001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019package org.apache.reef.examples.data.output; 020 021import org.apache.reef.io.data.output.OutputStreamProvider; 022import org.apache.reef.task.Task; 023 024import javax.inject.Inject; 025import java.io.DataOutputStream; 026import java.io.IOException; 027 028/** 029 * The Task code for the output service demo app. 030 * This task receives an output stream from the output service 031 * and writes "Hello REEF!" on it. 032 */ 033public final class OutputServiceTask implements Task { 034 035 /** 036 * Output stream provider object through which tasks create output streams. 037 */ 038 private final OutputStreamProvider outputStreamProvider; 039 040 /** 041 * Task constructor - instantiated via TANG. 042 * 043 * @param outputStreamProvider Output stream provider object through which tasks create output streams. 044 */ 045 @Inject 046 public OutputServiceTask(final OutputStreamProvider outputStreamProvider) { 047 this.outputStreamProvider = outputStreamProvider; 048 } 049 050 /** 051 * Receives an output stream from the output service and writes "Hello REEF!" on it. 052 * 053 * @param memento the memento objected passed down by the driver. 054 * @return null 055 * @throws java.io.IOException 056 */ 057 @Override 058 public byte[] call(final byte[] memento) throws IOException { 059 try (final DataOutputStream outputStream = outputStreamProvider.create("hello")) { 060 outputStream.writeBytes("Hello REEF!"); 061 } 062 return null; 063 } 064}