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Abstract-Unlike traditional networked embedded systems, the Internet of Things interconnects heterogeneous devices from various manufacturers with diverse functionalities. To foster the emergence of novel applications, this vast infrastructure requires a common application layer. As a single global standard for all device types and application domains is impracticable, we propose an architecture where the infrastructure is agnostic of applications and application development is fully decoupled from the embedded domain. In our design, the application logic of devices is running on application servers, while thin servers embedded into devices export only their elementary functionality using REST resources. In this paper, we present our design goals and preliminary results of this approach, featuring the Californium (Cf) CoAP framework.

Abstract-Programming Internet of Things (IoT) applications is challenging because developers have to be knowledgeable in various technical domains, from low-power networking, over embedded operating systems, to distributed algorithms. Hence, it will be challenging to find enough experts to provide software for the vast number of expected devices, which must also be scalable and particularly safe due to the connection to the physical world. To remedy this situation, we propose an architecture that provides Web-like scripting for low-end devices through Cloud-based application servers and a consistent, RESTful programming model. Our novel runtime container Actinium (Ac) exposes scripts, their configuration, and their lifecycle management through a fully RESTful programming interface using the Constrained Application Protocol (CoAP). We endow the JavaScript language with an API for direct interaction with mote-class IoT devices, the CoapRequest object, and means to export script data as Web resources. With Actinium, applications can be created by simply mashing up resources provided by CoAP servers on devices, other scripts, and classic Web services. We also discuss security considerations and show the suitability of this architecture in terms of performance with our publicly available implementation.

One of the central research challenges in the Internet of Things and Ubiquitous Computing domains is how users can be enabled to "program" their personal and industrial smart environments by combining services that are provided by devices around them. We present a service composition system that enables the goal-driven configuration of smart environments for end users by combining semantic metadata and reasoning with a visual modeling tool. In contrast to process-driven approaches where service mashups are statically defined, we make use of embedded semantic API descriptions to dynamically create mashups that fulfill the user's goal. The main advantage of our system is its high degree of flexibility, as service mashups can adapt to dynamic environments and are fault-tolerant with respect to individual services becoming unavailable. To support users in expressing their goals, we integrated a visual programming tool with our system that allows to model the desired state of a smart environment graphically, thereby hiding the technicalities of the underlying semantics. Possible applications of the presented system include the management of smart homes to increase individual well-being, and reconfigurations of smart environments, for instance in the industrial automation or healthcare domains. Note to Practitioners-Machine tooling times are an important factor especially when producing small batch sizes. Our approach holds the potential to have manufacturing lines reconfigure themselves at runtime, based on descriptions of the functionality of individual devices. It can even consider properties that influence the process indirectly ("nonfunctional"), such as the time or monetary cost of a process. We additionally implemented a system that makes these rather complex descriptions understandable for nonspecialists. In this paper, we describe use cases from the home automation and future manufacturing domains.