Object Technology for Ambient Intelligence

The notion of proximity is a key to scalable interactions in distributed systems of any kind, both natural and artificial, and in particular in pervasive computing environments. However, proximity as such is a vague notion that can be considered both in a very factual manner (spatial distance) and in a very subjective manner (user affinity). We claim that an adequate system or programming language for ambient intelligence applications ought to support an open notion of proximity, making it possible to rely on different, possibly subjective, understandings of proximity, as well as their combinations. 1 Proximity: A Key to Scalability Proximity can be defined as a state of nearest, the perception of being close to something or someone. Proximity naturally plays a significant role in how, as humans, we interact with our environment. This can be seen in the relationships we maintain with others, or in the manner in which we interact with everyday objects around us. Think about the closeness of a friend or relative, or about how books of a particular topic are considered to be close to each other. The concept of proximity is interesting in the field of pervasive computing and ambient intelligence, where the focus is on unobtrusively managing and assisting in the tasks of users. Introducing proximity in these systems allow for better scalability both at the level of interactions [8] and at the level of demarking content of interest [6]. The scoping strategies enabled by proximity make it possible to tailor system behavior to better match the situations of users, going a step further in the direction of the non-intrusiveness requirement identified by Weiser [9]. As an example, consider how service discovery in a pervasive computing environment can take advantage of proximity. Instead of trying to discover any accessible service provider that matches the required service type, embedding a proximity criteria within the discovery process can drastically reduce the set of answers to process at the client side. Service providers that are able to determine that they do not meet the proximity requirement will simply skip the service request, thereby alleviating the burden of the client. Also, the concept of proximity is indeed prevalent in biological systems, such as shoals of fish and social insects like ants and termites, where interactions are