Extreme-scale Cloud/Fog Data Processing refers to the capability of processing exceptionally large and complex datasets in cloud and fog computing environments, with a particular emphasis on scalability, efficiency, and real-time or near-real-time processing. The EMERALDS services will be tailored for urban mobility data, to support ultra-scalable query processing algorithms over road networks, from similarity search of spatio-temporal data to more complex processing tasks for trajectory joins, discovery of hot-spots, as well as for supporting mobility analytics.