In the last few years, we have been witnessing the spread of computing devices getting smaller and smaller (e.g., Smartphones, Smart Devices, Raspberry, etc.), and the production and availability of data getting bigger and bigger. In this work we introduce DLV Large Scale (DLV-LS), a framework based on Answer Set Programming (ASP) for performing declarative-based reasoning tasks over data-intensive applications, possibly on Smart Devices. The framework encompasses DLV Mobile Edition(DLV-ME), an ASP based solver for Android systems and Raspberry devices, and DLV Enterprise Edition (DLV-EE), an ASP-based platform, accessible by REST interfaces, for large-scale reasoning over Big Data, classical relational database systems, and NoSQL databases. DLV-LS enables Smart Devices to both locally perform reasoning over data generated by their own sensors and properly interact with DLV-EE when more computational power is needed for harder tasks, possibly over bigger centralized data. We present also a real-world application of DLV-LS; the use case consists of a tourist navigator that calculates the best routes and optimizes a tour of a tourist under custom-defined time constraints.