     # Subscribe to the 'err' response for topicId
     # We don't pass a callback immediately so that we can
     # refer to the subscription itself in the callback.
-    errSub = core.bus.subscribe {
+    errSub = bus.subscribe {
       channel: replyTo.channel
       topic: replyTo.topic.err
       callback: callback


  # just listen
  listen: (channel, topic, callback) ->
    sub = core.bus.subscribe
      channel: channel
      topic: topic
      callback: (data, envelope) ->

    # Subscribe to the 'success' response for topicId
    # As above, we don't pass a callback immediately so that
    # we can refer to the subscription itself in the callback.
    successSub = bus.subscribe {
      channel: replyTo.channel
      topic: replyTo.topic.success
      callback: callback
