BUSINESS INTELLIGENCE BASED ON A WI-FI REAL TIME POSITIONING ENGINE - A Practical Application in a Major Retail Company Topics: Coupling and Integrating Heterogeneous Data Sources; Data Warehouse; Middleware Integration; Organisational Issues on Systems Integration; Strategic Decision Support Systems In Proceedings of the 11th International Conference on Enterprise Information Systems - Volume 3: ICEIS, 11-16, 2009 , Milan, Italy