Hadoop MapReduce HTTP Notification

Normally MapReduce programs tend to run for long time and you might want to setup a way to get notification when the job is done finishing to find out if the job was executed successfully or not. Hadoop provides a mechanism in which you can get notification on the progress of your MapReduce job. This is two step process

1. First set up job.end.notification.url property with value equal to a web application URL that should get invoked with the progress of job job.getConfiguration().set("job.end.notification.url", "http://localhost:8080/mrnotification/MRNotification/$jobId?status=$jobStatus");
2. Next create a web application that will receive the notification and printout the job status and job name like this

   	package com.spnotes.hadoop;
   	import java.io.IOException;
   	import java.util.Enumeration;
   	import javax.servlet.ServletException;
   	import javax.servlet.http.HttpServlet;
   	import javax.servlet.http.HttpServletRequest;
   	import javax.servlet.http.HttpServletResponse;
   	/**
   	* Servlet implementation class MRNotification
   	*/
   	public class MRNotification extends HttpServlet {
   	private static final long serialVersionUID = 1L;
   	/**
   	* Default constructor.
   	*/
   	public MRNotification() {
   	// TODO Auto-generated constructor stub
   	}
   	/**
   	* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
   	*/
   	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   	System.out.println("Entering MRNotification.doGet()");
   	process(request,response);
   	System.out.println("Exiting MRNotification.doGet()");
   	}
   	/**
   	* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
   	*/
   	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   	System.out.println("Entering MRNotification.doPost()");
   	process(request,response);
   	System.out.println("Exiting MRNotification.doPost()");
   	}
   	protected void process(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
   	response.setContentType("text/html");
   	response.getWriter().println("<h1>Hello from MRNotification</h1>");
   	String pathInfo = request.getPathInfo();
   	System.out.println("Job Id -> " +pathInfo.substring(pathInfo.lastIndexOf("/")+1));
   	System.out.println("Job Status -> " + request.getParameter("status"));
   	}
   	}

   view raw MRNotification.java hosted with ❤ by GitHub