diff --git a/apps/yms/api/src/main/java/org/onosproject/yms/ydt/YdtBuilder.java b/apps/yms/api/src/main/java/org/onosproject/yms/ydt/YdtBuilder.java
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+++ b/apps/yms/api/src/main/java/org/onosproject/yms/ydt/YdtBuilder.java
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+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * 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 org.onosproject.yms.ydt;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Abstraction of an entity which provides interfaces to build and obtain YANG
+ * data tree which is data (sub)instance representation, abstract of protocol.
+ *
+ * NBI protocols need to translate the protocol operation request, into a
+ * protocol independent abstract tree called the YANG data tree (YDT). In order
+ * to enable the protocol in building these abstract data tree, YANG
+ * management system provides a utility called the YANG data tree builder.
+ */
+public interface YdtBuilder
+        extends Ydt {
+
+    /**
+     * Sets root node tag attributes. This is used by protocol
+     * to specify tag attributes associated with root resource.
+     *
+     * @param attributeTag map of root tags attribute values indexed by root
+     *                     tag name.
+     */
+    void setRootTagAttributeMap(Map<String, String> attributeTag);
+
+    /**
+     * Returns map of tag attribute list associated with root resource.
+     *
+     * @return linked hash map of tag name with value
+     */
+    Map<String, String> getRootTagAttributeMap();
+
+    /**
+     * Adds a last child to YANG data tree, this method is to be used by
+     * protocols which are unaware of the nature (single/multiple) of node and
+     * also unaware of the operation type at every node(Example: RESTCONF).
+     *
+     * Add child is used to add module/sub-module nodes also. Request may
+     * contain revision number corresponding to Module/sub-module in that
+     * case YMS expect revision number to be appended to module/sub-module
+     * name in the below mentioned format.
+     * module-or-submodule-name ['@' date-arg]
+     * date-arg = 4DIGIT "-" 2DIGIT "-" 2DIGIT
+     * Example: testModule@2016-10-27.
+     *
+     * If the revision date is not specified YMS first search for
+     * registered module/sub-module without revision date, if still can't obtain
+     * then uses registered module/sub-module with latest revision date.
+     *
+     * @param name      name of child to be added
+     * @param namespace namespace of child to be added, if it's null, parent's
+     *                  namespace will be applied to child
+     */
+    void addChild(String name, String namespace);
+
+    /**
+     * Adds a last child to YANG data tree, this method is to be used by
+     * protocols which are aware of the nature (single/multiple) of node.
+     *
+     * Add child is used to add module/sub-module nodes also. Request may
+     * contain revision number corresponding to Module/sub-module in that
+     * case YMS expect revision number to be appended to module/sub-module
+     * name in the below mentioned format.
+     * module-or-submodule-name ['@' date-arg]
+     * date-arg = 4DIGIT "-" 2DIGIT "-" 2DIGIT
+     * Example: testModule@2016-10-27.
+     *
+     * If the revision date is not specified YMS first search for
+     * registered module/sub-module without revision date, if still can't obtain
+     * then uses registered module/sub-module with latest revision date.
+     *
+     * @param name      name of child to be added
+     * @param namespace namespace of child to be added, if it's null, parent's
+     *                  namespace will be applied to child
+     * @param ydtType   type of YDT node to be added
+     */
+    void addChild(String name, String namespace, YdtType ydtType);
+
+    /**
+     * Adds a last child to YANG data tree, this method is to be used by
+     * protocols which are unaware of the nature (single/multiple) of node.
+     * This is an overloaded method with operation type. This method can
+     * optionally
+     * be used when protocol doesn't want to specify operation type by
+     * keeping it null.
+     *
+     * Add child is used to add module/sub-module nodes also. Request may
+     * contain revision number corresponding to Module/sub-module in that
+     * case YMS expect revision number to be appended to module/sub-module
+     * name in the below mentioned format.
+     * module-or-submodule-name ['@' date-arg]
+     * date-arg = 4DIGIT "-" 2DIGIT "-" 2DIGIT
+     * Example: testModule@2016-10-27.
+     *
+     * If the revision date is not specified YMS first search for
+     * registered module/sub-module without revision date, if still can't obtain
+     * then uses registered module/sub-module with latest revision date.
+     *
+     * @param name      name of child to be added
+     * @param namespace namespace of child to be added, if it's null, parent's
+     *                  namespace will be applied to child
+     * @param opType    type of requested operation over a node
+     */
+    void addChild(String name, String namespace,
+                  YdtContextOperationType opType);
+
+    /**
+     * Adds a last child to YANG data tree, this method is to be used by
+     * protocols which are aware of the nature (single/multiple) of node.
+     * This is an overloaded method with operation type. This method can
+     * optionally
+     * be used when protocol doesn't want to specify operation type by
+     * keeping it null.
+     *
+     * Add child is used to add module/sub-module nodes also. Request may
+     * contain revision number corresponding to Module/sub-module in that
+     * case YMS expect revision number to be appended to module/sub-module
+     * name in the below mentioned format.
+     * module-or-submodule-name ['@' date-arg]
+     * date-arg = 4DIGIT "-" 2DIGIT "-" 2DIGIT
+     * Example: testModule@2016-10-27.
+     *
+     * If the revision date is not specified YMS first search for
+     * registered module/sub-module without revision date, if still can't obtain
+     * then uses registered module/sub-module with latest revision date.
+     *
+     * @param name      name of child to be added
+     * @param namespace namespace of child to be added, if it's null, parent's
+     *                  namespace will be applied to child
+     * @param ydtType   type of YDT node to be added
+     * @param opType    type of requested operation over a node
+     */
+    void addChild(String name, String namespace, YdtType ydtType,
+                  YdtContextOperationType opType);
+
+
+    /**
+     * Adds a last leaf with value to YANG data tree. Protocols unaware of
+     * nature
+     * of leaf (single/multiple) will use it to add both single instance and
+     * multi instance node. Protocols aware of nature of node will use it for
+     * single instance value node addition.
+     * Value of leaf can be null which indicates selection node in get
+     * operation.
+     *
+     * @param name      name of child to be added
+     * @param namespace namespace of child to be added, if it's null, parent's
+     *                  namespace will be applied to child
+     * @param value     value of the child
+     */
+    void addLeaf(String name, String namespace, String value);
+
+    /**
+     * Adds a last leaf with list of values to YANG data tree. This method is
+     * used by protocols which knows the nature (single/multiple) of node for
+     * multi instance node addition.
+     * Value of leaf can be null which indicates selection node in get
+     * operation.
+     *
+     * @param name      name of child to be added
+     * @param namespace namespace of child to be added, if it's null, parent's
+     *                  namespace will be applied to child
+     * @param valueSet  list of value of the child
+     */
+    void addLeaf(String name, String namespace, Set<String> valueSet);
+
+    /**
+     * Adds YANG list's keys value in the order defined in list's key statement.
+     * All the keys must be present any missing key or invalid key will result
+     * in exception.
+     *
+     * @param keysValueList values of the keys in URI in the same order
+     *                      as defined in YANG file
+     */
+    void addKeyLeafs(List<String> keysValueList);
+
+    /**
+     * Traverses up in YANG data tree to the parent node, it is to be used when
+     * protocol is using context type "current" and wanted to traverse up the
+     * tree.
+     */
+    void traverseToParent();
+
+    /**
+     * Returns the current context information available in YDT node.
+     *
+     * @return current YDT context
+     */
+    YdtContext getCurNode();
+
+    /**
+     * Sets default operation type. This operation type is taken if operation
+     * type is not explicitly specified in request. If default operation type
+     * is not set, merge will be taken as default operation type.
+     *
+     * @param ydtContextOperationType default edit operation type
+     */
+    void setDefaultEditOperationType(
+            YdtContextOperationType ydtContextOperationType);
+}