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>

17 files changed, 368 insertions, 155 deletions

diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/ModifiableSubtreeManagerRegistryBuilder.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/ModifiableSubtreeManagerRegistryBuilder.java
new file mode 100644
index 000000000..591a9e9bb
--- /dev/null
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/ModifiableSubtreeManagerRegistryBuilder.java
@@ -0,0 +1,77 @@
+/*
+ * 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;
+
+import java.util.Collection;
+import java.util.Set;
+import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+/**
+ * Registry builder where {@link SubtreeManager}s can be added with or without relationships between them.
+ * The relationships express what the order of execution should be.
+ */
+public interface ModifiableSubtreeManagerRegistryBuilder<S extends SubtreeManager<? extends DataObject>> {
+
+    /**
+     * Add a handler responsible for writing only a single complex node.
+     */
+    ModifiableSubtreeManagerRegistryBuilder<S> add(@Nonnull S handler);
+
+    /**
+     * Add a handler responsible for writing multiple complex nodes within a subtree its responsible for. Identifiers for
+     * subtree nodes handled by a single handler have to be relative from {@link DataObject} that represents subtree
+     * root.
+     */
+    ModifiableSubtreeManagerRegistryBuilder<S> subtreeAdd(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
+                                                          @Nonnull S handler);
+
+    /**
+     * Add a handler and make sure it will be executed before handler identifier by relatedType is executed.
+     */
+    ModifiableSubtreeManagerRegistryBuilder<S> addBefore(@Nonnull S handler,
+                                                         @Nonnull InstanceIdentifier<?> relatedType);
+
+    ModifiableSubtreeManagerRegistryBuilder<S> addBefore(@Nonnull S handler,
+                                                         @Nonnull Collection<InstanceIdentifier<?>> relatedTypes);
+
+    ModifiableSubtreeManagerRegistryBuilder<S> subtreeAddBefore(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
+                                                                @Nonnull S handler,
+                                                                @Nonnull InstanceIdentifier<?> relatedType);
+
+    ModifiableSubtreeManagerRegistryBuilder<S> subtreeAddBefore(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
+                                                                @Nonnull S handler,
+                                                                @Nonnull Collection<InstanceIdentifier<?>> relatedTypes);
+
+    /**
+     * Add a handler and make sure it will be executed after handler identifier by relatedType is executed.
+     */
+    ModifiableSubtreeManagerRegistryBuilder<S> addAfter(@Nonnull S handler,
+                                                        @Nonnull InstanceIdentifier<?> relatedType);
+
+    ModifiableSubtreeManagerRegistryBuilder<S> addAfter(@Nonnull S handler,
+                                                        @Nonnull Collection<InstanceIdentifier<?>> relatedTypes);
+
+    ModifiableSubtreeManagerRegistryBuilder<S> subtreeAddAfter(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
+                                                               @Nonnull S handler,
+                                                               @Nonnull InstanceIdentifier<?> relatedType);
+
+    ModifiableSubtreeManagerRegistryBuilder<S> subtreeAddAfter(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
+                                                               @Nonnull S handler,
+                                                               @Nonnull Collection<InstanceIdentifier<?>> relatedTypes);
+}
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/SubtreeManager.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/SubtreeManager.java
index 39e403642..40842763d 100644
--- a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/SubtreeManager.java
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/SubtreeManager.java
@@ -30,9 +30,9 @@ import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 public interface SubtreeManager<D extends DataObject> {
 
     /**
-     * Gets the type of node managed by this reader
+     * Gets the type of node managed by this reader.
      *
-     * @return Class object for node managed by this reader
+     * @return Absolute instance identifier for managed type
      */
     @Nonnull
     InstanceIdentifier<D> getManagedDataObjectType();
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/WriterRegistryBuilder.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/SubtreeManagerRegistryBuilder.java
index 55ef66ec6..2434deddb 100644
--- a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/WriterRegistryBuilder.java
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/SubtreeManagerRegistryBuilder.java
@@ -14,12 +14,9 @@
  * limitations under the License.
  */
 
-package io.fd.honeycomb.v3po.translate.write;
+package io.fd.honeycomb.v3po.translate;
 
-/**
- * Builder for writer registries.
- */
-public interface WriterRegistryBuilder {
+public interface SubtreeManagerRegistryBuilder<R> {
 
-    WriterRegistry build();
+    R build();
 }
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ChildReader.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ChildReader.java
deleted file mode 100644
index 02b6b8d26..000000000
--- a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ChildReader.java
+++ /dev/null
@@ -1,50 +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.read;
-
-import com.google.common.annotations.Beta;
-import javax.annotation.Nonnull;
-import org.opendaylight.yangtools.concepts.Builder;
-import org.opendaylight.yangtools.yang.binding.DataObject;
-import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
-
-/**
- * Child reader allowing its parent to pass the builder object
- *
- * @param <C> Specific DataObject derived type, that is handled by this reader
- */
-@Beta
-public interface ChildReader<C extends DataObject> extends Reader<C> {
-
-    /**
-     * Reads subtree starting from node managed by this reader and place the subtree within parent builder object if the
-     * data exists.
-     *
-     * @param id            Unique identifier pointing to the node managed by this reader. Useful when necessary to
-     *                      determine the exact position within more complex subtrees.
-     * @param parentBuilder Builder of parent DataObject. Objects read on this level (if any) must be placed into the
-     *                      parent builder.
-     * @param ctx Read context
-     *
-     * @throws ReadFailedException if read was unsuccessful
-     */
-    void read(@Nonnull final InstanceIdentifier<? extends DataObject> id,
-              @Nonnull final Builder<? extends DataObject> parentBuilder,
-              @Nonnull final ReadContext ctx) throws ReadFailedException;
-
-}
-
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ListReader.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ListReader.java
index faf6f0a19..13a7a55da 100644
--- a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ListReader.java
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ListReader.java
@@ -17,23 +17,26 @@
 package io.fd.honeycomb.v3po.translate.read;
 
 import com.google.common.annotations.Beta;
+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;
 
 /**
- * List reader, allowing read of all the elements
+ * List reader, allowing read of all the elements.
  *
  * @param <D> Specific DataObject derived type, that is handled by this reader
  */
 @Beta
-public interface ListReader<D extends DataObject & Identifiable<K>, K extends Identifier<D>> extends Reader<D> {
+public interface ListReader
+        <D extends DataObject & Identifiable<K>, K extends Identifier<D>, B extends Builder<D>> extends Reader<D, B> {
 
     /**
-     * Read all elements in this list
+     * Read all elements in this list.
      *
      * @param id Wildcarded identifier of list managed by this reader
      * @param ctx Read context
@@ -42,6 +45,22 @@ public interface ListReader<D extends DataObject & Identifiable<K>, K extends Id
      * @throws ReadFailedException if read was unsuccessful
      */
     @Nonnull
-    List<D> readList(@Nonnull final InstanceIdentifier<D> id,
-                     @Nonnull final ReadContext ctx) throws ReadFailedException;
+    List<D> readList(@Nonnull final InstanceIdentifier<D> id, @Nonnull final ReadContext ctx)
+            throws ReadFailedException;
+
+    /**
+     * Get IDs for all entries in the list.
+     */
+    List<K> getAllIds(@Nonnull InstanceIdentifier<D> id, @Nonnull ReadContext ctx)
+            throws ReadFailedException;
+
+    /**
+     * Merge read data into provided parent builder.
+     */
+    void merge(@Nonnull final Builder<? extends DataObject> builder, @Nonnull final List<D> readData);
+
+    @Override
+    default void merge(@Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final D readValue) {
+        merge(parentBuilder, Collections.singletonList(readValue));
+    }
 }
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/Reader.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/Reader.java
index 122263cb3..d0bf0dea1 100644
--- a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/Reader.java
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/Reader.java
@@ -20,16 +20,17 @@ import com.google.common.annotations.Beta;
 import com.google.common.base.Optional;
 import io.fd.honeycomb.v3po.translate.SubtreeManager;
 import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.concepts.Builder;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 
 /**
- * Base reader, responsible for translation between DataObjects and any other side
+ * Base reader, responsible for translation between DataObjects and any other side.
  *
  * @param <D> Specific DataObject derived type, that is handled by this reader
  */
 @Beta
-public interface Reader<D extends DataObject> extends SubtreeManager<D> {
+public interface Reader<D extends DataObject, B extends Builder<D>> extends SubtreeManager<D> {
 
     // TODO make async
 
@@ -45,7 +46,31 @@ public interface Reader<D extends DataObject> extends SubtreeManager<D> {
      * @throws ReadFailedException if read was unsuccessful
      */
     @Nonnull
-    Optional<? extends DataObject> read(@Nonnull final InstanceIdentifier<? extends DataObject> id,
+    Optional<? extends DataObject> read(@Nonnull InstanceIdentifier<? extends DataObject> id,
                                         @Nonnull ReadContext ctx) throws ReadFailedException;
 
+    /**
+     * Fill in current node's attributes
+     *
+     * @param id {@link InstanceIdentifier} pointing to current node. In case of keyed list, key must be present.
+     * @param builder Builder object for current node where the read attributes must be placed
+     * @param ctx Current read context
+     */
+    void readCurrentAttributes(@Nonnull InstanceIdentifier<D> id,
+                               @Nonnull B builder,
+                               @Nonnull ReadContext ctx) throws ReadFailedException;
+
+    /**
+     * Return new instance of a builder object for current node
+     *
+     * @param id {@link InstanceIdentifier} pointing to current node. In case of keyed list, key must be present.
+     * @return Builder object for current node type
+     */
+    @Nonnull
+    B getBuilder(InstanceIdentifier<D> id);
+
+    /**
+     * Merge read data into provided parent builder.
+     */
+    void merge(@Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final D readValue);
 }
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ReaderFactory.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ReaderFactory.java
new file mode 100644
index 000000000..6d6d52acc
--- /dev/null
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ReaderFactory.java
@@ -0,0 +1,33 @@
+/*
+ * 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.read;
+
+import com.google.common.annotations.Beta;
+import io.fd.honeycomb.v3po.translate.read.registry.ModifiableReaderRegistryBuilder;
+import javax.annotation.Nonnull;
+
+/**
+ * Factory producing readers for {@link ModifiableReaderRegistryBuilder}.
+ */
+@Beta
+public interface ReaderFactory {
+
+    /**
+     * Initialize 1 or more readers and add them to provided registry.
+     */
+    void init(@Nonnull ModifiableReaderRegistryBuilder registry);
+}
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/registry/ModifiableReaderRegistryBuilder.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/registry/ModifiableReaderRegistryBuilder.java
new file mode 100644
index 000000000..c2eba4f72
--- /dev/null
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/registry/ModifiableReaderRegistryBuilder.java
@@ -0,0 +1,41 @@
+/*
+ * 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.read.registry;
+
+import com.google.common.annotations.Beta;
+import io.fd.honeycomb.v3po.translate.ModifiableSubtreeManagerRegistryBuilder;
+import io.fd.honeycomb.v3po.translate.read.Reader;
+import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+
+/**
+ * Mutable registry that allows adding new readers.
+ */
+@Beta
+public interface ModifiableReaderRegistryBuilder
+        extends ModifiableSubtreeManagerRegistryBuilder<Reader<? extends DataObject, ? extends Builder<?>>> {
+
+    // TODO we should be able to add structural/reflexive readers automatically in the registry builder, we just need builder class
+    // We would need generated class loading strategy instance and then load builder classes relying on naming + package conventions of Binding spec
+    /**
+     * Add a structural reader that performs no read operation on its own, just fills in the hierarchy.
+     */
+    <D extends DataObject> void addStructuralReader(@Nonnull InstanceIdentifier<D> id,
+                                                    @Nonnull Class<? extends Builder<D>> builderType);
+}
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ReaderRegistry.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/registry/ReaderRegistry.java
index f34455a27..308ec238d 100644
--- a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/ReaderRegistry.java
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/registry/ReaderRegistry.java
@@ -14,10 +14,13 @@
  * limitations under the License.
  */
 
-package io.fd.honeycomb.v3po.translate.read;
+package io.fd.honeycomb.v3po.translate.read.registry;
 
 import com.google.common.annotations.Beta;
+import com.google.common.base.Optional;
 import com.google.common.collect.Multimap;
+import io.fd.honeycomb.v3po.translate.read.ReadContext;
+import io.fd.honeycomb.v3po.translate.read.ReadFailedException;
 import javax.annotation.Nonnull;
 import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
@@ -26,7 +29,7 @@ import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
  * Simple delegating reader suitable as a holder for all other root readers, providing readAll feature.
  */
 @Beta
-public interface ReaderRegistry extends Reader<DataObject> {
+public interface ReaderRegistry {
 
     /**
      * Performs read on all registered root readers and merges the results into a Multimap. Keys represent identifiers
@@ -40,4 +43,20 @@ public interface ReaderRegistry extends Reader<DataObject> {
     @Nonnull
     Multimap<InstanceIdentifier<? extends DataObject>, ? extends DataObject> readAll(@Nonnull final ReadContext ctx)
             throws ReadFailedException;
+
+    /**
+     * Reads data identified by id.
+     *
+     * @param id unique identifier of subtree to be read. The subtree must contain managed data object type. For
+     *           identifiers pointing below node managed by this reader, it's reader's responsibility to filter out the
+     *           right node or to delegate the read to a child reader.
+     * @param ctx Read context
+     *
+     * @return List of DataObjects identified by id. If the ID points to a single node, it will be wrapped in a list
+     * @throws ReadFailedException if read was unsuccessful
+     */
+    @Nonnull
+    Optional<? extends DataObject> read(@Nonnull InstanceIdentifier<? extends DataObject> id,
+                                        @Nonnull ReadContext ctx)
+            throws ReadFailedException;
 }
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/registry/ReaderRegistryBuilder.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/registry/ReaderRegistryBuilder.java
new file mode 100644
index 000000000..ff95d6248
--- /dev/null
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/read/registry/ReaderRegistryBuilder.java
@@ -0,0 +1,27 @@
+/*
+ * 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.read.registry;
+
+import com.google.common.annotations.Beta;
+import io.fd.honeycomb.v3po.translate.SubtreeManagerRegistryBuilder;
+
+/**
+ * Builder for reader registries.
+ */
+@Beta
+public interface ReaderRegistryBuilder extends SubtreeManagerRegistryBuilder<ReaderRegistry> {
+}
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/ListWriter.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/ListWriter.java
new file mode 100644
index 000000000..f29289d2d
--- /dev/null
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/ListWriter.java
@@ -0,0 +1,33 @@
+/*
+ * 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.write;
+
+import com.google.common.annotations.Beta;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.Identifiable;
+import org.opendaylight.yangtools.yang.binding.Identifier;
+
+/**
+ * List writer, responsible for translation between a list of DataObjects and any other side.
+ * Handling all update operations(create, update, delete)
+ *
+ * @param <D> Specific DataObject derived type, that is handled by this writer
+ * @param <K> Identifier/key for D
+ */
+@Beta
+public interface ListWriter<D extends DataObject & Identifiable<K>, K extends Identifier<D>> extends Writer<D> {
+}
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/ModifiableWriterRegistry.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/ModifiableWriterRegistry.java
deleted file mode 100644
index 71ecbb806..000000000
--- a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/ModifiableWriterRegistry.java
+++ /dev/null
@@ -1,78 +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.write;
-
-import com.google.common.annotations.Beta;
-import java.util.Collection;
-import java.util.Set;
-import javax.annotation.Nonnull;
-import org.opendaylight.yangtools.yang.binding.DataObject;
-import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
-
-/**
- * Mutable registry that allows adding new writers.
- */
-@Beta
-public interface ModifiableWriterRegistry {
-
-    /**
-     * Add a writer responsible for writing only a single complex node.
-     */
-    ModifiableWriterRegistry addWriter(@Nonnull Writer<? extends DataObject> writer);
-
-    /**
-     * Add a writer responsible for writing multiple complex nodes within a subtree its responsible for.
-     * Identifiers for subtree nodes handled by a single writer have to be relative from {@link DataObject} that
-     * represents subtree root.
-     */
-    ModifiableWriterRegistry addSubtreeWriter(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
-                                              @Nonnull Writer<? extends DataObject> writer);
-
-    /**
-     * Add a writer and make sure it will be executed before writer identifier by relatedType is executed.
-     */
-    ModifiableWriterRegistry addWriterBefore(@Nonnull Writer<? extends DataObject> writer,
-                                             @Nonnull InstanceIdentifier<?> relatedType);
-
-    ModifiableWriterRegistry addSubtreeWriterBefore(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
-                                                    @Nonnull Writer<? extends DataObject> writer,
-                                                    @Nonnull InstanceIdentifier<?> relatedType);
-
-    ModifiableWriterRegistry addWriterBefore(@Nonnull Writer<? extends DataObject> writer,
-                                             @Nonnull Collection<InstanceIdentifier<?>> relatedTypes);
-
-    ModifiableWriterRegistry addSubtreeWriterBefore(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
-                                                    @Nonnull Writer<? extends DataObject> writer,
-                                                    @Nonnull Collection<InstanceIdentifier<?>> relatedTypes);
-
-    /**
-     * Add a writer and make sure it will be executed after writer identifier by relatedType is executed.
-     */
-    ModifiableWriterRegistry addWriterAfter(@Nonnull Writer<? extends DataObject> writer,
-                                            @Nonnull InstanceIdentifier<?> relatedType);
-
-    ModifiableWriterRegistry addSubtreeWriterAfter(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
-                                                   @Nonnull Writer<? extends DataObject> writer,
-                                                   @Nonnull InstanceIdentifier<?> relatedType);
-
-    ModifiableWriterRegistry addWriterAfter(@Nonnull Writer<? extends DataObject> writer,
-                                            @Nonnull Collection<InstanceIdentifier<?>> relatedTypes);
-
-    ModifiableWriterRegistry addSubtreeWriterAfter(@Nonnull Set<InstanceIdentifier<?>> handledChildren,
-                                                   @Nonnull Writer<? extends DataObject> writer,
-                                                   @Nonnull Collection<InstanceIdentifier<?>> relatedTypes);
-}
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/WriterFactory.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/WriterFactory.java
index 4287964db..dfcffa47f 100644
--- a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/WriterFactory.java
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/WriterFactory.java
@@ -17,12 +17,17 @@
 package io.fd.honeycomb.v3po.translate.write;
 
 import com.google.common.annotations.Beta;
+import io.fd.honeycomb.v3po.translate.write.registry.ModifiableWriterRegistryBuilder;
+import javax.annotation.Nonnull;
 
+/**
+ * Factory producing writers for {@link ModifiableWriterRegistryBuilder}.
+ */
 @Beta
 public interface WriterFactory {
 
     /**
      * Initialize 1 or more writers and add them to provided registry.
      */
-    void init(ModifiableWriterRegistry registry);
+    void init(@Nonnull ModifiableWriterRegistryBuilder registry);
 }
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/registry/ModifiableWriterRegistryBuilder.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/registry/ModifiableWriterRegistryBuilder.java
new file mode 100644
index 000000000..8670a5059
--- /dev/null
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/registry/ModifiableWriterRegistryBuilder.java
@@ -0,0 +1,31 @@
+/*
+ * 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.write.registry;
+
+import com.google.common.annotations.Beta;
+import io.fd.honeycomb.v3po.translate.ModifiableSubtreeManagerRegistryBuilder;
+import io.fd.honeycomb.v3po.translate.write.Writer;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+
+/**
+ * Mutable registry that allows adding new writers.
+ */
+@Beta
+public interface ModifiableWriterRegistryBuilder
+        extends ModifiableSubtreeManagerRegistryBuilder<Writer<? extends DataObject>> {
+
+}
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/WriterRegistry.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/registry/WriterRegistry.java
index 64735017f..439a85410 100644
--- a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/WriterRegistry.java
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/registry/WriterRegistry.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.fd.honeycomb.v3po.translate.write;
+package io.fd.honeycomb.v3po.translate.write.registry;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
@@ -23,16 +23,18 @@ import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Sets;
 import io.fd.honeycomb.v3po.translate.TranslationException;
+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 java.util.Set;
 import javax.annotation.Nonnull;
-import org.opendaylight.yangtools.yang.binding.DataObject;
 import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 
 /**
  * Special {@link Writer} capable of performing bulk updates.
  */
 @Beta
-public interface WriterRegistry extends Writer<DataObject> {
+public interface WriterRegistry {
 
     /**
      * Performs bulk update.
diff --git a/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/registry/WriterRegistryBuilder.java b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/registry/WriterRegistryBuilder.java
new file mode 100644
index 000000000..3f0289ece
--- /dev/null
+++ b/v3po/translate-api/src/main/java/io/fd/honeycomb/v3po/translate/write/registry/WriterRegistryBuilder.java
@@ -0,0 +1,27 @@
+/*
+ * 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.write.registry;
+
+import com.google.common.annotations.Beta;
+import io.fd.honeycomb.v3po.translate.SubtreeManagerRegistryBuilder;
+
+/**
+ * Builder for writer registries.
+ */
+@Beta
+public interface WriterRegistryBuilder extends SubtreeManagerRegistryBuilder<WriterRegistry> {
+}
diff --git a/v3po/translate-api/src/main/yang/translate-api.yang b/v3po/translate-api/src/main/yang/translate-api.yang
index 414ee20e1..796632dd2 100644
--- a/v3po/translate-api/src/main/yang/translate-api.yang
+++ b/v3po/translate-api/src/main/yang/translate-api.yang
@@ -14,14 +14,19 @@ module translate-api {
             "Initial revision.";
     }
 
-    identity honeycomb-reader {
+    identity honeycomb-reader-factory {
         base "config:service-type";
-        config:java-class io.fd.honeycomb.v3po.translate.read.Reader;
+        config:java-class io.fd.honeycomb.v3po.translate.read.ReaderFactory;
     }
 
     identity honeycomb-reader-registry {
         base "config:service-type";
-        config:java-class io.fd.honeycomb.v3po.translate.read.ReaderRegistry;
+        config:java-class io.fd.honeycomb.v3po.translate.read.registry.ModifiableReaderRegistryBuilder;
+    }
+
+    identity honeycomb-reader-registry-builder {
+        base "config:service-type";
+        config:java-class io.fd.honeycomb.v3po.translate.read.registry.ReaderRegistryBuilder;
     }
 
     identity honeycomb-writer-factory {
@@ -31,12 +36,12 @@ module translate-api {
 
     identity honeycomb-writer-registry {
         base "config:service-type";
-        config:java-class io.fd.honeycomb.v3po.translate.write.ModifiableWriterRegistry;
+        config:java-class io.fd.honeycomb.v3po.translate.write.registry.ModifiableWriterRegistryBuilder;
     }
 
     identity honeycomb-writer-registry-builder {
         base "config:service-type";
-        config:java-class io.fd.honeycomb.v3po.translate.write.WriterRegistryBuilder;
+        config:java-class io.fd.honeycomb.v3po.translate.write.registry.WriterRegistryBuilder;
     }
 
     identity honeycomb-mapping-context {