"The domain of Internet of Things (IoT) is rapidly, expanding beyond research, and becoming a major industrial, market with such stakeholders as major manufacturers of chips, and connected entities (i.e., things), and fast-growing operators, of wide-area networks. Importantly, this emerging domain is, driven by applications that leverage an IoT infrastructure to, provide users with innovative, high-value services. IoT infrastructures, range from small scale (e.g., homes and personal, health) to large scale (e.g., cities and transportation systems). In this paper, we argue that there is a continuum between orchestrating, connected entities in the small and in the large. We, propose a unified approach to application development, which, covers this spectrum. To do so, we examine the requirements for, orchestrating connected entities and address them with domainspecific, design concepts. We then show how to map these design, concepts into dedicated programming patterns and runtime, mechanisms. Our work revolves around domain-specific concepts and, notations, integrated into a tool-based design methodology and, dedicated to develop IoT applications. We have applied our, work across a spectrum of infrastructure sizes, ranging from, an automated pilot in avionics, to an assisted living platform, for the home of seniors, to a parking management system in, a smart city."