Software Fault Injection: A Practical Perspective

Software fault injection (SFI) is an acknowledged method for assessing the dependability of software systems. After reviewing the state-of-the-art of SFI, we address the challenge of integrating it deeper into software development practice. We present a well-defined development methodology incorporating SFI—fault injection driven development (FIDD)—which begins by systematically constructing a dependability and failure cause model, from which relevant injection techniques, points, and campaigns are derived. We discuss possibilities and challenges for the end-to-end automation of such campaigns. The suggested approach can substantially improve the accessibility of dependability assessment in everyday software engineering practice

Performance of Real-TimeWireless Communication for Railway Environments with IEEE 802.11p

IEEE 802.11p complements the widespread 802.11 standard for use in vehicular environments. Designed for communication between wireless devices in rapidly changing environments, it handles situations where connection and communication must be completed in very short periods of time. Even though this is supposed to be a substantial improvement and essential for real-time applications, latencies have been rarely investigated in existing studies. Based on practical experiments, we evaluate how beneficial 802.11p’s changes in comparison to regular 802.11n are and whether the usage of IEEE 802.11p is suitable within environments with real-time constraints. We compare latencies of networks in OCB mode to both networks in IBSS (ad-hoc) and BSS/AP (access point) mode by measuring the initial connection speed and the latency of ICMP packets’ round-trip times. Furthermore, the response of the latter to disturbances is measured. The results show OCB to be superior to both BSS/AP and IBSS modes in average latency, maximum latency, and standard deviation under all tested circumstances

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

Rail2X - SmartServices (Projektabschlussbericht)

V2X (Vehicle2Everything) ist ein WLAN-ähnlicher Standard, der im Automobilbereich für den Informationsaustausch zwischen Fahrzeugen und / oder Infrastruktur genutzt wird. Beispiels-weise findet dieser Nachrichtenstandard im Straßenverkehr Anwendung, um den Autofahrer rechtzeitig vor kritischen Situationen zu warnen und so zu unterstützen. V2X-Komponenten befinden sich daher seit mehreren Jahren in der Entwicklung und Erpro-bung. Jedoch ist dieser Kommunikationsstandard nicht ausschließlich auf den Automobilbe-reich begrenzt, sondern verkehrsträgerunabhängig ausgelegt. Über das Projekt Rail2X-Smart Services wurde die Nutzung der V2X-Kommunikation für den Eisenbahnsektor evaluiert. Ziel des Projektkonsortiums war die Erforschung und Erweiterung von V2X als Rail2X in den Bahnbereich, um den Komfort sowie die Effektivität und Wirtschaftlichkeit des Bahnbetriebs im Regionalverkehr zu steigern. Grundsätzlich wurde ein Verkehrsträger und Verkehrsmittel übergreifender Informationsaustausch ermöglicht. Sowohl die Nutzung einheitlicher Standards als auch die Verknüpfung mit einem zentralen Datenmanagementsystem, das Daten bearbeitet und mit anderen Datenquellen wie der mCLOUD korreliert, spielten dabei eine zentrale Rolle. Für die Erprobung und Evaluierung wurden drei relevanten Anwendungsfällen im Bahnbereich definiert und ausgestaltet die durch die V2X-Anwendung einen wirtschaftlichen Betrieb ermöglichen. Mittels dieser Anwendungsfälle konnte gezeigt werden, dass einerseits die Nutzung des V2X-Standards möglich und andererseits die Anwendung von kostengünstigen Standardkomponenten aus dem Automobilbereich auch im Bahnbereich zielführend ist

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

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

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 are