STAR ONLINE Status Viewer
Location: development version of this viewer is located here : http://online.star.bnl.gov/dbPlots/
Rationale: STAR has many standalone scripts written to show online status of some specific subsystem during Run time. Usually, plots or histograms are created using either data from Online Database, or Slow Controls Archive or CDEV inteface. Almost every subsystem expert writes her own script, because no unified API/approach is available at the moment. I decided to provide generic plots for various subsystems data, recorded in online db by online collector daemons + some data fetched directly from SC Archive. SC Archive is used because STAR online database contains primarily subsystem-specific data like voltages, and completely ignores basic parameters like hall temperature and humidity (not required for calibrations). There is no intention to provide highly specialized routines for end-users (thus replacing existing tools like SPIN monitor), only basic display of collected values is presented.
Implementation:
- online.star.bnl.gov/dbPlots/ scripts use single configuration file to fetch data from online db slave, thus creating no load on primary online db;
- to reduce CPU load, gnuplot binary is used instead of php script to process data fetched from database and draw plots. This reduces overall CPU usage by x10 factor to only 2-3% of CPU per gnuplot call (negligible).
- Slow Controls data is processed in this way: a) cron-based script, located at onldb2(slave) is polling SC Archive every 5 minutes and writes data logs in a [timestamp] [value] format; b) gnuplot is called to process those files; c) images are shipped to dean.star.bnl.gov via NFS exported directory;
Maintenance: resulting tool is really easy to maintain, since it has only one config file for database, and only one config file for graphs information - setup time for a new Run is about 10 minutes. In addition, it is written in a forward-compatible way, so php version upgrade should not affect this viever.
Browser compatibility: Firefox, Konqueror, Safari, IE7+, Google Chrome are compatible. Most likely, old netscape should work fine too.