LinkedList predecessors = new LinkedList();
Iterator inPorts = actor.inputPortList().iterator();
while (inPorts.hasNext()) {
IOPort port = (IOPort) inPorts.next();
Iterator outPorts = port.deepConnectedOutPortList().iterator();
while (outPorts.hasNext()) {
IOPort outPort = (IOPort) outPorts.next();
Actor pre = (Actor) outPort.getContainer();