/**
  * Start listening for incoming connections. Only for server SAPs.
  *
  * @throws IOException if an error occures starting to listen
  */
 public void startListening() throws IOException {
   if (associationListener == null || serverTSap == null) {
     throw new IllegalStateException(
         "AcseSAP is unable to listen because it was not initialized.");
   }
   serverTSap.startListening();
 }
 public void stopListening() {
   serverTSap.stopListening();
 }