Real-world implementation of the location stack: the universal location framework

Both the research community and developers in industry have identified the need for a clearly defined vocabulary and programming framework for location technologies. A layered location stack that provides appropriate abstractions, common terminology, and a clear API has been proposed in the last edition of WMCSA. We relate the experience gained in applying the location stack abstractions to the design and implementation of a location system using three separate location technologies integrated in a wireless computer. A single application interface, termed the universal location framework, is designed to aggregate indoor, outdoor, and proximity sensor technologies. Our focus is on how well partitioning and parameter passing between the layers worked for our purposes as well as identifying system requirements not currently part of the stack. In closing, we provide evidence in support of the location stack's usefulness and we make some recommendations for its potential evolution.