As most smart systems such as smart logistic and smart manufacturing are delay sensitive, the current mainstream cloud computing based system architecture is facing the critical issue of high latency over the Internet. Meanwhile, as huge amount of data is generated by smart devices with limited battery and computing power, the increasing demand for energy-efficient machine learning and secure data communication at the network edge has become a hurdle to the success of smart systems. To address these challenges with using smart UAV (Unmanned Aerial Vehicle) delivery system as an example, we propose EXPRESS, a novel energy-efficient and secure framework based on mobile edge computing and blockchain technologies. We focus on computation and data (resource) management which are two of the most prominent components in this framework. The effectiveness of the EXPRESS framework is demonstrated through the implementation of a real-world UAV delivery system. As an open-source framework, EXPRESS can help researchers implement their own prototypes and test their computation and data management strategies in different smart systems. The demo video can be found at https://youtu.be/r3U1iU8tSmk.