arXiv subjects

Ilja Behnke

Publications and source records attributed to Ilja Behnke.

17 recordsLinked to original sources

arXiv2025

Towards Machine-Generated Code for the Resolution of User Intentions

The growing capabilities of Artificial Intelligence (AI), particularly Large Language Models (LLMs), prompt a reassessment of the interaction mechanisms between users and their devices. Currently, users are required to use a set of high-level applications to achieve their desired results. However, the advent of AI may signal a shift in this regard, as its capabilities have generated novel prospects for user-provided intent resolution through the deployment of model-generated code. This development represents a significant progression in the realm of hybrid workflows, where human and artificial intelligence collaborate to address user intentions, with the former responsible for defining these intentions and the latter for implementing the solutions to address them. In this paper, we investigate the feasibility of generating and executing workflows through code generation that results from prompting an LLM with a concrete user intention, and a simplified application programming interface for a GUI-less operating system. We provide an in-depth analysis and comparison of various user intentions, the resulting code, and its execution. The findings demonstrate the general feasibility of our approach and that the employed LLM, GPT-4o-mini, exhibits remarkable proficiency in the generation of code-oriented workflows in accordance with provided user intentions.

cs.AI↗

arXiv2024

Real-Time Aware IP-Networking for Resource-Constrained Embedded Devices

This dissertation explores the area of real-time IP networking for embedded devices, especially those with limited computational resources. With the increasing convergence of information and operational technologies in various industries, and the growing complexity of communication requirements in (semi-)autonomous machines, there is a need for more advanced and reliable networking solutions. This research focuses on the challenge of integrating real-time embedded devices into packet-switched networks. Through a comprehensive review of current real-time communication technologies, standards, and practices in the context of Industry 4.0, a notable gap is identified: the lack of a robust real-time communication standard tailored for wireless mobile machines, and insufficient research on real-time embedded devices in highly networked environments. The study includes detailed experimentation with commercially available off-the-shelf networked microcontrollers, revealing a priority inversion problem where network packet processing interrupts real-time tasks, potentially causing real-time violations. To address this challenge, this thesis proposes mitigation methods and system designs that include software and hardware implementations. These include a new embedded network subsystem that prioritizes packet processing based on task priority, and a real-time-aware network interface controller that moderates interrupt requests. In addition, a hybrid hardware-software co-design approach is developed to ensure predictable and reliable real-time task execution despite network congestion. Furthermore, the research extends to task offloading in wireless Industrial Internet of Things environments, presenting a system architecture and scheduler capable of maintaining real-time constraints even under heavy loads and network uncertainties.

cs.NI↗

arXiv2024

Vessim: A Testbed for Carbon-Aware Applications and Systems

To reduce the carbon footprint of computing and stabilize electricity grids, there is an increasing focus on approaches that align the power usage of IT infrastructure with the availability of clean energy. Unfortunately, research on energy-aware and carbon-aware applications, as well as the interfaces between computing and energy systems, remains complex due to the scarcity of available testing environments. To this day, almost all new approaches are evaluated on custom simulation testbeds, which leads to repeated development efforts and limited comparability of results. In this paper, we present Vessim, a co-simulation environment for testing applications and computing systems that interact with their energy systems. Our testbed connects domain-specific simulators for renewable power generation and energy storage, and enables users to implement interfaces to integrate real systems through software and hardware-in-the-loop simulation. Vessim offers an easy-to-use interface, is extendable to new simulators, and provides direct access to historical datasets. We aim to not only accelerate research in carbon-aware computing but also facilitate development and operation, as in continuous testing or digital twins. Vessim is publicly available: https://github.com/dos-group/vessim.

cs.DC↗

arXiv2023

Real-Time Performance of Industrial IoT Communication Technologies: A Review

With the growing need for automation and the ongoing merge of OT and IT, industrial networks have to transport a high amount of heterogeneous data with mixed criticality such as control traffic, sensor data, and configuration messages. Current advances in IT technologies furthermore enable a new set of automation scenarios under the roof of Industry 4.0 and IIoT where industrial networks now have to meet new requirements in flexibility and reliability. The necessary real-time guarantees will place significant demands on the networks. In this paper, we identify IIoT use cases and infer real-time requirements along several axes before bridging the gap between real-time network technologies and the identified scenarios. We review real-time networking technologies and present peer-reviewed works from the past 5 years for industrial environments. We investigate how these can be applied to controllers, systems, and embedded devices. Finally, we discuss open challenges for real-time communication technologies to enable the identified scenarios. The review shows academic interest in the field of real-time communication technologies but also highlights a lack of a fixed set of standards important for trust in safety and reliability, especially where wireless technologies are concerned.

cs.NI↗

arXiv2023

Offloading Real-Time Tasks in IIoT Environments under Consideration of Networking Uncertainties

Offloading is a popular way to overcome the resource and power constraints of networked embedded devices, which are increasingly found in industrial environments. It involves moving resource-intensive computational tasks to a more powerful device on the network, often in close proximity to enable wireless communication. However, many Industrial Internet of Things (IIoT) applications have real-time constraints. Offloading such tasks over a wireless network with latency uncertainties poses new challenges. In this paper, we aim to better understand these challenges by proposing a system architecture and scheduler for real-time task offloading in wireless IIoT environments. Based on a prototype, we then evaluate different system configurations and discuss their trade-offs and implications. Our design showed to prevent deadline misses under high load and network uncertainties and was able to outperform a reference scheduler in terms of successful task throughput. Under heavy task load, where the reference scheduler had a success rate of 5%, our design achieved a success rate of 60%.

cs.NI↗

arXiv2023

Towards a Real-Time IoT: Approaches for Incoming Packet Processing in Cyber-Physical Systems

Embedded real-time devices for monitoring, controlling, and collaboration purposes in cyber-physical systems are now commonly equipped with IP networking capabilities. However, the reception and processing of IP packets generates workloads in unpredictable frequencies as networks are outside of a developer's control and difficult to anticipate, especially when networks are connected to the internet. As of now, embedded network controllers and IP stacks are not designed for real-time capabilities, even when used in real-time environments and operating systems. Our work focuses on real-time aware packet reception from open network connections, without a real-time networking infrastructure. This article presents two experimentally evaluated modifications to the IP processing subsystem and embedded network interface controllers of constrained IoT devices. The first, our software approach, introduces early packet classification and priority-aware processing in the network driver. In our experiments this allowed the network subsystem to remain active at a seven-fold increase in network traffic load before disabling the receive interrupts as a last resort. The second, our hardware approach, makes changes to the network interface controller, applying interrupt moderation based on real-time priorities to minimize the number of network-generated interrupts. Furthermore, this article provides an outlook on how the software and hardware approaches can be combined in a co-designed packet receive architecture.

cs.NI↗

arXiv2022

IoTreeplay: Synchronous Distributed Traffic Replay in IoT Environments

Use-cases in the Internet of Things (IoT) typically involve a high number of interconnected, heterogeneous devices. Due to the criticality of many IoT scenarios, systems and applications need to be tested thoroughly before rollout. Existing staging environments and testing frameworks are able to emulate network properties but fail to deliver actual network-wide traffic control to test systems application independently. To extend existing frameworks, we present the distributed traffic replaying tool IoTreeplay. The tool embeds TCPLivePlay into an environment that allows the synchronous replaying of network traffic with multiple endpoints and connections. Replaying takes place in a user-defined network or testbed containing IoT use-cases. Network traffic can be captured and compared to the original trace to evaluate accuracy and reliability. The resulting implementation is able to accurately replay connections within a maximum transmission rate but struggles with deviations from regular TCP connections, like packet loss or connection reset. An evaluation has been performed, measuring individual and aggregated delays between packets, based on the recorded timestamps.

cs.NI↗

arXiv2022

Differentiating Network Flows for Priority-Aware Scheduling of Incoming Packets in Real-Time IoT Systems

When IP-packet processing is unconditionally carried out on behalf of an operating system kernel thread, processing systems can experience overload in high incoming traffic scenarios. This is especially worrying for embedded real-time devices controlling their physical environment in industrial IoT scenarios and automotive systems. We propose an embedded real-time aware IP stack adaption with an early demultiplexing scheme for incoming packets and subsequent per-flow aperiodic scheduling. By instrumenting existing embedded IP stacks, rigid prioritization with minimal latency is deployed without the need of further task resources. Simple mitigation techniques can be applied to individual flows, causing hardly measurable overhead while at the same time protecting the system from overload conditions. Our IP stack adaption is able to reduce the low-priority packet processing time by over 86% compared to an unmodified stack. The network subsystem can thereby remain active at a 7x higher general traffic load before disabling the receive IRQ as a last resort to assure deadlines.

cs.NI↗

arXiv2022

A Priority-Aware Multiqueue NIC Design

Low-level embedded systems are used to control cyber-phyiscal systems in industrial and autonomous applications. They need to meet hard real-time requirements as unanticipated controller delays on moving machines can have devastating effects. Modern developments such as the industrial Internet of Things and autonomous machines require these devices to connect to large IP networks. Since Network Interface Controllers (NICs) trigger interrupts for incoming packets, real-time embedded systems are subject to unpredictable preemptions when connected to such networks. In this work, we propose a priority-aware NIC design to moderate network-generated interrupts by mapping IP flows to processes and based on that, consolidates their packets into different queues. These queues apply priority-dependent interrupt moderation. First experimental evaluations show that 93% of interrupts can be saved leading to an 80% decrease of processing delay of critical tasks in the configurations investigated.

cs.NI↗

arXiv2021

Continuously Testing Distributed IoT Systems: An Overview of the State of the Art

The continuous testing of small changes to systems has proven to be useful and is widely adopted in the development of software systems. For this, software is tested in environments that are as close as possible to the production environments. When testing IoT systems, this approach is met with unique challenges that stem from the typically large scale of the deployments, heterogeneity of nodes, challenging network characteristics, and tight integration with the environment among others. IoT test environments present a possible solution to these challenges by emulating the nodes, networks, and possibly domain environments in which IoT applications can be executed. This paper gives an overview of the state of the art in IoT testing. We derive desirable characteristics of IoT test environments, compare 18 tools that can be used in this respect, and give a research outlook of future trends in this area.

cs.DC↗

arXiv2021

Let's Wait Awhile: How Temporal Workload Shifting Can Reduce Carbon Emissions in the Cloud

Depending on energy sources and demand, the carbon intensity of the public power grid fluctuates over time. Exploiting this variability is an important factor in reducing the emissions caused by data centers. However, regional differences in the availability of low-carbon energy sources make it hard to provide general best practices for when to consume electricity. Moreover, existing research in this domain focuses mostly on carbon-aware workload migration across geo-distributed data centers, or addresses demand response purely from the perspective of power grid stability and costs. In this paper, we examine the potential impact of shifting computational workloads towards times where the energy supply is expected to be less carbon-intensive. To this end, we identify characteristics of delay-tolerant workloads and analyze the potential for temporal workload shifting in Germany, Great Britain, France, and California over the year 2020. Furthermore, we experimentally evaluate two workload shifting scenarios in a simulation to investigate the influence of time constraints, scheduling strategies, and the accuracy of carbon intensity forecasts. To accelerate research in the domain of carbon-aware computing and to support the evaluation of novel scheduling algorithms, our simulation framework and datasets are publicly available.

cs.DC↗

arXiv2021

Interrupting Real-Time IoT Tasks: How Bad Can It Be to Connect Your Critical Embedded System to the Internet?

Embedded systems have been used to control physical environments for decades. Usually, such use cases require low latencies between commands and actions as well as a high predictability of the expected worst-case delay. To achieve this on small, low-powered microcontrollers, Real-Time Operating Systems (RTOSs) are used to manage the different tasks on these machines as deterministically as possible. However, with the advent of the Internet of Things (IoT) in industrial applications, the same embedded systems are now equipped with networking capabilities, possibly endangering critical real-time systems through an open gate to interrupts. This paper presents our initial study of the impact network connections can have on real-time embedded systems. Specifically, we look at three aspects: The impact of network-generated interrupts, the overhead of the related networking tasks, and the feasibility of sharing computing resources between networking and real-time tasks. We conducted experiments on two setups: One treating NICs and drivers as black boxes and one simulating network interrupts on the machines. The preliminary results show that a critical task performance loss of up to 6.67% per received packet per second could be induced where lateness impacts of 1% per packet per second can be attributed exclusively to ISR-generated delays.

cs.NI↗

arXiv2021

Detecting and Mitigating Network Packet Overloads on Real-Time Devices in IoT Systems

Manufacturing, automotive, and aerospace environments use embedded systems for control and automation and need to fulfill strict real-time guarantees. To facilitate more efficient business processes and remote control, such devices are being connected to IP networks. Due to the difficulty in predicting network packets and the interrelated workloads of interrupt handlers and drivers, devices controlling time critical processes stand under the risk of missing process deadlines when under high network loads. Additionally, devices at the edge of large networks and the internet are subject to a high risk of load spikes and network packet overloads. In this paper, we investigate strategies to detect network packet overloads in real-time and present four approaches to adaptively mitigate local deadline misses. In addition to two strategies mitigating network bursts with and without hysteresis, we present and discuss two novel mitigation algorithms, called Budget and Queue Mitigation. In an experimental evaluation, all algorithms showed mitigating effects, with the Queue Mitigation strategy enabling most packet processing while preventing lateness of critical tasks.

cs.NI↗

arXiv2021

PIERES: A Playground for Network Interrupt Experiments on Real-Time Embedded Systems in the IoT

IoT devices have become an integral part of our lives and the industry. Many of these devices run real-time systems or are used as part of them. As these devices receive network packets over IP networks, the network interface informs the CPU about their arrival using interrupts that might preempt critical processes. Therefore, the question arises whether network interrupts pose a threat to the real-timeness of these devices. However, there are few tools to investigate this issue. We present a playground which enables researchers to conduct experiments in the context of network interrupt simulation. The playground comprises different network interface controller implementations, load generators and timing utilities. It forms a flexible and easy to use foundation for future network interrupt research. We conduct two verification experiments and two real world examples. The latter give insight into the impact of the interrupt handling strategy parameters and the influence of different load types on the execution time with respect to these parameters.

cs.NI↗

arXiv2021

A Scalable and Dependable Data Analytics Platform for Water Infrastructure Monitoring

With weather becoming more extreme both in terms of longer dry periods and more severe rain events, municipal water networks are increasingly under pressure. The effects include damages to the pipes, flash floods on the streets and combined sewer overflows. Retrofitting underground infrastructure is very expensive, thus water infrastructure operators are increasingly looking to deploy IoT solutions that promise to alleviate the problems at a fraction of the cost. In this paper, we report on preliminary results from an ongoing joint research project, specifically on the design and evaluation of its data analytics platform. The overall system consists of energy-efficient sensor nodes that send their observations to a stream processing engine, which analyzes and enriches the data and transmits the results to a GIS-based frontend. As the proposed solution is designed to monitor large and critical infrastructures of cities, several non-functional requirements such as scalability, responsiveness and dependability are factored into the system architecture. We present a scalable stream processing platform and its integration with the other components, as well as the algorithms used for data processing. We discuss significant challenges and design decisions, introduce an efficient data enrichment procedure and present empirical results to validate the compliance with the target requirements. The entire code for deploying our platform and running the data enrichment jobs is made publicly available with this paper.

cs.DC↗

arXiv2021

Towards a Staging Environment for the Internet of Things

Internet of Things (IoT) applications promise to make many aspects of our lives more efficient and adaptive through the use of distributed sensing and computing nodes. A central aspect of such applications is their complex communication behavior that is heavily influenced by the physical environment of the system. To continuously improve IoT applications, a staging environment is needed that can provide operating conditions representative of deployments in the actual production environments -- similar to what is common practice in cloud application development today. Towards such a staging environment, we present Marvis, a framework that orchestrates hybrid testbeds, co-simulated domain environments, and a central network simulation for testing distributed IoT applications. Our preliminary results include an open source prototype and a demonstration of a Vehicle-to-everything (V2X) communication scenario.

cs.DC↗

arXiv2020

Fingerprinting Analog IoT Sensors for Secret-Free Authentication

Especially in context of critical urban infrastructures, trust in IoT data is of utmost importance. While most technology stacks provide means for authentication and encryption of device-to-cloud traffic, there are currently no mechanisms to rule out physical tampering with an IoT device's sensors. Addressing this gap, we introduce a new method for extracting a hardware fingerprint of an IoT sensor which can be used for secret-free authentication. By comparing the fingerprint against reference measurements recorded prior to deployment, we can tell whether the sensing hardware connected to the IoT device has been changed by environmental effects or with malicious intent. Our approach exploits the characteristic behavior of analog circuits, which is revealed by applying a fixed-frequency alternating current to the sensor, while recording its output voltage. To demonstrate the general feasibility of our method, we apply it to four commercially available temperature sensors using laboratory equipment and evaluate the accuracy. The results indicate that with a sensible configuration of the two hyperparameters we can identify individual sensors with high probability, using only a few recordings from the target device.

cs.CR↗