An instance of FlowListener may be configured as a SipListener. Whenever the flow fails, the container invokes all configured FlowListeners. Applications may retrieve the flow and complete the necessary business logic, which typically includes sending the REGISTER message again.

Example 8-2 shows the FlowListener and FlowFailedEvent definitions.

public interface FlowListener extends EventListener {
  void flowFailed(FlowFailedEvent flowFailedEvent);
}
public class FlowFailedEvent extends EventObject {
  public FlowFailedEvent(Flow flow) {
    super(flow);
  }
  public Flow getFlow() {
    return (Flow) super.getSource();
  }
}