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 org.eclipse.jdt.annotation.NonNull;
12 import org.opendaylight.yangtools.yang.binding.DataObject;
15 * Interface implemented by classes interested in receiving notifications about
16 * data tree changes. It provides a cursor-based view of the change, which has potentially
17 * lower overhead and allow more flexible consumption of change event.
19 public interface DataTreeChangeListener<T extends DataObject> {
21 * Invoked when there was data change for the supplied path, which was used
22 * to register this listener.
25 * This method may be also invoked during registration of the listener if
26 * there is any pre-existing data in the conceptual data tree for supplied
27 * path. This initial event will contain all pre-existing data as created.
30 * Note: If there is no pre-existing data, the method {@link #onInitialData} will be invoked.
33 * A data change event may be triggered spuriously, e.g. such that data before
34 * and after compare as equal. Implementations of this interface are expected
35 * to recover from such events. Event producers are expected to exert reasonable
36 * effort to suppress such events.
39 * In other words, it is completely acceptable to observe
40 * a {@link DataObjectModification}, while the state observed before and
41 * after- data items compare as equal.
43 * @param changes Collection of change events, may not be null or empty.
45 void onDataTreeChanged(@NonNull Collection<DataTreeModification<T>> changes);
48 * Invoked only once during registration of the listener if there was no data in the conceptual data tree
49 * for the supplied path, which was used to register this listener, and after this
50 * {@link #onDataTreeChanged(Collection)} would always be invoked for data changes.
53 * Default implementation does nothing and is appropriate for users who do not care about ascertaining
56 // FIXME: 8.0.0: this method should be non-default
57 default void onInitialData() {