Novel Architectures for Location-based Services

Applications or services which take into account the current location will become increasingly popular in the future. Especially mobile phone providers expect a huge market for such services. Typical applications answer questions like “Where is the nearest hotel?” or “Who of my friends is in proximity?”. Further examples are city guides or navigation systems. Currently, the development of such services is costintensive due to the heterogeneity of positioning techniques, positioning systems and location data [3, 9]. To support developers of location-based services we created the Nimbus framework. Nimbus provides a common interface to location data and hides the position capturing mechanisms. To achieve an optimal flexibility, it provides physical coordinates as well as semantic information about the current location. With Nimbus, mobile users can switch between satellite navigation systems such as GPS, positioning systems based on cell-phone infrastructures, or indoor positioning systems without affecting the location-based service. As our infrastructure is self-organizing, it is flexible and easy to extend. The concept of semantic locations heavily influenced the Nimbus framework. Semantic locations have a certain meaning for users or applications. Typical examples of such locations are "Campus, University of Hagen" or "City centre of Paris". The key idea of our location model was to strongly couple semantic and physical locations. Having both types of locations has a number of advantages: