Progress bars with jQuery UI, WebSocket & Play

<div id="progressbar" data-url="@@{jqueryui.ProgressSocket.progress(processId)}"></div>

$(function() {

   // Initialise the progress bar.
   var $progressbar = $('#progressbar').progressbar();

   // Open the web socket connection.
   var serverUrl = $progressbar.data('url');
   var socket = new WebSocket(serverUrl);

   // Use web socket messages to update the progress bar.
   socket.onmessage = function(event) {
      $progressbar.progressbar('value', parseInt(event.data));
   };
});

package models.jqueryui;

import play.jobs.Job;
import play.libs.Codec;
import play.libs.F;

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

/**
 * Example job that publishes progress as an event stream.
 */
public class Process extends Job implements Serializable {

   public static Map<String, Process> registry = new HashMap<String, Process>();

   public String id = Codec.UUID();

   /**
    * Event stream for events that report job completion percentage.
    */
   public F.EventStream<Integer> percentComplete = new F.EventStream<Integer>();

   public void doJob() {
      // Report completion percentage every 100 ms.
      for (int i = 1; i <= 50; i++) {
         try {
            Thread.sleep(100l);
            final int percent = i * 2;
            this.percentComplete.publish(percent);
         } catch (InterruptedException e) {
            // ignore
         }
      }
   }
}

package controllers.jqueryui;

import models.jqueryui.Process;

/**
 * Progressbar example.
 */
public class Progressbar extends JQueryUI {

   /**
    * Start a job, cache it and re-render the page
    */
   public static void startJob() {
      final Process process = new Process();
      process.now();
      final String processId = process.id;
      Process.registry.put(processId, process);
      renderTemplate("jqueryui/Progressbar/index.html", processId);
   }
}

package controllers.jqueryui;

import models.jqueryui.Process;
import play.libs.F;
import play.mvc.Http;
import play.mvc.WebSocketController;

import static play.libs.F.Matcher.ClassOf;

/**
 * Web socket controller for use by the progress bar.
 */
public class ProgressSocket extends WebSocketController {

   public static void progress(final String processId) {

      final Process process = Process.registry.get(processId);
      final F.EventStream<Integer> progress = process.percentComplete;

      // Loop while the socket is open
      while (inbound.isOpen()) {

         // Wait for either an inbound socket event or a process progress event.
         F.Either<Http.WebSocketEvent, Integer> e = await(F.Promise.waitEither(
            inbound.nextEvent(),
            progress.nextEvent()
         ));

         // Case: The socket has been closed
         for (Http.WebSocketClose closed : Http.WebSocketEvent.SocketClosed.match(e._1)) {
            disconnect();
         }

         // Case: percentComplete published - send the value to the client.
         for (Integer percentComplete : ClassOf(Integer.class).match(e._2)) {
            outbound.send(percentComplete.toString());
            if (percentComplete >= 100) {
               disconnect();
            }
         }
      }
   }

}