u2DA: Heterogeneous Distributed Database for Ubiquitous Computing Based on ucode 2.0 Architecture

In order for successful deployment of IoT in our society, context awareness holds the key for computers to understand the real-world contexts and behave based on them, which has long been the goal referred to as ubiquitous computing. However, the information about this real world is often stored in different locations like cloud databases, device memories, and may sometimes come directly from sensors without being stored, which makes the context awareness partial and divided. In order to aggregate such context information stored and generated at different locations, we propose u2DA, a heterogeneous distributed database for ubiquitous computing based on ucode 2.0 architecture. u2DA works as a front-end that realizes a virtual, distributed database realized on existing databases, decomposes the queries into sub-queries being sent to such underlying databases, and aggregates the sub-query results into the results of the original query. We have implemented u2DA on OCaml, and proved through our case study that our system can help applications to realize context awareness in real world scenarios.