YMS broker and Notification handler

Change-Id: Ic3659b2c2ad26ea2db1f03725b4883f19db2cc41
diff --git a/apps/yms/api/src/main/java/org/onosproject/yms/ynh/YangNotificationEvent.java b/apps/yms/api/src/main/java/org/onosproject/yms/ynh/YangNotificationEvent.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.ynh;
+
+import org.onosproject.event.AbstractEvent;
+
+/**
+ * Represents YANG notification event.
+ *
+ * YANG notification handler listens for the notification from the application.
+ * It convert the received notification in YANG notification events.
+ *
+ * YangNotificationEvent represents event generated by YANG management system
+ * in response to the YANG defined application notification. The applications
+ * notification information is in abstract YANG data tree.
+ */
+public class YangNotificationEvent
+        extends AbstractEvent<YangNotificationEvent.Type, YangNotification> {
+
+    /**
+     * Event type is the notification as defined in the YANG file.
+     */
+    public enum Type {
+        /**
+         * Indicates a YANG notification.
+         */
+        YANG_NOTIFICATION
+    }
+
+    /**
+     * YANG notification information shared to NBI protocol in YANG data tree
+     * using the registered callback.
+     *
+     * @param subject notification information in YANG data tree.
+     */
+    public YangNotificationEvent(YangNotification subject) {
+        super(Type.YANG_NOTIFICATION, subject);
+    }
+}