“…Accordingly, a real challenge for future pervasive services is the investigation of principles, algorithms, and middleware infrastructures, via which this growing amount of distributed information can be properly represented, organized, aggregated, and made more meaningful, so as to facilitate the successful retrieval by pervasive services [7,3]. Many approaches [10,4] are currently going in the direction of adopting specific middleware layer, i.e., a knowledge network layer embedding data and knowledge network algorithms and providing effective access to such data by services.…”