In this paper we show how an interactive system can be distributed among several peer devices. By taking advantage of the current trend towards ambient intelligent environments, we can make use of a combination of computing resources in the surrounding of the user to function as one logical interactive system; an interaction space. Our approach relies on the fact that nowadays most computing resources are network-enabled and publish their device pro- file using some special-purpose protocol. For this reason, federations of devices that support the tasks of the user can be composed automatically according to the requirements of these tasks. This distribution of the user interface over a federation of devices can be local or non-local. It raises the opportunity for supporting collaborative tasks with the same user interface with little or no extra effort from the user interface designer. Future tools supporting the design, creation and deployment of distributed interactive systems using device federations should maintain usability and usefulness of a dynamic distributed system. We use two different metrics to cope with these problems: interface completeness and interface continuity.