The goal of this paper is to present practical techniques for improving the
scalability of a distributed objects architecture built around an event-dr
iven paradigm and the evaluation of their effectiveness in the case of loca
tion systems. As a case study, the ABng location system constructed using a
publisher/subscriber pattern over a CORBA compliant middleware is presente
d. The main contribution of this paper is the elaboration and evaluation of
three main concepts that play a crucial role in improving the scalability
of event-driven architectures: events dissemination quality of service, not
ification tree based events-routing, and transparent multicast event-channe
l notification service. The applicability and efficiency of these technique
s have been verified in practice by the ABng system implementation and perf
ormance testing. Copyright (C) 2000 John Wiley & Sons, Ltd.