Interpreting task oriented programs on tiny computers

Small Microcontroller Units (MCUs) drive the omnipresent Internet of Things (IoT). These devices are small, cheap, and energy efficient. However, they are not very powerful and lack an Operating System. Hence it is difficult to apply high level abstractions and write software that stays close to the design. Task Oriented Programming (TOP) is a paradigm for creating multi-user collaborative systems. A program consists of tasks---descriptions of what needs to be done. The tasks represent the actual work and a task value is observable during execution. Furthermore, tasks can be combined and transformed using combinators. mTask is an embedded Domain Specific Language (eDSL) to program MCUs following the TOP paradigm. Previous work has described the mTask language, a static C code generator, and how to integrate mTask with TOP servers. This paper shows that for dynamic IOT applications, tasks must be sent at runtime to the devices for interpretation. It describes in detail how to compile specialized IOT TOP tasks to bytecode and how to interpret them on devices with very little memory. These additions allow the creation of complete, dynamic IOT applications arising from a single source using a mix of iTasks and mTask tasks. Details such as serialization and communication are captured in simple abstractions.