/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.mapred;

import java.io.*;

import org.apache.hadoop.ipc.VersionedProtocol;

/** 
 * Protocol that a JobClient and the central JobTracker use to communicate.  The
 * JobClient can use these methods to submit a Job for execution, and learn about
 * the current system status.
 */ 
public interface JobSubmissionProtocol extends VersionedProtocol {
  /*
   *Changing the versionID to 2L since the getTaskCompletionEvents method has
   *changed
   */
  public static final long versionID = 3L;
  /**
   * Submit a Job for execution.  Returns the latest profile for
   * that job.
   */
  public JobStatus submitJob(String jobFile) throws IOException;

  /**
   * Get the current status of the cluster
   * @return summary of the state of the cluster
   */
  public ClusterStatus getClusterStatus() throws IOException;
    
  /**
   * Kill the indicated job
   */
  public void killJob(String jobid) throws IOException;

  /**
   * Grab a handle to a job that is already known to the JobTracker
   */
  public JobProfile getJobProfile(String jobid) throws IOException;

  /**
   * Grab a handle to a job that is already known to the JobTracker
   */
  public JobStatus getJobStatus(String jobid) throws IOException;

  /**
   * Grab the current job counters
   */
  public Counters getJobCounters(String jobid) throws IOException;
    
  /**
   * Grab a bunch of info on the map tasks that make up the job
   */
  public TaskReport[] getMapTaskReports(String jobid) throws IOException;

  /**
   * Grab a bunch of info on the reduce tasks that make up the job
   */
  public TaskReport[] getReduceTaskReports(String jobid) throws IOException;

  /**
   * A MapReduce system always operates on a single filesystem.  This 
   * function returns the fs name.  ('local' if the localfs; 'addr:port' 
   * if dfs).  The client can then copy files into the right locations 
   * prior to submitting the job.
   */
  public String getFilesystemName() throws IOException;

  /** 
   * Get the jobs that are not completed and not failed
   * @return array of JobStatus for the running/to-be-run
   * jobs.
   */
  public JobStatus[] jobsToComplete() throws IOException;
    
  /**
   * Get task completion events for the jobid, starting from fromEventId. 
   * Returns empty aray if no events are available. 
   * @param jobid job id 
   * @param fromEventId event id to start from.
   * @param maxEvents the max number of events we want to look at 
   * @return array of task completion events. 
   * @throws IOException
   */
  public TaskCompletionEvent[] getTaskCompletionEvents(
                                                       String jobid, int fromEventId, int maxEvents) throws IOException;
    
}
