     @runtime = null
     @graph = null
     @changes = []
+    @changesStates = {}
     @subscribed = false
     @inPorts = new noflo.InPorts
       runtime:

    @outPorts.sent.send true
    @outPorts.sent.endGroup() if @graph
    @outPorts.queued.send @changes.length

  shutdown: ->
    do @unsubscribe

      topic: topic
      payload: payload
    @outPorts.queued.send @changes.length
    return @changes.length - 1

  replaceChange: (offset, topic, payload) =>
    @changes[offset] =
      topic: topic
      payload: payload

  addNode: (node) =>
    @registerChange 'addnode',
