Source code

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
024import java.util.concurrent.Callable;
025
026/**
027 * The interface for Tasks.
028 * <p/>
029 * This interface is to be implemented for Tasks.
030 * <p/>
031 * The main entry point for a Task is the call() method inherited from
032 * {@link Callable}. The REEF Evaluator will call this method in order to run
033 * the Task. The byte[] returned by it will be pushed to the Job Driver.
034 */
035@TaskSide
036@Public
037public interface Task {
038
039  /**
040   * Called by the resourcemanager harness to execute the task.
041   *
042   * @param memento the memento objected passed down by the driver.
043   * @return the user defined return value
044   * @throws Exception whenever the Task encounters an unsolved issue.
045   *                   This Exception will be thrown at the Driver's event handler.
046   */
047  public byte[] call(final byte[] memento) throws Exception;
048}