Impedance Matching: When you need to know What

Devina Ramduny-Ellis and Alan Dix

Lancaster University, UK.
email: and

Paper to be presented at HCI2002, London, September 2002.

Download draft paper as PDF (269Kb)

Full reference:

D. Ramduny-Ellis and A. Dix (2002). Impedance Matching: When you need to know What. Proceedings of HCI2002 . Faulkner X., Finlay J.and Detienne F. (eds), London, UK, Springer, pp 121 -137..

See also:
more on web architectures at:
related work on time at:


Feedthrough and awareness of user activities are major issues in CSCW. A key difference between awareness and goal-directed feedthrough lies in the required pace and quality of feedthrough. Getting the right pace of feedthrough is important for usability and to avoid overloading networks. Notification mechanisms should therefore allow dynamic tuning of the pace and volume of update events. This matching of the required and supplied pace of update events we call impedance matching. A separable notification server is often ideally placed to perform impedance matching between end-user clients. These design principles have been applied in an experimental notification server Getting-to-Know.

keywords: awareness, feedthrough, notification mechanism, separable notification server, event notification, pace, CSCW infrastructure.

References Alan Dix 3/4/2002