/**
* 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.util;
import org.apache.hadoop.conf.Configurable;
/**
* A tool interface that supports handling of generic command-line options.
*
* <p><code>Tool</code>, is the standard for any Map-Reduce tool/application.
* The tool/application should delegate the handling of
* <a href="{@docRoot}/org/apache/hadoop/util/GenericOptionsParser.html#GenericOptions">
* standard command-line options</a> to {@link ToolRunner#run(Tool, String[])}
* and only handle its custom arguments.</p>
*
* <p>Here is how a typical <code>Tool</code> is implemented:</p>
* <p><blockquote><pre>
* public class MyApp extends Configured implements Tool {
*
* public int run(String[] args) throws Exception {
* // <code>Configuration</code> processed by <code>ToolRunner</code>
* Configuration conf = getConf();
*
* // Create a JobConf using the processed <code>conf</code>
* JobConf job = new JobConf(conf, MyApp.class);
*
* // Process custom command-line options
* Path in = new Path(args[1]);
* Path out = new Path(args[2]);
*
* // Specify various job-specific parameters
* job.setJobName("my-app");
* job.setInputPath(in);
* job.setOutputPath(out);
* job.setMapperClass(MyApp.MyMapper.class);
* job.setReducerClass(MyApp.MyReducer.class);
*
* // Submit the job, then poll for progress until the job is complete
* JobClient.runJob(job);
* }
*
* public static void main(String[] args) throws Exception {
* // Let <code>ToolRunner</code> handle generic command-line options
* int res = ToolRunner.run(new Configuration(), new Sort(), args);
*
* System.exit(res);
* }
* }
* </pre></blockquote></p>
*
* @see GenericOptionsParser
* @see ToolRunner
*/
public interface Tool extends Configurable {
/**
* Execute the command with the given arguments.
*
* @param args command specific arguments.
* @return exit code.
* @throws Exception
*/
int run(String [] args) throws Exception;
}