[ONOS-3117] Adding Port-Chain event handler

Change-Id: I65df15f0bfe650b2398004bb392777e82a3ba953

+/*
+ * Copyright 2015 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.vtnrsc.portchain;
+
+import org.onosproject.event.AbstractEvent;
+import org.onosproject.vtnrsc.PortChain;
+
+/**
+ * Describes network Port-Chain event.
+ */
+public class PortChainEvent extends AbstractEvent<PortChainEvent.Type, PortChain> {
+    /**
+     * Type of port-chain events.
+     */
+    public enum Type {
+        /**
+         * Signifies that port-chain has been created.
+         */
+        PORT_CHAIN_PUT,
+        /**
+         * Signifies that port-chain has been deleted.
+         */
+        PORT_CHAIN_DELETE,
+        /**
+         * Signifies that port-chain has been updated.
+         */
+        PORT_CHAIN_UPDATE
+    }
+
+    /**
+     * Creates an event of a given type and for the specified Port-Chain.
+     *
+     * @param type Port-Chain event type
+     * @param portChain Port-Chain subject
+     */
+    public PortChainEvent(Type type, PortChain portChain) {
+        super(type, portChain);
+    }
+
+    /**
+     * Creates an event of a given type and for the specified Port-Chain.
+     *
+     * @param type Port-Chain event type
+     * @param portChain Port-Chain subject
+     * @param time occurrence time
+     */
+    public PortChainEvent(Type type, PortChain portChain, long time) {
+        super(type, portChain, time);
+    }
+}