COMPASS is a location framework where location sources are realized as plugins that contribute probability density functions to the overall localization result. In addition, COMPASS uses a decentralized location-based service discovery based on Peer-2-Peer distributed hashtables to retrieve semantical data on the determined position. In order to demonstrate the usefulness of COMPASS as a localization middleware, we have developed iNAV, an indoor navigation system that makes extensive use of the previously described mechanisms.