Christos Tsigkanos

Christos Tsigkanos

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Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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4 October 2019 in IEEE Transactions on Software Engineering
Verified
Journal Article
Open access
Claudio MenghiClaudio Menghi
Claudio Menghi
CTChristos Tsigkanos
Christos Tsigkanos
PPPatrizio Pelliccione
Patrizio Pelliccione
CGCarlo Ghezzi
Carlo Ghezzi
TBThorsten Berger
Thorsten Berger
Mobile and general-purpose robots increasingly support our everyday life, requiring dependable robotics control software. Creating such software mainly amounts to implementing their complex behaviors known as missions. Recognizing this need, a large number of domain-specific specification languages has been proposed. These, in addition to traditional logical languages, allow the use of formally specified missions for synthesis, verification, simulation or guiding implementation. For instance, the logical language LTL is commonly used by experts to specify missions as an input for planners, which synthesize the behavior a robot should have. Unfortunately, domain-specific languages are usually tied to specific robot models, while logical languages such as LTL are difficult to use by non-experts. We present a catalog of 22 mission specification patterns for mobile robots, together with tooling for instantiating, composing, and compiling the patterns to create mission specifications. The patterns provide solutions for recurrent specification problems, each of which detailing the usage intent, known uses, relationships to other patterns, and-most importantly-a template mission specification in temporal logic. Our tooling produces specifications expressed in the temporal logics LTL and CTL to be used by planners, simulators or model checkers. The patterns originate from 245 realistic textual mission requirements extracted from the robotics literature, and they are evaluated upon a total of 441 real-world mission requirements and 1251 mission specifications. Five of these reflect scenarios we defined with two well-known industrial partners developing human-size robots. We validated our patterns' correctness with simulators and two different types of real robots.

12 August 2016 in IEEE Transactions on Dependable and Secure Computing
Verified
Journal Article
Closed access
CTChristos Tsigkanos
Christos Tsigkanos
LPLiliana Pasquale
Liliana Pasquale
CGCarlo Ghezzi
Carlo Ghezzi
BNBashar Nuseibeh
Bashar Nuseibeh
Ubiquitous computing is resulting in a proliferation of cyber-physical systems that host or manage valuable physical and digital assets. These assets can be harmed by malicious agents through both cyber-enabled or physically-enabled attacks, particularly ones that exploit the often ignored interplay between the cyber and physical world. The explicit representation of spatial topology is key to supporting adaptive security policies. In this paper we explore the use of Bigraphical Reactive Systems to model the topology of cyber and physical spaces and their dynamics. We utilise such models to perform speculative threat analysis through model checking to reason about the consequences of the evolution of topological configurations on the satisfaction of security requirements. We further propose an automatic planning technique to identify an adaptation strategy enacting security policies at runtime to prevent, circumvent, or mitigate possible security requirements violations. We evaluate our approach using a case study concerned with countering insider threats in a building automation system.

20 April 2021 in IEEE Transactions on Services Computing
Verified
Journal Article
Closed access
CACosmin Avasalcai
Cosmin Avasalcai
CTChristos Tsigkanos
Christos Tsigkanos
Schahram DustdarSchahram Dustdar
Schahram Dustdar
Satisfying the software requirements of emerging service-based Internet of Things (IoT) applications has become challenging for cloud-centric architectures, as applications demand fast response times and availability of computational resources closer to end-users. Meeting application demands must occur at runtime, facing uncertainty and in a decentralized manner, something that must be reflected in system deployment. We propose a decentralized resource management technique and accompanying technical framework for the deployment of service-based IoT applications at the edge. Faithful to services engineering, applications we consider are composed of interdependent tasks, which in the IoT setting may be concretized as containerized microservices or serverless functions. A deployment for an arbitrary application is found at runtime through satisfiability; the mapping produced is compliant with tasks’ individual resource requirements and latency constraints by construction. Our approach ensures seamless deployment at runtime, assuming no design-time knowledge of device resources or the current network topology. We evaluate the applicability and realizability of our technique over single-board computers as edge devices, particularly in the absence of cloud resources.

1 May 2015
Verified
Conference Paper
Closed access
CTChristos Tsigkanos
Christos Tsigkanos
LPLiliana Pasquale
Liliana Pasquale
CGCarlo Ghezzi
Carlo Ghezzi
BNBashar Nuseibeh
Bashar Nuseibeh
This paper presents Ariadne, a tool for engineering topology aware adaptive security for cyber-physical systems. It allows security software engineers to model security requirements together with the topology of the operational environment. This model is then used at runtime to perform speculative threat analysis to reason about the consequences that topological changes arising from the movement of agents and assets can have on the satisfaction of security requirements. Our tool also identifies an adaptation strategy that applies security controls when necessary to prevent potential security requirements violations.

23 April 2021 in IEEE Transactions on Services Computing
Verified
Journal Article
Open access
CTChristos Tsigkanos
Christos Tsigkanos
MBMarcello M. Bersani
Marcello M. Bersani
PFPantelis Frangoudis
Pantelis Frangoudis
Schahram DustdarSchahram Dustdar
Schahram Dustdar
Complex distributed systems such as the ones induced by Internet of Things (IoT) deployments, are expected to operate in compliance to their requirements. This can be checked by inspecting events flowing throughout the system, typically originating from end-devices and reflecting arbitrary actions, changes in state or sensing. Such events typically reflect the behavior of the overall IoT system – they may indicate executions which satisfy or violate its requirements. This article presents a service-based software architecture and technical framework supporting runtime verification for widely deployed, volatile IoT systems. At the lowest level, systems we consider are comprised of resource-constrained devices connected over wide area networks generating events. In our approach, monitors are deployed on edge components, receiving events originating from end-devices or other edge nodes. Temporal logic properties expressing desired requirements are then evaluated on each edge monitor in a runtime fashion. The system exhibits decentralization since evaluation occurs locally on edge nodes, and verdicts possibly affecting satisfaction of properties on other edge nodes are propagated accordingly. This reduces dependence on cloud infrastructures for IoT data collection and centralized processing. We illustrate how specification and runtime verification can be achieved in practice on a characteristic case study of smart parking. Finally, we demonstrate the feasibility of our design over a testbed instantiation, whereupon we evaluate performance and capacity limits of different hardware classes under monitoring workloads of varying intensity using state-of-the-art LPWAN technology.