Twitter.scala

package controllers

import play.api._
import play.api.mvc._

import play.api.libs.oauth._
import play.api.libs.ws._
import play.api.libs.iteratee._

object Twitter extends Controller {

  // Twitter OAuth keys - retrieve them from dev.twitter.com or via authorization
  val consumerKey = ConsumerKey(
    "???", "???"
  )

  val accessToken = RequestToken(
    "???", "???"
  )

  // -- Server Sent Events --

  val bytesToString: Enumeratee[Array[Byte], String] = Enumeratee.map[Array[Byte]] { bytes: Array[Byte] =>
    new String(bytes)
  }

  val filterRTs = Enumeratee.filter[String] (!_.startsWith("RT"))

  val toServerEvent = Enumeratee.map[String] { tweet =>
    "data: " + tweet + "\n"
  }

  def streamForKeyword(track: String) = Action { request =>
    // Stream to output using an Iteratee
    Ok stream { socket: Socket.Out[String] => //Socket.Out = Iteratee[Array[Byte], ?]
      WS.url("https://stream.twitter.com/1/statuses/filter.json?track=" + track) // withQueryString seems to have a bug
        .sign(OAuthCalculator(consumerKey, accessToken))
        // Compose the Enumeratees (><> or compose) and apply the result to the Iteratee
        .get(_ => bytesToString ><> filterRTs ><> toServerEvent &> socket)
    } as "text/event-stream"
  }

  def showStream = Action { implicit request =>
    Ok(views.html.twitterStream())
  }

}

twitterStream.scala.html

@()(implicit request: RequestHeader)

@main("Stream") {
  <h1>What's happening right now?</h1>

  <form id="form">
    <input type="text" name="track" id="track" />
    <input type="submit" value="Stream!" />
  </form>

  <ul id="tweets"></ul>

  @helper.javascriptRouter("jsRoutes")(
    routes.javascript.Twitter.streamForKeyword
  )

  <script type="text/javascript">
  $(function() {
    var source = undefined;
    $("#track").focus();

    $("#form").submit(function() {
      if (source !== undefined)
        source.close();

      var track = $("#track").val();
      source = new EventSource(jsRoutes.controllers.Twitter.streamForKeyword(track).url);

      source.onmessage = function(e) {
        var tweet = jQuery.parseJSON(e.data);
        var fullName = tweet.user.name || "unknown";
        var user = tweet.user.screen_name;
        var text = tweet.text;
        var display = fullName + "(@@" + user + ") - " + text;
        $('<li />').text(display).appendTo('#tweets');
      };

      return false;
    });
  })
  </script>
}