Ever wanted to find out how many hours did your HVAC actually work? Keep forgetting to replace the filter? Well, here's your cure -
Subversion contains the implementation of the resource usage counter. As usual, if you can read source code (
FileUsageCounter is probably the one you're looking for) and configure a Spring IoC container, you will have no trouble utilizing it.
DataSinks and can count whatever is
DataSource<Double>themselves and can be fed into data loggers - you'll easily see when exactly did your HVAC equipment work.