6.1.1 CertiCAN

• Name:
  Certifier of CAN bus analysis results
• Keywords:
  Certification, CAN bus, Real time, Static analysis
• Functional Description:
  CertiCAN is a tool, produced using the Coq proof assistant, allowing the formal certification of the correctness of CAN bus analysis results. Result certification is a process that is light-weight and flexible compared to tool certification, which makes it a practical choice for industrial purposes. The analysis underlying CertiCAN, which is based on a combined use of two well-known CAN analysis techniques, is computationally efficient. Experiments demonstrate that CertiCAN is able to certify the results of RTaW-Pegase, an industrial CAN analysis tool, even for large systems. Furthermore, CertiCAN can certify the results of any other RTA tool for the same analysis and system model (periodic tasks with offsets in transactions).
• URL:
  https://­team.­inria.­fr/­spades/­certican/
• Authors:
  Xiaojie Guo, Pascal Fradet, Sophie Quinton
• Contact:
  Xiaojie Guo

6.1.2 cloudnet

• Name:
  Cloudnet
• Keywords:
  Cloud configuration, Tosca, Docker Compose, Heat Orchestration Template, Alloy
• Scientific Description:

  The multiplication of models, languages, APIs and tools for cloud and network configuration management raises heterogeneity issues that can be tackled by introducing a reference model. A reference model provides a common basis for interpretation for various models and languages, and for bridging different APIs and tools. The Cloudnet Computational Model formally specifies, in the Alloy specification language, a reference model for cloud configuration management. The Cloudnet software formally interprets several configuration languages in it, including the TOSCA configuration language, the OpenStack Heat Orchestration Template and the Docker Compose configuration language.

  The use of the software shoes, for examples, how the Alloy formalization allowed us to discover several classes of errors in the OpenStack HOT specification.

• Functional Description:

  Application of the Cloudnet model developed by Inria to software network deployment and reconfiguration description languages.

  The Cloudnet model allows syntax and type checking for cloud configuration templates as well as their visualization (network diagram, UML deployment diagram). Three languages are addressed for the moment with the modules:

  * Cloudnet TOSCA toolbox for TOSCA inncluding NFV description * cloudnet-hot for HOT (Heat Orchestration Template) from OpenStack * cloudnet-compose for Docker Compose

  We can use directly the software from an Orange web portal: https://toscatoolbox.orange.com

• URL:
  https://­github.­com/­Orange-OpenSource/­Cloudnet-TOSCA-toolbox
• Publication:
  hal-02940938v1
• Contact:
  Philippe Merle
• Participants:
  Philippe Merle, Jean-Bernard Stefani, Roger Pissard-Gibollet, Souha Ben Rayana, Karine Guillouard, Meryem Ouzzif, Frédéric Klamm, Jean-Luc Coulin
• Partner:
  Orange Labs

6.1.3 WasmCert

• Name:
  WasmCert-Coq
• Keywords:
  WebAssembly, Coq, Formalisation
• Functional Description:
  WasmCert-Coq is a formalisation of WebAssembly (Wasm) in the Coq proof assistant. It precisely follows the standard Wasm 1.0, featuring a formalisation of the type system, the runtime semantics, the binary decoding, numeric operations, and the instantiation phase. It also features proof of soundness of the type system, as well as an executable interpreter proven correct with respect to the semantics.
• URL:
  https://­github.­com/­WasmCert/­WasmCert-Coq
• Contact:
  Martin Bodin
• Partners:
  University of Cambridge, Imperial College London

7.1.1 Hypercells

The Hypercell framework, presented in  51, allows the definition of different component models for dynamic software architectures featuring both sharing and encapsulation. Its behavioral theory is still in its initial stages but features the definition of a form of contextual bisimilarity. This year has seen the further development of the framework with the completion of Martin Vassor's PhD thesis 53, which reports on the formal characterization in the Hypercell framework of several encapsulation policies, and on a first implementation of the Hypercell framework in the Rust programming language.

7.1.2 Dynamicity in dataflow models

Recent dataflow programming environments support applications whose behavior is characterized by dynamic variations in resource requirements. The high expressive power of the underlying models (e.g., Kahn Process Networks or the CAL actor language) makes it challenging to ensure predictable behavior. In particular, checking liveness (i.e., no part of the system will deadlock) and boundedness (i.e., the system can be executed in finite memory) is known to be hard or even undecidable for such models. This situation is troublesome for the design of high-quality embedded systems. In the past few years, we have proposed several parametric dataflow models of computation (MoCs)  35, 26, we have written a survey providing a comprehensive description of the existing parametric dataflow MoCs  29, and we have studied symbolic analyses of dataflow graphs  30. More recently, we have proposed an original method to deal with lossy communication channels in dataflow graphs  33.

We are nowadays studying models allowing dynamic reconfigurations of the topology of the dataflow graphs. This is required by many modern streaming applications that have a strong need for reconfigurability, for instance to accommodate changes in the input data, the control objectives, or the environment.

We have proposed a new MoC called Reconfigurable Dataflow (RDF)  34. RDF extends SDF with transformation rules that specify how the topology and actors of the graph may be reconfigured. Starting from an initial RDF graph and a set of transformation rules, an arbitrary number of new RDF graphs can be generated at runtime. Transformations can be seen as graph rewriting rules that match some sub-part of the dataflow graph and replace it by another one. Transformations can be applied an arbitrary number of times during execution and therefore can produce an arbitrary number of new graphs. The major feature and advantage of RDF is that it can be statically analyzed to guarantee that all possible graphs generated at runtime will be connected, consistent, and live. To the best of our knowledge, RDF is the only dataflow MoC allowing an arbitrary number of topological reconfigurations while remaining statically analyzable. The RDF MoC has been implemented by Arash Shafiei within a software tool that allows the designer to write an initial RDF graph and its transformation rules. The static analyses for connectivity, consistency, and liveness have been implemented too. And a canny edge detector case study shows that dynamic reconfigurations to increase the parallelism level, when the incoming video stream becomes more computationally intensive, can be performed seamlessly. Finally, we have proposed in 2020 a new latency analysis for RDF that allows us to bound the latendy variation incurred by applying a given transformation rule whatever the RDF graph it is applied to.

This was the research topic of Arash Shafiei's PhD defended in Dec. 2021 17 in collaboration with Orange Labs. This work has been summarized in a long paper 19 submitted for publication to a journal.

7.2.1 A Markov Decision Process approach for energy minimization policies

In 2021, we have worked on a very general model of real-time systems, made of a single-core processor equipped with DVFS and an infinite sequence of preemptive real-time jobs. Each job $J_i$ is characterized by the triplet $({\tau }_i,w_i,d_i)$, where ${\tau }_i$ is the inter-arrival time between $J_i$ and $J_{i-1}$, $w_i$ is the Actual Execution Time (AET), upper-bounded by the WCET $W$, and $d_i$ is the relative deadline, upper-bounded by $\Delta$. The key point is that the system is non-clairvoyant, meaning that, at release time, $w_i$ is not known until the job $J_i$ actually terminates. What is available to the processor are the statistical information on the jobs' characteristics: release time, AET, and relative deadline. In this context, we have proposed a Markov Decision Process (MDP) solution to compute the optimal online speed policy guaranteeing that each job completes before its deadline and minimizing the energy consumption. To the best of our knowledge, our MDP solution is the first to be optimal. We have provided counter examples to prove that the two previous state of the art algorithms, namely OA  54 and PACE  45, are both sub-optimal.

Simulations show that our MDP solution outperforms the existing online solutions (OA and PACE), and can be very attractive in particular when the mean value of the execution time distribution is far from the WCET.

This was the topic of Stephan Plassart's PhD  4910, funded by the Caserm Persyval project, who defended his PhD in June 2020.

7.2.2 Formal proofs for schedulability analysis of real-time systems

We contribute to Prosa 22, a Coq library of reusable concepts and proofs for real-time systems analysis. A key scientific challenge is to achieve a modular structure of proofs, e.g., for response time analysis. Our goal is to use this library for:

1. the formal specification of real-time concepts
2. a better understanding of the role played by some assumptions in existing proofs;
3. a formal verification and comparison of different analysis techniques; and

4. the certification of (results of) existing analysis techniques or tools.

In the recent past, we have developed CertiCAN, a tool produced using the Coq proof assistant, allowing the formal certification of CAN bus analysis results. CertiCAN is able to certify the results of industrial CAN analysis tools, even for large systems. We have described this work in a long paper 20 submitted for publication to a journal.

Paolo Torrini has been pursuing his work on the development of certified schedulers in Coq 15.

Additional work (to be submitted for publication in 2022) has been done on the formal connection between Network Calculus and Response Time Analysis, as well as on the formalization in Prosa of Compositional Performance Analysis.

7.3.1 Causal Explanations for Embedded Systems

Model-Based Diagnosis of discrete event systems (DES) usually aims at detecting failures and isolating faulty event occurrences based on a behavioural model of the system and an observable execution log. The strength of a diagnostic process is to determine what happened that is consistent with the observations. In order to go a step further and explain why the observed outcome occurred, we borrow techniques from causal analysis. We are currently exploring techniques that are able to extract, from an execution trace, the causally relevant part for a property violation.

In particular, as part of the SEC project, we are investigating how such techniques can be extended to classes of hybrid systems. As a first result we have studied the problem of explaining faults in real-time systems 14. We have provided a formal definition of causal explanations on dense-time models, based on the well-studied formalisms of timed automata and zone-based abstractions. We have proposed a symbolic formalization to effectively construct such explanations, which we have implemented in a prototype tool.

7.3.2 Causal Explanations in Concurrent Programs

As part of the DCore project on causal debugging of concurrent programs, the goal of Aurélie Kong Win Chang's PhD thesis is to investigate the use of abstractions to construct causal explanations for Erlang programs. We are interested in developing abstractions that "compose well" with causal analyses, and understanding precisely how explanations found on the abstraction relate to explanations on the concrete system. It is worth noting that the presence of abstraction, which inherently comes with some induction and extrapolation processes, completely recasts the issue of reasoning about causality. Causal traces do no longer describe only potential scenarios in the concrete semantics, but also mix some approximation steps coming from the computation of the abstraction itself. Therefore, not all explanations are replayable counter-examples: they may contain some steps witnessing some lack of accuracy in the analysis. Vice versa, a research question to be addressed is how to define causal analyses that have a well understood behavior under abstraction.

7.3.3 Fault Management in Virtualized Networks

From a more applied point of view we have been investigating approaches for fault explanation and localization in virtualized networks. In essence, Network Function Virtualization (NFV), widely adopted by the industry and the standardization bodies, is about running network functions as software workloads on commodity hardware to optimize deployment costs and simplify the life-cycle management of network functions. However, it introduces new fault management challenges including dynamic topology and multi-tenant fault isolation.

In 9 we have proposed a self-modeling approach and an active diagnosis process for virtual networks that considers two types of knowledge to build the model: acquired knowledge and learned knowledge provided by fault injection to expand and validate the proposed model. Our experimental results from their application to a real-world virtual IP Multimedia Subsystem (vIMS) use case have shown their effectiveness in determining the root cause(s) of a failure and explaining fault propagation.

7.3.4 Reversibility for concurrent and distributed debugging

Concurrent and distributed debugging is a promising application of the notion of reversible computation 37. As part of the ANR DCore project, we have contributed to the theory behind, and the development of the CauDEr reversible debugger for the Erlang programming language. Among our contributions, we expect to tackle the shared memory features and the distributed features if the Erlang environment, including its crash and recovery failure model. Initial steps in this direction, which tackled distributed primitives in Erlang allowing Erlang processes to gather a view of their environment, are reported in the publication 13.

7.3.5 Automatic transformations for fault tolerant circuits

In the past years, we have proposed automatic transformations to ensure fault-tolerance properties in digital circuits. We considered program transformations for hardware description languages (HDL) to tolerate single-event transients (SET) and fault models of the form “at most 1 SEU or SET within n clock cycles”. This year, we have studied program transformations to tolerate single-event multiple transients (SEMT) a more general kind of fault where a particle strike may cause multiple transient glitches in adjacent wires, cells or gates. A generalization of triple modular redundancy (TMR) that tolerates SEMT has been proposed. This work was the topic of Vincent Bonczak's master project.

9.1.1 ANR

9.1.2 Institute of Technology (IRT)

10.1.1 Scientific events: selection

10.1.2 Journal

10.1.3 Invited talks

• Sophie Quinton gave invited talks on the environmental impact of ICT at ECRTS'21, CEA-LETI, the HiPEAC Autumn Computer Systems Week, and RDA VP18.
• Sophie Quinton gave a talk on the history of ECRTS industrial challenges at ECRTS'21.

10.1.4 Leadership within the scientific community

• Sophie Quinton is a member of the ECRTS Executive Committee.
• Sophie Quinton was a member of the ACM SIGBED Executive Committee and Associate Editor of the SIGBED Blog until June 2021.
• Sophie Quinton co-chairs a working group of the GDR CIS associated with the Center for Internet and Society focused on environmental issues.

10.1.5 Scientific expertise

• Sophie Quinton was interviewed by France Stratégie for their report on the Internet of Things.
• Sophie Quinton contributed to the upcoming "Guide de bonnes pratiques numérique responsable" by the DINUM (Direction interministérielle du numérique).

10.1.6 Research administration

• Pascal Fradet is head of the committee for doctoral studies (“Responsable du comité des études doctorales”) of the Inria Grenoble research center. He is the local correspondent for the young researchers Inria mission (“Mission jeunes chercheurs”) and the substitute of the director of the Inria Grenoble research center at the doctoral school council (MSTII).
• Alain Girault is Deputy Scientific Director for Inria, in charge of the domain “Algorithmics, Programming, Software and Architecture”.
• Sophie Quinton leads the SEnS-GRA group which hosts discussions and proposes actions regarding the environmental and societal impact of our research at Inria Grenoble Rhône-Alpes.
• Jean-Bernard Stefani has been the Délégué Scientifique of the INRIA Grenoble-Rhône-Alpes research center till June 2021.

10.2.1 Teaching

• Licence : Pascal Fradet, Théorie des Langages 1 & 2, 36 HeqTD, niveau L3, Grenoble INP (Ensimag), France
• Licence : Pascal Fradet, Modèles de Calcul : $\lambda$-calcul, 12 HeqTD, niveau L3, Univ. Grenoble Alpes, France
• Master : Xavier Nicollin, Analyse de Code pour la Sûreté et la Sécurité, 45 HeqTD, niveau M1, Grenoble INP (Ensimag), France
• Licence : Xavier Nicollin, Théorie des Langages 1, 48 HeqTD, niveau L3. Grenoble INP (Ensimag), France
• Licence : Xavier Nicollin, Théorie des Langages 2, 37,5 HeqTD, niveau L3, Grenoble INP (Ensimag), France
• Licence : Xavier Nicollin, Bases de la Programmation Impérative, 30 HeqTD, niveau L3, Grenoble INP (Ensimag), France
• Master: Jean-Bernard Stefani, Formal Aspects of Component Software, 9h, MOSIG, Univ. Grenoble Alpes, France.
• Master: Sophie Quinton gave a lecture (3h) on the environmental impact of ICT ("Les enjeux environnementaux du numérique") at Polytech Grenoble (niveau M2).
• Master: Sophie Quinton gave a guest lecture (2h) on "Formal Methods for Real-Time Systems" at TU Kaiserslautern (niveau M2).
• Formation continue: Sophie Quinton co-organized two work groups during the ANF (Action Nationale de Formation) organized by EcoInfo on the environmental impact of ICT.

10.2.2 Supervision

• Pascal Fradet, Alain Girault & Xavier Nicollin: PhD completed: Arash Shafiei, "RDF : A Reconfigurable Dataflow Model of Computation", Université Grenoble - Alpes, December 2021 17.
• Gregor Gössler: PhD in progress: Thomas Mari, “Construction of Safe Explainable Cyber-physical systems”; Grenoble INP; since October 2019; co-advised by Gregor Gössler and Thao Dang.
• Gregor Gössler: PhD in progress: Aurélie Kong Win Chang, "Abstractions for causal analysis and explanations in concurrent programs"; since January 2021; co-advised by Gregor Gössler and Jérôme Feret.
• Sophie Quinton and Alain Girault: PhD in progress: Aina Rasoldier, ICT in the Anthropocene: Technical and social challenges at the local scale.
• Jean-Bernard Stefani: PhD in progress: Giovanni Fabbretti, "Reversibility for distributed computations", since February 2021.
• Jean-Bernard Stefani: PhD in progress: Pietro Lami, "Reversibility and transactions", since October 2021.
• Jean-Bernard Stefani: PhD completed: Martin Vassor, "Graphes de localités : une approche formelle à l'encapsulation et implémentation", Université Grenoble-Alpes, May 2021 53

10.2.3 Juries

• Alain Girault was referee for the PhD thesis of Gautham Nayak Seetanadi (Lund University).
• Alain Girault was referee for the PhD thesis of Amna Gharbi (Telecom Paris Tech).
• Gregor Gössler was president of the PhD jury of Karim Assaad (Univ. Grenoble Alpes).
• Sophie Quinton was member of the PhD jury of Zakaria Ournani (University of Lille).
• Sophie Quinton was a member of the Master thesis committee of Bastien Béchadergue (EHESS).
• Sophie Quinton was member of a recruiting committee for a MCF position in Nantes.

10.3.1 Articles and contents

• Sophie Quinton wrote two articles ("fiches concepts") for the INRIA MOOC on the environmental impacts of ICT: one on the environmental footprint of a piece of personal equipment and the second on the main concepts behind the Life Cycle Analysis method.

10.3.2 Education

• Sophie Quinton was part of the scientific committee of the "COP2 étudiante".

10.3.3 Interventions

• Sophie Quinton gave a keynote on the environmental impact of ICT ("Numérique et environnement : Quels impacts ? Quels enjeux ?") at the MathC2+ event organized by Inria and at the Fête de la science.
• Sophie Quinton contributed to a workshop on the ethics of ICT at Sharin'Grenoble 2021.
• Sophie Quinton gave an interview on the environmental impact of ICT on AlligreFM and participated to a panel on digital sobriety ("Faut-il faire des usages un levier de la sobriété numérique ?") organized the FGI (Forum pour la Gouvernance d'Internet).
• Sophie Quinton contributed to a quiz on sustainable development for the DGD-I seminar.

International journals

• 9 articleS.Sihem Cherrared, S.Sofiane Imadali, E.Eric Fabre and G.Gregor Gössler. SFC Self-Modeling and Active Diagnosis.IEEE Transactions on Network and Service Management183September 2021, 2515-2530
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• 10 articleB.Bruno Gaujal, A.Alain Girault and S.Stéphan Plassart. A Pseudo-Linear Time Algorithm for the Optimal Discrete Speed Minimizing Energy Consumption.Discrete Event Dynamic Systems2021
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• 11 articleK.-B.Kai-Björn Gemlau, L.Leonie KÖHLER, R.Rolf Ernst and S.Sophie Quinton. System-level Logical Execution Time: Augmenting the Logical Execution Time Paradigm for Distributed Real-Time Automotive Software.ACM Transactions on Cyber-Physical Systems52January 2021, 1-27
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• 12 articleR.Ronan Le Guillou, M.Martin Schmoll, B.Benoît Sijobert, D.David Lobato Borges, E.Emerson Fachin-Martins, H.Henrique Resende, R.Roger Pissard-Gibollet, C.Charles Fattal and C.Christine Azevedo Coste. A Novel Framework for Quantifying Accuracy and Precision of Event Detection Algorithms in FES-Cycling.Sensors21132021, 1-13
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International peer-reviewed conferences

• 13 inproceedingsG.Giovanni Fabbretti, I.Ivan Lanese and J.-B.Jean-Bernard Stefani. Causal-Consistent Debugging of Distributed Erlang Programs.Reversible ComputationRC 2021 - 13th Conference on Reversible Computation12805Lecture Notes in Computer ScienceNagoya, JapanSpringerJune 2021, 79-95
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• 14 inproceedingsT.Thomas Mari, T.Thao Dang and G.Gregor Gössler. Explaining Safety Violations in Real-Time Systems.Proc. 19th FORMATS 2021, Paris, FranceFORMATS 2021 - Formal Modeling and Analysis of Timed SystemsParis, FranceAugust 2021, 100-116
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Conferences without proceedings

• 15 inproceedingsX.Xiaojie Guo, L.Lionel Rieg and P.Paolo Torrini. A generic approach for the certified schedulability analysis of software systems.Real-Time Computing Systems and ApplicationsHouston (online), United StatesAugust 2021
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• 16 inproceedingsC.Conrad Watt, X.Xiaojia Rao, J.Jean Pichon-Pharabod, M.Martin Bodin and P.Philippa Gardner. Two Mechanisations of WebAssembly 1.0.FM 2021 - Formal MethodsBeijing, ChinaNovember 2021, 1-19
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Doctoral dissertations and habilitation theses

• 17 thesisA.Arash Shafiei. RDF : A Reconfigurable Dataflow Model of Computation.Université Grenoble - AlpesDecember 2021
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Reports & preprints

• 18 reportG.Giovanni Fabbretti, I.Ivan Lanese and J.-B.Jean-Bernard Stefani. Causal-Consistent Debugging of Distributed Erlang Programs - Technical Report.Inria - Research Centre Grenoble – Rhône-AlpesJuly 2021
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• 19 reportP.Pascal Fradet, A.Alain Girault, R.Ruby Krishnaswamy, X.Xavier Nicollin and A.Arash Shafiei. RDF: A Reconfigurable Dataflow Model of Computation.RR-9439Inria Grenoble Rhône-Alpes, Université de GrenobleDecember 2021
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• 20 reportP.Pascal Fradet, X.Xiaojie Guo and S.Sophie Quinton. CertiCAN: Certifying CAN Analyses and Their Results.RR-9443Inria - Research Centre Grenoble – Rhône-AlpesDecember 2021, 1-32
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• 21 reportT.Thomas Mari, T.Thao Dang and G.Gregor Gössler. Explaining Safety Violations in Real-Time Systems.RR-9420INRIA; Verimag, Université Grenoble AlpesParis, FranceSeptember 2021
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