Various kinds of nodes, including cellular telephones and information appliances, are to become popular and are expected to provide a variety of services. Cooperation of these services will result in more convenient services than keeping them isolated would. A ubiquitous network is characterized by changeable system configurations. Because of this and the fact that a node is so frequently connected to and disconnected from the network, the global cooperation of services is difficult to describe in flow languages such as Web Services Flow Language (WSFL). One of the solutions to this problem is a policy technology. A policy attached to a node can be added or removed when the node is connected or disconnected. The policies can re-configure a changed system.
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