.experimental.dag.DirectedAcyclicGraph;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+final class TypeHierarchy {
+    private final DirectedAcyclicGraph<InstanceIdentifier<?>, Parent> hierarchy;
+
+    private TypeHierarchy(@Nonnull final DirectedAcyclicGraph<InstanceIdentifier<?>, Parent> hierarchy) {
+        this.hierarchy = hierarchy;
+    }
+
+    Set<InstanceIdentifier<?>> getAllChildren(InstanceIdentifier<?> id) {
+        final HashSet<InstanceIdentifier<?>> instanceIdentifiers = new HashSet<>();
+        for (InstanceIdentifier<?> childId : getDirectChildren(id)) {
+            instanceIdentifiers.add(childId);
+            instanceIdentifiers.addAll(getAllChildren(childId));
+        }
+        return instanceIdentifiers;
+    }
+
+    Set<InstanceIdentifier<?>> getDirectChildren(InstanceIdentifier<?> id) {
+        checkArgument(hierarchy.vertexSet().contains(id),
+                "Unknown reader: %s. Known readers: %s", id, hierarchy.vertexSet());
+
+        return hierarchy.outgoingEdgesOf(id).stream()
+                .map(hierarchy::getEdgeTarget)
+                .collect(Collectors.toSet());
+    }
+
+    Set<InstanceIdentifier<?>> getRoots() {
+        return hierarchy.vertexSet().stream()
+                .filter(vertex -> hierarchy.incomingEdgesOf(vertex).size() == 0)
+                .collect(Collectors.toSet());
+    }
+
+    /**
+     * Create reader hierarchy from a flat set of instance identifiers.
+     *
+     * @param allIds Set of unkeyed instance identifiers
+     */
+    static TypeHierarchy create(@Nonnull Set<InstanceIdentifier<?>> allIds) {
+        final DirectedAcyclicGraph<InstanceIdentifier<?>, Parent>
+                readersHierarchy = new DirectedAcyclicGraph<>((sourceVertex, targetVertex) -> new Parent());
+
+        for (InstanceIdentifier<?> allId : allIds) {
+            checkArgument(!Iterables.isEmpty(allId.getPathArguments()), "Empty ID detected");
+
+            if (Iterables.size(allId.getPathArguments()) == 1) {
+                readersHierarchy.addVertex(allId);
+            }
+
+            List<InstanceIdentifier.PathArgument> pathArgs = new LinkedList<>();
+            pathArgs.add(allId.getPathArguments().iterator().next());
+
+            for (InstanceIdentifier.PathArgument pathArgument : Iterables.skip(allId.getPathArguments(), 1)) {
+                final InstanceIdentifier<?> previous = InstanceIdentifier.create(pathArgs);
+                pathArgs.add(pathArgument);
+                final InstanceIdentifier<?> current = InstanceIdentifier.create(pathArgs);
+
+                readersHierarchy.addVertex(previous);
+                readersHierarchy.addVertex(current);
+
+                try {
+                    readersHierarchy.addDagEdge(previous, current);
+                } catch (DirectedAcyclicGraph.CycleFoundException e) {
+                    throw new IllegalArgumentException("Loop in hierarchy detected", e);
+                }
+            }
+        }
+
+        return new TypeHierarchy(readersHierarchy);
+    }
+
+    private static final class Parent{}
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/AbstractGenericWriter.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/AbstractGenericWriter.java
new file mode 100644
index 000000000..44b36edae
--- /dev/null
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/AbstractGenericWriter.java
@@ -0,0 +1,137 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util.write;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import io.fd.honeycomb.v3po.translate.util.RWUtils;
+import io.fd.honeycomb.v3po.translate.write.WriteContext;
+import io.fd.honeycomb.v3po.translate.write.WriteFailedException;
+import io.fd.honeycomb.v3po.translate.write.Writer;
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public abstract class AbstractGenericWriter<D extends DataObject> implements Writer<D> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(AbstractGenericWriter.class);
+
+    private final InstanceIdentifier<D> instanceIdentifier;
+
+    protected AbstractGenericWriter(final InstanceIdentifier<D> type) {
+        this.instanceIdentifier = RWUtils.makeIidWildcarded(type);
+    }
+
+    protected void writeCurrent(final InstanceIdentifier<D> id, final D data, final WriteContext ctx)
+        throws WriteFailedException {
+        LOG.debug("{}: Writing current: {} data: {}", this, id, data);
+        writeCurrentAttributes(id, data, ctx);
+        LOG.debug("{}: Current node written successfully", this);
+    }
+
+    protected void updateCurrent(final InstanceIdentifier<D> id, final D dataBefore, final D dataAfter,
+                                 final WriteContext ctx) throws WriteFailedException {
+        LOG.debug("{}: Updating current: {} dataBefore: {}, datAfter: {}", this, id, dataBefore, dataAfter);
+
+        if (dataBefore.equals(dataAfter)) {
+            LOG.debug("{}: Skipping current(no update): {}", this, id);
+            // No change, ignore
+            return;
+        }
+        updateCurrentAttributes(id, dataBefore, dataAfter, ctx);
+        LOG.debug("{}: Current node updated successfully", this);
+    }
+
+    protected void deleteCurrent(final InstanceIdentifier<D> id, final D dataBefore, final WriteContext ctx)
+        throws WriteFailedException {
+        LOG.debug("{}: Deleting current: {} dataBefore: {}", this, id, dataBefore);
+        deleteCurrentAttributes(id, dataBefore, ctx);
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public void update(@Nonnull final InstanceIdentifier<? extends DataObject> id,
+                       @Nullable final DataObject dataBefore,
+                       @Nullable final DataObject dataAfter,
+                       @Nonnull final WriteContext ctx) throws WriteFailedException {
+        LOG.debug("{}: Updating : {}", this, id);
+        LOG.trace("{}: Updating : {}, from: {} to: {}", this, id, dataBefore, dataAfter);
+
+        checkArgument(idPointsToCurrent(id), "Cannot handle data: %s. Only: %s can be handled by writer: %s",
+                id, getManagedDataObjectType(), this);
+
+        if (isWrite(dataBefore, dataAfter)) {
+            writeCurrent((InstanceIdentifier<D>) id, castToManaged(dataAfter), ctx);
+        } else if (isDelete(dataBefore, dataAfter)) {
+            deleteCurrent((InstanceIdentifier<D>) id, castToManaged(dataBefore), ctx);
+        } else {
+            checkArgument(dataBefore != null && dataAfter != null, "No data to process");
+            updateCurrent((InstanceIdentifier<D>) id, castToManaged(dataBefore), castToManaged(dataAfter), ctx);
+        }
+    }
+
+    private void checkDataType(@Nonnull final DataObject dataAfter) {
+        checkArgument(getManagedDataObjectType().getTargetType().isAssignableFrom(dataAfter.getClass()));
+    }
+
+    private D castToManaged(final DataObject data) {
+        checkDataType(data);
+        return getManagedDataObjectType().getTargetType().cast(data);
+    }
+
+    private static boolean isWrite(final DataObject dataBefore,
+                                    final DataObject dataAfter) {
+        return dataBefore == null && dataAfter != null;
+    }
+
+    private static boolean isDelete(final DataObject dataBefore,
+                                    final DataObject dataAfter) {
+        return dataAfter == null && dataBefore != null;
+    }
+
+    private boolean idPointsToCurrent(final @Nonnull InstanceIdentifier<? extends DataObject> id) {
+        return id.getTargetType().equals(getManagedDataObjectType().getTargetType());
+    }
+
+    protected abstract void writeCurrentAttributes(@Nonnull final InstanceIdentifier<D> id,
+                                                   @Nonnull final D data,
+                                                   @Nonnull final WriteContext ctx) throws WriteFailedException;
+
+    protected abstract void deleteCurrentAttributes(@Nonnull final InstanceIdentifier<D> id,
+                                                    @Nonnull final D dataBefore,
+                                                    @Nonnull final WriteContext ctx) throws WriteFailedException;
+
+    protected abstract void updateCurrentAttributes(@Nonnull final InstanceIdentifier<D> id,
+                                                    @Nonnull final D dataBefore,
+                                                    @Nonnull final D dataAfter,
+                                                    @Nonnull final WriteContext ctx) throws WriteFailedException;
+
+    @Nonnull
+    @Override
+    public InstanceIdentifier<D> getManagedDataObjectType() {
+        return instanceIdentifier;
+    }
+
+
+    @Override
+    public String toString() {
+        return String.format("Writer[%s]", getManagedDataObjectType().getTargetType().getSimpleName());
+    }
+}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/CloseableWriter.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/CloseableWriter.java
deleted file mode 100644
index 3442f8370..000000000
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/CloseableWriter.java
+++ /dev/null
@@ -1,63 +0,0 @@
-/*
- * Copyright (c) 2016 Cisco and/or its affiliates.
- *
- * Licensed 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 io.fd.honeycomb.v3po.translate.util.write;
-
-import io.fd.honeycomb.v3po.translate.write.WriteContext;
-import io.fd.honeycomb.v3po.translate.write.WriteFailedException;
-import io.fd.honeycomb.v3po.translate.write.Writer;
-import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
-import org.opendaylight.yangtools.yang.binding.DataObject;
-import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
-
-/**
- * Closeable wrapper for a writer
- */
-public final class CloseableWriter<D extends DataObject> implements Writer<D>, AutoCloseable {
-
-    private Writer<D> vppCompositeRootWriter;
-
-    public CloseableWriter(
-        final Writer<D> vppCompositeRootWriter) {
-        this.vppCompositeRootWriter = vppCompositeRootWriter;
-    }
-
-    @Override
-    public void update(
-        @Nonnull final InstanceIdentifier<? extends DataObject> id,
-        @Nullable final DataObject dataBefore,
-        @Nullable final DataObject dataAfter,
-        @Nonnull final WriteContext ctx) throws WriteFailedException {
-        vppCompositeRootWriter.update(id, dataBefore, dataAfter, ctx);
-    }
-
-    @Nonnull
-    @Override
-    public InstanceIdentifier<D> getManagedDataObjectType() {
-        return vppCompositeRootWriter.getManagedDataObjectType();
-    }
-
-    @Override
-    public String toString() {
-        return vppCompositeRootWriter.toString();
-    }
-
-    @Override
-    public void close() throws Exception {
-
-    }
-}
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/NoopWriterRegistry.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/NoopWriterRegistry.java
index 236ad8917..7c45fcd82 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/NoopWriterRegistry.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/NoopWriterRegistry.java
@@ -18,14 +18,8 @@ package io.fd.honeycomb.v3po.translate.util.write;
 
 import io.fd.honeycomb.v3po.translate.TranslationException;
 import io.fd.honeycomb.v3po.translate.write.WriteContext;
-import io.fd.honeycomb.v3po.translate.write.WriteFailedException;
-import io.fd.honeycomb.v3po.translate.write.WriterRegistry;
+import io.fd.honeycomb.v3po.translate.write.registry.WriterRegistry;
 import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
-import org.opendaylight.yangtools.yang.binding.DataObject;
-import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 /**
  * Empty registry that does not perform any changes. Can be used in data layer, if we want to disable passing data to
@@ -33,29 +27,12 @@ import org.slf4j.LoggerFactory;
  */
 public class NoopWriterRegistry implements WriterRegistry, AutoCloseable {
 
-    private static final Logger LOG = LoggerFactory.getLogger(NoopWriterRegistry.class);
-
-    @Override
-    public void update(@Nonnull final InstanceIdentifier<? extends DataObject> id,
-                       @Nullable final DataObject dataBefore, @Nullable final DataObject dataAfter,
-                       @Nonnull final WriteContext ctx) throws WriteFailedException {
-        LOG.trace("NoopWriterRegistry.update id={}, dataBefore{}, dataAfter={], ctx={}", id, dataBefore, dataAfter,
-                ctx);
-        // NOOP
-    }
-
     @Override
     public void update(@Nonnull final DataObjectUpdates updates,
                        @Nonnull final WriteContext ctx) throws TranslationException {
         // NOOP
     }
 
-    @Nonnull
-    @Override
-    public InstanceIdentifier<DataObject> getManagedDataObjectType() {
-        throw new UnsupportedOperationException("Noop registry has no type");
-    }
-
     @Override
     public void close() throws Exception {
         // NOOP
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistry.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistry.java
index 4abad23a6..7433de813 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistry.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistry.java
@@ -21,7 +21,6 @@ import static com.google.common.base.Preconditions.checkArgument;
 import com.google.common.base.Optional;
 import com.google.common.collect.HashMultimap;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Multimap;
@@ -32,7 +31,7 @@ import io.fd.honeycomb.v3po.translate.write.DataObjectUpdate;
 import io.fd.honeycomb.v3po.translate.write.WriteContext;
 import io.fd.honeycomb.v3po.translate.write.WriteFailedException;
 import io.fd.honeycomb.v3po.translate.write.Writer;
-import io.fd.honeycomb.v3po.translate.write.WriterRegistry;
+import io.fd.honeycomb.v3po.translate.write.registry.WriterRegistry;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
@@ -91,15 +90,6 @@ final class FlatWriterRegistry implements WriterRegistry {
     }
 
     @Override
-    public void update(@Nonnull final InstanceIdentifier<? extends DataObject> id,
-                       @Nullable final DataObject dataBefore,
-                       @Nullable final DataObject dataAfter,
-                       @Nonnull final WriteContext ctx) throws WriteFailedException {
-        singleUpdate(ImmutableMultimap.of(
-                RWUtils.makeIidWildcarded(id), DataObjectUpdate.create(id, dataBefore, dataAfter)), ctx);
-    }
-
-    @Override
     public void update(@Nonnull final DataObjectUpdates updates,
                        @Nonnull final WriteContext ctx) throws TranslationException {
         if (updates.isEmpty()) {
@@ -265,12 +255,6 @@ final class FlatWriterRegistry implements WriterRegistry {
         return writers.get(singleType);
     }
 
-    @Nonnull
-    @Override
-    public InstanceIdentifier<DataObject> getManagedDataObjectType() {
-        throw new UnsupportedOperationException("Registry has no managed type");
-    }
-
     // FIXME unit test
     private final class ReverterImpl implements Reverter {
 
diff --git a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilder.java b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilder.java
index f5d218f55..bfac2eedd 100644
--- a/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilder.java
+++ b/v3po/translate-utils/src/main/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilder.java
@@ -17,20 +17,16 @@
 package io.fd.honeycomb.v3po.translate.util.write.registry;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableMap;
-import io.fd.honeycomb.v3po.translate.util.RWUtils;
-import io.fd.honeycomb.v3po.translate.write.ModifiableWriterRegistry;
+import io.fd.honeycomb.v3po.translate.util.AbstractSubtreeManagerRegistryBuilderBuilder;
 import io.fd.honeycomb.v3po.translate.write.Writer;
-import io.fd.honeycomb.v3po.translate.write.WriterRegistryBuilder;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.Map;
+import io.fd.honeycomb.v3po.translate.write.registry.ModifiableWriterRegistryBuilder;
+import io.fd.honeycomb.v3po.translate.write.registry.WriterRegistry;
+import io.fd.honeycomb.v3po.translate.write.registry.WriterRegistryBuilder;
 import java.util.Set;
 import java.util.stream.Collectors;
 import javax.annotation.Nonnull;
 import javax.annotation.concurrent.NotThreadSafe;
-import org.jgrapht.experimental.dag.DirectedAcyclicGraph;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 import org.slf4j.Logger;
@@ -40,156 +36,24 @@ import org.slf4j.LoggerFactory;
  * Builder for {@link FlatWriterRegistry} allowing users to specify inter-writer relationships.
  */
 @NotThreadSafe
-public final class FlatWriterRegistryBuilder implements ModifiableWriterRegistry, WriterRegistryBuilder, AutoCloseable {
+public final class FlatWriterRegistryBuilder
+        extends AbstractSubtreeManagerRegistryBuilderBuilder<Writer<? extends DataObject>, WriterRegistry>
+        implements ModifiableWriterRegistryBuilder, WriterRegistryBuilder {
 
     private static final Logger LOG = LoggerFactory.getLogger(FlatWriterRegistryBuilder.class);
 
-    // Using directed acyclic graph to represent the ordering relationships between writers
-    private final DirectedAcyclicGraph<InstanceIdentifier<?>, WriterRelation>
-            writersRelations = new DirectedAcyclicGraph<>((sourceVertex, targetVertex) -> new WriterRelation());
-    private final Map<InstanceIdentifier<?>, Writer<?>> writersMap = new HashMap<>();
-
-    /**
-     * AddWriter without any special relationship to any other type.
-     */
-    @Override
-    public FlatWriterRegistryBuilder addWriter(@Nonnull final Writer<? extends DataObject> writer) {
-        // Make IID wildcarded just in case
-        // + the way InstanceIdentifier.create + equals work for Identifiable items is unexpected, meaning updates would
-        // not be matched to writers in registry
-        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(writer.getManagedDataObjectType());
-        checkWriterNotPresentYet(targetType);
-        writersRelations.addVertex(targetType);
-        writersMap.put(targetType, writer);
-        return this;
-    }
-
-    /**
-     * AddWriter without any special relationship to any other type.
-     */
-    @Override
-    public FlatWriterRegistryBuilder addSubtreeWriter(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
-                                                      @Nonnull final Writer<? extends DataObject> writer) {
-        addWriter(SubtreeWriter.createForWriter(handledChildren, writer));
-        return this;
-    }
-
-    private void checkWriterNotPresentYet(final InstanceIdentifier<?> targetType) {
-        Preconditions.checkArgument(!writersMap.containsKey(targetType),
-                "Writer for type: %s already present: %s", targetType, writersMap.get(targetType));
-    }
-
-    /**
-     * Add writer with relationship: to be executed before writer handling relatedType.
-     */
-    @Override
-    public FlatWriterRegistryBuilder addWriterBefore(@Nonnull final Writer<? extends DataObject> writer,
-                                                     @Nonnull final InstanceIdentifier<?> relatedType) {
-        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(writer.getManagedDataObjectType());
-        final InstanceIdentifier<?> wildcardedRelatedType = RWUtils.makeIidWildcarded(relatedType);
-        checkWriterNotPresentYet(targetType);
-        writersRelations.addVertex(targetType);
-        writersRelations.addVertex(wildcardedRelatedType);
-        addEdge(targetType, wildcardedRelatedType);
-        writersMap.put(targetType, writer);
-        return this;
-    }
-
-    @Override
-    public FlatWriterRegistryBuilder addSubtreeWriterBefore(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
-                                                            @Nonnull final Writer<? extends DataObject> writer,
-                                                            @Nonnull final InstanceIdentifier<?> relatedType) {
-        return addWriterBefore(SubtreeWriter.createForWriter(handledChildren, writer), relatedType);
-    }
-
-    @Override
-    public FlatWriterRegistryBuilder addWriterBefore(@Nonnull final Writer<? extends DataObject> writer,
-                                                     @Nonnull final Collection<InstanceIdentifier<?>> relatedTypes) {
-        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(writer.getManagedDataObjectType());
-        checkWriterNotPresentYet(targetType);
-        writersRelations.addVertex(targetType);
-        relatedTypes.stream()
-                .map(RWUtils::makeIidWildcarded)
-                .forEach(writersRelations::addVertex);
-        relatedTypes.stream()
-                .map(RWUtils::makeIidWildcarded)
-                .forEach(type -> addEdge(targetType, type));
-        writersMap.put(targetType, writer);
-        return this;
-    }
-
-    @Override
-    public FlatWriterRegistryBuilder addSubtreeWriterBefore(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
-                                                            @Nonnull final Writer<? extends DataObject> writer,
-                                                            @Nonnull final Collection<InstanceIdentifier<?>> relatedTypes) {
-        return addWriterBefore(SubtreeWriter.createForWriter(handledChildren, writer), relatedTypes);
-    }
-
-    /**
-     * Add writer with relationship: to be executed after writer handling relatedType.
-     */
-    @Override
-    public FlatWriterRegistryBuilder addWriterAfter(@Nonnull final Writer<? extends DataObject> writer,
-                                                    @Nonnull final InstanceIdentifier<?> relatedType) {
-        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(writer.getManagedDataObjectType());
-        final InstanceIdentifier<?> wildcardedRelatedType = RWUtils.makeIidWildcarded(relatedType);
-        checkWriterNotPresentYet(targetType);
-        writersRelations.addVertex(targetType);
-        writersRelations.addVertex(wildcardedRelatedType);
-        // set edge to indicate before relationship, just reversed
-        addEdge(wildcardedRelatedType, targetType);
-        writersMap.put(targetType, writer);
-        return this;
-    }
-
-    @Override
-    public FlatWriterRegistryBuilder addSubtreeWriterAfter(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
-                                                           @Nonnull final Writer<? extends DataObject> writer,
-                                                           @Nonnull final InstanceIdentifier<?> relatedType) {
-        return addWriterAfter(SubtreeWriter.createForWriter(handledChildren, writer), relatedType);
-    }
-
-    @Override
-    public FlatWriterRegistryBuilder addWriterAfter(@Nonnull final Writer<? extends DataObject> writer,
-                                                    @Nonnull final Collection<InstanceIdentifier<?>> relatedTypes) {
-        final InstanceIdentifier<?> targetType = RWUtils.makeIidWildcarded(writer.getManagedDataObjectType());
-        checkWriterNotPresentYet(targetType);
-        writersRelations.addVertex(targetType);
-        relatedTypes.stream()
-                .map(RWUtils::makeIidWildcarded)
-                .forEach(writersRelations::addVertex);
-        // set edge to indicate before relationship, just reversed
-        relatedTypes.stream()
-                .map(RWUtils::makeIidWildcarded)
-                .forEach(type -> addEdge(type, targetType));
-        writersMap.put(targetType, writer);
-        return this;
-    }
-
     @Override
-    public FlatWriterRegistryBuilder addSubtreeWriterAfter(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
-                                                           @Nonnull final Writer<? extends DataObject> writer,
-                                                           @Nonnull final Collection<InstanceIdentifier<?>> relatedTypes) {
-        return addWriterAfter(SubtreeWriter.createForWriter(handledChildren, writer), relatedTypes);
-    }
-
-
-    private void addEdge(final InstanceIdentifier<?> targetType,
-                         final InstanceIdentifier<?> relatedType) {
-        try {
-            writersRelations.addDagEdge(targetType, relatedType);
-        } catch (DirectedAcyclicGraph.CycleFoundException e) {
-            throw new IllegalArgumentException(String.format(
-                    "Unable to add writer with relation: %s -> %s. Loop detected", targetType, relatedType), e);
-        }
+    protected Writer<? extends DataObject> getSubtreeHandler(final @Nonnull Set<InstanceIdentifier<?>> handledChildren,
+                                                             final @Nonnull Writer<? extends DataObject> writer) {
+        return SubtreeWriter.createForWriter(handledChildren, writer);
     }
 
     /**
      * Create FlatWriterRegistry with writers ordered according to submitted relationships.
      */
     @Override
-    public FlatWriterRegistry build() {
-        final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters = getMappedWriters();
+    public WriterRegistry build() {
+        final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters = getMappedHandlers();
         LOG.debug("Building writer registry with writers: {}",
                 mappedWriters.keySet().stream()
                         .map(InstanceIdentifier::getTargetType)
@@ -200,26 +64,8 @@ public final class FlatWriterRegistryBuilder implements ModifiableWriterRegistry
     }
 
     @VisibleForTesting
-    ImmutableMap<InstanceIdentifier<?>, Writer<?>> getMappedWriters() {
-        final ImmutableMap.Builder<InstanceIdentifier<?>, Writer<?>> builder = ImmutableMap.builder();
-        // Iterate writer types according to their relationships from graph
-        writersRelations.iterator()
-                .forEachRemaining(writerType -> {
-                    // There might be types stored just for relationship sake, no real writer, ignoring those
-                    if (writersMap.containsKey(writerType)) {
-                        builder.put(writerType, writersMap.get(writerType));
-                    }
-                });
-        return builder.build();
-    }
-
     @Override
-    public void close() throws Exception {
-        writersMap.clear();
-        writersRelations.removeAllEdges(writersRelations.edgeSet());
-        writersRelations.removeAllVertices(writersRelations.vertexSet());
+    protected ImmutableMap<InstanceIdentifier<?>, Writer<? extends DataObject>> getMappedHandlers() {
+        return super.getMappedHandlers();
     }
-
-    // Represents edges in graph
-    private static final class WriterRelation {}
 }
diff --git a/v3po/translate-utils/src/main/java/org/opendaylight/yang/gen/v1/urn/honeycomb/params/xml/ns/yang/translate/utils/rev160406/DelegatingReaderRegistryModule.java b/v3po/translate-utils/src/main/java/org/opendaylight/yang/gen/v1/urn/honeycomb/params/xml/ns/yang/translate/utils/rev160406/DelegatingReaderRegistryModule.java
index fccd6b1c2..e1f04ebe2 100644
--- a/v3po/translate-utils/src/main/java/org/opendaylight/yang/gen/v1/urn/honeycomb/params/xml/ns/yang/translate/utils/rev160406/DelegatingReaderRegistryModule.java
+++ b/v3po/translate-utils/src/main/java/org/opendaylight/yang/gen/v1/urn/honeycomb/params/xml/ns/yang/translate/utils/rev160406/DelegatingReaderRegistryModule.java
@@ -1,18 +1,6 @@
 package org.opendaylight.yang.gen.v1.urn.honeycomb.params.xml.ns.yang.translate.utils.rev160406;
 
-import com.google.common.base.Function;
-import com.google.common.base.Optional;
-import com.google.common.collect.Lists;
-import com.google.common.collect.Multimap;
-import io.fd.honeycomb.v3po.translate.read.ReadContext;
-import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
-import io.fd.honeycomb.v3po.translate.read.Reader;
-import io.fd.honeycomb.v3po.translate.read.ReaderRegistry;
-import io.fd.honeycomb.v3po.translate.util.read.DelegatingReaderRegistry;
-import java.util.List;
-import javax.annotation.Nonnull;
-import org.opendaylight.yangtools.yang.binding.DataObject;
-import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import io.fd.honeycomb.v3po.translate.util.read.registry.CompositeReaderRegistryBuilder;
 
 public class DelegatingReaderRegistryModule extends org.opendaylight.yang.gen.v1.urn.honeycomb.params.xml.ns.yang.translate.utils.rev160406.AbstractDelegatingReaderRegistryModule {
     public DelegatingReaderRegistryModule(org.opendaylight.controller.config.api.ModuleIdentifier identifier, org.opendaylight.controller.config.api.DependencyResolver dependencyResolver) {
@@ -30,53 +18,8 @@ public class DelegatingReaderRegistryModule extends org.opendaylight.yang.gen.v1
 
     @Override
     public java.lang.AutoCloseable createInstance() {
-        final List<Reader<? extends DataObject>> rootReadersDependency = Lists.transform(getRootReadersDependency(),
-            new Function<Reader, Reader<? extends DataObject>>() {
-
-                @SuppressWarnings("unchecked")
-                @Override
-                public Reader<? extends DataObject> apply(final Reader input) {
-                    return input;
-                }
-            });
-        return new CloseableReaderRegistry(new DelegatingReaderRegistry(rootReadersDependency));
-    }
-
-
-
-    // TODO move to translate-utils
-    private static final class CloseableReaderRegistry implements ReaderRegistry, AutoCloseable {
-        private final DelegatingReaderRegistry delegatingReaderRegistry;
-
-        CloseableReaderRegistry(
-            final DelegatingReaderRegistry delegatingReaderRegistry) {
-            this.delegatingReaderRegistry = delegatingReaderRegistry;
-        }
-
-        @Override
-        @Nonnull
-        public Multimap<InstanceIdentifier<? extends DataObject>, ? extends DataObject> readAll(
-            @Nonnull final ReadContext ctx) throws ReadFailedException {
-            return delegatingReaderRegistry.readAll(ctx);
-        }
-
-        @Nonnull
-        @Override
-        public Optional<? extends DataObject> read(
-            @Nonnull final InstanceIdentifier<? extends DataObject> id,
-            @Nonnull final ReadContext ctx) throws ReadFailedException {
-            return delegatingReaderRegistry.read(id, ctx);
-        }
-
-        @Nonnull
-        @Override
-        public InstanceIdentifier<DataObject> getManagedDataObjectType() {
-            return delegatingReaderRegistry.getManagedDataObjectType();
-        }
-
-        @Override
-        public void close() throws Exception {
-            // NOOP
-        }
+        final CompositeReaderRegistryBuilder flatReaderRegistryBuilder = new CompositeReaderRegistryBuilder();
+        getReaderFactoryDependency().forEach(readerFactory -> readerFactory.init(flatReaderRegistryBuilder));
+        return flatReaderRegistryBuilder;
     }
 }
diff --git a/v3po/translate-utils/src/main/java/org/opendaylight/yang/gen/v1/urn/honeycomb/params/xml/ns/yang/translate/utils/rev160406/NoopWriterRegistryModule.java b/v3po/translate-utils/src/main/java/org/opendaylight/yang/gen/v1/urn/honeycomb/params/xml/ns/yang/translate/utils/rev160406/NoopWriterRegistryModule.java
index fedd069f1..0f72df9da 100644
--- a/v3po/translate-utils/src/main/java/org/opendaylight/yang/gen/v1/urn/honeycomb/params/xml/ns/yang/translate/utils/rev160406/NoopWriterRegistryModule.java
+++ b/v3po/translate-utils/src/main/java/org/opendaylight/yang/gen/v1/urn/honeycomb/params/xml/ns/yang/translate/utils/rev160406/NoopWriterRegistryModule.java
@@ -1,8 +1,8 @@
 package org.opendaylight.yang.gen.v1.urn.honeycomb.params.xml.ns.yang.translate.utils.rev160406;
 
 import io.fd.honeycomb.v3po.translate.util.write.NoopWriterRegistry;
-import io.fd.honeycomb.v3po.translate.write.WriterRegistry;
-import io.fd.honeycomb.v3po.translate.write.WriterRegistryBuilder;
+import io.fd.honeycomb.v3po.translate.write.registry.WriterRegistry;
+import io.fd.honeycomb.v3po.translate.write.registry.WriterRegistryBuilder;
 
 public class NoopWriterRegistryModule extends org.opendaylight.yang.gen.v1.urn.honeycomb.params.xml.ns.yang.translate.utils.rev160406.AbstractNoopWriterRegistryModule {
     public NoopWriterRegistryModule(org.opendaylight.controller.config.api.ModuleIdentifier identifier, org.opendaylight.controller.config.api.DependencyResolver dependencyResolver) {
diff --git a/v3po/translate-utils/src/main/yang/translate-utils.yang b/v3po/translate-utils/src/main/yang/translate-utils.yang
index 2c00bb548..b543bba0d 100644
--- a/v3po/translate-utils/src/main/yang/translate-utils.yang
+++ b/v3po/translate-utils/src/main/yang/translate-utils.yang
@@ -18,6 +18,7 @@ module translate-utils {
     identity delegating-reader-registry {
         base config:module-type;
         config:provided-service tapi:honeycomb-reader-registry;
+        config:provided-service tapi:honeycomb-reader-registry-builder;
         config:java-name-prefix DelegatingReaderRegistry;
     }
 
@@ -25,11 +26,11 @@ module translate-utils {
         case delegating-reader-registry {
             when "/config:modules/config:module/config:type = 'delegating-reader-registry'";
 
-                list root-readers {
+                list reader-factory {
                     uses config:service-ref {
                         refine type {
                             mandatory true;
-                            config:required-identity tapi:honeycomb-reader;
+                            config:required-identity tapi:honeycomb-reader-factory;
                         }
                     }
                 }
diff --git a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveAugmentReaderCustomizerTest.java b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveAugmentReaderCustomizerTest.java
deleted file mode 100644
index 3edc001a8..000000000
--- a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/read/ReflexiveAugmentReaderCustomizerTest.java
+++ /dev/null
@@ -1,46 +0,0 @@
-/*
- * Copyright (c) 2016 Cisco and/or its affiliates.
- *
- * Licensed 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 io.fd.honeycomb.v3po.translate.util.read;
-
-import static org.junit.Assert.assertSame;
-
-import org.junit.Before;
-import org.junit.Test;
-import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.interfaces.rev140508.interfaces.state.InterfaceBuilder;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.VppInterfaceStateAugmentation;
-import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.v3po.rev150105.VppInterfaceStateAugmentationBuilder;
-
-public class ReflexiveAugmentReaderCustomizerTest {
-
-    private ReflexiveAugmentReaderCustomizer<VppInterfaceStateAugmentation, VppInterfaceStateAugmentationBuilder>
-        vppIfcStateAugmentCustomizer;
-
-    @Before
-    public void setUp() throws Exception {
-        vppIfcStateAugmentCustomizer =
-            new ReflexiveAugmentReaderCustomizer<>(VppInterfaceStateAugmentationBuilder.class,
-                VppInterfaceStateAugmentation.class);
-    }
-
-    @Test
-    public void testAddAugment() throws Exception {
-        final InterfaceBuilder parentBuilder = new InterfaceBuilder();
-        final VppInterfaceStateAugmentation augmentation = vppIfcStateAugmentCustomizer.getBuilder(null).build();
-        vppIfcStateAugmentCustomizer.merge(parentBuilder, augmentation);
-        assertSame(augmentation, parentBuilder.getAugmentation(VppInterfaceStateAugmentation.class));
-    }
-}
\ No newline at end of file
diff --git a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/read/registry/TypeHierarchyTest.java b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/read/registry/TypeHierarchyTest.java
new file mode 100644
index 000000000..92449af28
--- /dev/null
+++ b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/read/registry/TypeHierarchyTest.java
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed 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 io.fd.honeycomb.v3po.translate.util.read.registry;
+
+import static org.hamcrest.CoreMatchers.hasItem;
+import static org.hamcrest.CoreMatchers.hasItems;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import com.google.common.collect.Sets;
+import org.junit.Test;
+import org.opendaylight.yangtools.yang.binding.ChildOf;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+public class TypeHierarchyTest {
+
+    @Test
+    public void testHierarchy() throws Exception {
+        final TypeHierarchy typeHierarchy = TypeHierarchy.create(Sets.newHashSet(
+                DataObject3.DataObject31.DataObject311.IID,
+                DataObject3.DataObject31.IID,/* Included in previous already */
+                DataObject1.IID,
+                DataObject2.DataObject21.IID));
+
+        // Roots
+        assertThat(typeHierarchy.getRoots().size(), is(3));
+        assertThat(typeHierarchy.getRoots(), hasItems(DataObject1.IID, DataObject2.IID, DataObject3.IID));
+
+        // Leaves
+        assertThat(typeHierarchy.getDirectChildren(DataObject1.IID).size(), is(0));
+        assertThat(typeHierarchy.getDirectChildren(DataObject2.DataObject21.IID).size(), is(0));
+        assertThat(typeHierarchy.getDirectChildren(DataObject3.DataObject31.DataObject311.IID).size(), is(0));
+
+        // Intermediate leaves
+        assertThat(typeHierarchy.getDirectChildren(DataObject2.IID).size(), is(1));
+        assertThat(typeHierarchy.getDirectChildren(DataObject2.IID), hasItem(DataObject2.DataObject21.IID));
+        assertEquals(typeHierarchy.getDirectChildren(DataObject2.IID), typeHierarchy.getAllChildren(DataObject2.IID));
+
+        assertThat(typeHierarchy.getDirectChildren(DataObject3.DataObject31.IID).size(), is(1));
+        assertThat(typeHierarchy.getDirectChildren(DataObject3.DataObject31.IID), hasItem(
+                DataObject3.DataObject31.DataObject311.IID));
+        assertEquals(typeHierarchy.getDirectChildren(DataObject3.DataObject31.IID), typeHierarchy.getAllChildren(
+                DataObject3.DataObject31.IID));
+
+        assertThat(typeHierarchy.getDirectChildren(DataObject3.IID).size(), is(1));
+        assertThat(typeHierarchy.getDirectChildren(DataObject3.IID), hasItem(DataObject3.DataObject31.IID));
+        assertThat(typeHierarchy.getAllChildren(DataObject3.IID).size(), is(2));
+        assertTrue(typeHierarchy.getAllChildren(DataObject3.IID).contains(DataObject3.DataObject31.IID));
+        assertTrue(typeHierarchy.getAllChildren(DataObject3.IID).contains(DataObject3.DataObject31.DataObject311.IID));
+    }
+
+    private abstract static class DataObject1 implements DataObject {
+        static InstanceIdentifier<DataObject1> IID = InstanceIdentifier.create(DataObject1.class);
+    }
+    private abstract static class DataObject2 implements DataObject {
+        static InstanceIdentifier<DataObject2> IID = InstanceIdentifier.create(DataObject2.class);
+        private abstract static class DataObject21 implements DataObject, ChildOf<DataObject2> {
+            static InstanceIdentifier<DataObject21> IID = DataObject2.IID.child(DataObject21.class);
+        }
+    }
+    private abstract static class DataObject3 implements DataObject {
+        static InstanceIdentifier<DataObject3> IID = InstanceIdentifier.create(DataObject3.class);
+        private abstract static class DataObject31 implements DataObject, ChildOf<DataObject3> {
+            static InstanceIdentifier<DataObject31> IID = DataObject3.IID.child(DataObject31.class);
+            private abstract static class DataObject311 implements DataObject, ChildOf<DataObject31> {
+                static InstanceIdentifier<DataObject311> IID = DataObject31.IID.child(DataObject311.class);
+            }
+        }
+    }
+}
+
diff --git a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilderTest.java b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilderTest.java
index ec407b685..da7ac0947 100644
--- a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilderTest.java
+++ b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryBuilderTest.java
@@ -31,13 +31,13 @@ public class FlatWriterRegistryBuilderTest {
             1   ->  2   ->  3
                         ->  4
          */
-        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject3.class));
-        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject4.class));
-        flatWriterRegistryBuilder.addWriterBefore(mockWriter(DataObject2.class),
+        flatWriterRegistryBuilder.add(mockWriter(DataObject3.class));
+        flatWriterRegistryBuilder.add(mockWriter(DataObject4.class));
+        flatWriterRegistryBuilder.addBefore(mockWriter(DataObject2.class),
                 Lists.newArrayList(DataObject3.IID, DataObject4.IID));
-        flatWriterRegistryBuilder.addWriterBefore(mockWriter(DataObject1.class), DataObject2.IID);
+        flatWriterRegistryBuilder.addBefore(mockWriter(DataObject1.class), DataObject2.IID);
         final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters =
-                flatWriterRegistryBuilder.getMappedWriters();
+                flatWriterRegistryBuilder.getMappedHandlers();
 
         final ArrayList<InstanceIdentifier<?>> typesInList = Lists.newArrayList(mappedWriters.keySet());
         assertEquals(DataObject1.IID, typesInList.get(0));
@@ -53,12 +53,12 @@ public class FlatWriterRegistryBuilderTest {
             1   ->  2   ->  3
                         ->  4
          */
-        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject1.class));
-        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject2.class), DataObject1.IID);
-        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject3.class), DataObject2.IID);
-        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject4.class), DataObject2.IID);
+        flatWriterRegistryBuilder.add(mockWriter(DataObject1.class));
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObject2.class), DataObject1.IID);
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObject3.class), DataObject2.IID);
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObject4.class), DataObject2.IID);
         final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters =
-                flatWriterRegistryBuilder.getMappedWriters();
+                flatWriterRegistryBuilder.getMappedHandlers();
 
         final List<InstanceIdentifier<?>> typesInList = Lists.newArrayList(mappedWriters.keySet());
         assertEquals(DataObject1.IID, typesInList.get(0));
@@ -73,27 +73,27 @@ public class FlatWriterRegistryBuilderTest {
         /*
             1   ->  2   ->  1
          */
-        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject1.class));
-        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject2.class), DataObject1.IID);
-        flatWriterRegistryBuilder.addWriterAfter(mockWriter(DataObject1.class), DataObject2.IID);
+        flatWriterRegistryBuilder.add(mockWriter(DataObject1.class));
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObject2.class), DataObject1.IID);
+        flatWriterRegistryBuilder.addAfter(mockWriter(DataObject1.class), DataObject2.IID);
     }
 
     @Test(expected = IllegalArgumentException.class)
     public void testAddWriterTwice() throws Exception {
         final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
-        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject1.class));
-        flatWriterRegistryBuilder.addWriter(mockWriter(DataObject1.class));
+        flatWriterRegistryBuilder.add(mockWriter(DataObject1.class));
+        flatWriterRegistryBuilder.add(mockWriter(DataObject1.class));
     }
 
     @Test
     public void testAddSubtreeWriter() throws Exception {
         final FlatWriterRegistryBuilder flatWriterRegistryBuilder = new FlatWriterRegistryBuilder();
-        flatWriterRegistryBuilder.addSubtreeWriter(
+        flatWriterRegistryBuilder.subtreeAdd(
                 Sets.newHashSet(DataObject4.DataObject5.IID,
                                 DataObject4.DataObject5.IID),
                 mockWriter(DataObject4.class));
         final ImmutableMap<InstanceIdentifier<?>, Writer<?>> mappedWriters =
-                flatWriterRegistryBuilder.getMappedWriters();
+                flatWriterRegistryBuilder.getMappedHandlers();
         final ArrayList<InstanceIdentifier<?>> typesInList = Lists.newArrayList(mappedWriters.keySet());
 
         assertEquals(DataObject4.IID, typesInList.get(0));
diff --git a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryTest.java b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryTest.java
index df3296557..1b4a059ea 100644
--- a/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryTest.java
+++ b/v3po/translate-utils/src/test/java/io/fd/honeycomb/v3po/translate/util/write/registry/FlatWriterRegistryTest.java
@@ -20,7 +20,7 @@ import com.google.common.collect.Multimap;
 import io.fd.honeycomb.v3po.translate.write.DataObjectUpdate;
 import io.fd.honeycomb.v3po.translate.write.WriteContext;
 import io.fd.honeycomb.v3po.translate.write.Writer;
-import io.fd.honeycomb.v3po.translate.write.WriterRegistry;
+import io.fd.honeycomb.v3po.translate.write.registry.WriterRegistry;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.InOrder;
@@ -49,19 +49,6 @@ public class FlatWriterRegistryTest {
     }
 
     @Test
-    public void testSingleUpdate() throws Exception {
-        final FlatWriterRegistry flatWriterRegistry =
-                new FlatWriterRegistry(ImmutableMap.of(DataObject1.IID, writer1));
-
-        final InstanceIdentifier<DataObject1> iid = InstanceIdentifier.create(DataObject1.class);
-        final DataObject1 before = mock(DataObject1.class);
-        final DataObject1 after = mock(DataObject1.class);
-        flatWriterRegistry.update(iid, before, after, ctx);
-
-        verify(writer1).update(iid, before, after, ctx);
-    }
-
-    @Test
     public void testMultipleUpdatesForSingleWriter() throws Exception {
         final FlatWriterRegistry flatWriterRegistry =
                 new FlatWriterRegistry(ImmutableMap.of(DataObject1.IID, writer1, DataObject2.IID, writer2));
@@ -272,17 +259,6 @@ public class FlatWriterRegistryTest {
         updates.put(iid, DataObjectUpdate.create(iid, mock(type), mock(type)));
     }
 
-    @Test(expected = IllegalArgumentException.class)
-    public void testSingleUpdateMissingWriter() throws Exception {
-        final FlatWriterRegistry flatWriterRegistry =
-                new FlatWriterRegistry(ImmutableMap.of());
-
-        final InstanceIdentifier<DataObject1> iid = InstanceIdentifier.create(DataObject1.class);
-        final DataObject1 before = mock(DataObject1.class);
-        final DataObject1 after = mock(DataObject1.class);
-        flatWriterRegistry.update(iid, before, after, ctx);
-    }
-
     private abstract static class DataObject1 implements DataObject {
         static final InstanceIdentifier<DataObject1> IID = InstanceIdentifier.create(DataObject1.class);
     }