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     */
017    package org.apache.camel.component.file;
018    
019    import org.apache.camel.Exchange;
020    
021    /**
022     * Represents a pluggable strategy when processing files.
023     */
024    public interface GenericFileProcessStrategy<T> {
025    
026        /**
027         * Allows custom logic to be run on startup 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 startup 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         * Releases any file locks and possibly deletes or moves the file after
053         * successful processing
054         *
055         * @param operations file operations
056         * @param endpoint   the endpoint
057         * @param exchange   the exchange
058         * @param file       the file
059         * @throws Exception can be thrown in case of errors
060         */
061        void commit(GenericFileOperations<T> operations, GenericFileEndpoint<T> endpoint,
062                Exchange exchange, GenericFile<T> file) throws Exception;
063    
064        /**
065         * Releases any file locks and possibly deletes or moves the file after
066         * unsuccessful processing
067         *
068         * @param operations file operations
069         * @param endpoint   the endpoint
070         * @param exchange   the exchange
071         * @param file       the file
072         * @throws Exception can be thrown in case of errors
073         */
074        void rollback(GenericFileOperations<T> operations, GenericFileEndpoint<T> endpoint,
075                Exchange exchange, GenericFile<T> file) throws Exception;
076    
077    }