@Override public void toData(DataOutput out) throws IOException {
  super.toData(out);
  out.writeLong(refreshInterval);
  DataSerializer.writeObjectArray(alertDefs,out);
}

@ Override public void toData ( DataOutput out ) throws IOException { super . toData ( out ) ; out . writeLong ( refreshInterval ) ; DataSerializer . writeObjectArray ( alertDefs , out ) ; }
a callback used by gemfire data serialization mechanism to write to a stream .
