@Override
 public void write(DataOutput out) throws IOException {
   DataIoUtil.writeString(out, key);
   DataIoUtil.writeString(out, docuuid);
   DataIoUtil.writeString(out, xml);
 }
 @Override
 public void readFields(DataInput in) throws IOException {
   key = DataIoUtil.readString(in);
   docuuid = DataIoUtil.readString(in);
   xml = DataIoUtil.readString(in);
 }