Putting computing in context: An infrastructure to support extensible context-enhanced collaborative applications

Context-aware computing exposes a unique tension in how information about human context is modeled and used. On the one hand, approaches that use loosely structured information have been shown to be useful in situations where humans are the final consumers of contextual information; these approaches have found favor in many CSCW applications. On the other hand, more rigidly structured information supports machine interpretation and exchange; these approaches have been explored in the ubiquitous computing community. The system presented here, dubbed Intermezzo, represents an exploration of a space between these two extremes. Intermezzo combines a loose data structuring with a number of unique features designed to allow applications to embed specialized semantic interpretations of data into the infrastructure, allowing them to be reused by other applications. This approach can enable the construction of applications that can take advantage of rich, layered interpretations of context without requiring that they understand all aspects of that context. This approach is explored through the creation of two higher-level services that provide context-enhanced session management and context-enhanced access control.© 2005 ACM.