001package org.eclipse.aether.spi.connector.transport; 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 java.io.Closeable; 023 024/** 025 * A transporter for a remote repository. A transporter is responsible for transferring resources between the remote 026 * repository and the local system. During its operation, the transporter must provide progress feedback via the 027 * {@link TransportListener} configured on the underlying task. 028 * <p> 029 * If applicable, a transporter should obey connect/request timeouts and other relevant settings from the 030 * {@link org.eclipse.aether.RepositorySystemSession#getConfigProperties() configuration properties} of the repository 031 * system session. 032 * <p> 033 * <strong>Note:</strong> Implementations must be thread-safe such that a given transporter instance can safely be used 034 * for concurrent requests. 035 */ 036public interface Transporter 037 extends Closeable 038{ 039 040 /** 041 * Classification for exceptions that denote connectivity or authentication issues and any other kind of error that 042 * is not mapped to another classification code. 043 * 044 * @see #classify(Throwable) 045 */ 046 int ERROR_OTHER = 0; 047 048 /** 049 * Classification for exceptions that denote a requested resource does not exist in the remote repository. Note that 050 * cases where a remote repository is completely inaccessible should be classified as {@link #ERROR_OTHER}. 051 * 052 * @see #classify(Throwable) 053 */ 054 int ERROR_NOT_FOUND = 1; 055 056 /** 057 * Classifies the type of exception that has been thrown from a previous request to the transporter. The exception 058 * types employed by a transporter are generally unknown to its caller. Where a caller needs to distinguish between 059 * certain error cases, it employs this method to detect which error case corresponds to the exception. 060 * 061 * @param error The exception to classify, must not be {@code null}. 062 * @return The classification of the error, either {@link #ERROR_NOT_FOUND} or {@link #ERROR_OTHER}. 063 */ 064 int classify( Throwable error ); 065 066 /** 067 * Checks the existence of a resource in the repository. If the remote repository can be contacted successfully but 068 * indicates the resource specified in the request does not exist, an exception is thrown such that invoking 069 * {@link #classify(Throwable)} with that exception yields {@link #ERROR_NOT_FOUND}. 070 * 071 * @param task The existence check to perform, must not be {@code null}. 072 * @throws Exception If the existence of the specified resource could not be confirmed. 073 */ 074 void peek( PeekTask task ) 075 throws Exception; 076 077 /** 078 * Downloads a resource from the repository. If the resource is downloaded to a file as given by 079 * {@link GetTask#getDataFile()} and the operation fails midway, the transporter should not delete the partial file 080 * but leave its management to the caller. 081 * 082 * @param task The download to perform, must not be {@code null}. 083 * @throws Exception If the transfer failed. 084 */ 085 void get( GetTask task ) 086 throws Exception; 087 088 /** 089 * Uploads a resource to the repository. 090 * 091 * @param task The upload to perform, must not be {@code null}. 092 * @throws Exception If the transfer failed. 093 */ 094 void put( PutTask task ) 095 throws Exception; 096 097 /** 098 * Closes this transporter and frees any network resources associated with it. Once closed, a transporter must not 099 * be used for further transfers, any attempt to do so would yield a {@link IllegalStateException} or similar. 100 * Closing an already closed transporter is harmless and has no effect. 101 */ 102 void close(); 103 104}