--- /dev/null
+
+/*
+ * Copyright (c) 2013 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package org.opendaylight.controller.sal.topology;
+
+import java.util.Set;
+
+import org.opendaylight.controller.sal.core.Edge;
+import org.opendaylight.controller.sal.core.Property;
+import org.opendaylight.controller.sal.core.UpdateType;
+
+/**
+ * @file IListenTopoUpdates.java
+ *
+ * @brief Topology notifications provided by SAL toward the application
+ *
+ * For example an application that wants to keep up to date with the
+ * updates coming from SAL it will register in the OSGi service
+ * registry this interface (on a per-container base) and SAL will call it
+ * providing the update
+ */
+
+/**
+ * Topology notifications provided by SAL toward the application
+ *
+ */
+public interface IListenTopoUpdates {
+ /**
+ * Called to update on Edge in the topology graph
+ *
+ * @param e Edge being updated
+ * @param type Type of update
+ * @param props Properties of the edge, like BandWidth and/or Latency etc.
+ */
+ public void edgeUpdate(Edge e, UpdateType type, Set<Property> props);
+
+ /**
+ * Called when an Edge utilization is above the safety threshold
+ * configured on the controller
+ *
+ * @param edge The edge which bandwidth usage is above the safety level
+ */
+ public void edgeOverUtilized(Edge edge);
+
+ /**
+ * Called when the Edge utilization is back to normal, below the safety
+ * threshold level configured on the controller
+ *
+ * @param edge
+ */
+ public void edgeUtilBackToNormal(Edge edge);
+}