001/*
002 * Copyright 2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *       https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.springframework.batch.integration.chunk;
017
018import org.springframework.batch.core.step.item.SimpleChunkProcessor;
019import org.springframework.batch.item.ItemProcessor;
020import org.springframework.batch.item.ItemWriter;
021import org.springframework.batch.item.support.PassThroughItemProcessor;
022import org.springframework.integration.dsl.IntegrationFlow;
023import org.springframework.integration.dsl.IntegrationFlows;
024import org.springframework.messaging.MessageChannel;
025import org.springframework.util.Assert;
026
027/**
028 * Builder for a worker in a remote chunking setup. This builder:
029 *
030 * <ul>
031 *     <li>creates a {@link ChunkProcessorChunkHandler} with the provided
032 *     item processor and writer. If no item processor is provided, a
033 *     {@link PassThroughItemProcessor} will be used</li>
034 *     <li>creates an {@link IntegrationFlow} with the
035 *     {@link ChunkProcessorChunkHandler} as a service activator which listens
036 *     to incoming requests on <code>inputChannel</code> and sends replies
037 *     on <code>outputChannel</code></li>
038 * </ul>
039 *
040 * @param <I> type of input items
041 * @param <O> type of output items
042 *
043 * @since 4.1
044 * @author Mahmoud Ben Hassine
045 */
046public class RemoteChunkingWorkerBuilder<I, O> {
047
048        private static final String SERVICE_ACTIVATOR_METHOD_NAME = "handleChunk";
049
050        private ItemProcessor<I, O> itemProcessor;
051        private ItemWriter<O> itemWriter;
052        private MessageChannel inputChannel;
053        private MessageChannel outputChannel;
054
055        /**
056         * Set the {@link ItemProcessor} to use to process items sent by the master
057         * step.
058         *
059         * @param itemProcessor to use
060         * @return this builder instance for fluent chaining
061         */
062        public RemoteChunkingWorkerBuilder<I, O> itemProcessor(ItemProcessor<I, O> itemProcessor) {
063                Assert.notNull(itemProcessor, "itemProcessor must not be null");
064                this.itemProcessor = itemProcessor;
065                return this;
066        }
067
068        /**
069         * Set the {@link ItemWriter} to use to write items sent by the master step.
070         *
071         * @param itemWriter to use
072         * @return this builder instance for fluent chaining
073         */
074        public RemoteChunkingWorkerBuilder<I, O> itemWriter(ItemWriter<O> itemWriter) {
075                Assert.notNull(itemWriter, "itemWriter must not be null");
076                this.itemWriter = itemWriter;
077                return this;
078        }
079
080        /**
081         * Set the input channel on which items sent by the master are received.
082         *
083         * @param inputChannel the input channel
084         * @return this builder instance for fluent chaining
085         */
086        public RemoteChunkingWorkerBuilder<I, O> inputChannel(MessageChannel inputChannel) {
087                Assert.notNull(inputChannel, "inputChannel must not be null");
088                this.inputChannel = inputChannel;
089                return this;
090        }
091
092        /**
093         * Set the output channel on which replies will be sent to the master step.
094         *
095         * @param outputChannel the output channel
096         * @return this builder instance for fluent chaining
097         */
098        public RemoteChunkingWorkerBuilder<I, O> outputChannel(MessageChannel outputChannel) {
099                Assert.notNull(outputChannel, "outputChannel must not be null");
100                this.outputChannel = outputChannel;
101                return this;
102        }
103
104        /**
105         * Create an {@link IntegrationFlow} with a {@link ChunkProcessorChunkHandler}
106         * configured as a service activator listening to the input channel and replying
107         * on the output channel.
108         *
109         * @return the integration flow
110         */
111        public IntegrationFlow build() {
112                Assert.notNull(this.itemWriter, "An ItemWriter must be provided");
113                Assert.notNull(this.inputChannel, "An InputChannel must be provided");
114                Assert.notNull(this.outputChannel, "An OutputChannel must be provided");
115
116                if(this.itemProcessor == null) {
117                        this.itemProcessor = new PassThroughItemProcessor();
118                }
119                SimpleChunkProcessor<I, O> chunkProcessor = new SimpleChunkProcessor<>(this.itemProcessor, this.itemWriter);
120
121                ChunkProcessorChunkHandler<I> chunkProcessorChunkHandler = new ChunkProcessorChunkHandler<>();
122                chunkProcessorChunkHandler.setChunkProcessor(chunkProcessor);
123
124                return IntegrationFlows
125                                .from(this.inputChannel)
126                                .handle(chunkProcessorChunkHandler, SERVICE_ACTIVATOR_METHOD_NAME)
127                                .channel(this.outputChannel)
128                                .get();
129        }
130
131}