Wolfgang Wander
University of Erlangen/Nuernberg / Erwin-Rommel-Str. 1 / D-91058 Erlangen
HERMES Collaboration
AbstractSoftware development for the HERMES experiment faces the challenges of many other experiments in modern High Energy Physics: Complex data structures and relationships have to be processed at high I/O rate. Experimental control and data analysis is done on a distributed environment of CPUs with various operating systems and requires access to different time dependent databases like calibration and geometry.
Slow- and experimental control have a need for flexible inter-process-communication.
Program development is done in different programming languages (here C, tk/tcl and f77) where interfaces to the libraries should not restrict the capabilities of the language.
The needs of handling complex data structures are perfectly fulfilled by the ADAMO entity relationship model.
DAD, the Distributed Adamo Database library, was developed to fulfil the rest of the needs. DAD is based on the ADAMO entity relationship model but extends ADAMO by fast machine independent I/O drivers which do not rely on the slow ZEBRA code. For parallel processing of events on multi processor machines the data stream can be split and events can be sent to the next idle cpu. Easily configurable filters evaluating expressions on the data stream can be used to select user defined subsamples of the data set. DAD Databases containing time dependent data sets can be accessed on a distributed set of servers from different processes and machines in parallel, e.g. analysis processes request the calibration data which is valid for the currently analysed run from a DAD server. DAD also includes a message system used by processes in slow- and experimental control for interprocess communication. Defined messages and data packages can be booked by clients and be used for hardware access, monitoring and control. Last but not least the DAD library contains object oriented interfaces to the ADAMO TAP library which simplyfy the development of generic tools in C a lot: PinK, a tk/tcl an extension to DAD and ADAMO based on the dad library, was developed by members of our collaboration which is used extensivly for the HERMES experimental- and slow control system.
Submitter's Name: Wolfgang Wander Submitter's Institution: University of Erlangen/Nuernberg Address of Institution: Erwin-Rommel-Str. 1 / D-91058 Erlangen Submitter's EMAIL address: wwc@hermes.desy.de Submitter's telephone number: +49 40 8998 2720 Fax number (if have): +49 +40 8998 3438