In this paper, we propose IoTChain, a combination of the OSCAR architecture [1] and the ACE authorization framework [2] to provide an E2E solution for the secure authorized access to IoT resources. IoTChain consists of two components, an authorization blockchain based on the ACE framework and the OSCAR object security model, extended with a group key scheme. The blockchain provides a flexible and trustless way to handle authorization while OSCAR uses the public ledger to set up multicast groups for authorized clients. To evaluate the feasibility of our architecture, we have implemented the authorization blockchain on top of a private Ethereum network. We report on several experiments that assess the performance of different architecture components.

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Due to the high number of sensors managed and need to perform complex reasoning activities, real-time control systems of autonomous robots exhibit a high potential for overload, i.e., real-time tasks missing their deadlines. In these systems overload should be regarded as a likely occurrence and hence managed accordingly. In this paper we illustrate a novel scheduling technique for adaptation of soft real-time load to available computational capacity in the context of autonomous robot control architectures. The technique is based o n r ate modulation of a set of periodic tasks in a range of admissible rates. The technique is shown to be easily computable and several variations in implementation are reviewed within the paper.

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Currently available discrete event simulation tools exhibit important limitations, either being too specific, or providing only a partial API and possibly not enough scalability. In this paper we introduce our novel general purpose simulator, called DEUS, which aims at becoming one of the reference tools in the field of complex system simulation. Its essential Java API provides basic interfaces and classes for modelling nodes, events and processes characterizing the structure and dynamics of any complex system. High usability, configurability and memory efficiency are among the strengths of DEUS, as exemplified in this paper by means of the simulator of Chord peer-to-peer systems we implemented with minor coding effort.