The CMS ECAL Database services for detector control and monitoring

The Electromagnetic Calorimeter (ECAL) of the CMS experiment at the LHC is made of about 75000 scintillating crystals. The detector properties must be continuously monitored in order to ensure the extreme stability and precision required by its design. This leads to a very large volume of non-event data to be accessed continuously by shifters, experts, automatic monitoring tasks, detector configuration for trigger and data acquisition systems and offline data reconstruction programs. This talk describes the measurements and calibrations taken for slow control, the data handling strategy and the workflow as well as the architecture of the configuration and conditions databases. An important component of the system is the so-called web based browser, a software tool used by shifters and experts to visualize the data on a web browser and to keep the detector under control.