The database services for the distributed application environment of the HE
RA-13 experiment are presented. Achieving the required 10(6) trigger reduct
ion implies that all reconstruction. including calibration and alignment pr
ocedures, must run online, making extensive usage of the database systems.
The associations from the events to the database objects are carefully intr
oduced considering efficiency and flexibility. The challenges of managing t
he slow control information were addressed by introducing data and update o
bjects used in special processing on dedicated servers. The system integrat
es the DAQ client/server protocols with customized active database servers
and relies on a high-performance database support toolkit. For applications
that required complex selection mechanisms, as in the data-quality databas
es, the relevant data is replicated using a relational database management
system. (C) 2001 Elsevier Science B.V. All rights reserved.