Chilingaryan, S., et al.

in Journal of Physics: Conference Series. Vol. 219. No. 4. IOP Publishing, 2010.


During operation of high energy physics experiments a big amount of slow control
data is recorded. It is necessary to examine all collected data checking the integrity and validity
of measurements. With growing maturity of AJAX technologies it becomes possible to construct
sophisticated interfaces using web technologies only.
Our solution for handling time series, generally slow control data, has a modular architecture:
backend system for data analysis and preparation, a web service interface for data access and a
fast AJAX web display. In order to provide fast interactive access the time series are aggregated
over time slices of few predefined lengths. The aggregated values are stored in the temporary
caching database and, then, are used to create generalizing data plots. These plots may include
indication of data quality and are generated within few hundreds of milliseconds even if very
high data rates are involved. The extensible export subsystem provides data in multiple formats
including CSV, Excel, ROOT, and TDMS. The search engine can be used to find periods of
time where indications of selected sensors are falling into the specified ranges. Utilization of
the caching database allows performing most of such lookups within a second. Based on this
functionality a web interface facilitating fast (Google-maps style) navigation through the data
has been implemented.
The solution is at the moment used by several slow control systems at Test Facility for
Fusion Magnets (TOSKA) and Karlsruhe Tritium Neutrino (KATRIN).