Collecting and Analyzing Failure Data of Bluetooth Personal Area Networks

This work presents a failure data analysis campaign on Bluetooth Personal Area Networks (PANs) conducted on two kind of heterogeneous testbeds (working for more than one year). The obtained results reveal how failures distribution are characterized and suggest how to improve the dependability of Bluetooth PANs. Specically, we dene the failure model and we then identify the most effective recovery actions and masking strategies that can be adopted for each failure. We then integrate the discovered recovery actions and masking strategies in our testbeds, improving the availability and the reliability of 3.64% (up to 36.6%) and 202% (referred to the Mean Time To Failure), respectively

Integrated Support for Handoff Management and Context-Awareness in Heterogeneous Wireless Networks

The overwhelming success of mobile devices and wireless communications is stressing the need for the development of mobility-aware services. Device mobility requires services adapting their behavior to sudden context changes and being aware of handoffs, which introduce unpredictable delays and intermittent discontinuities. Heterogeneity of wireless technologies (Wi-Fi, Bluetooth, 3G) complicates the situation, since a different treatment of context-awareness and handoffs is required for each solution. This paper presents a middleware architecture designed to ease mobility-aware service development. The architecture hides technology-specific mechanisms and offers a set of facilities for context awareness and handoff management. The architecture prototype works with Bluetooth and Wi-Fi, which today represent two of the most widespread wireless technologies. In addition, the paper discusses motivations and design details in the challenging context of mobile multimedia streaming applications

On Data Dissemination for Large-Scale Complex Critical Infrastructures

Middleware plays a key role for the achievement of the mission of future largescalecomplexcriticalinfrastructures, envisioned as federations of several heterogeneous systems over Internet. However, available approaches for datadissemination result still inadequate, since they are unable to scale and to jointly assure given QoS properties. In addition, the best-effort delivery strategy of Internet and the occurrence of node failures further exacerbate the correct and timely delivery of data, if the middleware is not equipped with means for tolerating such failures. This paper presents a peer-to-peer approach for resilient and scalable datadissemination over large-scalecomplexcriticalinfrastructures. The approach is based on the adoption of epidemic dissemination algorithms between peer groups, combined with the semi-active replication of group leaders to tolerate failures and assure the resilient delivery of data, despite the increasing scale and heterogeneity of the federated system. The effectiveness of the approach is shown by means of extensive simulation experiments, based on Stochastic Activity Networks

An Effective Approach for Injecting Faults in Wireless Sensor Networks Operating Systems

This paper presents an effective approach for injecting faults/errors in WSN nodes operating systems. The approach is based on the injection of faults at the assembly level. Results show that depending on the concurrency model and on the memory management, the operating systems react to injected errors differently, indicating that fault containment strategies and hang-checking assertions should be implemented to avoid spreading and activations of errors

The heuristic strategies for assessing wireless sensor network: an event-based formal approach

Wireless Sensor Networks (WSNs) are increasingly being adopted in critical applications. In these networks undesired events may undermine the reliability level; thus their effects need to be properly assessed from the early stages of the development process onwards to minimize the chances of unexpected problems during use. In this paper we propose two heuristic strategies: what-if analysis and robustness checking. They allow to drive designers towards optimal WSN deployment solutions, from the point of view of the connection and data delivery resiliency, exploiting a formal approach based on the event calculus formal language. The heuristics are backed up by a support tool aimed to simplify their adoption by system designers. The tool allows to specify the target WSN in a user-friendly way and it is able to elaborate the two heuristic strategies by means of the event calculus specifications automatically generated. The WSN reliability is assessed computing a set of specific metrics. The effectiveness of the strategies is shown in the context of three case studies

Achieving Isolation in Mixed-Criticality Industrial Edge Systems with Real-Time Containers Appendix

Real-time containers are a promising solution to reduce latencies in time-sensitive cloud systems. Recent efforts are emerging to extend their usage in industrial edge systems with mixed-criticality constraints. In these contexts, isolation becomes a major concern: a disturbance (such as timing faults or unexpected overloads) affecting a container must not impact the behavior of other containers deployed on the same hardware. In this paper, we propose a novel architectural solution to achieve isolation in real-time containers, based on real-time co-kernels, hierarchical scheduling, and time-division networking. The architecture has been implemented on Linux patched with the Xenomai co-kernel, extended with a new hierarchical scheduling policy, named SCHED_DS, and integrating the RTNet stack. Experimental results are promising in terms of overhead and latency compared to other Linux-based solutions. More importantly, the isolation of containers is guaranteed even in presence of severe co-located disturbances, such as faulty tasks (elapsing more time than declared) or high CPU, network, or I/O stress on the same machine

A formal methodology to design and deploy dependable wireless sensor networks

Wireless Sensor Networks (WSNs) are being increasingly adopted in critical applications, where verifying the correct operation of sensor nodes is a major concern. Undesired events may undermine the mission of the WSNs. Hence their effects need to be properly assessed before deployment to obtain a good level of expected performance and during the operation in order to avoid dangerous unexpected results. In this paper we propose amethodology that aims at assessing and improving the dependability level of WSNs by means of an event-based formal verification technique. The methodology includes a process to guide designers towards the realization of dependable WSN and a tool ("ADVISES") to simplify its adoption. The tool is applicable to homogeneous WSNs with static routing topologies. It allows to generate automatically formal specifications used to check correctness properties and evaluate dependability metrics at design time and at runtime for WSNs where an acceptable percentage of faults can be defined. During the runtime we can check the behavior of the WSN accordingly to the results obtained at design time and we can detect sudden and unexpected failures, in order to trigger recovery procedures. The effectiveness of the methodology is shown in the context of two case studies, as proof-of-concept, aiming to illustrate how the tool is helpful to drive design choices and to check the correctness properties of the WSN at runtime. Although the method scales up to very large WSNs, the applicability of the methodology maybe compromised by the state space explosion of the reasoning model, which must be faced partitioning large topologies into sub-topologies

SECTOR: Secure Common Information Space for the Interoperability of First Responders

AbstractThe ever-growing human, economic and environmental losses due to natural and/or man-made disasters demand a systematic, holistic, inter-governmental and multi-disciplinary approach to the management of large-scale crisis. However, crisis management is usually coordinated by local authorities, supported by a variety of different national and international crisis management organizations, all acting relatively autonomously. Coordination actions usually adopt non-interoperable information management tools, due to the heterogeneity of the involved organizations, limiting or even hindering the coordination efforts. This paper introduces the efforts conducted in the context of the EU-funded project called SECTOR, which aims at establishing the foundations of future Collaborative Crisis Management (CCM) Information Spaces by expanding the European scientific knowledge base on (cross-border) multi-agency processes and their complications when setting-up and designing the enabling information systems

Technical Report: Anomaly Detection for a Critical Industrial System using Context, Logs and Metrics

Recent advances in contextual anomaly detection attempt to combine resource metrics and event logs to un- cover unexpected system behaviors and malfunctions at run- time. These techniques are highly relevant for critical software systems, where monitoring is often mandated by international standards and guidelines. In this technical report, we analyze the effectiveness of a metrics-logs contextual anomaly detection technique in a middleware for Air Traffic Control systems. Our study addresses the challenges of applying such techniques to a new case study with a dense volume of logs, and finer monitoring sampling rate. We propose an automated abstraction approach to infer system activities from dense logs and use regression analysis to infer the anomaly detector. We observed that the detection accuracy is impacted by abrupt changes in resource metrics or when anomalies are asymptomatic in both resource metrics and event logs. Guided by our experimental results, we propose and evaluate several actionable improvements, which include a change detection algorithm and the use of time windows on contextual anomaly detection. This technical report accompanies the paper “Contextual Anomaly Detection for a Critical Industrial System based on Logs and Metrics” [1] and provides further details on the analysis method, case study and experimental results