Actor providing JMX over REST (fault-tolerant)

Actor providing JMX over REST (fault-tolerant)

/**
 * REST interface to Akka's JMX service.
 * <p/>
 * Here is an example that retreives the current number of Actors. 
 * <pre>
 * http://localhost:9998/management
 *   ?service=service:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi
 *   &component=se.scalablesolutions.akka:type=Stats
 *   &attribute=counter_NrOfActors
 * </pre>
 */
@Path("/management")
class RestfulJMX extends Actor with Logging {
  private case class Request(service: String, component: String, attribute: String)
  private val connectors = new ConcurrentHashMap[String, JMXConnector]

  @GET
  @Produces(Array("text/html"))
  def queryJMX(
    @QueryParam("service") service: String, 
    @QueryParam("component") component: String, 
    @QueryParam("attribute") attribute: String) = 
    (this !! Request(service, component, attribute)).getOrElse(<error>Error in REST JMX management service</error>)

  override def receive: PartialFunction[Any, Unit] = {
    case Request(service, component, attribute) => reply(retrieveAttribute(service, component, attribute))
  }

  private def retrieveAttribute(service: String, component: String, attribute: String): scala.xml.Elem = {
    try {
      var connector = connectors.putIfAbsent(service, JMXConnectorFactory.connect(new JMXServiceURL(service)))
      <div>{connector.getMBeanServerConnection.getAttribute(new ObjectName(component), attribute).toString}</div>
    } catch {
      case e: Exception =>
        if (connectors.contains(service)) connectors.remove(service)
        throw e
    }
  }
}