This paper describes the architecture and implementation of the HERA-B
framework for online calibration and alignment. At HERA-B the performance of
all trigger levels, including the online reconstruction, strongly depends on
using the appropriate calibration and alignment constants, which might change
during data taking. A system to monitor, recompute and distribute those
constants to online processes has been integrated in the data acquisition and
trigger systems.Comment: Submitted to NIM A. 4 figures, 15 page
