001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.eclipse.aether.spi.connector.transport;
020
021import java.nio.ByteBuffer;
022
023import org.eclipse.aether.transfer.TransferCancelledException;
024
025/**
026 * A skeleton class for listeners used to monitor transport operations. Reusing common regular expression syntax, the
027 * sequence of events is generally as follows:
028 *
029 * <pre>
030 * ( STARTED PROGRESSED* )*
031 * </pre>
032 *
033 * The methods in this class do nothing.
034 */
035public abstract class TransportListener {
036
037    /**
038     * Enables subclassing.
039     */
040    protected TransportListener() {}
041
042    /**
043     * Notifies the listener about the start of the data transfer. This event may arise more than once if the transfer
044     * needs to be restarted (e.g. after an authentication failure).
045     *
046     * @param dataOffset The byte offset in the resource at which the transfer starts, must not be negative.
047     * @param dataLength The total number of bytes in the resource or {@code -1} if the length is unknown.
048     * @throws TransferCancelledException If the transfer should be aborted.
049     */
050    public void transportStarted(long dataOffset, long dataLength) throws TransferCancelledException {}
051
052    /**
053     * Notifies the listener about some progress in the data transfer. This event may even be fired if actually zero
054     * bytes have been transferred since the last event, for instance to enable cancellation.
055     *
056     * @param data The (read-only) buffer holding the bytes that have just been tranferred, must not be {@code null}.
057     * @throws TransferCancelledException If the transfer should be aborted.
058     */
059    public void transportProgressed(ByteBuffer data) throws TransferCancelledException {}
060}