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;
022import java.util.Map;
023
024import org.eclipse.aether.transfer.TransferCancelledException;
025import org.eclipse.aether.transfer.TransferEvent;
026
027/**
028 * A skeleton class for listeners used to monitor transport operations. Reusing common regular expression syntax, the
029 * sequence of events is generally as follows:
030 *
031 * <pre>
032 * ( STARTED PROGRESSED* )*
033 * </pre>
034 *
035 * The methods in this class do nothing.
036 */
037public abstract class TransportListener {
038
039    /**
040     * Enables subclassing.
041     */
042    protected TransportListener() {}
043
044    /**
045     * Notifies the listener about the start of the data transfer. This event may arise more than once if the transfer
046     * needs to be restarted (e.g. after an authentication failure).
047     *
048     * @param dataOffset The byte offset in the resource at which the transfer starts, must not be negative.
049     * @param dataLength The total number of bytes in the resource or {@code -1} if the length is unknown.
050     * @throws TransferCancelledException If the transfer should be aborted.
051     */
052    public void transportStarted(long dataOffset, long dataLength) throws TransferCancelledException {}
053
054    /**
055     * Notifies the listener about some progress in the data transfer. This event may even be fired if actually zero
056     * bytes have been transferred since the last event, for instance to enable cancellation.
057     *
058     * @param data The (read-only) buffer holding the bytes that have just been tranferred, must not be {@code null}.
059     * @throws TransferCancelledException If the transfer should be aborted.
060     */
061    public void transportProgressed(ByteBuffer data) throws TransferCancelledException {}
062
063    /**
064     * Notifies the listener about the transport properties that are available for this transfer.
065     * This method is called either before or after other notifications are sent:
066     * <ul>
067     * <li>for remote put tasks this is called after {@link #transportStarted(long, long)}</li>
068     * <li>for remote peek tasks this is is the only event that is called</li>
069     * <li>for all other remote tasks this is called before {@link #transportStarted(long, long)}</li>
070     * </ul>
071     * @param transportProperties The transport properties associated with this transfer, may be empty. The keys are transporter specific and the value types are key specific.
072     * @throws TransferCancelledException If the transfer should be aborted.
073     * @since 2.0.21
074     */
075    public void transportPropertiesAvailable(Map<TransferEvent.TransportPropertyKey, Object> transportProperties)
076            throws TransferCancelledException {}
077}