Context-Aware Tuples for the Ambient

In tuple space approaches to context-aware mobile systems, the notion of context is defined by the presence or absence of certain tuples in the tuple space. Existing approaches define such presence either by collocation of devices holding the tuples or by replication of those tuples across all devices. We show that both approaches can lead to an erroneous perception of context. The former ties the perception of context to network connectivity which does not always yield the expected result. The latter causes context to be perceived even if a device has left that context a long time ago. We propose a tuple space approach in which tuples themselves carry a predicate that determines whether they are in the right context or not. We present a practical API for our approach and show its use by means of the implementation of a mobile game.