Solution topic subscribers via websockets

.gitignore

@@ -10,3 +10,6 @@ dist
 .settings
 .target
 .cache
+*.iml
+*.ipr
+*.iws

app/controllers/TopicSubscriberWebSockets.scala

@@ -0,0 +1,83 @@
+package controllers
+
+import play.api.mvc.{WebSocket, Controller}
+import play.api.libs.iteratee.{Iteratee, Enumerator}
+import akka.actor.{Props, ActorSystem, Actor}
+import scala.collection.mutable
+import play.api.libs.concurrent.Promise
+import akka.util.duration._
+import java.util
+import management.ManagementFactory
+
+/**
+ *
+ * Challenge #2: Clients subscribe to different topics (weather news and system load info) through websockets and receive updates every X seconds
+ *
+ * @author: Edi Weissmann
+ */
+object TopicSubscriberWebSockets extends Controller {
+
+  /**
+   * Topics - System load and Weather
+   */
+  trait Topic
+  object SystemLoad extends Topic {
+    val statsSystem = ManagementFactory.getOperatingSystemMXBean
+    override def toString = "System load [%s]".format(statsSystem.getSystemLoadAverage)
+  }
+  object WeatherForecast extends Topic {
+    override def toString = "Weather [sunny all day]"
+  }
+  object Topic {
+    def apply(name:String):Option[Topic] = name match {
+      case "weather" => Some(WeatherForecast)
+      case "system" => Some(SystemLoad)
+      case _ => None
+    }
+  }
+
+  def topicSubscribers() = WebSocket.using[String] { request =>
+
+    /**
+     * Topics to which current client is subscribed to
+     */
+    val topics = mutable.Set[Topic]()
+
+    /**
+     * Prints topic updates to subscribed clients
+     */
+    val topicOut = Enumerator.fromCallback { () =>
+      Promise.timeout({
+        Some(topics.mkString(" "))
+      }, 3 seconds)
+    }
+
+    /**
+     * Prints usage options
+     */
+    val usageOut = Enumerator("Commands are: 'subscribe' and 'unsubscribe'.\nTopics are: 'weather' and 'system'\nType your command: subscribe weather")
+
+    /**
+     * Processes incoming commands
+     */
+    val in = Iteratee.foreach[String] { msg => {
+      val Command = """(\w+) (\w+)""".r
+      msg match {
+        case Command(action, topicName) =>
+          Topic(topicName) match {
+            case Some(topic) =>
+              action match {
+                case "subscribe" => topics.add(topic)
+                case "unsubscribe" => topics.remove(topic)
+                case _ => // unknown action
+              }
+            case _ => // unknown topic
+          }
+        case _ => // unknown, noop
+      }
+    }}
+
+
+    (in, topicOut >- usageOut)
+  }
+}

app/views/websockets/index.scala.html

@@ -45,7 +45,7 @@
 </script>
 <div id="websocket-controls" class="side-column">
 	<p>
-		<label>Websocket Address</label> <input name="address" id="address" />
+		<label>Websocket Address</label> <input name="address" id="address" value="ws://localhost:9000/websockets/topic-subscribers" />
 	</p>
 	<p>
 		<button id="connect">Connect</button>

conf/routes

@@ -18,6 +18,7 @@ GET		/websockets/logging controllers.WebSockets.logging()
 GET		/websockets/echo controllers.WebSockets.echo()
 GET		/websockets/counter controllers.WebSockets.counter()
 GET		/websockets/echo-and-counter controllers.WebSockets.echoAndCounter()
+GET     /websockets/topic-subscribers             controllers.TopicSubscriberWebSockets.topicSubscribers
 
 GET		/twitter/stream controllers.Twitter.stream(keywords)
 

project/build.properties

@@ -1 +1 @@
-sbt.version=0.11.2
+sbt.version=0.11.3