001package org.eclipse.aether.spi.connector.checksum;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 * 
012 *  http://www.apache.org/licenses/LICENSE-2.0
013 * 
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import org.eclipse.aether.RepositorySystemSession;
023import org.eclipse.aether.repository.RemoteRepository;
024import org.eclipse.aether.transfer.TransferResource;
025
026/**
027 * Assists repository connectors in applying checksum policies to downloaded resources.
028 * 
029 * @noimplement This interface is not intended to be implemented by clients.
030 * @noextend This interface is not intended to be extended by clients.
031 */
032public interface ChecksumPolicyProvider
033{
034
035    /**
036     * Retrieves the checksum policy with the specified identifier for use on the given remote resource.
037     * 
038     * @param session The repository system session during which the request is made, must not be {@code null}.
039     * @param repository The repository hosting the resource being transferred, must not be {@code null}.
040     * @param resource The transfer resource on which the policy will be applied, must not be {@code null}.
041     * @param policy The identifier of the policy to apply, must not be {@code null}.
042     * @return The policy to apply or {@code null} if checksums should be ignored.
043     */
044    ChecksumPolicy newChecksumPolicy( RepositorySystemSession session, RemoteRepository repository,
045                                      TransferResource resource, String policy );
046
047    /**
048     * Returns the least strict policy. A checksum policy is said to be less strict than another policy if it would
049     * accept a downloaded resource in all cases where the other policy would reject the resource.
050     * 
051     * @param session The repository system session during which the request is made, must not be {@code null}.
052     * @param policy1 A policy to compare, must not be {@code null}.
053     * @param policy2 A policy to compare, must not be {@code null}.
054     * @return The least strict policy among the two input policies.
055     */
056    String getEffectiveChecksumPolicy( RepositorySystemSession session, String policy1, String policy2 );
057
058}