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.task; 020 021import org.apache.reef.annotations.audience.Public; 022import org.apache.reef.annotations.audience.TaskSide; 023 024/** 025 * The interface for Tasks. 026 * <p> 027 * This interface is to be implemented for Tasks. 028 * <p> 029 * The main entry point for a Task is the call() method inherited from 030 * {@link java.util.concurrent.Callable}. The REEF Evaluator will call this method in order to run 031 * the Task. The byte[] returned by it will be pushed to the Job Driver. 032 */ 033@TaskSide 034@Public 035public interface Task { 036 037 /** 038 * Called by the resourcemanager harness to execute the task. 039 * 040 * @param memento the memento objected passed down by the driver. 041 * @return the user defined return value 042 * @throws Exception whenever the Task encounters an unsolved issue. 043 * This Exception will be thrown at the Driver's event handler. 044 */ 045 byte[] call(final byte[] memento) throws Exception; 046}