Functional Programming for Embedded Systems

Embedded Systems application development has traditionally been carried out in low-level machine-oriented programming languages like C or Assembler that can result in unsafe, error-prone and difficult-to-maintain code. Functional programming with features such as higher-order functions, algebraic data types, polymorphism, strong static typing and automatic memory management appears to be an ideal candidate to address the issues with low-level languages plaguing embedded systems. However, embedded systems usually run on heavily memory-constrained devices with memory in the order of hundreds of kilobytes and applications running on such devices embody the general characteristics of being (i) I/O- bound, (ii) concurrent and (iii) timing-aware. Popular functional language compilers and runtimes either do not fare well with such scarce memory resources or do not provide high-level abstractions that address all the three listed characteristics. This work attempts to address this gap by investigating and proposing high-level abstractions specialised for I/O-bound, concurrent and timing-aware embedded-systems programs. We implement the proposed abstractions on eagerly-evaluated, statically-typed functional languages running natively on microcontrollers. Our contributions are divided into two parts - Part 1 presents a functional reactive programming language - Hailstorm - that tracks side effects like I/O in its type system using a feature called resource types. Hailstorm’s programming model is illustrated on the GRiSP microcontroller board.Part 2 comprises two papers that describe the design and implementation of Synchron, a runtime API that provides a uniform message-passing framework for the handling of software messages as well as hardware interrupts. Additionally, the Synchron API supports a novel timing operator to capture the notion of time, common in embedded applications. The Synchron API is implemented as a virtual machine - SynchronVM - that is run on the NRF52 and STM32 microcontroller boards. We present programming examples that illustrate the concurrency, I/O and timing capabilities of the VM and provide various benchmarks on the response time, memory and power usage of SynchronVM

Software Development Support for Shared Sensing Infrastructures: A Generative and Dynamic Approach

International audienceSensors networks are the backbone of large sensing infras-tructures such as Smart Cities or Smart Buildings. Classical approaches suffer from several limitations hampering developers' work (e.g., lack of sensor sharing, lack of dynamicity in data collection policies, need to dig inside big data sets, absence of reuse between implementation platforms). This paper presents a tooled approach that tackles these issues. It couples (i) an abstract model of developers' requirements in a given infrastructure to (ii) timed automata and code generation techniques, to support the efficient deployment of reusable data collection policies on different infrastructures. The approach has been validated on several real-world scenarios and is currently experimented on an academic campus

A Semantic Theory of the Internet of Things (extended abstract)

We propose a process calculus for modelling and reasoning on systems in the Internet of Things paradigm. Our systems interact both with the physical environment, via sensors and actuators, and with smart devices, via short-range and Internet channels. The calculus is equipped with a standard notion of labelled bisimilarity which represents a fully abstract characterisation of a well-known contextual equivalence. We use our semantic proof-methods to prove run-time properties of a non-trivial case study as well as system equalities

Federated Embedded Systems – a review of the literature in related fields

This report is concerned with the vision of smart interconnected objects, a vision that has attracted much attention lately. In this paper, embedded, interconnected, open, and heterogeneous control systems are in focus, formally referred to as Federated Embedded Systems. To place FES into a context, a review of some related research directions is presented. This review includes such concepts as systems of systems, cyber-physical systems, ubiquitous computing, internet of things, and multi-agent systems. Interestingly, the reviewed fields seem to overlap with each other in an increasing number of ways

Decentralized Identity and Access Management Framework for Internet of Things Devices

The emerging Internet of Things (IoT) domain is about connecting people and devices and systems together via sensors and actuators, to collect meaningful information from the devices surrounding environment and take actions to enhance productivity and efficiency. The proliferation of IoT devices from around few billion devices today to over 25 billion in the next few years spanning over heterogeneous networks defines a new paradigm shift for many industrial and smart connectivity applications. The existing IoT networks faces a number of operational challenges linked to devices management and the capability of devices’ mutual authentication and authorization. While significant progress has been made in adopting existing connectivity and management frameworks, most of these frameworks are designed to work for unconstrained devices connected in centralized networks. On the other hand, IoT devices are constrained devices with tendency to work and operate in decentralized and peer-to-peer arrangement. This tendency towards peer-to-peer service exchange resulted that many of the existing frameworks fails to address the main challenges faced by the need to offer ownership of devices and the generated data to the actual users. Moreover, the diversified list of devices and offered services impose that more granular access control mechanisms are required to limit the exposure of the devices to external threats and provide finer access control policies under control of the device owner without the need for a middleman. This work addresses these challenges by utilizing the concepts of decentralization introduced in Distributed Ledger (DLT) technologies and capability of automating business flows through smart contracts. The proposed work utilizes the concepts of decentralized identifiers (DIDs) for establishing a decentralized devices identity management framework and exploits Blockchain tokenization through both fungible and non-fungible tokens (NFTs) to build a self-controlled and self-contained access control policy based on capability-based access control model (CapBAC). The defined framework provides a layered approach that builds on identity management as the foundation to enable authentication and authorization processes and establish a mechanism for accounting through the adoption of standardized DLT tokenization structure. The proposed framework is demonstrated through implementing a number of use cases that addresses issues related identity management in industries that suffer losses in billions of dollars due to counterfeiting and lack of global and immutable identity records. The framework extension to support applications for building verifiable data paths in the application layer were addressed through two simple examples. The system has been analyzed in the case of issuing authorization tokens where it is expected that DLT consensus mechanisms will introduce major performance hurdles. A proof of concept emulating establishing concurrent connections to a single device presented no timed-out requests at 200 concurrent connections and a rise in the timed-out requests ratio to 5% at 600 connections. The analysis showed also that a considerable overhead in the data link budget of 10.4% is recorded due to the use of self-contained policy token which is a trade-off between building self-contained access tokens with no middleman and link cost

A new task scheduling approach for energy conservation in Internet of Things

Internet of Things (IoT) and mobile edge computing (MEC) architectures are common in real-time application scenarios for improving the reliability of service responses. Energy conservation (EC) and energy harvesting (EH) are significant concerns in such architectures due to the self-sustainable devices and resource-constraint edge nodes. The density of the users and service requirements are further reasons for energy conservation and the need for energy harvesting in these scenarios. This article proposes decisive task scheduling for energy conservation (DTS-EC). The proposed energy conservation method relies on conditional decision-making through classification disseminations and energy slots for data handling. By classifying the energy requirements and the states of the mobile edge nodes, the allocation and queuing of data are determined, preventing overloaded nodes and dissemination. This process is recurrent for varying time slots, edge nodes, and tasks. The proposed method is found to achieve a high data dissemination rate (8.16%), less energy utilization (10.65%), and reduced latency (11.44%) at different time slots