How to use a raw MapReduce job in Cascading

package com.xcombinator.hadoopjobs.mapreducetest;
 
import cascading.cascade.*;
import cascading.flow.Flow;
import cascading.flow.FlowConnector;
import cascading.flow.MapReduceFlow;
import cascading.operation.aggregator.Count;
import cascading.operation.regex.*;
import cascading.pipe.*;
import cascading.scheme.*;
import cascading.tap.*;
import cascading.tuple.Fields;
import cascading.operation.Identity;
import java.util.Properties;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.TextInputFormat;
import org.apache.hadoop.mapred.TextOutputFormat;
import org.apache.hadoop.mapred.lib.IdentityMapper;
import org.apache.hadoop.mapred.lib.IdentityReducer;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.log4j.Logger;
import cascading.operation.Debug;
 
import org.apache.hadoop.mapred.KeyValueTextInputFormat;
 
/**
 * An example file to use a raw MapReduce job in cascading
 */
public class Main extends Configured implements Tool
  {
  private static final Logger LOG = Logger.getLogger( Main.class );
 
  public int run(String[] args)
  {
    JobConf conf = new JobConf(getConf(), this.getClass());
    Properties properties = new Properties();
    FlowConnector.setApplicationJarClass(properties, this.getClass());
 
    CascadeConnector cascadeConnector = new CascadeConnector();
    FlowConnector flowConnector = new FlowConnector(properties);
 
    String inputPath  = args[0];
    String outputPath = args[1];
    String intermediatePath1 = args[1] + "-mr-input";
    String intermediatePath2 = args[1] + "-mr-output";
 
    Scheme textLineScheme = new TextLine();
 
    Tap sourceTap = new Hfs(textLineScheme, inputPath);
    Tap intermediateTap1 = new Hfs(new TextLine(new Fields("line")), intermediatePath1);
    Tap intermediateTap2 = new Hfs(textLineScheme, intermediatePath2);
    Tap sinkTap   = new Hfs(textLineScheme, outputPath);
 
    // create our first flow, sink to the intermediateTap
    Pipe wsPipe = new Each("wordsplit", 
        new Fields("line"), 
        new RegexSplitGenerator(new Fields("word"), "\\s+"), 
        new Fields("word"));
 
    Flow parsedLogFlow = flowConnector.connect(sourceTap, intermediateTap1, wsPipe);
 
    // Create a pipe and set our mr job for it 
    Pipe importPipe = new Pipe("mr pipe");
 
    JobConf mrconf = new JobConf();
    mrconf.setJobName("custom mr");
 
    mrconf.setOutputKeyClass(LongWritable.class);
    mrconf.setOutputValueClass(Text.class);
 
    // the IdentityMapper, in this case, will actually output the key, which is
    // a long of offset in bytes. Not what we'd usually want, but we'll leave
    // it in for now.
    mrconf.setMapperClass(IdentityMapper.class);
    mrconf.setReducerClass(IdentityReducer.class);
 
    // note that your input is straight text-lines. This means in a real mr job
    // you'd most likely need to split the line by some convention
    TextInputFormat format = new TextInputFormat();
    format.configure(mrconf);
 
    // NOTE: this is both here and in the MapReduceFlow below
    FileInputFormat.setInputPaths(mrconf, intermediateTap1.getPath());  
    FileOutputFormat.setOutputPath(mrconf, intermediateTap2.getPath()); // likewise
 
    // create our second flow, this one is for the mrjob. Notice source and sink taps
    Flow mrFlow = new MapReduceFlow("mrflow", 
      mrconf, intermediateTap1, intermediateTap2, false, true);
 
    // create our third "regular" cascading pipe
    Pipe countPipe = new Pipe("count");
 
    // b/c our IdentityMapper is emitting long of offset in the line, just
    // strip that out. You wouldn't have to do this if you had a smarter Mapper
    // class.
    countPipe = new Each(countPipe, 
        new Fields("line"), 
        new RegexParser(new Fields("word"), ".*?\\t(.*)"), 
        new Fields("word"));
 
    countPipe = new GroupBy(countPipe, new Fields("word"));
    countPipe = new Every(countPipe, new Count(), new Fields("count", "word"));
 
    // create the flow for the last count pipe
    Flow countFlow = flowConnector.connect(intermediateTap2, sinkTap, countPipe);
 
    Cascade cascade = cascadeConnector.connect(parsedLogFlow, mrFlow, countFlow);
    cascade.complete();
 
    // if you want to get rid of the intermediate files you 
    // could do something like the following here:
    // Path tmp = tap.getPath();
    // FileSystem fs = tmp.getFileSystem(conf);
    // fs.delete(tmp, true);
 
    return 0;
  }
 
  public static void main(String[] args) throws Exception 
  {
    int res = ToolRunner.run(new Configuration(), new Main(), args);
    System.exit(res);
  }
 
  }