The Blockchain for the Internet of Things (IoT) has considered to "change the future." Despite a myriad of studies on the blockchain IoT, few studies have investigated how an IoT blockchain system develops with open source technologies, open standards, web technologies, and a p2p network. In this presentation, Jollen will share the Flowchain case study, an open source IoT blockchain project in Node.js; he will discuss the practice, the technical challenges, and the engineering experiences. Furthermore, to provide the real-time data transaction capabilities for current IoT requirements, he will utilize the "virtual block" idea to facilitate such technical challenges.