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Context-aware applications and services require ubiquitous access to context information about the users or sensors such as preferences, spatial & environmental data, available connectivity, and device capabilities. Systems for the brokering or the provisioning of context data via wireless networks do so with centralized servers or by employing protocols that do not scale well with real-time distribution capabilities. In other cases, such as the extending of presence systems, the data models are limited in expressive capabilities and consequently incur unnecessary signaling overhead. This paper presents a distributed protocol, the Distributed Context eXchange Protocol (DCXP), and an architecture for the real-time distribution of context information to ubiquitous mobile services: We present the architecture and its principle operation in a sample ubiquitous mobile awareness service. Preliminary results indicate that our …