ELEGANT aims to solve the ever-increasing problem of software fragmentation in the IoT/Big Data interoperability domain. Software fragmentation prohibits the unification of these two ecosystems severely limiting the ability to regard them as a single system and tune the whole infrastructure towards defining its a) Performance, b) Energy Efficiency, c) Security, d) Reliability, and d) Dependability (PESRD) requirements. ELEGANT proposes a novel software programming paradigm, along with an associated set of methodologies and toolchains, to program IoT and Big Data frameworks using a unified programming framework. Its key proposed innovations in the areas of: a) Light-weight application virtualization, b) Automatic code extraction compatible with both IoT and Big Data frameworks, c) AI-assisted Intelligent Orchestration, d) dynamic code motion, and e) advanced code verification and cybersecurity mechanisms, will enable the seamless operation of end-to-end IoT/Big Data complex systems. This way, users employing the ELEGANT software stack and methodologies will be able to seamlessly define the pareto-optimal point in the PESRD optimization space while the entire system will be able to dynamically adjust itself during execution. To achieve its ambitious goals, ELEGANT assembles a consortium of experts across all domains ranging from low-level system software, IoT, Big Data, AI-assisted scheduling, and DevOps. Finally, the proposed solutions will be evaluated against pre-defined KPIs across a wide range of operational use cases from four distinct domains: health, automotive, smart metering, and video surveillance.