As low-level architectural support for context-aware computing matures, we are ready to explore more general and powerful
means of accessing context data. Information required by a context-aware application may be partitioned by any number of physical,
organizational, or privacy boundaries. This suggests the need for mechanisms by which applications can issue context-sensitive
queries without having to explicitly manage the complex storage layout and access policies of the underlying data. To address
this need, we have developed liquid, a prototype query service that supports distributed, continuous query processing of context
data. This paper articulates the current need for such systems, describes the design of the liquidsystem, and presents both
a room-awareness application and notification service demonstrating its functionality.