2 * Copyright (c) 2015 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.mdsal.binding.api;
10 import java.util.Collection;
11 import java.util.EventListener;
12 import org.eclipse.jdt.annotation.NonNull;
13 import org.opendaylight.yangtools.yang.binding.DataObject;
16 * Interface implemented by classes interested in receiving notifications about
17 * data tree changes. It provides a cursor-based view of the change, which has potentially
18 * lower overhead and allow more flexible consumption of change event.
20 public interface DataTreeChangeListener<T extends DataObject> extends EventListener {
22 * Invoked when there was data change for the supplied path, which was used
23 * to register this listener.
26 * This method may be also invoked during registration of the listener if
27 * there is any pre-existing data in the conceptual data tree for supplied
28 * path. This initial event will contain all pre-existing data as created.
31 * Note: If there is no pre-existing data, the method {@link #onInitialData} will be invoked.
34 * A data change event may be triggered spuriously, e.g. such that data before
35 * and after compare as equal. Implementations of this interface are expected
36 * to recover from such events. Event producers are expected to exert reasonable
37 * effort to suppress such events.
40 * In other words, it is completely acceptable to observe
41 * a {@link DataObjectModification}, while the state observed before and
42 * after- data items compare as equal.
44 * @param changes Collection of change events, may not be null or empty.
46 void onDataTreeChanged(@NonNull Collection<DataTreeModification<T>> changes);
49 * Invoked only once during registration of the listener if there was no data in the conceptual data tree
50 * for the supplied path, which was used to register this listener, and after this
51 * {@link #onDataTreeChanged(Collection)} would always be invoked for data changes.
54 * Default implementation does nothing and is appropriate for users who do not care about ascertaining
57 default void onInitialData() {