diff --git a/apps/yms/api/src/main/java/org/onosproject/yms/ydt/YdtWalker.java b/apps/yms/api/src/main/java/org/onosproject/yms/ydt/YdtWalker.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;
+
+/**
+ * Abstraction of an entity which provides interfaces for YDT walk.
+ *
+ * When YANG management system gets data from application to be returned
+ * to protocol for any protocol operation or as a part of notification, YANG
+ * management system encodes this data in a YANG data tree and sends the same
+ * to protocol.
+ * Protocols can use the YANG data tree walker utility to have their
+ * callbacks to be invoked as per the YANG data tree walking.
+ * By this way protocols can encode the data from abstract YANG data tree
+ * into a protocol specific representation.
+ *
+ * YDT walker provides entry and exit callbacks for each node in YANG data
+ * tree.
+ */
+public interface YdtWalker {
+
+    /**
+     * Walks the YANG data tree. Protocols implements YDT listener service
+     * and walks YDT tree with input as implemented object. YDT walker provides
+     * call backs to implemented methods.
+     *
+     * @param ydtListener YDT listener implemented by the protocol
+     * @param rootNode    root node of YDT
+     */
+    void walk(YdtListener ydtListener, YdtContext rootNode);
+}