private String getFileName(SensorVariable sensorVariable, AGGREGATION_TYPE aggrType) {
   Sensor sensor = DaoUtils.getSensorDao().getById(sensorVariable.getSensor().getId());
   StringBuilder builder = new StringBuilder();
   builder
       .append(sensor.getNode().getName())
       .append("_")
       .append(sensor.getName())
       .append("_Nid-")
       .append(sensor.getNode().getEui())
       .append("_Sid-")
       .append(sensor.getSensorId())
       .append("_")
       .append(sensorVariable.getVariableType().getText());
   if (sensorVariable.getMetricType() == METRIC_TYPE.DOUBLE) {
     builder.append("_").append("SampleType_").append(aggrType);
   }
   builder
       .append("_")
       .append(new SimpleDateFormat("yyyy-MMM-dd_hh-mm-ss").format(new Date()))
       .append(".csv");
   return builder.toString().replaceAll(" ", "_");
 }