code: public void start(final AttributeGroupReader valueReader, final long readingPeriod) {
          this.valueReader = valueReader;
          this.readingPeriod = readingPeriod;
          // create a timer to read attributes
          executor = Executors.newScheduledThreadPool(1);
          future = executor.scheduleAtFixedRate(valueReader, 0L, readingPeriod, TimeUnit.MILLISECONDS);
      }
docs: Start the periodic update
  
  @param valueReader the group reader
  @param readingPeriod the period in milliseconds