001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.component.file;
018
019import org.apache.camel.Exchange;
020
021/**
022 * Represents a pluggable strategy when processing files.
023 */
024public interface GenericFileProcessStrategy<T> {
025
026    /**
027     * Allows custom logic to be run on first poll preparing the strategy,
028     * such as removing old lock files etc.
029     *
030     * @param operations file operations
031     * @param endpoint   the endpoint
032     * @throws Exception can be thrown in case of errors which causes poll to fail
033     */
034    void prepareOnStartup(GenericFileOperations<T> operations, GenericFileEndpoint<T> endpoint) throws Exception;
035
036    /**
037     * Called when work is about to begin on this file. This method may attempt
038     * to acquire some file lock before returning true; returning false if the
039     * file lock could not be obtained so that the file should be ignored.
040     *
041     * @param operations file operations
042     * @param endpoint   the endpoint
043     * @param exchange   the exchange
044     * @param file       the file
045     * @return true if the file can be processed (such as if a file lock could be obtained)
046     * @throws Exception can be thrown in case of errors
047     */
048    boolean begin(GenericFileOperations<T> operations, GenericFileEndpoint<T> endpoint,
049                  Exchange exchange, GenericFile<T> file) throws Exception;
050
051    /**
052     * Called when a begin is aborted, for example to release any resources which may have
053     * been acquired during the {@link #begin(GenericFileOperations, GenericFileEndpoint, org.apache.camel.Exchange, GenericFile)}
054     * operation.
055     *
056     * @param operations file operations
057     * @param endpoint   the endpoint
058     * @param exchange   the exchange
059     * @param file       the file
060     * @throws Exception can be thrown in case of errors
061     */
062    void abort(GenericFileOperations<T> operations, GenericFileEndpoint<T> endpoint,
063               Exchange exchange, GenericFile<T> file) throws Exception;
064
065    /**
066     * Releases any file locks and possibly deletes or moves the file after
067     * successful processing
068     *
069     * @param operations file operations
070     * @param endpoint   the endpoint
071     * @param exchange   the exchange
072     * @param file       the file
073     * @throws Exception can be thrown in case of errors
074     */
075    void commit(GenericFileOperations<T> operations, GenericFileEndpoint<T> endpoint,
076                Exchange exchange, GenericFile<T> file) throws Exception;
077
078    /**
079     * Releases any file locks and possibly deletes or moves the file after
080     * unsuccessful processing
081     *
082     * @param operations file operations
083     * @param endpoint   the endpoint
084     * @param exchange   the exchange
085     * @param file       the file
086     * @throws Exception can be thrown in case of errors
087     */
088    void rollback(GenericFileOperations<T> operations, GenericFileEndpoint<T> endpoint,
089                  Exchange exchange, GenericFile<T> file) throws Exception;
090
091}